Network isolation tool for monitoring and restricting HTTP/HTTPS requests from processes

jail creates an isolated network environment for target processes, intercepting all HTTP/HTTPS traffic through a transparent proxy that enforces user-defined allow rules.

• 🔒 Process-level network isolation - Linux namespaces, macOS process groups
• 🌐 HTTP/HTTPS interception - Transparent proxy with TLS certificate injection
• 🎯 Wildcard pattern matching - Simple * wildcards for URL patterns
• 📝 Request logging - Monitor and log all HTTP/HTTPS requests
• 🖥️ Cross-platform - Native support for Linux and macOS
• ⚡ Zero configuration - Works out of the box with sensible defaults
• 🛡️ Default deny-all - Secure by default, only allow what you explicitly permit

# Build the tool go build -o jail . # Allow only requests to github.com ./jail --allow "github.com" -- curl https://github.com # Allow full access to GitHub issues API, but only GET/HEAD elsewhere on GitHub ./jail \ --allow "github.com/api/issues/*" \ --allow "GET,HEAD github.com" \ -- npm install # Default deny-all: everything is blocked unless explicitly allowed ./jail -- curl https://example.com

jail uses simple wildcard patterns for URL matching.

--allow "pattern" --allow "METHOD[,METHOD] pattern" 

• If only a pattern is provided, all HTTP methods are allowed
• If methods are provided, only those HTTP methods are allowed (case-insensitive)
• Patterns use wildcards: * (matches any characters)

# Basic patterns jail --allow "github.com" -- git pull # Wildcard patterns jail --allow "*.github.com" -- npm install # GitHub subdomains jail --allow "api.*" -- ./app # Any API domain # Method-specific rules jail --allow "GET,HEAD api.github.com" -- curl https://api.github.com

Default Policy: All traffic is denied unless explicitly allowed.

# Monitor all requests with info logging jail --log-level info --allow "*" -- npm install # Debug logging for troubleshooting jail --log-level debug --allow "github.com" -- git pull # Error-only logging jail --log-level error --allow "*" -- ./app

Log Levels:

• error: Shows only errors
• warn: Shows blocked requests and errors (default)
• info: Shows all requests (allowed and blocked)
• debug: Shows detailed information including TLS operations

When a request is blocked, jail provides helpful guidance:

🚫 Request Blocked by Jail Request: GET / Host: google.com Reason: No matching allow rules (default deny-all policy) To allow this request, restart jail with: --allow "google.com" # Allow all methods to this host --allow "GET google.com" # Allow only GET requests to this host For more help: https://github.com/coder/jail 

Linux:

• Linux kernel 3.8+ (network namespace support)
• iptables
• Go 1.21+ (for building)
• sudo access

macOS:

• macOS 10.15+ (Catalina or later)
• pfctl (included)
• Go 1.21+ (for building)
• sudo access

git clone https://github.com/coder/jail cd jail go build -o jail .

jail automatically generates a Certificate Authority (CA) to intercept HTTPS traffic:

• CA stored in ~/.config/jail/ (or $XDG_CONFIG_HOME/jail/)
• CA certificate provided via JAIL_CA_CERT environment variable
• Certificates generated on-demand for intercepted domains
• CA expires after 1 year

jail --no-tls-intercept --allow "*" -- ./app

jail [flags] -- command [args...] OPTIONS: --allow <SPEC> Allow rule (repeatable) Format: "pattern" or "METHOD[,METHOD] pattern" --log-level <LEVEL> Set log level (error, warn, info, debug) --no-tls-intercept Disable HTTPS interception -h, --help Print help 

# Build go build -o jail . # Test go test ./... # Cross-compile GOOS=linux GOARCH=amd64 go build -o jail-linux . GOOS=darwin GOARCH=amd64 go build -o jail-macos .

MIT License - see LICENSE file for details.