Running an SSH server with an ipchains firewall

• To run the openssh server, use service sshd start. Add it to your boot time services with chkconfig --add sshd. (The sshd rc script is part of the OpenSSH rpm)
• Now we need to allow connections to port 22, so that you can connect from elsewhere. Add the following line to your ipchains.sh script (before the final reject all rule):

  #allow ssh connections
  ipchains -A input -j ACCEPT -i eth0 -s any/0 --dport 22 -p tcp
  

  Then rerun the script and save the rules (as discussed before). (Note that this works for any service, just replace the port number)
• You can fine tune allowed hosts by replacing -s any/0 with any IP address (or range of IP addresses, see the ipchains manual). Or use tcpwrappers to provide further access control (/etc/hosts.{allow,deny}).