[Tfug] Kernel Recompile for Network

[Michael Stenner]

On Mon, May 31, 2004 at 06:41:58PM -0700, Charles Kiss wrote:
> I've got a separate machine, named "server" running OpenBSD as a firewall, 
> and am pinging both the inward (ne1) and outward (ne3) card from "server".  
> I have a Debian workstation, named "home," and it can ping it's card 
> (eth0). Server can ping outside the network, but can't ping Home.  And 
>  Home can't ping Server (even though, somehow it picked up the DNS server 
> IP's, as they show in the routing table).

In the routing table?  Like, the output of /sbin/route ?  Or do you
mean /etc/resolve.conf ?

There are really 3 ways that "home" might get the dns servers:
  1) you insert them manually
  2) it still has them from a previous config and hasn't reset them
  3) it got them through dhcp

What does ping return?  "No route to host"?  Nothing?  Be sure to
check your firewall rules.  You may be accidentally denying ping
access.  You might try other things like a direct telnet to some port
you think is open.  I also find packet sniffers very helpful when
troubleshooting network problems.

> A long time ago, Debian was compiled to use dhcp, I think this means it's 
> listening for IP traffic when it boots up, but now it's plugged into ne1 (a 
> new sub-network, that I imagine isn't passing TCP/IP).  Does this mean I 
> must recompile the kernel to enable the new network support?  How do I do 
> this?  Or do I bridge the cards ne1 and ne3, allow some IP traffic, then 
> reboot the workstation?  Or neither, or both.

DHCP is a protocol on top of standard tcp/ip networking.  No kernel
modification is required to go back and forth between DHCP and
static.  Static simply means you hand-set the ip address, netmask, dns
servers, etc.  When you use DHCP, the client broadcasts a request
looking for a DHCP server.  If you have a DHCP server on the network,
it will (barring firewall rules or configuration forbidding it) reply
and tell the client all of the networking details that you would
otherwise hand-set.  That's really all there is to it.

So, no.  If you previously used dhcp and now don't, you do not need
to recompile your kernel.  You'll need to turn off DHCP and set those
parameters manually.  I don't know how that's done in debian these
days.  It's a very common task, though, so I would expect there to be
a helper tool or a document somewhere.  Search on "DHCP" and
"static".

					-Michael

-- 
  Michael D. Stenner                            mstenner at ece.arizona.edu
  ECE Department, the University of Arizona                 520-626-1619
  1230 E. Speedway Blvd., Tucson, AZ 85721-0104                 ECE 524G