opening a port on the server

[hortonhearsawho]

hello,

what is the command to open certain ports on linux. Is there a way to see what is also currently opened and if any ports are being blocked when attempted?

thank you.

 

[ChrisHirst]

Assuming iptables.

open a port:

iptables -A INPUT -p tcp --dport portnum -j ACCEPT

See existing rules

iptables -L

If you want to to log what packets are being dropped you need to explicitly deny those ports first.

http://www.thegeekstuff.com/2012/08/iptables-log-packets/

Always bearing in mind that once you start firewall logging the syslog (/var/log/messages) can get pretty BIG, pretty quickly if your server has any "well known" sites that the Internet lowlifes try to crack




Chris.

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