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# Next change the default port number that sshd uses (TCP:22).
# Edit the '''/etc/ssh/sshd_config''' file again, un-comment the port option and change the port number it uses from ''22'' to '''2200'''.
# <u>Restart </u> the service.
# Confirm the new port is being used with the '''netstat''' command.
# Before we can use this new port we must change our firewall to allow traffic through the new port number and block access to port 22 by issuing the command:<br /><b><code><span style="color:#3366CC;font-size:1.2em;">iptables -I INPUT -p tcp -s0/0 --dport 2200 -j ACCEPT</span></code></b><code>
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<ol><li value="1617">Finally as a system administrator you should periodically monitor your system logs for unauthorized login attempts.</li>
<li>On CentOS systems the log file that is used is '''/var/log/secure''' </li>
<li>It also logs all uses of the '''su''' and '''sudo''' commands.</li>
