Fedora 17: Open port for TCP connection

To open a port for TCP connection you have to edit /etc/sysconfig/iptables and append the following line before the COMMIT line

-A INPUT -m state --state NEW -m tcp -p tcp --dport <PORT> -j ACCEPT

And then restart the iptables service by executing

service iptables restart

*EDIT*
I created this post before knowing that you could actually use iptables directly as below :P :

# iptables -A INPUT -m state --state NEW -m tcp -p tcp --dport <PORT> -j ACCEPT

You should list your iptables rules first to check whether there's any DROP rule. If your new rule comes after a rule that DROPs any connection on you target port, the port you're trying to open will stay closed. If there's a DROP rule, use -I (insert) instead:

# iptables -I INPUT <rulenum> -m state --state NEW -m tcp -p tcp --dport <PORT> -j ACCEPT

where <rulenum> is the rule index in the chain. and <PORT> is your target port.

Python: Fun with sockets (remote desktop)

Server

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#!/usr/bin/python import os import socket s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.bind((HOST, PORT)) s.listen(5) client, addr = s.accept() cmd = s.recv(1024) try:     os.system(cmd)     client.sendall("OK") except:     client.sendall("FAIL") client.close()

Client

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#!/usr/bin/python import socket import sys s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((HOST, PORT)) s.sendall(sys.argv[1]) data = s.recv(32) print data s.close() print "Received: '%s'"%data