Rate-limit connections

Allow max 3 new SSH connections per minute

iptables -A INPUT -p tcp --dport 22 -m state --state NEW -m limit --limit 3/min --limit-burst 5 -j ACCEPT

More iptables commands

nftables: list all rules

nft list ruleset

Show complete nftables configuration
nftables: add accept rule

nft add rule inet filter input tcp dport 8080 accept

Accept inbound TCP traffic on port 8080 in nftables
nftables: flush all rules

nft flush ruleset

Delete all nftables rules (caution: drops all firewall rules)
List rules with line numbers

iptables -L INPUT --line-numbers -n -v

Show INPUT chain rules with packet/byte counters
Allow incoming port

iptables -A INPUT -p tcp --dport 443 -j ACCEPT

Append a rule to accept inbound HTTPS traffic