firewall with 2 ports and mask only one of the two, possible ?

Hi, I can´t find the solution for the following problem: Net 1 (10.1.0.0) | firewall / \ internet <-> ippp0 isdn0 | | internet <-> ippp0 isdn0 \ / firewall | Net 2 (10.2.0.0) I use SuSe 7.0 and the firewall should masquerade on ippp0 (for some systems) but not on isdn0. I need to allow samba on isdn0 with a list of systems between Net1 and Net2. Can this be done with kernel 2.2.16 ? Thanks J. Schläger