Here are some quick IPtables’ commands :-
To list the rules related to a particular IP Address:
iptables -L -n | grep (IP Address)
To insert a rule ( block) :
iptables -I INPUT -s (IP) -j DROP
To insert a rule ( allow) :
iptables -I INPUT -s (IP) -j ACCEPT
To delete a rule :
iptables -D INPUT -s (IP) -j DROP
To block access to a particular port :
iptables -A INPUT -s (IP) -p tcp –destination-port (port number) -j DROP
To see the number of connections to ‘http’ :
netstat -nap | grep :80 | wc –l
To show total no: of connections per IP
netstat -ntu | awk ‘{print $5}’ | cut -d: -f1 | sort | uniq -c | sort –n
To flush iptables :
iptables -F
Note: The above load the chains/rules into the ram memory only and won’t hold after a server reboot. You must run the ‘save’ command in order to keep your settings.
service iptables save
