I'm having trouble configuring the firewall in Mandrake 9.0. I haven't quite made sense of shorewall's rules or iptables yet, so I took the quick route in drakconf by simply denying access to all services that are options (web server, ftp, ssh, etc) and in the additional ports allowed tcp and udp on 137, 138, and 139 so that samba would still work over my lan...but the other machines on the network cant access my machine unless I turn the firewall off. I thought allowing tcp and udp on those ports would be sufficient. Was I wrong?? All I need to do is block everything except what is needed to access the samba share on my pc over the lan.

Does your firewall log blocked packets? If so, it might tell you what is hosed. Of course using a packet sniffer would be way quicker.

Can those machines ping your machine when your firewall is up?

Are you accessing the machine using the IP? If not, try it -- \\ww.xx.yy.zz in the windows browser...