Advanced Policy Firewall

What Advanced Policy Firewall is

Advanced Policy Firewall (APF) is a free firewall system for Internet-deployed Linux servers, built on iptables/netfilter. It combines static rules, stateful connection policies, and checks for attack patterns and forged source IP addresses. Administrators can configure inbound and outbound filtering, including outbound rules based on users and applications. Other controls include reactive address blocking, GeoIP country filtering, and Spamhaus and DShield block lists. APF supports IPv6 dual-stack filtering with automatic ip6tables rules. Its documentation describes fast-load snapshots that can load more than 1,000 rules in under one second, as well as integrations with BFD, cron, systemd, Docker/Kubernetes, and logrotate. It requires Linux with iptables/netfilter and Bash, and supports both legacy and nft iptables backends. Documented systems include RHEL/Rocky/AlmaLinux 8 and 9, CentOS 6 and 7, Debian 12, and Ubuntu 12.04, 20.04, and 24.04. APF is distributed under GNU GPL, with no paid tiers or enterprise editions. By default, only SSH port 22 is open; outbound filtering, reactive blocking, and virtual network policies are disabled. Development mode is enabled by default and flushes the firewall every five minutes to help prevent lockout during initial configuration.