routing?

routing?

Post by Ta » Sat, 05 Dec 1998 04:00:00



Hi,
        I have a slight problem.  I have 3 machines.  PPro200, P133 and
laptop.  P133 also has the modem + ppp to the world.  P133 has two NICs,
one Intel Pro/100 and a NE2000 10base2.

P133   address  broadcast    netmask
----   -------  ---------    -------
ppp0 - x.y.z.1  PtP a.b.c.d   255.255.255.252 (should be 255.255.255.248
                                                have to go scream at isp)
[intel pro/100]
eth0 - x.y.z.2  x.y.z.4       255.255.255.252

[ne2000]
eth1 - x.y.z.5  x.y.z.4       255.255.255.252

/sbin/ifconfig eth0 x.y.z.2 broadcast x.y.z.4 netmask 255.255.255.252
/sbin/ifconfig eth1 x.y.z.5 broadcast x.y.z.4 netmask 255.255.255.252
/sbin/route add -host x.y.z.3 gw x.y.z.2
/sbin/route add -host x.y.z.6 gw x.y.z.5

Laptop with docking station/NE2000 running win95
==================================
       x.y.z.6  x.y.z.4       255.255.255.252

PPro200 with intel pro/100 running win95
==========================
       x.y.z.3  x.y.z.4       255.255.255.252  [tried 255.255.255.0,
                                                don't work either]

        Problem:  laptop can see the world, but ppro can't.  tcpdump
on eth0 shows pings from ppro:
03:30:26.940000 arp who-has name.of.machine tell x.y.z.3
03:30:26.940000 arp reply name.of.machine is-at 0:a0:c9:3a:fa:6a
03:26:27.170000 x.y.z.3 > x.y.z.2: icmp: echo request
03:26:27.170000 x.y.z.2 > x.y.z.3: icmp: echo reply

but if you look at the win95 box it says ping timed out.  The first ping
also generates an arp which apparently 208.142.41.2 replied to.  Ping from
the linux box on x.y.z.2 to x.y.z.3 on the win95 box don't just times out.
tcpdump don't even see an echo reply.

Telnet from ppro box generates some packets for tcpdump, but win95 still
can't see the world - can't even connect to the linux box.

I'm guessing I have one very minor mistake somewhere, right now, at 3:45am
I can't spot it.  Any help is gratefully accepted.  Thanx.

-Tai
--
Software suppliers are trying to make their software packages more
"user-friendly".  ...  Their best approach, so far, has been to take all
the old brochures, and stamp the words, "user-friendly" on the cover.
                -- Bill Gates, Microsoft, Inc.
        [Pot. Kettle. Black.]

 
 
 

routing?

Post by Vincent Zweij » Sun, 06 Dec 1998 04:00:00



||      I have a slight problem.  I have 3 machines.  PPro200, P133 and
||  laptop.  P133 also has the modem + ppp to the world.  P133 has two NICs,
||  one Intel Pro/100 and a NE2000 10base2.
||
||  P133   address  broadcast    netmask
||  ----   -------  ---------    -------
||  ppp0 - x.y.z.1  PtP a.b.c.d   255.255.255.252 (should be 255.255.255.248
||                                              have to go scream at isp)
||  [intel pro/100]
||  eth0 - x.y.z.2  x.y.z.4       255.255.255.252
||
||  [ne2000]
||  eth1 - x.y.z.5  x.y.z.4           255.255.255.252

||  /sbin/ifconfig eth0 x.y.z.2 broadcast x.y.z.4 netmask 255.255.255.252
||  /sbin/ifconfig eth1 x.y.z.5 broadcast x.y.z.4 netmask 255.255.255.252

The broadcast of eth0 is not on its subnet.  You either need x.y.z.0
or x.y.z.3 (more probable).  While you're at it, check if .4 for eth1
shouldn't be .7.

In retrospect, I'm not sure these are wrong.

||  /sbin/route add -host x.y.z.3 gw x.y.z.2
||  /sbin/route add -host x.y.z.6 gw x.y.z.5

A gateway is never an address of your own machine: forwarding packets to
yourself is a bit useless.  You want network routes to both interfaces
instead:

    /sbin/route add -net x.y.z.0 netmask 255.255.255.252 dev eth0
    /sbin/route add -net x.y.z.4 netmask 255.255.255.252 dev eth1

||  Laptop with docking station/NE2000 running win95
||  ==================================
||         x.y.z.6  x.y.z.4           255.255.255.252
||
||  PPro200 with intel pro/100 running win95
||  ==========================
||         x.y.z.3  x.y.z.4           255.255.255.252  [tried 255.255.255.0,
||                                              don't work either]

Again, .3 and .4 are not in the same subnet.  You might need .3 and .0,
respectively.

||      Problem:  laptop can see the world, but ppro can't.  tcpdump
||  on eth0 shows pings from ppro:
||  03:30:26.940000 arp who-has name.of.machine tell x.y.z.3
||  03:30:26.940000 arp reply name.of.machine is-at 0:a0:c9:3a:fa:6a
||  03:26:27.170000 x.y.z.3 > x.y.z.2: icmp: echo request
||  03:26:27.170000 x.y.z.2 > x.y.z.3: icmp: echo reply
||
||  but if you look at the win95 box it says ping timed out.  The first ping
||  also generates an arp which apparently 208.142.41.2 replied to.  Ping from
||  the linux box on x.y.z.2 to x.y.z.3 on the win95 box don't just times out.
||  tcpdump don't even see an echo reply.

The icmp echo reply is sent by the P133 to itself.  The packet loops
around until it dies of old age.  It never reaches win95.

||  I'm guessing I have one very minor mistake somewhere, right now, at 3:45am
||  I can't spot it.  Any help is gratefully accepted.  Thanx.

Misunderstanding the meaning of "gateway" in Linux, most probably.  It is
supposed to be the address of a machine that will forward packets for you.
The only gateway your P133 needs is a.b.c.d to your ISP, for forwarding
packets to Internet.

Good luck.                                                        Vincent.
--

<http://www.xs4all.nl/~zweije/>      | don't read, does anybody get burnt?"
[Xhost should be taken out and shot] |            -- Paul Tomblin on a.s.r.