Q I have four computers at home and one of them is acting as a router. This computer has Mandriva Linux 2005 and two network cards installed. It connects to the ISP with eth0 using a static IP address, while eth1 is sharing internet with the other three computers through the internet connection sharing utility in the Mandriva Control Center. I would like to enable some services on the client computers that require port forwarding from the router - for example, forward port 22 access to the public address to port 22 on a particular local address. How is this done? Are there any easy step-by-step instructions on how to do this, and continue using Mandriva's easy internet connection sharing utility?
A Mandriva's internet connection sharing setting in the Control Center only allows for basic connection sharing, not for running a full router. here are alternatives that will do what you want, though: Firestarter is probably best for your needs. This handles connection sharing, port forwarding and a firewall, all from a simple GUI. Firestarter is in the Mandriva contrib repository. If you have not already added this to your sources in Mandriva Control Center, go to http://easyurpmi.zarb.org and follow the instructions to add a contrib repository (add a PLF repository while you are there). Now install Firestarter from the Control Center and fire it up (sorry). If there is not a menu entry for it, run it from a terminal as root.
The Firestarter wizard will offer to set up internet connection sharing for you, which you should accept, so disable the Mandriva connection sharing first. Now click on the Policy tab, click in the bottom section of the window and select Add Rule. For standard services, like SSH, simply select it from the drop-down at the side of the Name box and give the IP address you wish to forward to. Click Apply Policy and it's done. Finally, go into Mandriva Control Center > System > Services and make sure Firestarter is set to run on boot-up - this should have been done when you installed - and your port forwarding will always be available. Check the Firestarter documentation for other options. As you have it installed, you can use it for your firewall too, it provides more control than the Control Center firewall.