[K12OSN] How to convert a server from two NICs to one NIC

[Petre Scheie]

What's the best way of converting a two-NIC server to a single NIC?  Or 
more precisely, moving the DHCP service from eth0 to eth1?

I've got a two-NIC server that is having trouble using the DNS info 
coming from a Linksys WRT54G which is connected to the internet.  Here's 
a crude diagram:

Internet---Linksys---ltsp server---switch---clients
             |
             |---clients



  My plan is to switch them around so the server is connected to the 
internet (there's a firewall in between there) and use the Linksys as 
just a WAP by not plugging anything into its upstream port.  Not being 
certain I can make this work, I may have to leave the Linksys as the 
primary internet gateway, and just turn off its DHCP service, and let 
the ltsp server provide DHCP.  In this case, I don't want the ltsp 
server to act as a gateway; rather, I'll need it to be/act like a 
single-nic server and still point to the Linksys as the default gateway. 
  The server's already running and providing file and print services, so 
I don't want to rebuild it.  If I have to go this route, I think it's 
just a matter of having the ltsp server's DHCP service running on eth1 
instead of eth0 where it is now.  Can I make that happen by just 
changing all the addresses using in /etc/dhcpd.conf?

Petre