#!/usr/bin/nft flush ruleset define SSH_PORT1 = 22 define SSH_PORT2 = 8022 table ip filter { set allowed_tcp_ports { type inet_service; flags constant; elements = { $SSH_PORT1, $SSH_PORT2 }; } chain in { type filter hook input priority filter; policy drop; ct state invalid drop; ct state {related,established} accept; tcp dport @allowed_tcp_ports accept; } chain forward { type filter hook forward priority filter; policy drop; } chain out { type filter hook output priority filter; policy drop; } }