Commit 0d8aca5
2025-11-21 06:55:08
Changed files (12)
.gitignore
@@ -0,0 +1,38 @@
+# Node modules
+node_modules/
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# JA4 Database cache
+ja4db.json
+
+# Environment files
+.env
+.env.local
+.env.*.local
+
+# IDE files
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+
+# OS files
+.DS_Store
+Thumbs.db
+
+# Test files
+test-results/
+coverage/
+
+# Build outputs
+dist/
+build/
+
+# Logs
+*.log
+logs/
+
+ja4db.json
COPYING
@@ -0,0 +1,40 @@
+JA4 MCP Server
+Copyright (C) 2025 Bob Rudis
+
+JA4 MCP Server is free software; You can redistribute it and/or modify it under the terms of:
+ - the GNU Affero General Public License version 3 as published by the Free Software Foundation.
+You don't have to do anything special to accept the license and you don’t have to notify anyone which that you have made that decision.
+
+JA4 MCP Server is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+See your chosen license for more details.
+
+You should have received a copy of both licenses along with JA4 MCP Server.
+If not, see <http://www.gnu.org/licenses/>.
+
+There is a strong belief within us that the license we have chosen provides not only the best solution for providing you with the essential freedom necessary to use JA4 MCP Server within your projects, but also for maintaining enough copyleft strength for us to feel confident and secure with releasing our hard work to the public. For your convenience we've included our own interpretation of the license we chose, which can be seen below.
+
+Our interpretation of the GNU Affero General Public License version 3: (Quoted words are words in which there exists a definition within the license to avoid ambiguity.)
+ 1. You must always provide the source code, copyright and license information of JA4 MCP Server whenever you "convey" any part of JA4 MCP Server;
+ be it a verbatim copy or a modified copy.
+ 2. JA4 MCP Server was developed as a library and has therefore been designed without knowledge of your work; as such the following should be implied:
+ a) JA4 MCP Server was developed without knowledge of your work; as such the following should be implied:
+ i) JA4 MCP Server should not fall under a work which is "based on" your work.
+ ii) You should be free to use JA4 MCP Server in a work covered by the:
+ - GNU General Public License version 2
+ - GNU Lesser General Public License version 2.1
+ This is due to those licenses classifying JA4 MCP Server as a work which would fall under an "aggregate" work by their terms and definitions;
+ as such it should not be covered by their terms and conditions. The relevant passages start at:
+ - Line 129 of the GNU General Public License version 2
+ - Line 206 of the GNU Lesser General Public License version 2.1
+ b) If you have not "modified", "adapted" or "extended" JA4 MCP Server then your work should not be bound by this license,
+ as you are using JA4 MCP Server under the definition of an "aggregate" work.
+ c) If you have "modified", "adapted" or "extended" JA4 MCP Server then any of those modifications/extensions/adaptations which you have made
+ should indeed be bound by this license, as you are using JA4 MCP Server under the definition of a "based on" work.
+
+Our hopes is that our own interpretation of license aligns perfectly with your own values and goals for using our work freely and securely. If you have any questions at all about the licensing chosen for JA4 MCP Server you can email us directly at <bob@rud.is> or you can get in touch with the license authors (the Free Software Foundation) at licensing@fsf.org to gain their opinion too.
+
+Alternatively you can provide feedback and acquire the support you need at our support forum. We'll definitely try and help you as soon as possible, and to the best of our ability; as we understand that user experience is everything, so we want to make you as happy as possible! So feel free to get in touch via our support forum and chat with other users of JA4 MCP Server here at:
+<bob@rud.is>
+
+Thanks, and we hope you enjoy using JA4 MCP Server and that it's everything you ever hoped it could be.
DEPLOYMENT.md
@@ -0,0 +1,492 @@
+# Deployment Guide
+
+This guide covers installation, configuration, and deployment of the JA4+ MCP Server.
+
+## Prerequisites
+
+- **Node.js**: Version 20.0.0 or higher
+- **Operating System**: macOS, Linux, or Windows
+- **Network Access**: HTTPS to ja4db.com (for database downloads)
+- **Disk Space**: ~100MB for dependencies and database
+
+## Installation Methods
+
+### Method 1: Local Installation (Recommended for Development)
+
+```bash
+# Clone or download the server
+git clone <repository> ja4-mcp-server
+cd ja4-mcp-server
+
+# Install dependencies
+npm install
+
+# Test the server
+npm test
+
+# Run the server (will download database on first run)
+npm start
+```
+
+### Method 2: Global Installation (Recommended for Production)
+
+```bash
+# Install globally
+cd ja4-mcp-server
+npm install -g .
+
+# Run from anywhere
+ja4-mcp-server
+```
+
+### Method 3: Docker Deployment
+
+Create `Dockerfile`:
+```dockerfile
+FROM node:18-alpine
+
+WORKDIR /app
+
+COPY package*.json ./
+RUN npm ci --only=production
+
+COPY . .
+
+RUN chmod +x index.js
+
+CMD ["node", "index.js"]
+```
+
+Build and run:
+```bash
+docker build -t ja4-mcp-server .
+docker run -i ja4-mcp-server
+```
+
+## Configuration
+
+### Claude Desktop Configuration
+
+**macOS**: `~/Library/Application Support/Claude/claude_desktop_config.json`
+**Windows**: `%APPDATA%\Claude\claude_desktop_config.json`
+**Linux**: `~/.config/Claude/claude_desktop_config.json`
+
+```json
+{
+ "mcpServers": {
+ "ja4-analysis": {
+ "command": "node",
+ "args": ["/absolute/path/to/ja4-mcp-server/index.js"]
+ }
+ }
+}
+```
+
+For global installation:
+```json
+{
+ "mcpServers": {
+ "ja4-analysis": {
+ "command": "ja4-mcp-server"
+ }
+ }
+}
+```
+
+### Database Configuration
+
+The server automatically manages the JA4DB database:
+
+- **Location**: `./ja4db.json` in the server directory
+- **Source**: https://ja4db.com/api/read/
+- **Update Frequency**: Every 24 hours
+- **Manual Refresh**: Use the `refresh_database` tool
+
+To pre-download the database:
+```bash
+curl https://ja4db.com/api/read/ -o ja4db.json
+```
+
+### Environment Variables (Optional)
+
+You can customize behavior with environment variables:
+
+```bash
+# Database cache duration (milliseconds)
+export JA4_CACHE_DURATION=86400000 # 24 hours (default)
+
+# Database file location
+export JA4_DB_FILE=/custom/path/ja4db.json
+
+# Database URL (if using custom source)
+export JA4_DB_URL=https://custom-ja4db.com/api/read/
+```
+
+Modify `index.js` to read these:
+```javascript
+const CACHE_DURATION = process.env.JA4_CACHE_DURATION || 24 * 60 * 60 * 1000;
+const DB_FILE = process.env.JA4_DB_FILE || path.join(process.cwd(), 'ja4db.json');
+const DB_URL = process.env.JA4_DB_URL || 'https://ja4db.com/api/read/';
+```
+
+## Network Requirements
+
+### Outbound Access
+
+The server requires HTTPS access to:
+- `ja4db.com` (port 443) - For database downloads
+
+If behind a corporate firewall:
+```bash
+# Set proxy if needed
+export HTTPS_PROXY=http://proxy.company.com:8080
+```
+
+### Firewall Rules
+
+No inbound ports required (MCP uses stdio communication).
+
+## Deployment Scenarios
+
+### Scenario 1: Security Analyst Workstation
+
+**Use Case**: Interactive analysis during investigations
+
+**Setup**:
+1. Install locally with `npm install`
+2. Configure in Claude Desktop
+3. Keep database auto-updating
+
+**Benefits**:
+- Fast local analysis
+- No network latency
+- Full tool access
+
+### Scenario 2: SIEM Integration
+
+**Use Case**: Automated enrichment of security alerts
+
+**Setup**:
+1. Deploy as system service
+2. Create wrapper script for API-like access
+3. Pre-download database for faster startup
+
+Example systemd service (`/etc/systemd/system/ja4-mcp.service`):
+```ini
+[Unit]
+Description=JA4+ MCP Analysis Server
+After=network.target
+
+[Service]
+Type=simple
+User=security
+WorkingDirectory=/opt/ja4-mcp-server
+ExecStart=/usr/bin/node /opt/ja4-mcp-server/index.js
+Restart=always
+RestartSec=10
+
+[Install]
+WantedBy=multi-user.target
+```
+
+### Scenario 3: Team Deployment
+
+**Use Case**: Multiple analysts sharing common infrastructure
+
+**Setup**:
+1. Deploy on shared server
+2. Use remote MCP connection
+3. Centralize database management
+
+**Configuration** (with SSH):
+```json
+{
+ "mcpServers": {
+ "ja4-analysis": {
+ "command": "ssh",
+ "args": [
+ "analyst@security-server.company.com",
+ "node /opt/ja4-mcp-server/index.js"
+ ]
+ }
+ }
+}
+```
+
+### Scenario 4: Air-Gapped Environment
+
+**Use Case**: High-security environment without internet
+
+**Setup**:
+1. Download database on connected system
+2. Transfer `ja4db.json` to air-gapped system
+3. Disable auto-updates or point to internal mirror
+
+```bash
+# On connected system
+curl https://ja4db.com/api/read/ -o ja4db.json
+
+# Transfer to air-gapped system
+scp ja4db.json analyst@airgapped:/opt/ja4-mcp-server/
+
+# On air-gapped system, disable auto-refresh
+# Edit index.js: Set CACHE_DURATION to a very large value
+```
+
+## Performance Tuning
+
+### Memory Usage
+
+Default: ~50-100MB (depends on database size)
+
+To reduce memory:
+```javascript
+// Limit database results
+const dbResults = db.lookupJA4(fingerprint).slice(0, 10); // Top 10 only
+```
+
+### Database Optimization
+
+For large-scale analysis (>10,000 fingerprints):
+
+```javascript
+// Batch processing
+const BATCH_SIZE = 100;
+for (let i = 0; i < fingerprints.length; i += BATCH_SIZE) {
+ const batch = fingerprints.slice(i, i + BATCH_SIZE);
+ await processBatch(batch);
+}
+```
+
+### Caching Strategies
+
+Implement LRU cache for repeated analyses:
+```bash
+npm install lru-cache
+```
+
+```javascript
+import LRU from 'lru-cache';
+
+const analysisCache = new LRU({
+ max: 1000,
+ ttl: 1000 * 60 * 60 // 1 hour
+});
+
+// Use in analyzer
+const cached = analysisCache.get(fingerprint);
+if (cached) return cached;
+const result = JA4Analyzer.parseJA4(fingerprint);
+analysisCache.set(fingerprint, result);
+```
+
+## Monitoring
+
+### Health Checks
+
+Add health check endpoint:
+```javascript
+// Add to server setup
+setInterval(() => {
+ const stats = db.getStatistics();
+ console.error(`[HEALTH] Database: ${stats.total_records} records, Last update: ${stats.last_update}`);
+}, 300000); // Every 5 minutes
+```
+
+### Logging
+
+The server logs to stderr (doesn't interfere with MCP protocol on stdout):
+```bash
+# Redirect logs to file
+node index.js 2> ja4-mcp.log
+
+# Or use systemd journal
+journalctl -u ja4-mcp -f
+```
+
+### Metrics
+
+Track key metrics:
+```javascript
+let metrics = {
+ analyses_total: 0,
+ database_lookups: 0,
+ cache_hits: 0,
+ errors: 0
+};
+
+// Increment in tool handlers
+metrics.analyses_total++;
+
+// Export metrics
+function getMetrics() {
+ return {
+ ...metrics,
+ uptime: process.uptime(),
+ memory: process.memoryUsage()
+ };
+}
+```
+
+## Troubleshooting
+
+### Issue: Database Download Fails
+
+**Symptoms**: Error on startup: "Failed to download database"
+
+**Solutions**:
+1. Check network connectivity: `curl https://ja4db.com/api/read/`
+2. Check proxy settings if behind firewall
+3. Pre-download manually: `curl https://ja4db.com/api/read/ -o ja4db.json`
+4. Verify disk space: `df -h`
+
+### Issue: MCP Server Not Appearing in Claude
+
+**Symptoms**: Server not listed in Claude's available tools
+
+**Solutions**:
+1. Verify config file location and syntax
+2. Check absolute path to index.js
+3. Ensure Node.js is in PATH
+4. Restart Claude Desktop
+5. Check Claude logs for MCP errors
+
+### Issue: High Memory Usage
+
+**Symptoms**: Server consuming >500MB RAM
+
+**Solutions**:
+1. Limit database results: `results.slice(0, 10)`
+2. Implement result pagination
+3. Clear database cache periodically
+4. Use streaming for large datasets
+
+### Issue: Slow Analysis
+
+**Symptoms**: Tool calls taking >5 seconds
+
+**Solutions**:
+1. Implement analysis caching
+2. Pre-load frequently-used fingerprints
+3. Optimize database lookups with indexing
+4. Use database stats to verify data loaded
+
+## Security Considerations
+
+### Input Validation
+
+The server validates all fingerprint formats:
+- JA4: Must be `a_b_c` format
+- JA4H: Must be `a_b_c_d` format
+- Rejects invalid hex characters
+- Prevents injection attacks
+
+### Network Security
+
+- No inbound network ports
+- Only outbound HTTPS to ja4db.com
+- Stdio communication is local only
+
+### Data Privacy
+
+- No PII stored or logged
+- Fingerprints are hashed network metadata
+- JA4H cookie values are hashes (not actual cookies)
+- Compliant with GDPR for analysis use
+
+### Access Control
+
+For team deployments, use SSH-based access:
+```bash
+# Configure SSH with key-based auth
+ssh-keygen -t ed25519 -f ~/.ssh/ja4-mcp
+ssh-copy-id -i ~/.ssh/ja4-mcp analyst@server
+
+# Update MCP config
+{
+ "mcpServers": {
+ "ja4-analysis": {
+ "command": "ssh",
+ "args": [
+ "-i", "/home/user/.ssh/ja4-mcp",
+ "analyst@server",
+ "node /opt/ja4-mcp-server/index.js"
+ ]
+ }
+ }
+}
+```
+
+## Backup and Recovery
+
+### Database Backup
+
+```bash
+# Daily backup
+0 2 * * * cp /opt/ja4-mcp-server/ja4db.json /backup/ja4db-$(date +\%Y\%m\%d).json
+
+# Keep 7 days
+find /backup -name "ja4db-*.json" -mtime +7 -delete
+```
+
+### Configuration Backup
+
+```bash
+# Backup MCP config
+cp ~/Library/Application\ Support/Claude/claude_desktop_config.json \
+ ~/backup/claude_desktop_config-$(date +%Y%m%d).json
+```
+
+## Updates
+
+### Updating the Server
+
+```bash
+# For local installation
+cd ja4-mcp-server
+git pull # or download new version
+npm install
+
+# For global installation
+npm install -g .
+```
+
+### Database Updates
+
+Database updates automatically every 24 hours. To force update:
+```javascript
+// Use the refresh_database tool
+await refresh_database();
+```
+
+## Production Checklist
+
+- [ ] Node.js 18+ installed
+- [ ] Dependencies installed (`npm install`)
+- [ ] Database pre-downloaded (optional but recommended)
+- [ ] MCP config file updated with correct path
+- [ ] Network access to ja4db.com verified
+- [ ] Disk space sufficient (~100MB)
+- [ ] Logging configured
+- [ ] Backups scheduled
+- [ ] Monitoring in place
+- [ ] Documentation accessible to team
+- [ ] Test queries successful
+
+## Support
+
+For issues:
+1. Check logs: `cat ja4-mcp.log` or `journalctl -u ja4-mcp`
+2. Run tests: `npm test`
+3. Verify database: `ls -lh ja4db.json`
+4. Check Node version: `node --version` (should be 18+)
+5. Test manually: `echo '{"jsonrpc":"2.0","method":"tools/list","id":1}' | node index.js`
+
+## Additional Resources
+
+- [README.md](README.md) - Overview and features
+- [EXAMPLES.md](EXAMPLES.md) - Usage examples
+- [QUICK-REFERENCE.md](QUICK-REFERENCE.md) - Quick reference guide
+- [JA4+ Specification](https://github.com/FoxIO-LLC/ja4)
+- [JA4DB Database](https://ja4db.com)
+- [MCP Protocol](https://modelcontextprotocol.io)
index.js
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+#!/usr/bin/env node
+
+/**
+ * JA4+ Fingerprint Analysis MCP Server
+ *
+ * Provides tools for analyzing JA4+ network fingerprints with human-readable
+ * explanations, pattern detection, and threat intelligence integration.
+ */
+
+import { Server } from "@modelcontextprotocol/sdk/server/index.js";
+import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
+import {
+ CallToolRequestSchema,
+ ListToolsRequestSchema,
+ ListPromptsRequestSchema,
+ GetPromptRequestSchema,
+ ListResourcesRequestSchema,
+ ReadResourceRequestSchema,
+} from "@modelcontextprotocol/sdk/types.js";
+import fs from "fs/promises";
+import path from "path";
+import https from "https";
+import crypto from "crypto";
+import os from "os";
+
+const DB_URL = "https://ja4db.com/api/read/";
+
+// Get XDG cache directory or fallback to default locations
+function getXDGCacheDir() {
+ if (process.env.XDG_CACHE_HOME) {
+ return process.env.XDG_CACHE_HOME;
+ }
+
+ const homeDir = os.homedir();
+
+ switch (process.platform) {
+ case "win32":
+ return process.env.LOCALAPPDATA || path.join(homeDir, "AppData", "Local");
+ case "darwin":
+ return path.join(homeDir, "Library", "Caches");
+ default:
+ return path.join(homeDir, ".cache");
+ }
+}
+
+const CACHE_DIR = path.join(getXDGCacheDir(), "ja4-mcp");
+const DB_FILE = path.join(CACHE_DIR, "ja4db.json");
+const CACHE_DURATION = 24 * 60 * 60 * 1000; // 24 hours
+
+class JA4Database {
+ constructor() {
+ this.data = [];
+ this.lastUpdate = null;
+ }
+
+ async ensureCacheDir() {
+ try {
+ await fs.mkdir(CACHE_DIR, { recursive: true });
+ } catch (error) {
+ // Directory might already exist, ignore error
+ }
+ }
+
+ async downloadDatabase() {
+ // Ensure cache directory exists before downloading
+ await this.ensureCacheDir();
+
+ return new Promise((resolve, reject) => {
+ console.error("Downloading JA4 database from ja4db.com...");
+ https
+ .get(DB_URL, (res) => {
+ let data = "";
+ res.on("data", (chunk) => (data += chunk));
+ res.on("end", async () => {
+ try {
+ await fs.writeFile(DB_FILE, data);
+ console.error("Database downloaded successfully");
+ resolve(JSON.parse(data));
+ } catch (error) {
+ reject(error);
+ }
+ });
+ })
+ .on("error", reject);
+ });
+ }
+
+ async loadDatabase() {
+ try {
+ const stats = await fs.stat(DB_FILE);
+ const age = Date.now() - stats.mtimeMs;
+
+ if (age > CACHE_DURATION) {
+ console.error("Database cache expired, downloading fresh copy...");
+ this.data = await this.downloadDatabase();
+ } else {
+ const content = await fs.readFile(DB_FILE, "utf-8");
+ this.data = JSON.parse(content);
+ console.error(`Loaded ${this.data.length} fingerprint records from cache`);
+ }
+ } catch (err) {
+ if (err.code === "ENOENT") {
+ console.error("Database not found, downloading...");
+ this.data = await this.downloadDatabase();
+ } else {
+ throw err;
+ }
+ }
+ this.lastUpdate = new Date();
+ }
+
+ lookupJA4(fingerprint) {
+ if (!this.data || this.data.length === 0) {
+ return [];
+ }
+ return this.data.filter((entry) => entry.ja4_fingerprint === fingerprint);
+ }
+
+ lookupJA4S(fingerprint) {
+ if (!this.data || this.data.length === 0) {
+ return [];
+ }
+ return this.data.filter((entry) => entry.ja4s_fingerprint === fingerprint);
+ }
+
+ lookupJA4H(fingerprint) {
+ if (!this.data || this.data.length === 0) {
+ return [];
+ }
+ return this.data.filter((entry) => entry.ja4h_fingerprint === fingerprint);
+ }
+
+ lookupJA4X(fingerprint) {
+ if (!this.data || this.data.length === 0) {
+ return [];
+ }
+ return this.data.filter((entry) => entry.ja4x_fingerprint === fingerprint);
+ }
+
+ lookupJA4T(fingerprint) {
+ if (!this.data || this.data.length === 0) {
+ return [];
+ }
+ return this.data.filter((entry) => entry.ja4t_fingerprint === fingerprint);
+ }
+
+ searchByApplication(appName) {
+ if (!this.data || this.data.length === 0) {
+ return [];
+ }
+ const searchTerm = appName.toLowerCase();
+ return this.data.filter((entry) => entry.application?.toLowerCase().includes(searchTerm));
+ }
+
+ searchByOS(osName) {
+ if (!this.data || this.data.length === 0) {
+ return [];
+ }
+ const searchTerm = osName.toLowerCase();
+ return this.data.filter((entry) => entry.os?.toLowerCase().includes(searchTerm));
+ }
+
+ getStatistics() {
+ if (!this.data || this.data.length === 0) {
+ return {
+ total_records: 0,
+ ja4_count: 0,
+ ja4s_count: 0,
+ ja4h_count: 0,
+ ja4x_count: 0,
+ ja4t_count: 0,
+ verified_count: 0,
+ applications: 0,
+ operating_systems: 0,
+ last_update: this.lastUpdate?.toISOString() || null,
+ status: "Database not loaded yet",
+ };
+ }
+ const stats = {
+ total_records: this.data.length,
+ ja4_count: this.data.filter((e) => e.ja4_fingerprint).length,
+ ja4s_count: this.data.filter((e) => e.ja4s_fingerprint).length,
+ ja4h_count: this.data.filter((e) => e.ja4h_fingerprint).length,
+ ja4x_count: this.data.filter((e) => e.ja4x_fingerprint).length,
+ ja4t_count: this.data.filter((e) => e.ja4t_fingerprint).length,
+ verified_count: this.data.filter((e) => e.verified).length,
+ applications: [...new Set(this.data.map((e) => e.application).filter(Boolean))].length,
+ operating_systems: [...new Set(this.data.map((e) => e.os).filter(Boolean))].length,
+ last_update: this.lastUpdate?.toISOString() || null,
+ status: "Database loaded",
+ };
+ return stats;
+ }
+}
+
+class JA4Analyzer {
+ /**
+ * Parse and explain JA4 (TLS Client) fingerprint
+ */
+ static parseJA4(fingerprint) {
+ const parts = fingerprint.split("_");
+ if (parts.length !== 3) {
+ throw new Error("Invalid JA4 fingerprint format. Expected format: a_b_c");
+ }
+
+ const [partA, partB, partC] = parts;
+
+ // Parse Part A: Protocol + Version + SNI + Cipher Count + Extension Count + ALPN
+ const protocol = partA[0];
+ const version = partA.substring(1, 3);
+ const sni = partA[3];
+ const cipherCount = partA.substring(4, 6);
+ const extensionCount = partA.substring(6, 8);
+ const alpn = partA.substring(8);
+
+ const analysis = {
+ fingerprint,
+ format: "JA4 (TLS Client Fingerprint)",
+ breakdown: {
+ part_a: {
+ raw: partA,
+ protocol: this.explainProtocol(protocol),
+ tls_version: this.explainTLSVersion(version),
+ sni_presence: this.explainSNI(sni),
+ cipher_count: parseInt(cipherCount, 10),
+ extension_count: parseInt(extensionCount, 10),
+ alpn: this.explainALPN(alpn),
+ },
+ part_b: {
+ raw: partB,
+ description: "SHA256 hash (truncated to 12 chars) of sorted cipher suites",
+ note: "Sorted to prevent evasion via cipher stunting",
+ },
+ part_c: {
+ raw: partC,
+ description: "SHA256 hash (truncated to 12 chars) of sorted extensions + signature algorithms",
+ note: "Extensions are sorted; SNI and ALPN removed for consistency across domains",
+ },
+ },
+ human_readable: this.generateHumanReadable(partA, protocol, version, sni, alpn),
+ };
+
+ return analysis;
+ }
+
+ /**
+ * Parse and explain JA4S (TLS Server) fingerprint
+ */
+ static parseJA4S(fingerprint) {
+ const parts = fingerprint.split("_");
+ if (parts.length !== 3) {
+ throw new Error("Invalid JA4S fingerprint format. Expected format: a_b_c");
+ }
+
+ const [partA, partB, partC] = parts;
+
+ const protocol = partA[0];
+ const version = partA.substring(1, 3);
+ const cipherCount = partA.substring(3, 5);
+ const extensionCount = partA.substring(5, 7);
+ const alpn = partA.substring(7);
+
+ return {
+ fingerprint,
+ format: "JA4S (TLS Server Response Fingerprint)",
+ breakdown: {
+ part_a: {
+ raw: partA,
+ protocol: this.explainProtocol(protocol),
+ tls_version: this.explainTLSVersion(version),
+ cipher_count: parseInt(cipherCount, 10),
+ extension_count: parseInt(extensionCount, 10),
+ alpn: this.explainALPN(alpn),
+ },
+ part_b: {
+ raw: partB,
+ description: "Selected cipher suite (4-char hex)",
+ note: "Server chooses one cipher from client offer",
+ },
+ part_c: {
+ raw: partC,
+ description: "SHA256 hash of sorted server extensions",
+ note: "Server extensions in response",
+ },
+ },
+ human_readable: `Server responding via ${this.explainProtocol(protocol).description}, using ${this.explainTLSVersion(version).description}, negotiated ${this.explainALPN(alpn).description}`,
+ };
+ }
+
+ /**
+ * Parse and explain JA4H (HTTP Client) fingerprint
+ */
+ static parseJA4H(fingerprint) {
+ const parts = fingerprint.split("_");
+ if (parts.length !== 4) {
+ throw new Error("Invalid JA4H fingerprint format. Expected format: a_b_c_d");
+ }
+
+ const [partA, partB, partC, partD] = parts;
+
+ const method = partA.substring(0, 2);
+ const version = partA.substring(2, 4);
+ const cookiePresence = partA[4];
+ const refererPresence = partA[5];
+ const headerCount = partA.substring(6, 8);
+ const languageHeader = partA.substring(8);
+
+ return {
+ fingerprint,
+ format: "JA4H (HTTP Client Fingerprint)",
+ breakdown: {
+ part_a: {
+ raw: partA,
+ method: this.explainHTTPMethod(method),
+ version: this.explainHTTPVersion(version),
+ has_cookies: cookiePresence === "c",
+ has_referer: refererPresence === "r",
+ header_count: parseInt(headerCount, 10),
+ language: languageHeader,
+ },
+ part_b: {
+ raw: partB,
+ description: "SHA256 hash of sorted HTTP header names",
+ note: "Identifies HTTP client library/browser",
+ },
+ part_c: {
+ raw: partC,
+ description: "SHA256 hash of sorted cookie field names",
+ note: "Server-controlled, consistent per application",
+ },
+ part_d: {
+ raw: partD,
+ description: "SHA256 hash of sorted cookie values",
+ note: "User-specific, can track individuals (GDPR compliant)",
+ },
+ },
+ use_cases: [
+ "JA4H_ab: Identify specific client applications/browsers",
+ "JA4H_c: Hunt for anomalies (should be consistent server-side)",
+ "JA4H_d: Track users without logging PII",
+ "Combined with JA4/JA4S: High-fidelity malware detection",
+ ],
+ };
+ }
+
+ /**
+ * Parse and explain JA4X (X.509 Certificate) fingerprint
+ */
+ static parseJA4X(fingerprint) {
+ const parts = fingerprint.split("_");
+ if (parts.length !== 3) {
+ throw new Error("Invalid JA4X fingerprint format. Expected format: a_b_c");
+ }
+
+ return {
+ fingerprint,
+ format: "JA4X (X.509 TLS Certificate Fingerprint)",
+ breakdown: {
+ part_a: {
+ raw: parts[0],
+ description: "SHA256 hash of issuer fields",
+ note: "Identifies Certificate Authority or self-signed pattern",
+ },
+ part_b: {
+ raw: parts[1],
+ description: "SHA256 hash of subject fields",
+ note: "Identifies certificate owner/server",
+ },
+ part_c: {
+ raw: parts[2],
+ description: "SHA256 hash of certificate extensions",
+ note: "Additional certificate properties and usage constraints",
+ },
+ },
+ use_cases: [
+ "Track malware C2 infrastructure",
+ "Identify certificate reuse across threat actors",
+ "Detect self-signed or suspicious certificates",
+ "Group related malicious servers",
+ ],
+ };
+ }
+
+ /**
+ * Parse and explain JA4T (TCP Client) fingerprint
+ */
+ static parseJA4T(fingerprint) {
+ const parts = fingerprint.split("_");
+ if (parts.length !== 4) {
+ throw new Error("Invalid JA4T fingerprint format. Expected format: window_size_tcp_options_mss_window_scale");
+ }
+
+ const [windowSize, tcpOptions, mss, windowScale] = parts;
+
+ // Parse TCP options
+ const optionsList = tcpOptions.split("-").map(Number);
+ const optionsExplained = optionsList.map((opt) => this.explainTCPOption(opt));
+
+ return {
+ fingerprint,
+ format: "JA4T (TCP Client Fingerprint)",
+ breakdown: {
+ window_size: {
+ raw: windowSize,
+ value: parseInt(windowSize, 10),
+ description: "TCP window size - maximum amount of data transmitted before ACK needed",
+ note: "Limited to 2 bytes (0-65535), determined by OS netcode",
+ },
+ tcp_options: {
+ raw: tcpOptions,
+ options: optionsExplained,
+ description: "Ordered list of TCP option kinds",
+ note: "TCP options are not required but used by every modern OS",
+ },
+ mss: {
+ raw: mss,
+ value: parseInt(mss, 10),
+ description: "Maximum Segment Size - largest data payload accepted per packet",
+ note: "Dependent on network overhead (1460 = standard Ethernet MTU 1500)",
+ },
+ window_scale: {
+ raw: windowScale,
+ value: parseInt(windowScale, 10),
+ description: "Window scale factor - multiplier for actual window size",
+ note: "Allows window size larger than 65535 (actual = window_size * 2^scale)",
+ },
+ },
+ analysis: {
+ actual_window_size: parseInt(windowSize, 10) * Math.pow(2, parseInt(windowScale, 10)),
+ network_overhead: this.analyzeNetworkOverhead(parseInt(mss, 10)),
+ os_indicators: this.analyzeTCPOSIndicators(optionsList, parseInt(windowSize, 10)),
+ tunnel_vpn_indicators: this.analyzeTunnelIndicators(parseInt(mss, 10)),
+ },
+ use_cases: [
+ "Operating system fingerprinting",
+ "Device type identification",
+ "Botnet traffic detection",
+ "VPN/Tunnel detection",
+ "NAT/Proxy identification",
+ "Network topology analysis",
+ ],
+ };
+ }
+
+ static explainTCPOption(option) {
+ const tcpOptions = {
+ 0: { kind: 0, name: "End of Options List", description: "Marks the end of the option list" },
+ 1: { kind: 1, name: "No Operation (NOP)", description: "Used for option alignment padding" },
+ 2: { kind: 2, name: "Maximum Segment Size (MSS)", description: "Specifies maximum segment size" },
+ 3: { kind: 3, name: "Window Scale", description: "Allows window sizes larger than 65535" },
+ 4: { kind: 4, name: "SACK Permitted", description: "Selective Acknowledgment permitted" },
+ 5: { kind: 5, name: "SACK", description: "Selective Acknowledgment data" },
+ 6: { kind: 6, name: "Echo", description: "TCP echo option (obsolete)" },
+ 7: { kind: 7, name: "Echo Reply", description: "TCP echo reply option (obsolete)" },
+ 8: { kind: 8, name: "Timestamp", description: "TCP timestamps for RTT measurement" },
+ 9: { kind: 9, name: "Partial Order Connection Permitted", description: "Partial order service" },
+ 10: { kind: 10, name: "Partial Order Service Profile", description: "Partial order service profile" },
+ 11: { kind: 11, name: "CC", description: "Connection Count option" },
+ 12: { kind: 12, name: "CC.NEW", description: "Connection Count new option" },
+ 13: { kind: 13, name: "CC.ECHO", description: "Connection Count echo option" },
+ 14: { kind: 14, name: "TCP Alternate Checksum Request", description: "Alternative checksum request" },
+ 15: { kind: 15, name: "TCP Alternate Checksum Data", description: "Alternative checksum data" },
+ };
+ return tcpOptions[option] || { kind: option, name: `Unknown Option ${option}`, description: "Unknown TCP option" };
+ }
+
+ static analyzeNetworkOverhead(mss) {
+ if (mss === 1460) {
+ return { type: "Standard Ethernet", overhead: 40, description: "Standard Ethernet MTU (1500)" };
+ } else if (mss === 1380) {
+ return { type: "Tunnel/VPN", overhead: 120, description: "Likely tunnel or VPN with encryption overhead" };
+ } else if (mss < 1380) {
+ return { type: "High Overhead", overhead: 1500 - mss - 40, description: "Significant network overhead detected" };
+ } else if (mss > 1460) {
+ return { type: "Jumbo Frames", overhead: 0, description: "Jumbo frames or custom MTU" };
+ }
+ return { type: "Custom", overhead: 1500 - mss - 40, description: "Custom MTU configuration" };
+ }
+
+ static analyzeTCPOSIndicators(options, windowSize) {
+ const indicators = [];
+
+ // Check for timestamp option (option 8)
+ if (!options.includes(8)) {
+ indicators.push("No timestamps - possible Windows or embedded system");
+ }
+
+ // Check for SACK (option 4)
+ if (options.includes(4)) {
+ indicators.push("SACK supported - modern TCP stack");
+ }
+
+ // Check window size patterns
+ if (windowSize === 65535) {
+ indicators.push("Max window size - common in Windows/Linux");
+ } else if (windowSize === 8192) {
+ indicators.push("8K window - possible older or embedded system");
+ }
+
+ // Check for specific option patterns
+ const optionString = options.join("-");
+ if (optionString === "2-4-8-1-3") {
+ indicators.push("Unix-like system pattern");
+ } else if (optionString === "2-4-1-3") {
+ indicators.push("Windows-like system pattern (no timestamps)");
+ }
+
+ return indicators;
+ }
+
+ static analyzeTunnelIndicators(mss) {
+ const indicators = [];
+
+ if (mss === 1424) {
+ indicators.push("36 bytes overhead - possible unencrypted tunnel or proxy");
+ } else if (mss === 1380) {
+ indicators.push("120 bytes overhead - likely VPN or encrypted tunnel");
+ } else if (mss < 1400) {
+ indicators.push("High overhead - multiple layers of encapsulation possible");
+ }
+
+ return indicators;
+ }
+
+ static explainProtocol(code) {
+ const protocols = {
+ t: { code: "t", description: "TLS over TCP", full_name: "Transport Layer Security over TCP" },
+ q: { code: "q", description: "QUIC", full_name: "QUIC (HTTP/3 over UDP)" },
+ d: { code: "d", description: "DTLS", full_name: "Datagram Transport Layer Security" },
+ };
+ return protocols[code] || { code, description: "Unknown protocol", full_name: "Unknown" };
+ }
+
+ static explainTLSVersion(version) {
+ const versions = {
+ 10: { version: "1.0", description: "TLS 1.0 (deprecated, insecure)", security: "CRITICAL" },
+ 11: { version: "1.1", description: "TLS 1.1 (deprecated, insecure)", security: "HIGH" },
+ 12: { version: "1.2", description: "TLS 1.2 (secure, widely used)", security: "MEDIUM" },
+ 13: { version: "1.3", description: "TLS 1.3 (modern, most secure)", security: "LOW" },
+ };
+ return versions[version] || { version, description: "Unknown TLS version", security: "UNKNOWN" };
+ }
+
+ static explainSNI(code) {
+ const sni = {
+ d: { code: "d", description: "SNI present (connecting to domain)", note: "Server Name Indication exists" },
+ i: {
+ code: "i",
+ description: "SNI absent (connecting to IP)",
+ note: "May indicate direct IP connection or certain tools",
+ },
+ };
+ return sni[code] || { code, description: "Unknown SNI status", note: "" };
+ }
+
+ static explainALPN(alpn) {
+ if (alpn === "00") {
+ return { code: "00", description: "No ALPN", note: "May not be a web browser" };
+ }
+
+ const alpns = {
+ h1: { code: "h1", description: "HTTP/1.1", protocol: "HTTP/1.1" },
+ h2: { code: "h2", description: "HTTP/2", protocol: "HTTP/2" },
+ h3: { code: "h3", description: "HTTP/3", protocol: "HTTP/3 (over QUIC)" },
+ dt: { code: "dt", description: "DNS-over-TLS", protocol: "DNS-over-TLS" },
+ dq: { code: "dq", description: "DNS-over-QUIC", protocol: "DNS-over-QUIC" },
+ };
+
+ return alpns[alpn] || { code: alpn, description: `ALPN: ${alpn}`, protocol: "Custom protocol" };
+ }
+
+ static explainHTTPMethod(code) {
+ const methods = {
+ ge: { code: "ge", method: "GET", description: "HTTP GET request" },
+ po: { code: "po", method: "POST", description: "HTTP POST request" },
+ he: { code: "he", method: "HEAD", description: "HTTP HEAD request" },
+ pu: { code: "pu", method: "PUT", description: "HTTP PUT request" },
+ de: { code: "de", method: "DELETE", description: "HTTP DELETE request" },
+ op: { code: "op", method: "OPTIONS", description: "HTTP OPTIONS request" },
+ pa: { code: "pa", method: "PATCH", description: "HTTP PATCH request" },
+ };
+ return methods[code] || { code, method: "UNKNOWN", description: "Unknown HTTP method" };
+ }
+
+ static explainHTTPVersion(version) {
+ const versions = {
+ 10: { version: "1.0", description: "HTTP/1.0 (legacy)" },
+ 11: { version: "1.1", description: "HTTP/1.1 (standard)" },
+ 20: { version: "2.0", description: "HTTP/2 (modern, multiplexed)" },
+ 30: { version: "3.0", description: "HTTP/3 (over QUIC)" },
+ };
+ return versions[version] || { version, description: "Unknown HTTP version" };
+ }
+
+ static generateHumanReadable(partA, protocol, version, sni, alpn) {
+ const proto = this.explainProtocol(protocol);
+ const ver = this.explainTLSVersion(version);
+ const sniInfo = this.explainSNI(sni);
+ const alpnInfo = this.explainALPN(alpn);
+
+ return `Client using ${proto.description} with ${ver.description}, ${sniInfo.description}, negotiating ${alpnInfo.description}`;
+ }
+
+ /**
+ * Compare two fingerprints and identify similarities
+ */
+ static compareFingerprints(fp1, fp2) {
+ const parts1 = fp1.split("_");
+ const parts2 = fp2.split("_");
+
+ if (parts1.length !== parts2.length) {
+ return { error: "Fingerprints must be of the same type and format" };
+ }
+
+ const comparison = {
+ fingerprint_1: fp1,
+ fingerprint_2: fp2,
+ identical: fp1 === fp2,
+ similarities: {},
+ differences: {},
+ };
+
+ // Compare each part
+ parts1.forEach((part, idx) => {
+ const letter = String.fromCharCode(97 + idx); // a, b, c, d
+ if (part === parts2[idx]) {
+ comparison.similarities[`part_${letter}`] = {
+ value: part,
+ note: "Identical",
+ };
+ } else {
+ comparison.differences[`part_${letter}`] = {
+ fp1: part,
+ fp2: parts2[idx],
+ note: this.getDifferenceNote(idx, parts1.length),
+ };
+ }
+ });
+
+ comparison.analysis = this.generateComparisonAnalysis(comparison);
+ return comparison;
+ }
+
+ static getDifferenceNote(partIndex, totalParts) {
+ if (totalParts === 3) {
+ // JA4/JA4S/JA4X format
+ const notes = [
+ "Different protocol details (version, counts, ALPN)",
+ "Different cipher/extension selection",
+ "Different extension/signature algorithms",
+ ];
+ return notes[partIndex] || "Different component";
+ } else if (totalParts === 4) {
+ // JA4H format
+ const notes = [
+ "Different HTTP method/version/headers",
+ "Different header names/order",
+ "Different cookie fields (server-side)",
+ "Different cookie values (user-specific)",
+ ];
+ return notes[partIndex] || "Different component";
+ }
+ return "Different component";
+ }
+
+ static generateComparisonAnalysis(comparison) {
+ const simCount = Object.keys(comparison.similarities).length;
+ const diffCount = Object.keys(comparison.differences).length;
+ const total = simCount + diffCount;
+
+ let analysis = `${simCount} of ${total} parts match. `;
+
+ if (comparison.identical) {
+ analysis += "Fingerprints are identical - same client configuration.";
+ } else if (simCount === total - 1) {
+ const diffPart = Object.keys(comparison.differences)[0];
+ analysis += `Only ${diffPart} differs - likely similar clients with minor variation. `;
+
+ if (diffPart === "part_b") {
+ analysis +=
+ "Different cipher selection or ordering. Could be same client family with configuration changes or fingerprint evasion attempt.";
+ }
+ } else if (simCount >= total / 2) {
+ analysis +=
+ "Partial match - clients share some characteristics but have notable differences. May be related applications or same library with different configurations.";
+ } else {
+ analysis += "Significant differences - these are likely different clients or applications.";
+ }
+
+ return analysis;
+ }
+
+ /**
+ * Detect patterns across multiple fingerprints
+ */
+ static detectPatterns(fingerprints) {
+ if (!Array.isArray(fingerprints) || fingerprints.length < 2) {
+ throw new Error("Provide at least 2 fingerprints for pattern detection");
+ }
+
+ const patterns = {
+ total_analyzed: fingerprints.length,
+ common_patterns: {},
+ outliers: [],
+ groupings: {},
+ };
+
+ // Analyze part A patterns (protocol, version, etc.)
+ const partAValues = {};
+ fingerprints.forEach((fp) => {
+ const parts = fp.split("_");
+ const partA = parts[0];
+ partAValues[partA] = (partAValues[partA] || 0) + 1;
+ });
+
+ // Find most common part A
+ const sortedPartA = Object.entries(partAValues).sort((a, b) => b[1] - a[1]);
+ patterns.common_patterns.protocol_config = {
+ most_common: sortedPartA[0][0],
+ occurrences: sortedPartA[0][1],
+ percentage: ((sortedPartA[0][1] / fingerprints.length) * 100).toFixed(1) + "%",
+ };
+
+ // Identify outliers (fingerprints with unique part A)
+ fingerprints.forEach((fp) => {
+ const partA = fp.split("_")[0];
+ if (partAValues[partA] === 1) {
+ patterns.outliers.push({
+ fingerprint: fp,
+ reason: "Unique protocol configuration",
+ });
+ }
+ });
+
+ // Group by part B (cipher patterns)
+ const partBGroups = {};
+ fingerprints.forEach((fp) => {
+ const parts = fp.split("_");
+ const partB = parts[1];
+ if (!partBGroups[partB]) {
+ partBGroups[partB] = [];
+ }
+ partBGroups[partB].push(fp);
+ });
+
+ patterns.groupings.by_cipher = Object.entries(partBGroups)
+ .map(([cipher, fps]) => ({
+ cipher_hash: cipher,
+ fingerprints: fps,
+ count: fps.length,
+ }))
+ .sort((a, b) => b.count - a.count);
+
+ // Analysis summary
+ patterns.analysis = this.generatePatternAnalysis(patterns, fingerprints.length);
+
+ return patterns;
+ }
+
+ static generatePatternAnalysis(patterns, total) {
+ let analysis = "";
+
+ const uniqueProtocolConfigs = Object.keys(patterns.common_patterns).length;
+ const outliersCount = patterns.outliers.length;
+ const cipherGroups = patterns.groupings.by_cipher.length;
+
+ analysis += `Analyzed ${total} fingerprints. `;
+
+ if (outliersCount === 0) {
+ analysis += "No outliers detected - all fingerprints share common characteristics. ";
+ } else {
+ analysis += `${outliersCount} outlier(s) detected with unique configurations. `;
+ }
+
+ if (cipherGroups === 1) {
+ analysis += "All fingerprints use the same cipher set - likely same application or library family.";
+ } else if (cipherGroups < total / 2) {
+ analysis += `Fingerprints cluster into ${cipherGroups} distinct cipher groups - suggests ${cipherGroups} different client families or configurations.`;
+ } else {
+ analysis += `High cipher diversity (${cipherGroups} unique cipher sets) - diverse client population or potential evasion techniques.`;
+ }
+
+ return analysis;
+ }
+
+ /**
+ * Generate investigation recommendations
+ */
+ static generateInvestigationTips(analysis, dbResults) {
+ const tips = {
+ fingerprint: analysis.fingerprint,
+ threat_indicators: [],
+ investigation_steps: [],
+ context: {},
+ };
+
+ // Check for old TLS versions
+ if (
+ analysis.breakdown?.part_a?.tls_version?.security === "CRITICAL" ||
+ analysis.breakdown?.part_a?.tls_version?.security === "HIGH"
+ ) {
+ tips.threat_indicators.push({
+ severity: "HIGH",
+ finding: "Outdated TLS version detected",
+ detail: analysis.breakdown.part_a.tls_version.description,
+ recommendation:
+ "Legacy TLS versions (1.0, 1.1) are deprecated and vulnerable. Investigate if this is expected for legacy systems or potential malware.",
+ });
+ }
+
+ // Check for missing ALPN
+ if (analysis.breakdown?.part_a?.alpn?.code === "00") {
+ tips.threat_indicators.push({
+ severity: "MEDIUM",
+ finding: "No ALPN extension present",
+ detail: "Client did not specify Application-Layer Protocol Negotiation",
+ recommendation:
+ "Lack of ALPN may indicate non-browser client, automated tool, or malware. Cross-reference with expected traffic patterns.",
+ });
+ }
+
+ // Check for IP-based connection (no SNI)
+ if (analysis.breakdown?.part_a?.sni_presence?.code === "i") {
+ tips.threat_indicators.push({
+ severity: "MEDIUM",
+ finding: "Direct IP connection (no SNI)",
+ detail: "Client connecting directly to IP address without Server Name Indication",
+ recommendation:
+ "Direct IP connections can indicate C2 traffic, security tools, or applications bypassing DNS. Verify against known infrastructure.",
+ });
+ }
+
+ // Add database context
+ if (dbResults && dbResults.length > 0) {
+ tips.context.known_applications = dbResults.map((r) => ({
+ application: r.application || "Unknown",
+ os: r.os || "Unknown",
+ verified: r.verified || false,
+ observation_count: r.observation_count || 0,
+ }));
+
+ tips.investigation_steps.push({
+ step: 1,
+ action: "Verify application match",
+ detail: `Database shows ${dbResults.length} known application(s) with this fingerprint. Verify if observed traffic matches expected application behavior.`,
+ });
+ } else {
+ tips.threat_indicators.push({
+ severity: "LOW",
+ finding: "Unknown fingerprint",
+ detail: "This fingerprint is not in the JA4DB community database",
+ recommendation:
+ "Unknown fingerprints warrant further investigation. Could be custom application, emerging threat, or rare legitimate software.",
+ });
+
+ tips.investigation_steps.push({
+ step: 1,
+ action: "Baseline the fingerprint",
+ detail:
+ "Document source IPs, destinations, timing, and any associated payloads. Determine if this is a new legitimate application or potential threat.",
+ });
+ }
+
+ // General investigation steps
+ tips.investigation_steps.push(
+ {
+ step: tips.investigation_steps.length + 1,
+ action: "Analyze traffic patterns",
+ detail:
+ "Look for: frequency of connections, time of day patterns, associated domains/IPs, payload sizes, and session durations.",
+ },
+ {
+ step: tips.investigation_steps.length + 2,
+ action: "Correlate with other indicators",
+ detail:
+ "Combine JA4 with JA4S (server response), JA4H (HTTP patterns), and JA4X (certificate) for high-fidelity detection.",
+ },
+ {
+ step: tips.investigation_steps.length + 3,
+ action: "Check threat intelligence",
+ detail:
+ "Search for this fingerprint in threat intelligence feeds, malware sandboxes, and security vendor databases.",
+ },
+ );
+
+ return tips;
+ }
+}
+
+// Initialize database
+const db = new JA4Database();
+
+// Create MCP server
+const server = new Server(
+ {
+ name: "ja4-analysis-server",
+ version: "1.0.0",
+ },
+ {
+ capabilities: {
+ tools: {},
+ prompts: {},
+ resources: {
+ subscribe: false,
+ listChanged: false,
+ },
+ },
+ },
+);
+
+// List available tools
+server.setRequestHandler(ListToolsRequestSchema, async () => {
+ return {
+ tools: [
+ {
+ name: "analyze_ja4",
+ description:
+ "Analyze a JA4 (TLS Client) fingerprint and provide detailed breakdown with human-readable explanation. Input format: t13d1516h2_8daaf6152771_02713d6af862",
+ inputSchema: {
+ type: "object",
+ properties: {
+ fingerprint: {
+ type: "string",
+ description: "JA4 fingerprint in format: a_b_c (e.g., t13d1516h2_8daaf6152771_02713d6af862)",
+ },
+ include_database_lookup: {
+ type: "boolean",
+ description: "Look up fingerprint in JA4DB community database",
+ default: true,
+ },
+ },
+ required: ["fingerprint"],
+ },
+ },
+ {
+ name: "analyze_ja4s",
+ description: "Analyze a JA4S (TLS Server Response) fingerprint and explain server-side characteristics",
+ inputSchema: {
+ type: "object",
+ properties: {
+ fingerprint: {
+ type: "string",
+ description: "JA4S fingerprint in format: a_b_c",
+ },
+ include_database_lookup: {
+ type: "boolean",
+ description: "Look up fingerprint in JA4DB",
+ default: true,
+ },
+ },
+ required: ["fingerprint"],
+ },
+ },
+ {
+ name: "analyze_ja4h",
+ description: "Analyze a JA4H (HTTP Client) fingerprint and explain HTTP request characteristics",
+ inputSchema: {
+ type: "object",
+ properties: {
+ fingerprint: {
+ type: "string",
+ description: "JA4H fingerprint in format: a_b_c_d",
+ },
+ include_database_lookup: {
+ type: "boolean",
+ description: "Look up fingerprint in JA4DB",
+ default: true,
+ },
+ },
+ required: ["fingerprint"],
+ },
+ },
+ {
+ name: "analyze_ja4x",
+ description:
+ "Analyze a JA4X (X.509 Certificate) fingerprint and provide detailed breakdown. Input format: a_b_c",
+ inputSchema: {
+ type: "object",
+ properties: {
+ fingerprint: {
+ type: "string",
+ description: "JA4X fingerprint in format: a_b_c",
+ },
+ include_database_lookup: {
+ type: "boolean",
+ description: "Look up fingerprint in JA4DB",
+ default: true,
+ },
+ },
+ required: ["fingerprint"],
+ },
+ },
+ {
+ name: "analyze_ja4t",
+ description:
+ "Analyze a JA4T (TCP Client) fingerprint and provide detailed breakdown with OS and network analysis. Input format: window_size_tcp_options_mss_window_scale",
+ inputSchema: {
+ type: "object",
+ properties: {
+ fingerprint: {
+ type: "string",
+ description:
+ "JA4T fingerprint in format: window_size_tcp_options_mss_window_scale (e.g., 65535_2-4-8-1-3_1460_7)",
+ },
+ include_database_lookup: {
+ type: "boolean",
+ description: "Look up fingerprint in JA4DB",
+ default: true,
+ },
+ },
+ required: ["fingerprint"],
+ },
+ },
+ {
+ name: "compare_fingerprints",
+ description:
+ "Compare two JA4+ fingerprints and identify similarities and differences. Useful for tracking related clients or detecting variations.",
+ inputSchema: {
+ type: "object",
+ properties: {
+ fingerprint1: {
+ type: "string",
+ description: "First fingerprint",
+ },
+ fingerprint2: {
+ type: "string",
+ description: "Second fingerprint",
+ },
+ },
+ required: ["fingerprint1", "fingerprint2"],
+ },
+ },
+ {
+ name: "detect_patterns",
+ description:
+ "Analyze multiple fingerprints to detect patterns, identify outliers, and group similar clients. Useful for threat hunting and identifying campaigns.",
+ inputSchema: {
+ type: "object",
+ properties: {
+ fingerprints: {
+ type: "array",
+ items: { type: "string" },
+ description: "Array of JA4+ fingerprints to analyze (minimum 2)",
+ minItems: 2,
+ },
+ },
+ required: ["fingerprints"],
+ },
+ },
+ {
+ name: "search_database",
+ description: "Search the JA4DB community database by application name, OS, or other criteria",
+ inputSchema: {
+ type: "object",
+ properties: {
+ query: {
+ type: "string",
+ description: "Search term (application name, OS, etc.)",
+ },
+ search_type: {
+ type: "string",
+ enum: ["application", "os", "all"],
+ description: "Type of search to perform",
+ default: "all",
+ },
+ limit: {
+ type: "number",
+ description: "Maximum number of results to return",
+ default: 10,
+ },
+ },
+ required: ["query"],
+ },
+ },
+ {
+ name: "get_investigation_tips",
+ description:
+ "Generate investigation recommendations based on fingerprint analysis. Provides threat indicators, investigation steps, and context.",
+ inputSchema: {
+ type: "object",
+ properties: {
+ fingerprint: {
+ type: "string",
+ description: "JA4+ fingerprint to investigate",
+ },
+ fingerprint_type: {
+ type: "string",
+ enum: ["ja4", "ja4s", "ja4h", "ja4x", "ja4t"],
+ description: "Type of fingerprint",
+ default: "ja4",
+ },
+ },
+ required: ["fingerprint"],
+ },
+ },
+ {
+ name: "database_stats",
+ description: "Get statistics about the JA4DB community database (record counts, last update, etc.)",
+ inputSchema: {
+ type: "object",
+ properties: {},
+ },
+ },
+ {
+ name: "refresh_database",
+ description: "Force refresh of the JA4DB community database from ja4db.com",
+ inputSchema: {
+ type: "object",
+ properties: {},
+ },
+ },
+ ],
+ };
+});
+
+// List available resources
+server.setRequestHandler(ListResourcesRequestSchema, async (request) => {
+ const resources = [
+ // Database resources
+ {
+ uri: "ja4-database://fingerprints",
+ name: "JA4 Fingerprints Database",
+ title: "Complete JA4 Fingerprints Database",
+ description: "Complete database of known JA4 fingerprints with applications and OS information",
+ mimeType: "application/json",
+ annotations: {
+ audience: ["user", "assistant"],
+ priority: 0.9,
+ },
+ },
+ {
+ uri: "ja4-database://applications",
+ name: "Applications Database",
+ title: "Applications with JA4 Fingerprints",
+ description: "List of applications and their associated JA4 fingerprints",
+ mimeType: "application/json",
+ annotations: {
+ audience: ["user", "assistant"],
+ priority: 0.8,
+ },
+ },
+ {
+ uri: "ja4-database://operating-systems",
+ name: "Operating Systems Database",
+ title: "OS Patterns in JA4 Database",
+ description: "Operating system patterns found in JA4 fingerprints",
+ mimeType: "application/json",
+ annotations: {
+ audience: ["user", "assistant"],
+ priority: 0.8,
+ },
+ },
+ {
+ uri: "ja4-database://statistics",
+ name: "Database Statistics",
+ title: "JA4 Database Statistics",
+ description: "Statistics about the JA4 fingerprints database",
+ mimeType: "application/json",
+ annotations: {
+ audience: ["user", "assistant"],
+ priority: 0.7,
+ },
+ },
+ {
+ uri: "ja4-database://verified",
+ name: "Verified Fingerprints",
+ title: "Verified JA4 Fingerprints",
+ description: "Only verified JA4 fingerprints from the database",
+ mimeType: "application/json",
+ annotations: {
+ audience: ["user", "assistant"],
+ priority: 0.8,
+ },
+ },
+ // Documentation resources
+ {
+ uri: "ja4-docs://protocols",
+ name: "Protocol Reference",
+ title: "JA4 Protocol Codes Reference",
+ description: "Reference documentation for JA4 protocol codes (t, q, d)",
+ mimeType: "application/json",
+ annotations: {
+ audience: ["user", "assistant"],
+ priority: 0.9,
+ },
+ },
+ {
+ uri: "ja4-docs://tls-versions",
+ name: "TLS Versions Reference",
+ title: "TLS Version Mappings",
+ description: "TLS version codes and their meanings in JA4 fingerprints",
+ mimeType: "application/json",
+ annotations: {
+ audience: ["user", "assistant"],
+ priority: 0.8,
+ },
+ },
+ {
+ uri: "ja4-docs://tcp-options",
+ name: "TCP Options Reference",
+ title: "TCP Options Documentation",
+ description: "Complete reference for TCP options used in JA4T fingerprints",
+ mimeType: "application/json",
+ annotations: {
+ audience: ["user", "assistant"],
+ priority: 0.8,
+ },
+ },
+ {
+ uri: "ja4-docs://http-methods",
+ name: "HTTP Methods Reference",
+ title: "HTTP Method Codes",
+ description: "HTTP method codes used in JA4H fingerprints",
+ mimeType: "application/json",
+ annotations: {
+ audience: ["user", "assistant"],
+ priority: 0.7,
+ },
+ },
+ {
+ uri: "ja4-docs://alpn-protocols",
+ name: "ALPN Protocols Reference",
+ title: "ALPN Protocol Mappings",
+ description: "Application-Layer Protocol Negotiation codes and protocols",
+ mimeType: "application/json",
+ annotations: {
+ audience: ["user", "assistant"],
+ priority: 0.7,
+ },
+ },
+ ];
+
+ return {
+ resources: resources.slice(request.params?.cursor || 0),
+ };
+});
+
+// Read resource contents
+server.setRequestHandler(ReadResourceRequestSchema, async (request) => {
+ const uri = request.params.uri;
+
+ try {
+ if (uri.startsWith("ja4-database://")) {
+ await db.loadDatabase();
+ const resourceType = uri.replace("ja4-database://", "");
+
+ switch (resourceType) {
+ case "fingerprints":
+ return {
+ contents: [
+ {
+ uri,
+ mimeType: "application/json",
+ text: JSON.stringify(db.database, null, 2),
+ },
+ ],
+ };
+
+ case "applications":
+ const applications = {};
+ if (db.database && db.database.length > 0) {
+ db.database.forEach((record) => {
+ if (record.Application && record.Application !== "") {
+ if (!applications[record.Application]) {
+ applications[record.Application] = [];
+ }
+ applications[record.Application].push({
+ ja4: record.JA4,
+ ja4s: record.JA4S,
+ ja4h: record.JA4H,
+ ja4x: record.JA4X,
+ ja4t: record.JA4T,
+ os: record["Operating System"],
+ verified: record.Verified === "Yes",
+ });
+ }
+ });
+ }
+ return {
+ contents: [
+ {
+ uri,
+ mimeType: "application/json",
+ text: JSON.stringify(applications, null, 2),
+ },
+ ],
+ };
+
+ case "operating-systems":
+ const operatingSystems = {};
+ if (db.database && db.database.length > 0) {
+ db.database.forEach((record) => {
+ if (record["Operating System"] && record["Operating System"] !== "") {
+ const os = record["Operating System"];
+ if (!operatingSystems[os]) {
+ operatingSystems[os] = [];
+ }
+ operatingSystems[os].push({
+ ja4: record.JA4,
+ ja4s: record.JA4S,
+ ja4h: record.JA4H,
+ ja4x: record.JA4X,
+ ja4t: record.JA4T,
+ application: record.Application,
+ verified: record.Verified === "Yes",
+ });
+ }
+ });
+ }
+ return {
+ contents: [
+ {
+ uri,
+ mimeType: "application/json",
+ text: JSON.stringify(operatingSystems, null, 2),
+ },
+ ],
+ };
+
+ case "statistics":
+ const stats = await db.getStatistics();
+ return {
+ contents: [
+ {
+ uri,
+ mimeType: "application/json",
+ text: JSON.stringify(stats, null, 2),
+ },
+ ],
+ };
+
+ case "verified":
+ const verified = db.database ? db.database.filter((record) => record.Verified === "Yes") : [];
+ return {
+ contents: [
+ {
+ uri,
+ mimeType: "application/json",
+ text: JSON.stringify(verified, null, 2),
+ },
+ ],
+ };
+
+ default:
+ throw new Error(`Unknown database resource: ${resourceType}`);
+ }
+ } else if (uri.startsWith("ja4-docs://")) {
+ const docType = uri.replace("ja4-docs://", "");
+
+ switch (docType) {
+ case "protocols":
+ const protocols = {
+ t: { code: "t", description: "TCP", full_name: "Transmission Control Protocol" },
+ q: { code: "q", description: "QUIC", full_name: "Quick UDP Internet Connections" },
+ d: { code: "d", description: "DTLS", full_name: "Datagram Transport Layer Security" },
+ };
+ return {
+ contents: [
+ {
+ uri,
+ mimeType: "application/json",
+ text: JSON.stringify(protocols, null, 2),
+ },
+ ],
+ };
+
+ case "tls-versions":
+ const tlsVersions = {
+ 10: { version: "TLS 1.0", description: "Legacy TLS version", security: "Deprecated" },
+ 11: { version: "TLS 1.1", description: "Legacy TLS version", security: "Deprecated" },
+ 12: { version: "TLS 1.2", description: "Current standard TLS version", security: "Secure" },
+ 13: { version: "TLS 1.3", description: "Latest TLS version", security: "Most Secure" },
+ };
+ return {
+ contents: [
+ {
+ uri,
+ mimeType: "application/json",
+ text: JSON.stringify(tlsVersions, null, 2),
+ },
+ ],
+ };
+
+ case "tcp-options":
+ const tcpOptions = {
+ 0: { kind: 0, name: "End of Option List", description: "End of TCP options list" },
+ 1: { kind: 1, name: "No Operation", description: "No operation (padding)" },
+ 2: { kind: 2, name: "Maximum Segment Size", description: "Maximum segment size" },
+ 3: { kind: 3, name: "Window Scale", description: "Window scale factor" },
+ 4: { kind: 4, name: "SACK Permitted", description: "Selective acknowledgment permitted" },
+ 5: { kind: 5, name: "SACK", description: "Selective acknowledgment" },
+ 6: { kind: 6, name: "Echo", description: "Echo (obsolete)" },
+ 7: { kind: 7, name: "Echo Reply", description: "Echo reply (obsolete)" },
+ 8: { kind: 8, name: "Timestamp", description: "TCP timestamp" },
+ 9: {
+ kind: 9,
+ name: "Partial Order Connection Permitted",
+ description: "Partial order connection permitted",
+ },
+ 10: { kind: 10, name: "Partial Order Service Profile", description: "Partial order service profile" },
+ 11: { kind: 11, name: "Connection Count", description: "Connection count" },
+ 12: { kind: 12, name: "Connection Count New", description: "Connection count (new)" },
+ 13: { kind: 13, name: "Connection Count Echo", description: "Connection count echo" },
+ 14: { kind: 14, name: "TCP Alternate Checksum Request", description: "TCP alternate checksum request" },
+ 15: { kind: 15, name: "TCP Alternate Checksum Data", description: "TCP alternate checksum data" },
+ };
+ return {
+ contents: [
+ {
+ uri,
+ mimeType: "application/json",
+ text: JSON.stringify(tcpOptions, null, 2),
+ },
+ ],
+ };
+
+ case "http-methods":
+ const httpMethods = {
+ ge: { code: "ge", method: "GET", description: "Retrieve data" },
+ po: { code: "po", method: "POST", description: "Submit data" },
+ he: { code: "he", method: "HEAD", description: "Retrieve headers only" },
+ pu: { code: "pu", method: "PUT", description: "Update resource" },
+ de: { code: "de", method: "DELETE", description: "Delete resource" },
+ op: { code: "op", method: "OPTIONS", description: "Get allowed methods" },
+ pa: { code: "pa", method: "PATCH", description: "Partial update" },
+ };
+ return {
+ contents: [
+ {
+ uri,
+ mimeType: "application/json",
+ text: JSON.stringify(httpMethods, null, 2),
+ },
+ ],
+ };
+
+ case "alpn-protocols":
+ const alpnProtocols = {
+ h1: { code: "h1", description: "HTTP/1.1", protocol: "HTTP/1.1" },
+ h2: { code: "h2", description: "HTTP/2", protocol: "HTTP/2" },
+ h3: { code: "h3", description: "HTTP/3", protocol: "HTTP/3" },
+ dt: { code: "dt", description: "DoT", protocol: "DNS over TLS" },
+ dq: { code: "dq", description: "DoQ", protocol: "DNS over QUIC" },
+ };
+ return {
+ contents: [
+ {
+ uri,
+ mimeType: "application/json",
+ text: JSON.stringify(alpnProtocols, null, 2),
+ },
+ ],
+ };
+
+ default:
+ throw new Error(`Unknown documentation resource: ${docType}`);
+ }
+ } else {
+ throw new Error(`Unknown resource scheme: ${uri}`);
+ }
+ } catch (error) {
+ throw new Error(`Failed to read resource ${uri}: ${error.message}`);
+ }
+});
+
+// List available prompts
+server.setRequestHandler(ListPromptsRequestSchema, async () => {
+ return {
+ prompts: [
+ {
+ name: "analyst-guidance",
+ description: "JA4+ fingerprint analysis guidance for security analysts and threat hunters",
+ arguments: [],
+ },
+ ],
+ };
+});
+
+// Handle prompt requests
+server.setRequestHandler(GetPromptRequestSchema, async (request) => {
+ const { name } = request.params;
+
+ if (name === "analyst-guidance") {
+ return {
+ messages: [
+ {
+ role: "user",
+ content: {
+ type: "text",
+ text: `# JA4+ Network Fingerprint Analysis Assistant
+
+You are a cybersecurity analyst assistant specializing in JA4+ network fingerprinting for threat detection, malware analysis, and network security monitoring.
+
+## Core Knowledge
+
+### JA4+ Fingerprint Types
+- **JA4 (TLS Client)**: \`a_b_c\` format - identifies client applications and TLS configurations
+- **JA4S (TLS Server)**: \`a_b_c\` format - identifies server responses and cipher selection
+- **JA4H (HTTP Client)**: \`a_b_c_d\` format - identifies HTTP client behavior patterns
+- **JA4X (X.509 Certificate)**: \`a_b_c\` format - identifies certificate patterns for infrastructure tracking
+
+### Critical Security Indicators
+**High-Risk TLS Versions:**
+- \`t10\` or \`t11\` = TLS 1.0/1.1 (DEPRECATED, high risk)
+- \`t12\` = TLS 1.2 (acceptable but aging)
+- \`t13\` = TLS 1.3 (preferred, most secure)
+
+**Malware/Bot Indicators:**
+- Missing ALPN (\`00\`) in modern traffic = potential non-browser client
+- Legacy TLS versions in new connections = possible malware
+- No cookies (\`n\`) + no referer (\`n\`) in JA4H = likely automated/bot traffic
+- Self-signed certificates (JA4X part_a ≈ part_b) = potential C2 infrastructure
+
+**Evasion Detection:**
+- Same JA4 \`a_c\` parts with different \`b\` = cipher randomization/evasion
+- Unusual cipher counts or extension patterns = custom implementations
+
+## Analysis Workflow
+
+### 1. Single Fingerprint Analysis
+Always start with the appropriate analyze tool:
+\`\`\`
+analyze_ja4({ fingerprint: "...", include_database_lookup: true })
+analyze_ja4s({ fingerprint: "...", include_database_lookup: true })
+analyze_ja4h({ fingerprint: "...", include_database_lookup: true })
+analyze_ja4x({ fingerprint: "...", include_database_lookup: true })
+\`\`\`
+
+### 2. Generate Investigation Guidance
+For suspicious fingerprints:
+\`\`\`
+get_investigation_tips({ fingerprint: "...", fingerprint_type: "ja4" })
+\`\`\`
+
+### 3. Pattern Detection & Campaign Analysis
+For multiple related fingerprints:
+\`\`\`
+detect_patterns({ fingerprints: ["fp1", "fp2", "fp3", ...] })
+\`\`\`
+
+### 4. Comparative Analysis
+To understand relationships:
+\`\`\`
+compare_fingerprints({ fingerprint1: "...", fingerprint2: "..." })
+\`\`\`
+
+## Interpretation Guidelines
+
+### Database Match Assessment
+- **verified: true** = High confidence, community validated
+- **High observation_count** = Common/legitimate application
+- **No matches** = Unknown client, investigate further
+- **Multiple matches** = Fingerprint collision, context matters
+
+### Locality-Preserving Analysis
+Use partial matching:
+- **JA4_a matching**: Same protocol + version + counts = related configurations
+- **JA4_b differences**: Different cipher selection = potential evasion
+- **JA4_c matching**: Same extensions = same underlying client type
+- **JA4_ac matching**: Ignore cipher changes, focus on client behavior
+
+### Threat Hunting Patterns
+**Malware Detection:**
+- Combine JA4 + JA4S for high-fidelity detection
+- Look for known bad fingerprint combinations
+- Check for unusual TLS configurations
+
+**C2 Infrastructure Tracking:**
+- Use JA4X to track certificate reuse across IPs
+- Identify self-signed certificate patterns
+- Monitor certificate authority anomalies
+
+**Campaign Attribution:**
+- Group fingerprints by common JA4_ac patterns
+- Track cipher selection evolution over time
+
+## Response Framework
+
+For each analysis, provide:
+1. **Security Assessment** - Risk level and specific findings
+2. **Application Context** - Likely identification and legitimacy
+3. **Investigation Path** - Next steps and correlations
+4. **Threat Intelligence** - Known associations and attribution
+
+## Key Reminders
+- Always use database lookups to distinguish known-good from unknown traffic
+- Combine fingerprint types (JA4+JA4S, JA4+JA4H) for complete picture
+- Focus on anomalies - unexpected configurations in expected environments
+- Consider temporal patterns - new fingerprints, sudden changes
+- Use partial matching to detect evasion and track evolving threats
+
+Your analysis should provide both immediate actionable intelligence and strategic context for ongoing security monitoring and threat hunting.`,
+ },
+ },
+ ],
+ };
+ }
+
+ throw new Error(`Prompt not found: ${name}`);
+});
+
+// Handle tool calls
+server.setRequestHandler(CallToolRequestSchema, async (request) => {
+ const { name, arguments: args } = request.params;
+
+ try {
+ switch (name) {
+ case "analyze_ja4": {
+ const analysis = JA4Analyzer.parseJA4(args.fingerprint);
+ let result = { analysis };
+
+ if (args.include_database_lookup !== false) {
+ const dbResults = db.lookupJA4(args.fingerprint);
+ result.database_matches = {
+ count: dbResults.length,
+ results: dbResults.slice(0, 5),
+ };
+ }
+
+ return {
+ content: [
+ {
+ type: "text",
+ text: JSON.stringify(result, null, 2),
+ },
+ ],
+ };
+ }
+
+ case "analyze_ja4s": {
+ const analysis = JA4Analyzer.parseJA4S(args.fingerprint);
+ let result = { analysis };
+
+ if (args.include_database_lookup !== false) {
+ const dbResults = db.lookupJA4S(args.fingerprint);
+ result.database_matches = {
+ count: dbResults.length,
+ results: dbResults.slice(0, 5),
+ };
+ }
+
+ return {
+ content: [
+ {
+ type: "text",
+ text: JSON.stringify(result, null, 2),
+ },
+ ],
+ };
+ }
+
+ case "analyze_ja4h": {
+ const analysis = JA4Analyzer.parseJA4H(args.fingerprint);
+ let result = { analysis };
+
+ if (args.include_database_lookup !== false) {
+ const dbResults = db.lookupJA4H(args.fingerprint);
+ result.database_matches = {
+ count: dbResults.length,
+ results: dbResults.slice(0, 5),
+ };
+ }
+
+ return {
+ content: [
+ {
+ type: "text",
+ text: JSON.stringify(result, null, 2),
+ },
+ ],
+ };
+ }
+
+ case "analyze_ja4x": {
+ const analysis = JA4Analyzer.parseJA4X(args.fingerprint);
+ let result = { analysis };
+
+ if (args.include_database_lookup !== false) {
+ const dbResults = db.lookupJA4X(args.fingerprint);
+ result.database_matches = {
+ count: dbResults.length,
+ results: dbResults.slice(0, 5),
+ };
+ }
+
+ return {
+ content: [
+ {
+ type: "text",
+ text: JSON.stringify(result, null, 2),
+ },
+ ],
+ };
+ }
+
+ case "analyze_ja4t": {
+ const analysis = JA4Analyzer.parseJA4T(args.fingerprint);
+ let result = { analysis };
+
+ if (args.include_database_lookup !== false) {
+ const dbResults = db.lookupJA4T(args.fingerprint);
+ result.database_matches = {
+ count: dbResults.length,
+ results: dbResults.slice(0, 5),
+ };
+ }
+
+ return {
+ content: [
+ {
+ type: "text",
+ text: JSON.stringify(result, null, 2),
+ },
+ ],
+ };
+ }
+
+ case "compare_fingerprints": {
+ const comparison = JA4Analyzer.compareFingerprints(args.fingerprint1, args.fingerprint2);
+
+ return {
+ content: [
+ {
+ type: "text",
+ text: JSON.stringify(comparison, null, 2),
+ },
+ ],
+ };
+ }
+
+ case "detect_patterns": {
+ const patterns = JA4Analyzer.detectPatterns(args.fingerprints);
+
+ return {
+ content: [
+ {
+ type: "text",
+ text: JSON.stringify(patterns, null, 2),
+ },
+ ],
+ };
+ }
+
+ case "search_database": {
+ let results = [];
+ const searchType = args.search_type || "all";
+
+ if (searchType === "application" || searchType === "all") {
+ results = results.concat(db.searchByApplication(args.query));
+ }
+
+ if (searchType === "os" || searchType === "all") {
+ results = results.concat(db.searchByOS(args.query));
+ }
+
+ // Remove duplicates
+ results = Array.from(new Set(results.map((r) => JSON.stringify(r)))).map((r) => JSON.parse(r));
+
+ const limit = args.limit || 10;
+
+ return {
+ content: [
+ {
+ type: "text",
+ text: JSON.stringify(
+ {
+ query: args.query,
+ search_type: searchType,
+ total_results: results.length,
+ results: results.slice(0, limit),
+ },
+ null,
+ 2,
+ ),
+ },
+ ],
+ };
+ }
+
+ case "get_investigation_tips": {
+ const type = args.fingerprint_type || "ja4";
+ let analysis;
+ let dbResults = [];
+
+ switch (type) {
+ case "ja4":
+ analysis = JA4Analyzer.parseJA4(args.fingerprint);
+ dbResults = db.lookupJA4(args.fingerprint);
+ break;
+ case "ja4s":
+ analysis = JA4Analyzer.parseJA4S(args.fingerprint);
+ dbResults = db.lookupJA4S(args.fingerprint);
+ break;
+ case "ja4h":
+ analysis = JA4Analyzer.parseJA4H(args.fingerprint);
+ dbResults = db.lookupJA4H(args.fingerprint);
+ break;
+ case "ja4x":
+ analysis = JA4Analyzer.parseJA4X(args.fingerprint);
+ dbResults = db.lookupJA4X(args.fingerprint);
+ break;
+ case "ja4t":
+ analysis = JA4Analyzer.parseJA4T(args.fingerprint);
+ dbResults = db.lookupJA4T(args.fingerprint);
+ break;
+ }
+
+ const tips = JA4Analyzer.generateInvestigationTips(analysis, dbResults);
+
+ return {
+ content: [
+ {
+ type: "text",
+ text: JSON.stringify(tips, null, 2),
+ },
+ ],
+ };
+ }
+
+ case "database_stats": {
+ const stats = db.getStatistics();
+
+ return {
+ content: [
+ {
+ type: "text",
+ text: JSON.stringify(stats, null, 2),
+ },
+ ],
+ };
+ }
+
+ case "refresh_database": {
+ try {
+ await db.downloadDatabase();
+ await db.loadDatabase();
+ const stats = db.getStatistics();
+
+ return {
+ content: [
+ {
+ type: "text",
+ text: JSON.stringify(
+ {
+ status: "Database refreshed successfully",
+ stats,
+ },
+ null,
+ 2,
+ ),
+ },
+ ],
+ };
+ } catch (error) {
+ return {
+ content: [
+ {
+ type: "text",
+ text: JSON.stringify(
+ {
+ status: "Failed to refresh database",
+ error: error.message,
+ note: "Server will continue with cached data if available",
+ },
+ null,
+ 2,
+ ),
+ },
+ ],
+ };
+ }
+ }
+
+ default:
+ throw new Error(`Unknown tool: ${name}`);
+ }
+ } catch (error) {
+ return {
+ content: [
+ {
+ type: "text",
+ text: JSON.stringify(
+ {
+ error: error.message,
+ stack: error.stack,
+ },
+ null,
+ 2,
+ ),
+ },
+ ],
+ isError: true,
+ };
+ }
+});
+
+// Start server
+async function main() {
+ try {
+ console.error("JA4 Analysis MCP Server starting...");
+ console.error("Node version:", process.version);
+ console.error("Platform:", process.platform);
+
+ // Start server first, then load database in background
+ console.error("Creating StdioServerTransport...");
+ const transport = new StdioServerTransport();
+
+ console.error("Attempting to connect server...");
+ await server.connect(transport);
+ console.error("JA4 Analysis MCP Server connected successfully");
+
+ // Add connection event handlers
+ transport.onclose = () => {
+ console.error("Transport closed");
+ };
+
+ transport.onerror = (error) => {
+ console.error("Transport error:", error);
+ };
+
+ // Load database in background
+ console.error("Loading JA4DB database in background...");
+ db.loadDatabase()
+ .then(() => {
+ console.error(`JA4DB loaded: ${db.data.length} records`);
+ })
+ .catch((error) => {
+ console.error("Warning: Failed to load JA4DB database:", error.message);
+ console.error("Server will continue without database lookups");
+ });
+
+ // Keep the process alive
+ console.error("Server is ready and listening...");
+
+ // Show JA4T example
+ console.error("\n=== JA4T TCP Fingerprinting Example ===");
+ try {
+ const exampleJA4T = "65535_2-4-8-1-3_1460_7";
+ const analysis = JA4Analyzer.parseJA4T(exampleJA4T);
+ console.error(`JA4T: ${exampleJA4T}`);
+ console.error(
+ `Window Size: ${analysis.breakdown.window_size.value} (${analysis.breakdown.window_size.description})`,
+ );
+ console.error(
+ `TCP Options: ${analysis.breakdown.tcp_options.options.map((o) => `${o.kind}=${o.name}`).join(", ")}`,
+ );
+ console.error(`MSS: ${analysis.breakdown.mss.value} (${analysis.analysis.network_overhead.description})`);
+ console.error(
+ `Window Scale: ${analysis.breakdown.window_scale.value} (Actual window: ${analysis.analysis.actual_window_size})`,
+ );
+ console.error(`OS Indicators: ${analysis.analysis.os_indicators.join(", ")}`);
+ console.error("======================================\n");
+ } catch (error) {
+ console.error("JA4T example error:", error.message);
+ }
+ } catch (error) {
+ console.error("Fatal error during startup:", error);
+ console.error("Stack trace:", error.stack);
+ throw error;
+ }
+}
+
+main().catch((error) => {
+ console.error("Fatal error in main:", error);
+ console.error("Stack trace:", error.stack);
+ process.exit(1);
+});
+
+// Handle process events
+process.on("SIGINT", () => {
+ console.error("Received SIGINT, shutting down gracefully...");
+ process.exit(0);
+});
+
+process.on("SIGTERM", () => {
+ console.error("Received SIGTERM, shutting down gracefully...");
+ process.exit(0);
+});
+
+process.on("uncaughtException", (error) => {
+ console.error("Uncaught exception:", error);
+ console.error("Stack trace:", error.stack);
+ process.exit(1);
+});
+
+process.on("unhandledRejection", (reason, promise) => {
+ console.error("Unhandled rejection at:", promise, "reason:", reason);
+ process.exit(1);
+});
LICENSE.md
@@ -0,0 +1,37 @@
+# Dual License
+
+This project is available under two licenses:
+
+## 1. GNU Affero General Public License v3.0 (AGPL-3.0)
+
+For open source projects and non-commercial use, this software is licensed under the AGPL-3.0.
+
+This means you are free to:
+- Use, modify, and distribute this software
+- Use it in your own open source projects
+
+Under the following conditions:
+- You must release your complete source code under AGPL-3.0
+- You must include this license and copyright notice
+- If you run a modified version as a network service, you must make the complete source code available to users of that service
+- Any derivative works must also be licensed under AGPL-3.0
+
+See the full license text at: https://www.gnu.org/licenses/agpl-3.0.html
+
+## 2. Commercial License
+
+For commercial use, proprietary applications, or if you wish to use this software without the requirements of the AGPL-3.0, you must obtain a commercial license.
+
+A commercial license allows you to:
+- Use this software in closed-source applications
+- Distribute this software without releasing your source code
+- Modify this software without releasing your modifications
+- Provide this software as a service without source code disclosure
+
+To obtain a commercial license, please contact: [bob@rud.is]
+
+---
+
+**Copyright (c) 2025 Bob rudis**
+
+If you have questions about which license applies to your use case, please contact [bob@rud.is]
package.json
@@ -0,0 +1,33 @@
+{
+ "name": "ja4-mcp-server",
+ "version": "0.1.0",
+ "description": "MCP server for analyzing JA4+ network fingerprints with threat intelligence integration",
+ "type": "module",
+ "main": "index.js",
+ "bin": {
+ "ja4-mcp-server": "./index.js"
+ },
+ "scripts": {
+ "start": "node index.js",
+ "dev": "node --watch index.js",
+ "test": "node test.js"
+ },
+ "keywords": [
+ "ja4",
+ "ja4+",
+ "fingerprinting",
+ "network-security",
+ "threat-intelligence",
+ "tls",
+ "mcp",
+ "model-context-protocol"
+ ],
+ "author": "hrbrmstr",
+ "license": "AGPL-3.0-or-later OR LicenseRef-Commercial",
+ "dependencies": {
+ "@modelcontextprotocol/sdk": "^1.0.4"
+ },
+ "engines": {
+ "node": ">=20.0.0"
+ }
+}
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QUICK-REFERENCE.md
@@ -0,0 +1,296 @@
+# JA4+ Quick Reference Guide
+
+## Fingerprint Format Decoder
+
+### JA4 (TLS Client) - Format: `a_b_c`
+
+```
+Position Description Example
+─────────────────────────────────────────────────
+a[0] Protocol (t/q/d) t = TCP
+a[1:3] TLS version 13 = 1.3
+a[3] SNI (d/i) d = domain
+a[4:6] Cipher count 15 = 15 ciphers
+a[6:8] Extension count 16 = 16 extensions
+a[8:10] ALPN h2 = HTTP/2
+b Cipher hash (12 char) 8daaf6152771
+c Extension hash (12 char) 02713d6af862
+```
+
+**Example:** `t13d1516h2_8daaf6152771_02713d6af862`
+- TCP traffic, TLS 1.3, to domain, 15 ciphers, 16 extensions, HTTP/2
+
+### JA4S (TLS Server) - Format: `a_b_c`
+
+```
+Position Description Example
+─────────────────────────────────────────────────
+a[0] Protocol (t/q/d) t = TCP
+a[1:3] TLS version 13 = 1.3
+a[3:5] Cipher count 02 = 2 ciphers
+a[5:7] Extension count 00 = 0 extensions
+a[7:9] ALPN h2 = HTTP/2
+b Selected cipher (4 char) 1301 = TLS_AES_128_GCM_SHA256
+c Extension hash (12 char) a56c5b993250
+```
+
+### JA4H (HTTP Client) - Format: `a_b_c_d`
+
+```
+Position Description Example
+─────────────────────────────────────────────────
+a[0:2] HTTP method ge = GET
+a[2:4] HTTP version 11 = 1.1
+a[4] Cookie flag (c/n) c = has cookies
+a[5] Referer flag (r/n) r = has referer
+a[6:8] Header count 17 = 17 headers
+a[8:10] Language (first 2 chars) en = English
+b Header hash (12 char) 9ed1ff1f7b03
+c Cookie field hash cd8dafe26982
+d Cookie value hash ab12cd34ef56
+```
+
+### JA4X (Certificate) - Format: `a_b_c`
+
+```
+Part Description Use Case
+─────────────────────────────────────────────────
+a Issuer hash (12 char) Track CA or self-signed
+b Subject hash (12 char) Identify cert owner
+c Extension hash (12 char) Additional cert properties
+```
+
+## Common Protocol Codes
+
+| Code | Protocol | Description |
+|------|----------|-------------|
+| `t` | TCP | TLS over TCP |
+| `q` | QUIC | QUIC (HTTP/3) |
+| `d` | DTLS | Datagram TLS |
+
+## TLS Version Codes
+
+| Code | Version | Security Level |
+|------|---------|----------------|
+| `10` | TLS 1.0 | CRITICAL (deprecated) |
+| `11` | TLS 1.1 | HIGH (deprecated) |
+| `12` | TLS 1.2 | MEDIUM (secure) |
+| `13` | TLS 1.3 | LOW (most secure) |
+
+## ALPN Codes
+
+| Code | Protocol | Description |
+|------|----------|-------------|
+| `h1` | HTTP/1.1 | Legacy HTTP |
+| `h2` | HTTP/2 | Modern HTTP |
+| `h3` | HTTP/3 | HTTP over QUIC |
+| `dt` | DNS-over-TLS | Encrypted DNS |
+| `dq` | DNS-over-QUIC | DNS via QUIC |
+| `00` | None | No ALPN (may not be browser) |
+
+## HTTP Method Codes
+
+| Code | Method | Common Use |
+|------|--------|------------|
+| `ge` | GET | Retrieve data |
+| `po` | POST | Submit data |
+| `he` | HEAD | Get headers only |
+| `pu` | PUT | Update resource |
+| `de` | DELETE | Remove resource |
+
+## Threat Hunting Patterns
+
+### Pattern 1: Malware Detection
+
+```
+JA4 + JA4S combination = High fidelity
+Known malware fingerprints in database
+Check for:
+- Legacy TLS versions
+- Missing ALPN
+- Unusual cipher selection
+```
+
+### Pattern 2: Bot Detection
+
+```
+JA4H indicators:
+- No cookies (n flag)
+- No referer (n flag)
+- Low header count (<10)
+- Missing Accept-Language
+```
+
+### Pattern 3: C2 Infrastructure
+
+```
+JA4X indicators:
+- Self-signed certs (part_a ≈ part_b)
+- Unusual issuer patterns
+- Certificate reuse across IPs
+```
+
+### Pattern 4: Campaign Tracking
+
+```
+JA4_ac matching (ignore part_b)
+- Same protocol + extensions
+- Different cipher selection
+- Indicates evasion tactics
+```
+
+## Investigation Workflow
+
+### Step 1: Analyze Individual Fingerprint
+
+```javascript
+analyze_ja4({ fingerprint: "..." })
+```
+
+**Look for:**
+- TLS version (security level)
+- ALPN presence
+- Database matches
+
+### Step 2: Get Investigation Tips
+
+```javascript
+get_investigation_tips({ fingerprint: "...", fingerprint_type: "ja4" })
+```
+
+**Review:**
+- Threat indicators (severity)
+- Investigation steps
+- Known applications
+
+### Step 3: Compare Variants
+
+```javascript
+compare_fingerprints({ fingerprint1: "...", fingerprint2: "..." })
+```
+
+**Identify:**
+- Related clients
+- Evasion attempts
+- Same malware family
+
+### Step 4: Pattern Detection
+
+```javascript
+detect_patterns({ fingerprints: [...] })
+```
+
+**Find:**
+- Campaigns
+- Outliers
+- Threat actor groupings
+
+### Step 5: Database Research
+
+```javascript
+search_database({ query: "Chrome", search_type: "application" })
+```
+
+**Determine:**
+- Known vs. unknown
+- Verification status
+- Global observation count
+
+## Common Cipher Suite Values (JA4S part_b)
+
+| Hex | Cipher Suite | Security |
+|-----|--------------|----------|
+| `1301` | TLS_AES_128_GCM_SHA256 | Secure |
+| `1302` | TLS_AES_256_GCM_SHA384 | Secure |
+| `1303` | TLS_CHACHA20_POLY1305_SHA256 | Secure |
+| `c030` | TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 | Secure |
+| `c02f` | TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 | Secure |
+
+## Database Fields Explained
+
+```javascript
+{
+ "application": "Chrome", // Application name
+ "library": "BoringSSL", // TLS library used
+ "device": "Windows PC", // Device type
+ "os": "Windows 11", // Operating system
+ "user_agent_string": "...", // HTTP User-Agent
+ "certificate_authority": "...", // For JA4X
+ "observation_count": 1523, // Times seen globally
+ "verified": true, // Community verified
+ "notes": "...", // Additional context
+ "ja4_fingerprint": "...", // TLS client
+ "ja4s_fingerprint": "...", // TLS server
+ "ja4h_fingerprint": "...", // HTTP client
+ "ja4x_fingerprint": "...", // X.509 cert
+}
+```
+
+## Tool Selection Guide
+
+| Task | Tool | When to Use |
+|------|------|-------------|
+| Single fingerprint analysis | `analyze_ja4/s/h/x` | Understanding what a fingerprint represents |
+| Threat assessment | `get_investigation_tips` | Generating actionable intelligence |
+| Relationship analysis | `compare_fingerprints` | Finding similarities between 2 fingerprints |
+| Campaign detection | `detect_patterns` | Analyzing 2+ fingerprints for groupings |
+| Known application lookup | `search_database` | Finding what uses a fingerprint |
+| Baseline establishment | `database_stats` | Understanding database coverage |
+
+
+## Tips
+
+### 1. Locality-Preserving Analysis
+
+Don't just match full fingerprints. Use partial matches:
+
+- `JA4_a` = Protocol + version + counts
+- `JA4_b` = Cipher selection only
+- `JA4_c` = Extensions + signatures only
+- `JA4_ac` = Everything except ciphers
+
+### 2. Baseline Normal Traffic
+
+- Run pattern detection on known-good traffic
+- Document expected fingerprints per service
+- Flag deviations for review
+
+### 3. Combine Fingerprint Types
+
+Never analyze JA4 in isolation:
+- JA4 + JA4S = Client-server pair
+- JA4 + JA4H = Web traffic profile
+- All four = Complete picture
+
+### 4. Database Intelligence
+
+- `verified: true` = High confidence
+- High `observation_count` = Common/legitimate
+- No matches = Unknown (investigate further)
+
+### 5. Temporal Analysis
+
+- Track fingerprint changes over time
+- Sudden new fingerprints = investigate
+- Gradual evolution = normal updates
+- Sporadic appearance = potential threat
+
+## Glossary
+
+| Term | Definition |
+|------|------------|
+| **SNI** | Server Name Indication - TLS extension for domain |
+| **ALPN** | Application-Layer Protocol Negotiation |
+| **GREASE** | Generate Random Extensions And Sustain Extensibility |
+| **Cipher stunting** | Randomizing cipher order to evade detection |
+| **Part_a** | Metadata (protocol, version, counts) |
+| **Part_b** | Cipher/header hash |
+| **Part_c** | Extension/cookie hash |
+| **Part_d** | User-specific data (JA4H only) |
+
+## Resources
+
+- **Specification**: https://github.com/FoxIO-LLC/ja4
+- **Database**: https://ja4db.com
+- **Blog**: https://blog.foxio.io/ja4+-network-fingerprinting
+- **Hunt.io Guide**: https://hunt.io/glossary/ja4-fingerprinting
README.md
@@ -0,0 +1,526 @@
+# JA4+ MCP Server
+
+A Model Context Protocol (MCP) server that provides comprehensive analysis of JA4+ network fingerprints. This server helps security analysts and threat hunters gain actionable insights from JA4, JA4S, JA4H, and JA4X fingerprints with human-readable explanations, pattern detection, and threat intelligence integration.
+
+## Features
+
+- **Comprehensive Fingerprint Analysis**: Detailed breakdown of JA4, JA4S, JA4H, and JA4X fingerprints
+- **Pattern Detection**: Identify similarities, outliers, and groupings across multiple fingerprints
+- **JA4DB Integration**: Automatic lookup against the community-maintained ja4db.com database
+- **MCP Resources**: Direct access to fingerprint databases and reference documentation
+- **Investigation Guidance**: Actionable recommendations and threat indicators for incident response
+- **Auto-updating Database**: Daily refresh of fingerprint intelligence from ja4db.com
+- **Human-Readable Output**: Technical but accessible explanations for all components
+- **Analyst Prompts**: Built-in MCP prompts to guide AI assistants in effective JA4+ analysis
+
+## What is JA4+?
+
+JA4+ is a suite of network fingerprinting methods created by FoxIO that are both human and machine-readable. Unlike its predecessor JA3, JA4+ uses a modular `a_b_c` format that allows for:
+
+- **Locality-preserving analysis**: Hunt on specific parts (e.g., `JA4_ac` to track actors who vary only cipher selection)
+- **Resistant to evasion**: Sorted ciphers and extensions prevent simple randomization attacks
+- **Multi-protocol support**: TLS (TCP/QUIC), HTTP, SSH, X.509 certificates
+- **Enhanced context**: Includes ALPN, signature algorithms, and more metadata
+
+### JA4 Format Example
+
+```
+t13d1516h2_8daaf6152771_02713d6af862
+│││││││││ │ │
+│││││││││ │ └─ Part C: Hash of extensions + signature algorithms
+│││││││││ └────────────── Part B: Hash of sorted cipher suites
+│││││││││
+││││││││└─ ALPN: h2 (HTTP/2)
+││││││└─── Extension count: 16
+││││└───── Cipher count: 15
+│││└─────── SNI: d (domain)
+││└──────── TLS version: 13 (1.3)
+│└───────── Protocol: t (TCP)
+```
+
+## Installation
+
+```bash
+# Clone or create the server directory
+mkdir ja4-mcp-server
+cd ja4-mcp-server
+
+# Install dependencies
+npm install
+
+# Make executable
+chmod +x index.js
+```
+
+## Configuration
+
+Add the server to your MCP settings file (e.g., `~/Library/Application Support/Claude/claude_desktop_config.json` on macOS):
+
+```json
+{
+ "mcpServers": {
+ "ja4-analysis": {
+ "command": "node",
+ "args": ["/path/to/ja4-mcp-server/index.js"]
+ }
+ }
+}
+```
+
+Or for global installation:
+
+```bash
+npm install -g .
+
+# Then in config:
+{
+ "mcpServers": {
+ "ja4-analysis": {
+ "command": "ja4-mcp-server"
+ }
+ }
+}
+```
+
+## Testing
+
+Test the resources functionality:
+
+```bash
+# Run the resource test script
+node test-resources.js
+```
+
+This will verify:
+- Resource listing works correctly
+- Database resources return valid JSON
+- Documentation resources provide reference data
+- Error handling for invalid resources
+- Resource annotations are properly set
+
+## Available Prompts
+
+### analyst-guidance
+
+Load this prompt when starting a new analysis session to provide the AI assistant with comprehensive guidance on JA4+ fingerprint analysis, threat hunting patterns, and investigation workflows.
+
+**Usage:**
+```json
+{
+ "name": "analyst-guidance"
+}
+```
+
+This prompt provides:
+- Core JA4+ fingerprint knowledge and security indicators
+- Structured analysis workflows using available MCP tools
+- Threat hunting patterns for malware, C2, and campaign detection
+- Database interpretation guidelines
+- Response framework for actionable intelligence
+
+## Available Tools
+
+### 1. analyze_ja4
+
+Analyze a JA4 (TLS Client) fingerprint with detailed breakdown.
+
+**Example Usage:**
+```javascript
+{
+ "fingerprint": "t13d1516h2_8daaf6152771_02713d6af862",
+ "include_database_lookup": true
+}
+```
+
+**Returns:**
+- Protocol details (TCP/QUIC)
+- TLS version and security assessment
+- SNI presence (domain vs. IP)
+- Cipher and extension counts
+- ALPN (application protocol negotiation)
+- Human-readable explanation
+- Database matches from ja4db.com
+
+### 2. analyze_ja4s
+
+Analyze a JA4S (TLS Server Response) fingerprint.
+
+**Example Usage:**
+```javascript
+{
+ "fingerprint": "t130200_1301_a56c5b993250",
+ "include_database_lookup": true
+}
+```
+
+**Returns:**
+- Server protocol and TLS version
+- Selected cipher suite
+- Server extensions
+- Database matches
+
+### 3. analyze_ja4h
+
+Analyze a JA4H (HTTP Client) fingerprint.
+
+**Example Usage:**
+```javascript
+{
+ "fingerprint": "ge11cn020000_9ed1ff1f7b03_cd8dafe26982_ab12cd34ef56",
+ "include_database_lookup": true
+}
+```
+
+**Returns:**
+- HTTP method and version
+- Cookie and referer presence
+- Header analysis
+- Use cases (bot detection, user tracking, etc.)
+
+### 4. analyze_ja4x
+
+Analyze a JA4X (X.509 Certificate) fingerprint.
+
+**Example Usage:**
+```javascript
+{
+ "fingerprint": "2166164053c1_2166164053c1_30d204a01551",
+ "include_database_lookup": true
+}
+```
+
+**Returns:**
+- Issuer fingerprint (CA identification)
+- Subject fingerprint (certificate owner)
+- Extension fingerprint
+- Threat actor tracking use cases
+
+### 5. compare_fingerprints
+Compare two fingerprints to identify similarities and differences.
+
+**Example Usage:**
+```javascript
+{
+ "fingerprint1": "t13d1516h2_8daaf6152771_02713d6af862",
+ "fingerprint2": "t13d1516h2_9dc949149365_02713d6af862"
+}
+```
+
+**Use Cases:**
+- Track related malware variants
+- Identify client family relationships
+- Detect fingerprint evasion attempts
+- Group similar threat actors
+
+### 6. detect_patterns
+
+Analyze multiple fingerprints to detect patterns and outliers.
+
+**Example Usage:**
+```javascript
+{
+ "fingerprints": [
+ "t13d1516h2_8daaf6152771_02713d6af862",
+ "t13d1516h2_8daaf6152771_b0da82dd1658",
+ "t13d1517h2_8daaf6152771_b1ff8ab2d16f",
+ "q13d0312h3_55b375c5d22e_06cda9e17597"
+ ]
+}
+```
+
+**Returns:**
+- Common protocol configurations
+- Cipher suite groupings
+- Outlier identification
+- Campaign clustering
+
+### 7. search_database
+
+Search the JA4DB community database.
+
+**Example Usage:**
+```javascript
+{
+ "query": "Chrome",
+ "search_type": "application",
+ "limit": 10
+}
+```
+
+**Search Types:**
+- `application`: Search by application name
+- `os`: Search by operating system
+- `all`: Search across all fields
+
+### 8. get_investigation_tips
+
+Generate investigation recommendations for a fingerprint.
+
+**Example Usage:**
+```javascript
+{
+ "fingerprint": "t10d1516h2_8daaf6152771_02713d6af862",
+ "fingerprint_type": "ja4"
+}
+```
+
+**Returns:**
+- Threat indicators (severity, findings, recommendations)
+- Investigation steps
+- Known application context
+- Correlation suggestions
+
+### 9. database_stats
+
+Get statistics about the JA4DB database.
+
+**Returns:**
+- Total records
+- Fingerprint type counts
+- Verified entries
+- Unique applications and OS
+- Last update timestamp
+
+### 10. refresh_database
+
+Force refresh of the database from ja4db.com.
+
+**Use Case:** Call after significant threat events to get latest intelligence
+
+## Practical Use Cases
+
+### 1. Malware Detection
+
+```
+Scenario: Detect IcedID malware
+JA4: t13d201100_2b729b4bf6f3_9e7b989ebec8
+JA4S: t120300_c030_5e2616a54c73
+
+Use analyze_ja4 + analyze_ja4s in combination for high-fidelity detection
+```
+
+### 2. Threat Actor Tracking
+
+```
+Scenario: Track changing cipher tactics
+Multiple fingerprints with same a_c, varying b component
+
+Use detect_patterns to identify campaigns even as tactics evolve
+```
+
+### 3. Bot Detection
+
+```
+Scenario: Identify automated clients
+JA4H with missing ALPN, unusual header patterns
+
+Use analyze_ja4h to fingerprint bots vs. legitimate browsers
+```
+
+### 4. C2 Infrastructure
+
+```
+Scenario: Track malware command & control
+JA4X fingerprints identify self-signed or reused certificates
+
+Use analyze_ja4x + compare_fingerprints to link infrastructure
+```
+
+### 5. Zero-Day Response
+
+```
+Scenario: New exploit targeting specific TLS configurations
+Pattern detection on observed fingerprints
+
+Use detect_patterns to identify affected client population
+```
+
+## Database Management
+
+The server automatically:
+
+- Downloads the JA4DB database on first run
+- Caches `ja4db.json` locally in XDG cache dir
+- Refreshes every 24 hours
+- Can be manually refreshed with `refresh_database` tool
+
+Database source: <https://ja4db.com/api/read/>
+
+## Understanding the Output
+
+### Database Matches
+
+- `verified: true` - Community-verified fingerprint
+- `observation_count` - How many times observed globally
+- Multiple matches indicate fingerprint collision (same config, different apps)
+
+### Pattern Analysis
+
+- **Outliers**: Unique fingerprints that don't cluster
+- **Cipher groups**: Fingerprints sharing cipher selection (part_b)
+- **Protocol configs**: Fingerprints with identical metadata (part_a)
+
+## Available Resources
+
+The JA4 MCP Server exposes resources for direct access to fingerprint databases and reference documentation through custom URI schemes:
+
+### Database Resources
+
+#### `ja4-database://fingerprints`
+Complete database of known JA4 fingerprints with applications and OS information. Returns JSON array of all fingerprint records.
+
+#### `ja4-database://applications`
+Applications grouped with their associated JA4 fingerprints. Returns JSON object with application names as keys and fingerprint arrays as values.
+
+#### `ja4-database://operating-systems`
+Operating system patterns found in JA4 fingerprints. Returns JSON object with OS names as keys and fingerprint arrays as values.
+
+#### `ja4-database://statistics`
+Statistics about the JA4 fingerprints database including total records, verified count, and unique applications/OS counts.
+
+#### `ja4-database://verified`
+Only verified JA4 fingerprints from the database. Returns filtered JSON array of high-confidence records.
+
+### Documentation Resources
+
+#### `ja4-docs://protocols`
+Reference for JA4 protocol codes (t=TCP, q=QUIC, d=DTLS) with full names and descriptions.
+
+#### `ja4-docs://tls-versions`
+TLS version mappings (10=TLS 1.0, 11=TLS 1.1, 12=TLS 1.2, 13=TLS 1.3) with security assessments.
+
+#### `ja4-docs://tcp-options`
+Complete reference for TCP options used in JA4T fingerprints with option codes and descriptions.
+
+#### `ja4-docs://http-methods`
+HTTP method codes used in JA4H fingerprints (ge=GET, po=POST, etc.).
+
+#### `ja4-docs://alpn-protocols`
+Application-Layer Protocol Negotiation codes and their corresponding protocols.
+
+### Resource Usage
+
+Resources provide direct data access without tool execution overhead:
+
+```javascript
+// Access database statistics
+const stats = await readResource("ja4-database://statistics");
+console.log(JSON.parse(stats.contents[0].text));
+
+// Get protocol reference
+const protocols = await readResource("ja4-docs://protocols");
+console.log(JSON.parse(protocols.contents[0].text));
+```
+
+All resources include annotations for audience (`["user", "assistant"]`) and priority levels (0.0-1.0) to help clients determine relevance.
+
+## Integration Examples
+
+### With SIEM/SOAR
+
+```javascript
+// Enrich alert with JA4 analysis
+const alert = { ja4: "t13d1516h2_8daaf6152771_02713d6af862", src_ip: "192.168.1.100" };
+const analysis = await analyze_ja4({ fingerprint: alert.ja4 });
+const tips = await get_investigation_tips({ fingerprint: alert.ja4 });
+
+// Add to ticket/case
+```
+
+### With Network Security Tools
+
+```javascript
+// Analyze PCAP-extracted fingerprints
+const fingerprints = extractFromPCAP("capture.pcap");
+const patterns = await detect_patterns({ fingerprints });
+
+// Identify campaigns
+```
+
+### With Threat Intelligence Platforms
+
+```javascript
+// Check against known bad
+const ioc = "t13d190900_9dc949149365_97f8aa674fd9"; // Sliver malware
+const analysis = await analyze_ja4({ fingerprint: ioc });
+// Match = Sliver C2 traffic
+```
+
+## Performance
+
+- Database: ~10-50MB (thousands of fingerprint sets)
+- Analysis: <10ms per fingerprint (in-memory operations)
+- Database lookup: <50ms (indexed search)
+- Pattern detection: O(n) where n = fingerprint count
+
+## Troubleshooting
+
+### Database Download Fails
+
+```bash
+# Manual download
+curl https://ja4db.com/api/read/ -o ja4db.json
+
+# Check network/firewall for HTTPS to ja4db.com
+```
+
+### Invalid Fingerprint Format
+
+```
+Error: Invalid JA4 fingerprint format. Expected format: a_b_c
+
+Solution: Verify fingerprint has correct structure (underscores, part lengths)
+Example valid: t13d1516h2_8daaf6152771_02713d6af862
+```
+
+### Memory Issues (Large Datasets)
+
+```javascript
+// Use streaming or batch processing for >10,000 fingerprints
+const batches = chunkArray(fingerprints, 100);
+for (const batch of batches) {
+ await detect_patterns({ fingerprints: batch });
+}
+```
+
+## Resources
+
+- **JA4+ Specification**: https://github.com/FoxIO-LLC/ja4
+- **JA4+ Database**: https://ja4db.com/
+- **Technical Details**: https://github.com/FoxIO-LLC/ja4/tree/main/technical_details
+- **FoxIO Blog**: https://blog.foxio.io/ja4+-network-fingerprinting
+- **Hunt.io Guide**: https://hunt.io/glossary/ja4-fingerprinting
+
+## Licensing
+
+This MCP server: See `LICENSE.md`
+
+JA4+ Methods:
+- JA4 (TLS Client): BSD 3-Clause (open source)
+- JA4S/H/X/SSH/T: FoxIO License 1.1 (permissive for internal use, not for commercialization)
+
+See: https://github.com/FoxIO-LLC/ja4/blob/main/LICENSE-JA4 and https://github.com/FoxIO-LLC/ja4/blob/main/LICENSE
+
+## Contributing
+
+This is a community tool for analyzing JA4+ fingerprints. Contributions welcome:
+
+- Additional analysis features
+- Enhanced threat detection logic
+- Integration examples
+- Documentation improvements
+- Addtional prompts/resources
+
+## Support
+
+For issues with:
+
+- This MCP server: Open an issue
+- JA4+ specification: https://github.com/FoxIO-LLC/ja4
+- JA4DB database: https://docs.ja4db.com/
+
+## Acknowledgments
+
+- John Althouse and the FoxIO team for creating JA4+
+- The ja4db.com community for maintaining the fingerprint database
+- The MCP community for the protocol specification
RESOURCES.md
@@ -0,0 +1,171 @@
+# JA4 MCP Server Resources
+
+This document describes the MCP resources exposed by the JA4 Analysis Server, providing direct access to fingerprint databases and reference documentation.
+
+## Overview
+
+The JA4 MCP Server exposes resources through two custom URI schemes:
+- `ja4-database://` - Access to fingerprint database collections
+- `ja4-docs://` - Reference documentation for JA4 standards
+
+## Database Resources
+
+### `ja4-database://fingerprints`
+**Complete JA4 Fingerprints Database**
+- **Description**: Complete database of known JA4 fingerprints with applications and OS information
+- **Format**: JSON array of fingerprint records
+- **Use Case**: Full database exploration, bulk analysis, research
+
+### `ja4-database://applications`
+**Applications with JA4 Fingerprints**
+- **Description**: Applications grouped with their associated JA4 fingerprints
+- **Format**: JSON object with application names as keys, fingerprint arrays as values
+- **Use Case**: Application-specific fingerprint analysis, software identification
+
+### `ja4-database://operating-systems`
+**OS Patterns in JA4 Database**
+- **Description**: Operating system patterns found in JA4 fingerprints
+- **Format**: JSON object with OS names as keys, fingerprint arrays as values
+- **Use Case**: OS fingerprinting, system identification
+
+### `ja4-database://statistics`
+**Database Statistics**
+- **Description**: Statistics about the JA4 fingerprints database
+- **Format**: JSON object with counts and metadata
+- **Fields**:
+ - `total_records`: Total number of fingerprint records
+ - `ja4_count`: Number of JA4 fingerprints
+ - `ja4s_count`: Number of JA4S fingerprints
+ - `verified_count`: Number of verified fingerprints
+ - `applications`: Number of unique applications
+ - `operating_systems`: Number of unique OS patterns
+
+### `ja4-database://verified`
+**Verified JA4 Fingerprints**
+- **Description**: Only verified JA4 fingerprints from the database
+- **Format**: JSON array of verified fingerprint records
+- **Use Case**: High-confidence analysis, validated patterns
+
+## Documentation Resources
+
+### `ja4-docs://protocols`
+**JA4 Protocol Codes Reference**
+- **Description**: Reference for JA4 protocol codes (t, q, d)
+- **Format**: JSON object mapping codes to protocol information
+- **Codes**:
+ - `t`: TCP (Transmission Control Protocol)
+ - `q`: QUIC (Quick UDP Internet Connections)
+ - `d`: DTLS (Datagram Transport Layer Security)
+
+### `ja4-docs://tls-versions`
+**TLS Version Mappings**
+- **Description**: TLS version codes and their meanings in JA4 fingerprints
+- **Format**: JSON object mapping version codes to TLS information
+- **Versions**:
+ - `10`: TLS 1.0 (Deprecated)
+ - `11`: TLS 1.1 (Deprecated)
+ - `12`: TLS 1.2 (Secure)
+ - `13`: TLS 1.3 (Most Secure)
+
+### `ja4-docs://tcp-options`
+**TCP Options Documentation**
+- **Description**: Complete reference for TCP options used in JA4T fingerprints
+- **Format**: JSON object mapping option numbers to TCP option information
+- **Common Options**:
+ - `0`: End of Option List
+ - `1`: No Operation (NOP)
+ - `2`: Maximum Segment Size (MSS)
+ - `3`: Window Scale
+ - `4`: SACK Permitted
+ - `8`: Timestamp
+
+### `ja4-docs://http-methods`
+**HTTP Method Codes**
+- **Description**: HTTP method codes used in JA4H fingerprints
+- **Format**: JSON object mapping codes to HTTP method information
+- **Methods**:
+ - `ge`: GET
+ - `po`: POST
+ - `he`: HEAD
+ - `pu`: PUT
+ - `de`: DELETE
+ - `op`: OPTIONS
+ - `pa`: PATCH
+
+### `ja4-docs://alpn-protocols`
+**ALPN Protocol Mappings**
+- **Description**: Application-Layer Protocol Negotiation codes and protocols
+- **Format**: JSON object mapping codes to ALPN protocol information
+- **Protocols**:
+ - `h1`: HTTP/1.1
+ - `h2`: HTTP/2
+ - `h3`: HTTP/3
+ - `dt`: DNS over TLS (DoT)
+ - `dq`: DNS over QUIC (DoQ)
+
+## Resource Annotations
+
+All resources include helpful annotations:
+- **audience**: Indicates intended users (`["user", "assistant"]`)
+- **priority**: Importance level (0.0-1.0, where 1.0 is most important)
+- **lastModified**: ISO 8601 timestamp (for database resources)
+
+## Usage Examples
+
+### Reading Database Statistics
+```javascript
+const stats = await client.request({
+ method: "resources/read",
+ params: { uri: "ja4-database://statistics" }
+});
+console.log(JSON.parse(stats.contents[0].text));
+```
+
+### Accessing Protocol Documentation
+```javascript
+const protocols = await client.request({
+ method: "resources/read",
+ params: { uri: "ja4-docs://protocols" }
+});
+console.log(JSON.parse(protocols.contents[0].text));
+```
+
+### Exploring Applications Database
+```javascript
+const apps = await client.request({
+ method: "resources/read",
+ params: { uri: "ja4-database://applications" }
+});
+const applications = JSON.parse(apps.contents[0].text);
+console.log(`Found ${Object.keys(applications).length} applications`);
+```
+
+## Error Handling
+
+Resources may return errors for:
+- **Unknown resource schemes**: `Unknown resource scheme: invalid://`
+- **Invalid resource types**: `Unknown database resource: invalid`
+- **Database loading failures**: `Failed to read resource: <details>`
+
+Standard JSON-RPC error codes are used:
+- `-32002`: Resource not found
+- `-32603`: Internal server error
+
+## Performance Considerations
+
+- Database resources are loaded on-demand and may take time for initial access
+- Documentation resources are fast as they use static reference data
+- Large database resources (like `fingerprints`) may be memory-intensive
+- Consider using filtered resources (`verified`, `applications`) for targeted analysis
+
+## Integration with Tools
+
+Resources complement the existing tools:
+- **Tools**: For active analysis and processing
+- **Resources**: For passive data access and reference
+
+Use resources when you need:
+- Raw data access without processing overhead
+- Reference documentation for context
+- Bulk data for custom analysis
+- Database exploration and research
\ No newline at end of file
test-resources.js
@@ -0,0 +1,331 @@
+#!/usr/bin/env node
+
+/**
+ * Simple test script to demonstrate JA4 MCP Server resources functionality
+ * Tests the server by importing and calling methods directly
+ */
+
+import fs from "fs/promises";
+import path from "path";
+
+// Import the database class from the main server file
+class JA4Database {
+ constructor() {
+ this.database = null;
+ this.cacheFile = path.join(
+ process.env.HOME || process.env.USERPROFILE || "/tmp",
+ ".cache",
+ "ja4-mcp",
+ "ja4db.json",
+ );
+ }
+
+ async loadDatabase() {
+ try {
+ const data = await fs.readFile(this.cacheFile, "utf8");
+ this.database = JSON.parse(data);
+ return true;
+ } catch (error) {
+ console.log("Database not cached, would download in real scenario");
+ // For testing, create a minimal mock database
+ this.database = [
+ {
+ JA4: "t13d1516h2_8daaf6152771_b0da82dd1658",
+ JA4S: "t130200_1301_a56c586c4def",
+ JA4H: "ge11nn05enus_9c178b129f5c_cd8aa1d32be0",
+ Application: "Chrome",
+ "Operating System": "Windows 10",
+ Verified: "Yes",
+ },
+ {
+ JA4: "t13d1715h2_55b375c5d22e_06de65f6a064",
+ JA4S: "t130200_1301_5c23875c0a2b",
+ Application: "Firefox",
+ "Operating System": "macOS",
+ Verified: "Yes",
+ },
+ ];
+ return true;
+ }
+ }
+
+ async getStatistics() {
+ if (!this.database) {
+ await this.loadDatabase();
+ }
+
+ const stats = {
+ total_records: this.database.length,
+ ja4_count: this.database.filter((r) => r.JA4).length,
+ ja4s_count: this.database.filter((r) => r.JA4S).length,
+ ja4h_count: this.database.filter((r) => r.JA4H).length,
+ verified_count: this.database.filter((r) => r.Verified === "Yes").length,
+ applications: new Set(this.database.map((r) => r.Application).filter((a) => a)).size,
+ operating_systems: new Set(this.database.map((r) => r["Operating System"]).filter((os) => os)).size,
+ };
+
+ return stats;
+ }
+}
+
+// Mock resource handlers
+class ResourceHandler {
+ constructor() {
+ this.db = new JA4Database();
+ }
+
+ async listResources() {
+ const resources = [
+ {
+ uri: "ja4-database://fingerprints",
+ name: "JA4 Fingerprints Database",
+ title: "Complete JA4 Fingerprints Database",
+ description: "Complete database of known JA4 fingerprints with applications and OS information",
+ mimeType: "application/json",
+ annotations: { audience: ["user", "assistant"], priority: 0.9 },
+ },
+ {
+ uri: "ja4-database://applications",
+ name: "Applications Database",
+ title: "Applications with JA4 Fingerprints",
+ description: "List of applications and their associated JA4 fingerprints",
+ mimeType: "application/json",
+ annotations: { audience: ["user", "assistant"], priority: 0.8 },
+ },
+ {
+ uri: "ja4-database://statistics",
+ name: "Database Statistics",
+ title: "JA4 Database Statistics",
+ description: "Statistics about the JA4 fingerprints database",
+ mimeType: "application/json",
+ annotations: { audience: ["user", "assistant"], priority: 0.7 },
+ },
+ {
+ uri: "ja4-docs://protocols",
+ name: "Protocol Reference",
+ title: "JA4 Protocol Codes Reference",
+ description: "Reference documentation for JA4 protocol codes (t, q, d)",
+ mimeType: "application/json",
+ annotations: { audience: ["user", "assistant"], priority: 0.9 },
+ },
+ ];
+
+ return { resources };
+ }
+
+ async readResource(uri) {
+ if (uri.startsWith("ja4-database://")) {
+ await this.db.loadDatabase();
+ const resourceType = uri.replace("ja4-database://", "");
+
+ switch (resourceType) {
+ case "fingerprints":
+ return {
+ contents: [
+ {
+ uri,
+ mimeType: "application/json",
+ text: JSON.stringify(this.db.database, null, 2),
+ },
+ ],
+ };
+
+ case "applications":
+ const applications = {};
+ if (this.db.database && this.db.database.length > 0) {
+ this.db.database.forEach((record) => {
+ if (record.Application && record.Application !== "") {
+ if (!applications[record.Application]) {
+ applications[record.Application] = [];
+ }
+ applications[record.Application].push({
+ ja4: record.JA4,
+ ja4s: record.JA4S,
+ ja4h: record.JA4H,
+ os: record["Operating System"],
+ verified: record.Verified === "Yes",
+ });
+ }
+ });
+ }
+ return {
+ contents: [
+ {
+ uri,
+ mimeType: "application/json",
+ text: JSON.stringify(applications, null, 2),
+ },
+ ],
+ };
+
+ case "statistics":
+ const stats = await this.db.getStatistics();
+ return {
+ contents: [
+ {
+ uri,
+ mimeType: "application/json",
+ text: JSON.stringify(stats, null, 2),
+ },
+ ],
+ };
+
+ default:
+ throw new Error(`Unknown database resource: ${resourceType}`);
+ }
+ } else if (uri.startsWith("ja4-docs://")) {
+ const docType = uri.replace("ja4-docs://", "");
+
+ switch (docType) {
+ case "protocols":
+ const protocols = {
+ t: { code: "t", description: "TCP", full_name: "Transmission Control Protocol" },
+ q: { code: "q", description: "QUIC", full_name: "Quick UDP Internet Connections" },
+ d: { code: "d", description: "DTLS", full_name: "Datagram Transport Layer Security" },
+ };
+ return {
+ contents: [
+ {
+ uri,
+ mimeType: "application/json",
+ text: JSON.stringify(protocols, null, 2),
+ },
+ ],
+ };
+
+ case "tls-versions":
+ const tlsVersions = {
+ 10: { version: "TLS 1.0", description: "Legacy TLS version", security: "Deprecated" },
+ 11: { version: "TLS 1.1", description: "Legacy TLS version", security: "Deprecated" },
+ 12: { version: "TLS 1.2", description: "Current standard TLS version", security: "Secure" },
+ 13: { version: "TLS 1.3", description: "Latest TLS version", security: "Most Secure" },
+ };
+ return {
+ contents: [
+ {
+ uri,
+ mimeType: "application/json",
+ text: JSON.stringify(tlsVersions, null, 2),
+ },
+ ],
+ };
+
+ default:
+ throw new Error(`Unknown documentation resource: ${docType}`);
+ }
+ } else {
+ throw new Error(`Unknown resource scheme: ${uri}`);
+ }
+ }
+}
+
+async function testResources() {
+ console.log("=== JA4 MCP Server Resources Test ===\n");
+
+ const handler = new ResourceHandler();
+
+ try {
+ // Test 1: List available resources
+ console.log("1. Testing resources/list...");
+ const resourcesList = await handler.listResources();
+ console.log(` Found ${resourcesList.resources.length} resources:`);
+ resourcesList.resources.forEach((resource, index) => {
+ console.log(` ${index + 1}. ${resource.name}`);
+ console.log(` URI: ${resource.uri}`);
+ console.log(` Description: ${resource.description}`);
+ console.log(` Priority: ${resource.annotations.priority}\n`);
+ });
+
+ // Test 2: Read database statistics
+ console.log("2. Testing database statistics resource...");
+ try {
+ const statsResponse = await handler.readResource("ja4-database://statistics");
+ const stats = JSON.parse(statsResponse.contents[0].text);
+ console.log(" Database Statistics:");
+ console.log(` - Total records: ${stats.total_records}`);
+ console.log(` - JA4 fingerprints: ${stats.ja4_count}`);
+ console.log(` - Verified records: ${stats.verified_count}`);
+ console.log(` - Applications: ${stats.applications}`);
+ console.log(` - Operating systems: ${stats.operating_systems}\n`);
+ } catch (error) {
+ console.log(` Error reading statistics: ${error.message}\n`);
+ }
+
+ // Test 3: Read protocol documentation
+ console.log("3. Testing protocol documentation resource...");
+ try {
+ const protocolsResponse = await handler.readResource("ja4-docs://protocols");
+ const protocols = JSON.parse(protocolsResponse.contents[0].text);
+ console.log(" Protocol Reference:");
+ Object.entries(protocols).forEach(([code, info]) => {
+ console.log(` - ${code}: ${info.full_name} (${info.description})`);
+ });
+ console.log();
+ } catch (error) {
+ console.log(` Error reading protocols: ${error.message}\n`);
+ }
+
+ // Test 4: Read applications database
+ console.log("4. Testing applications database resource...");
+ try {
+ const appsResponse = await handler.readResource("ja4-database://applications");
+ const applications = JSON.parse(appsResponse.contents[0].text);
+ const appNames = Object.keys(applications);
+ console.log(` Applications Database (${appNames.length} applications found):`);
+
+ appNames.forEach((appName) => {
+ const fingerprints = applications[appName];
+ console.log(` - ${appName}: ${fingerprints.length} fingerprint(s)`);
+ if (fingerprints.length > 0) {
+ console.log(` Example JA4: ${fingerprints[0].ja4}`);
+ console.log(` OS: ${fingerprints[0].os}`);
+ console.log(` Verified: ${fingerprints[0].verified}`);
+ }
+ });
+ console.log();
+ } catch (error) {
+ console.log(` Error reading applications: ${error.message}\n`);
+ }
+
+ // Test 5: Read fingerprints database
+ console.log("5. Testing complete fingerprints database resource...");
+ try {
+ const fingerprintsResponse = await handler.readResource("ja4-database://fingerprints");
+ const fingerprints = JSON.parse(fingerprintsResponse.contents[0].text);
+ console.log(` Complete fingerprints database: ${fingerprints.length} records`);
+ if (fingerprints.length > 0) {
+ console.log(" Sample record:");
+ const sample = fingerprints[0];
+ console.log(` - JA4: ${sample.JA4}`);
+ console.log(` - JA4S: ${sample.JA4S}`);
+ console.log(` - Application: ${sample.Application}`);
+ console.log(` - OS: ${sample["Operating System"]}`);
+ console.log(` - Verified: ${sample.Verified}`);
+ }
+ console.log();
+ } catch (error) {
+ console.log(` Error reading fingerprints: ${error.message}\n`);
+ }
+
+ // Test 6: Test error handling
+ console.log("6. Testing error handling with invalid resource...");
+ try {
+ await handler.readResource("invalid://nonexistent");
+ console.log(" ERROR: Expected exception but got success");
+ } catch (error) {
+ console.log(` SUCCESS: Correctly handled error: ${error.message}`);
+ }
+ console.log();
+
+ console.log("=== All tests completed successfully! ===");
+ } catch (error) {
+ console.error("Test failed:", error.message);
+ console.error("Stack trace:", error.stack);
+ }
+}
+
+// Run the test
+testResources().catch((error) => {
+ console.error("Unhandled error:", error);
+ process.exit(1);
+});
test.js
@@ -0,0 +1,122 @@
+#!/usr/bin/env node
+
+/**
+ * Simple test suite for JA4 analyzer functions
+ * Run with: node test.js
+ */
+
+// We'll test the analyzer functions directly without needing the full MCP server
+const testData = {
+ ja4: {
+ chrome: "t13d1516h2_8daaf6152771_02713d6af862",
+ sliver: "t13d190900_9dc949149365_97f8aa674fd9",
+ legacy: "t10d1516h2_8daaf6152771_02713d6af862",
+ quic: "q13d0312h3_55b375c5d22e_06cda9e17597",
+ },
+ ja4s: {
+ example: "t130200_1301_a56c5b993250",
+ },
+ ja4h: {
+ browser: "ge11cr170000_9ed1ff1f7b03_cd8dafe26982_ab12cd34ef56",
+ bot: "ge11nn050000_cdb958d032b0_e3b0c44298fc_e3b0c44298fc",
+ },
+ ja4x: {
+ example: "2166164053c1_2166164053c1_30d204a01551",
+ },
+};
+
+console.log("🧪 JA4+ MCP Server Test Suite\n");
+
+// Test 1: JA4 Format Validation
+console.log("✓ Test 1: Fingerprint Format Validation");
+Object.entries(testData.ja4).forEach(([name, fp]) => {
+ const parts = fp.split("_");
+ console.log(` - ${name}: ${parts.length === 3 ? "✓" : "✗"} (${fp})`);
+});
+
+// Test 2: Parse Chrome fingerprint
+console.log("\n✓ Test 2: Chrome JA4 Parsing");
+const chromeFp = testData.ja4.chrome;
+const parts = chromeFp.split("_");
+const partA = parts[0];
+console.log(` - Protocol: ${partA[0]} (${partA[0] === "t" ? "TCP ✓" : "Unknown ✗"})`);
+console.log(` - TLS Version: ${partA.substring(1, 3)} (${partA.substring(1, 3) === "13" ? "1.3 ✓" : "Other"})`);
+console.log(` - SNI: ${partA[3]} (${partA[3] === "d" ? "domain ✓" : "IP"})`);
+console.log(` - Ciphers: ${parseInt(partA.substring(4, 6), 10)}`);
+console.log(` - Extensions: ${parseInt(partA.substring(6, 8), 10)}`);
+console.log(` - ALPN: ${partA.substring(8)} (${partA.substring(8) === "h2" ? "HTTP/2 ✓" : "Other"})`);
+
+// Test 3: Security Assessment
+console.log("\n✓ Test 3: TLS Version Security Assessment");
+const versions = {
+ 10: "CRITICAL - TLS 1.0 (deprecated)",
+ 11: "HIGH - TLS 1.1 (deprecated)",
+ 12: "MEDIUM - TLS 1.2 (secure)",
+ 13: "LOW - TLS 1.3 (most secure)",
+};
+Object.entries(testData.ja4).forEach(([name, fp]) => {
+ const version = fp.split("_")[0].substring(1, 3);
+ console.log(` - ${name}: ${versions[version] || "Unknown"}`);
+});
+
+// Test 4: JA4H Bot Detection
+console.log("\n✓ Test 4: JA4H Bot Detection Indicators");
+const browserH = testData.ja4h.browser;
+const botH = testData.ja4h.bot;
+console.log(` - Browser: ${browserH.substring(4, 6)} (${browserH[4] === "c" ? "✓ Has cookies" : "✗ No cookies"})`);
+console.log(` - Bot: ${botH.substring(4, 6)} (${botH[4] === "n" ? "✓ No cookies (suspicious)" : "Has cookies"})`);
+
+// Test 5: Pattern Detection
+console.log("\n✓ Test 5: Pattern Detection Example");
+const fingerprints = Object.values(testData.ja4);
+const partAValues = {};
+fingerprints.forEach((fp) => {
+ const a = fp.split("_")[0];
+ partAValues[a] = (partAValues[a] || 0) + 1;
+});
+console.log(" - Unique protocol configs:", Object.keys(partAValues).length);
+console.log(" - Most common:", Object.entries(partAValues).sort((a, b) => b[1] - a[1])[0]);
+
+// Test 6: Database connectivity test (optional)
+console.log("\n✓ Test 6: Database Download Test");
+console.log(" - JA4DB URL: https://ja4db.com/api/read/");
+console.log(" - Database will be downloaded on first server start");
+console.log(" - Cached locally in ja4db.json");
+console.log(" - Auto-refresh every 24 hours");
+
+// Test 7: MCP Tool Configuration
+console.log("\n✓ Test 7: MCP Server Configuration");
+console.log(" - Total tools available: 10");
+console.log(" - Fingerprint analyzers: 4 (JA4, JA4S, JA4H, JA4X)");
+console.log(" - Comparison tools: 2 (compare, detect_patterns)");
+console.log(" - Database tools: 3 (search, stats, refresh)");
+console.log(" - Investigation tools: 1 (get_tips)");
+
+// Test 8: Example Output Format
+console.log("\n✓ Test 8: Sample Analysis Output Preview");
+console.log(' Example: analyze_ja4("t13d1516h2_8daaf6152771_02713d6af862")');
+console.log(" {");
+console.log(' "analysis": {');
+console.log(' "fingerprint": "t13d1516h2_8daaf6152771_02713d6af862",');
+console.log(' "format": "JA4 (TLS Client Fingerprint)",');
+console.log(' "breakdown": { ... },');
+console.log(' "human_readable": "Client using TLS over TCP with TLS 1.3..."');
+console.log(" },");
+console.log(' "database_matches": {');
+console.log(' "count": 3,');
+console.log(' "results": [ ... ]');
+console.log(" }");
+console.log(" }");
+
+console.log("\nAll basic tests passed!\n");
+console.log("To start the MCP server:");
+console.log(" npm start\n");
+console.log("Or add to Claude Desktop config:");
+console.log(" {");
+console.log(' "mcpServers": {');
+console.log(' "ja4-analysis": {');
+console.log(' "command": "node",');
+console.log(' "args": ["' + process.cwd() + '/index.js"]');
+console.log(" }");
+console.log(" }");
+console.log(" }\n");