Internet Problems

[der Mouse]

In article <17023 at adm.ARPA>, clapper at nadc.arpa (Brian M. Clapper) writes:
> I am trying to set up a gateway between two LANs, and I'm having some
> difficulties [...].  [Machines are two Ultrix 2.0-1 VAXen and a
> Sun-3/160 on class C addressed Ethernet; one VAX has a point-to-point
> link with class B adresses.]

> [the Ethernet]
> 	192.9.200.6	sun
> 	192.9.200.50    vax1
> 	192.9.200.51	vax2
> [the p-to-p link]
> 	130.1.0.50	vax1alias
> 	130.1.0.1	remotevax

> I'm trying to set up 'vax1' as a gateway,

In order to make this work, you need:

- vax1 needs to be willing to forward packets it receives destined for
  the "other" network.
- remotevax needs to know to send packets for 192.9.200.* to 130.1.0.50.
- sun and vax2 need to know to send packets for 130.1.*.* to
  192.9.200.50.

> When I attempted to connect directly to 'remotevax' from the Sun, the
> system responded with the message 'network is unreachable'.

Aha.  What happens is effectively this.  The Sun kernel is handed a
packet addressed to 130.1.0.1.  It tries to figure out what to do with
it.  First it looks for a route to 130.1.0.1 explicitly; it doesn't
find one.  Then it looks for a route to 130.1 and doesn't find that
either.  Then it looks for a route to 0.0.0.0 (aka "default") and fails
there too.  Then it refuses to send the packet, with error ENETUNREACH,
Network is unreachable.

> What am I missing?

Routes, most likely.

I'd suggest setting up routed on all your machines.  (I'd suggest
gated, the more modern thing, except that you almost certainly don't
have it.  And since you clearly aren't connected to the Internet, I
don't know any easy way for you to get it.)

First though, just to make sure that's the problem:

	sun# /usr/etc/route add remotevax vax1 1

	vax2# /etc/route add remotevax vax1 1

	remotevax# /etc/route add sun vax1alias 1
	remotevax# /etc/route add vax2 vax1alias 1

and see if it works better.  (I think I have /etc and /usr/etc right,
but I'm not sure.  If they aren't where I suggest, poke around.)

If this isn't it, I don't know what's wrong.  I'd have to have a closer
look.  Good luck.

					der Mouse

			old: mcgill-vision!mouse
			new: mouse at larry.mcrcim.mcgill.edu