You can see a demo here
Firegex is a firewall that includes different functionalities, created for CTF Attack-Defense competitions that has the aim to limit or totally deny malicious traffic through the use of different kind of filters.
What you need is a linux machine and docker ( + docker-compose )
# One-command installer (works for both Docker and standalone modes)
sh <(curl -sLf https://pwnzer0tt1.it/firegex.sh)With this command you will download firegex.py, and run it, it will require you the password to use for firegex and start it with docker-compose
Or, you can start in a similar way firegex, cloning this repository and executing this command
python3 run.py start --prebuiltWithout the --prebuilt flag, it will build the docker image from source, which may take longer.
If Docker is not available or you're running it in a rootless environment, Firegex can run in standalone mode. The one-command installer above also works for standalone mode and will automatically detect and use standalone mode when Docker is unavailable or in rootless mode.
sh <(curl -sLf https://pwnzer0tt1.it/firegex.sh)
# Or manually force standalone mode:
python3 run.py start --standalone
# Or directly using the one-command installer:
sh <(curl -sLf https://pwnzer0tt1.it/firegex.sh) --standalone
# Check status
python3 run.py status [--standalone]
# Stop standalone mode
python3 run.py stop [--standalone]Standalone mode automatically:
- Downloads pre-built rootfs from GitHub releases
- Detects your architecture (amd64/arm64)
- Sets up chroot environment with necessary bind mounts
- Runs as a background daemon process
- Manages PID files for process control
If the server is restarted, docker mode will automatically restart the service, while standalone mode will require you to run the start command again manually.
Cloning the repository run.py will automatically build the docker image of firegex from source, and start it. Image building of firegex will require more time, so it's recommended to use the version just builded and available in the github packages. This is default behaviour if run.py is not in the firegex source root directory.
By default firegex will start in a multithread configuration using the number of threads available in your system. The default port of firegex is 4444. At the startup you will choose a password, that is essential for your security. All the configuration at the startup is customizable in firegex.py or directly in the firegex interface.
run.py has a dedicated config subcommand to inspect or change the persisted settings (port, host, socket dir, allowed IPs, password) without needing to stop or rebuild firegex:
# Show the current configuration
python3 run.py config --show
# Change the port/host firegex will bind to on the next start
python3 run.py config --port 8080 --host 0.0.0.0
# Reset the password of an already-running instance
# (omit the value to be prompted for it interactively instead)
python3 run.py config --password newpasswordThis is especially useful if you lost the current password: it's applied directly to the running instance (or the standalone rootfs) without requiring the old one.
- Netfilter Regex: filtering using NFQUEUE with nftables uses a c++ file that handle the regexes and the requests, blocking the malicius requests. PCRE2 regexes are used. The requests are intercepted kernel side, so this filter works immediatly (IPv4/6 and TCP/UDP supported)
- Firewall Rules: create basic firewall rules to allow and deny specific traffic, like ufw or iptables but using firegex graphic interface (by using nftable)
- Hijack Port to Proxy: redirect the traffic on a specific port to another port. Thanks to this you can start your own proxy, connecting to the real service using the loopback interface. Firegex will be resposable about the routing of the packets using internally nftables
- Netfilter Proxy: uses nfqueue to simulate a python proxy, you can write your own filter in python and use it to filter the traffic. There are built-in some data handler to parse protocols like HTTP, and before apply the filter you can test it with fgex command (you need to install firegex lib from pypi).
- TLS Decryption: a decrypt-and-reinspect bridge for services that speak TLS natively. It transparently terminates the public TLS connection, exposes the decrypted traffic on a loopback port so a Netfilter Regex/Proxy service can inspect it, then re-encrypts before forwarding to the real backend.
Firegex can also be restricted to accept connections only from a set of trusted CIDR ranges (--allowed-ips, optionally combined with --proxy-ip-header when running behind a reverse proxy) — see python3 run.py start -h.
To delegate access control entirely to a reverse proxy, start Firegex with --unsafe-disable-auth:
python3 run.py start --host 127.0.0.1 --unsafe-disable-auth -P 'a-password-for-later'This disables Firegex's password, JWT, and Socket.IO authentication: every request that reaches Firegex is a full administrator, so bind it to loopback, a Unix socket, or otherwise make sure nothing but the proxy can reach it. Requests forwarded by the proxy, including headers such as X-Forwarded-For, reach Firegex normally. Use --no-unsafe-disable-auth to turn the built-in authentication back on.
A few things worth knowing before using it:
- The setting is persisted in
.firegex-conf.json, like--portor--allowed-ips: a later plainpython3 run.py startkeeps authentication disabled until you pass--no-unsafe-disable-auth. Every start prints a banner while it is active, andpython3 run.py config --showreports it. - Set a password anyway (
-P, or laterpython3 run.py config --password). It is unused while authentication is disabled, but it is what you fall back on if you re-enable it. Without one,--no-unsafe-disable-authbrings Firegex up in its initial-setup state, where anyone who can reach it chooses the password. - The password cannot be changed over the API while authentication is disabled (
/api/login,/api/set-passwordand/api/change-passwordanswer403) — otherwise an anonymous caller could plant a credential that keeps working once authentication is back on.python3 run.py config --passwordstill works, since it writes to the database from the host. --allowed-ipsis not a substitute for the proxy's access control. Combined with--proxy-ip-headerit trusts a client-supplied header, so it only holds up if the proxy overwrites that header and nothing else can reach the port directly.
Each module above has its own markdown guide under docs/, covering how to use it and how it works internally. The same files are rendered directly in the Firegex web interface (via the docs button on each page), so they're always in sync with what you see in the app.
Heres a brief description about the firegex structure:
More specific information about how Firegex works, and in particular about the nfproxy module, are available here (in italian only): https://github.com/domysh/engineering-thesis (PDF in the release attachments)
Firegex should not slow down the traffic on the network. For this the core of the main functionalities of firegex is a c++ binary file.
Firegex must not become a problem for the SLA points! This means that firegex is projected to avoid any possibility to have the service down. We know that passing all the traffic through firegex, means also that if it fails, all services go down. It's for this that firegex implements different logics to avoid this. Also, if you add a wrong filter to your services, firegex will always offer you a fast or instant way to reset it to the previous state.
Initiially the project was based only on regex filters, and also now the main function uses regexes, but firegex have and will have also other filtering tools.
- Copyright (c) 2022-2026 Pwnzer0tt1