Allow incoming port iptables
Append a rule to accept inbound HTTPS traffic
iptables -A INPUT -p tcp --dport 443 -j ACCEPT
more iptables
all 10 commands →
Block IP address
iptables -I INPUT 1 -s 203.0.113.5 -j DROP
NAT: masquerade outbound
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
Save and restore rules
iptables-save > /etc/iptables/rules.v4
iptables-restore < /etc/iptables/rules.v4
Delete a rule by number
iptables -D INPUT 3
Rate-limit connections
iptables -A INPUT -p tcp --dport 22 -m state --state NEW -m limit --limit 3/min --limit-burst 5 -j ACCEPT