I would like to know the iptable command for blocking port 80???



If you have also a good link to iptable rules it would be great.


Tx.

iptables -A INPUT -p tcp --dport 80 -j DROP

Will close port 80 quite nicely. As for rule sets, do a search on iptables with the search buttons. A significant number of sets have been posted here.

If you need a tutorial on iptables, the one at FrozenTux is best.

If you want to block it out from the computer as opposed to in from the rest of the world, then change the INPUT above to OUTPUT.

B.

The principle of least priviledge says to block everything coming in by default, then add rules to allow the services you want make available.

Let's say you want to allow connection to only your email server. Create a chain that can be appended to both the INPUT and FORWARD chains in the filter table. Here's how you set things up:

iptables --table filter --new-chain myrules

iptables --table filter \
--append myrules \
--protocol tcp \
--destination-port 25 \
--match state \
--state NEW \
--jump ACCEPT

iptables --table filter \
--append myrules \
--match state \
--state NEW,INVALID \
--jump DROP

iptables --table filter \
--append INPUT \
--jump myrules

iptables --table filter \
--append FORWARD \
--jump myrules