OpenBSD: PF firewall for the paranoid
by Alpha01
Block all traffic except for ssh.
/etc/pf.conf
tcp_services = "{ 22 }"
block all
pass out on em0 proto tcp to any port $tcp_services keep state
pass in on em0 proto tcp to any port $tcp_services keep state
Enabling rules:
pfctl -e ; pfctl -f /etc/pf.conf
pfctl: pf already enabled
pf