Mac wont connect to internet with ipcop

[AMD_Gamer]

i setup an ipcop box last night, not my first time i have used ipcop before as my firewall but this is the first time i have a mac on the network, all my other computers work fine but not the iMac running OSX, it gets an ip via the ipcop DHCP server and i can ping and all that over my network but the mac has no outside internet connectivity, i dont know much about Macs it is my parents but i did find in the system options the network config screen and everything looks good to me?

any ideas?

also when i first set it up last night it worked fine but when i woke up this morning it stopped working?

 

[AMD_Gamer]

i fixed it, in the network setup screen for the mac/osx there is a box for DNS server, it says it is optional but when i put in 192.168.1.1 for my ipcop box it started to work.

not sure why the dhcp server did not fill that in or whatever?