[NTLUG:Discuss] networking questions

[Richard Cobbe]

Hello, all.  I've got a couple of related networking questions that I'd
like some input on.  The computer in common between these two scenarios is
running a fairly stock RH6.2, kernel 2.2.16 (with the redhat patches,
though I've recompiled it).  My ethernet card is a PCI 3Com 3c905, and I'm
using the driver that's included in the kernel source: it's apparently
3Com's driver, v 1.0.0d (1999).

1) A couple of times over the last few months, I've tried to hook two
   (Linux) computers together---directly---using ethernet 10baseT.  My
   understanding is that you can do this by hooking the ethernet cards of
   the two systems together, using a crossover cable.

   It doesn't seem to work.  When I try to go from my normal system (stock
   RH6.2, kernel 2.2.16), it locks up the machine hard enough to require a
   power cycle.  At first, I thought this was because my routing table was
   messed up, so I manually removed all of the incorrect routes and added a
   specific route for the other host, going out eth0.  (I left the loopback
   and ``reflexive'' routes alone.)  Didn't help.

   Is this, in fact, possible?  If so, what am I missing?  Or do I need a
   10baseT hub?

2) Separate issue.  At one point (I don't recall exactly why I got into
   this situation), I had my system/network set up almost as normal.  The
   only difference was that the 10baseT crossover cable which normally
   connects my PC and my DSL modem wasn't plugged into the modem.

   I tried to ping some host, and the computer immediately hard-booted
   itself.

   That shouldn't have happened, yes?  Obviously, if the cable isn't
   plugged in, I shouldn't get a response, but it shouldn't hardboot the
   machine, right?

   I don't know if it matters, but the cable in question is actually two
   cables.  There's the two-foot crossover cable which came with the modem,
   then a straight-through female-female connector, then a ~25-foot patch
   cable.  The patch cable is plugged into my PC, and the crossover cable
   is (usually) plugged into the DSL modem.

Any insights as to what the story is here?

Richard