I’ve built Meds, a high-performance Linux firewall written in Golang, integrating with Netfilter NFQUEUE. It inspects inbound packets in user space and blocks malicious traffic in real time — completely lock-free and built for speed.

Key features:

- NFQUEUE-based packet interception

- Lock-free packet pipeline using atomic ops only

- Per-IP token bucket rate limiting

- TLS SNI & JA3 fingerprint filtering

- Blacklist/whitelist (FireHOL, Spamhaus, Abuse.ch, StevenBlack)

- Prometheus metrics ready

- HTTP API for runtime configuration (add/remove IPs/domains)

Repo: https://github.com/cnaize/meds

Any feedback is very welcome!