Troubles with networking
 

Hi guys. I built server, use Ubuntu 5.10 os. Server must be working as firewall and also share network to another worksations.
I have static ip (ex 195.50.123.90 netmask 255.255.255.224)
But i'm in trouble with broadcast and network ip's.
I understand how i cand find broadcast ip for dhcp server.
But how i can find broadcast and network ip's for ethernet ? (/etc/network/interfaces)

Well, you do not present enough information.

Are you writing a firewall or using a firewall?

Firewall default regarding the Ubuntu Sources:
firestarter
fwbuilder
shorewall

Are you trying to ask a question about how to configure a DHCP server or client?

Right click the empty part of your upper toolbar - click Add to Panel - scroll down to "Network Monitor" in the "System & Hardware" group. Drag the Network Monitor icon to the toolbar. Right click the icon and a connection properties window pops up. Enter "eth0" in Name: and the monitor is set up. Now whenever you click this icon you get the window you placed "eth0" in. The support tab will show you the IP information you seek for that PC. The icon will change while data is transferring in or out.