captive-firefox

A Bash script to launch Firefox with the DNS server provided by your Wi-Fi network, making it easy to access and pass through captive portals. Inspired by @FiloSottile/captive-browser, but designed for Firefox and Linux with a few extra dependencies.

Features

• Zero-install: just copy the script
• Auto-detects Wi-Fi DNS
• Uses a private, temporary Firefox profile
• Sandboxed with firejail
• Disables JIT and WebAssembly by default for a reduced attack surface on untrusted networks

Usage

./captive-firefox.sh [OPTIONS]

Options:

• -u, --url URL URL to open (default: Firefox captive portal check)
• -i, --iface IFACE Wi-Fi interface (default: auto)
• --no-disable-jit Do not disable JIT and WebAssembly (they are disabled by default for security)
• -h, --help Show help

Example:

./captive-firefox.sh # this will work for most users
./captive-firefox.sh --iface wlan0 --url "http://example.com"

How it works

• Detects your Wi-Fi interface and DNS
• Launches Firefox in a sandbox with a temporary profile and the correct DNS

Requirements

• bash, firefox, firejail, nmcli, iw

Security

• No data is saved; all traffic uses the Wi-Fi DNS; session is sandboxed
• JIT compilation and WebAssembly are disabled by default to reduce the attack surface on untrusted networks; use --no-disable-jit to opt out

License

MIT