Ubuntu/iptables

iptables

allows you to configure network ports and more

lookup current active rules

iptables -L -n -v

remove a rule from IP Tables. Make sure to include the comment if a comment exists.

iptables -D INPUT 1
or
iptables -D INPUT -s 0.0.0.0/0 -p tcp --dport 22 -j ACCEPT
or
iptables -D INPUT -s 0.0.0.0/0 -p tcp --dport 22 -j ACCEPT -m comment --comment "limit ssh access"

specify policy default

-P INPUT DROP

allow anything from itself (loopback)

-A INPUT -i lo -j ACCEPT

allow connection from specific address, inbound, using only TCP on a specific port

-A INPUT -s ip.address -p tcp --dport 22 -j ACCEPT

add a comment to the iptables rule

-m comment --comment "limit ssh access"

allow related and established

-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

prevent packets from forwarding (like a router)

iptables -P FORWARD DROP

delete chain from iptables

iptables -X chain.name

save current IP Tables config

sudo sh -c "iptables-save > /etc/iptables.rules"

restore IP Tables config (also add this line to /etc/rc.local for it to auto run during boot)

iptables-restore < /etc/iptables.rules