iptables

iptables⚑

Usage⚑

Allow from range from an interface to an specific port⚑

iptables -A INPUT -p tcp -i -s --dport -j ACCEPT

(https://serverfault.com/questions/161401/how-to-allow-a-range-of-ips-with-iptables)

Install⚑

iptables-persistent⚑

When installed, it will save the current rules. If you want to save more afterwards, you have to manually save them:

iptables-save >/etc/iptables/rules.v4

(https://unix.stackexchange.com/questions/125833/why-isnt-the-iptables-persistent-service-saving-my-changes)

Tips⚑

Clear all rules and allow all traffic⚑

iptables -F
iptables -X
iptables -t nat -F
iptables -t nat -X
iptables -t mangle -F
iptables -t mangle -X
iptables -P INPUT ACCEPT
iptables -P FORWARD ACCEPT
iptables -P OUTPUT ACCEPT

(https://www.adminsehow.com/2009/08/how-to-clear-all-iptables-rules/)