Sharing a Internet connection requires several distinct systems, although several OSes provide a ready made configuration that you can activate without knowing the details. IIRC, Mandrake 9 had a wizard to do this, although it didn't work for me.
At minimum you need:
- Valid networking settings on each machine (or use DHCP to automatically assign settings to the clients).
- Routing enabled on the gateway machine.
Routing can be handled by the Shorewall firewall, which Webmin provide an interface for. I don't know about Mandrake 10, but 9 used Shorewall as the default firewall. Shorewall is designed for gateway systems, so it enables routing automatically when it's switched on.
It is also useful to have:
- A DNS server (Webmin can manage BIND), although your machines could just use your ISP's DNS until you get it working.
- Squid proxy server, which makes Web access lightning quick. Again, your machines could just use your ISP's proxy, but Squid is well worth the time to set up.
For Samba I would recommend installing the samba-swat package, which is very easy. Once installed you can get to it's interface by typing this in a Web browser on the machine:
Samba has a zillion options, and the regular Webmin interface doesn't make it easy to spot the small number you actually need to set. Webmin is compatible with SWAT so you can switch later on.