Date: Fri, 18 Jan 2002 21:40:48 -0800 From: "Crist J . Clark" <cjc@FreeBSD.ORG> To: "Reto Trachsel (NetModule)" <reto.trachsel@netmodule.com> Cc: "'net@freebsd.org'" <net@FreeBSD.ORG> Subject: Re: ICMP Redirect Message-ID: <20020118214048.N40472@blossom.cjclark.org> In-Reply-To: <F58DFF990DB0D411841D000102A7CD70090C04@tigris.pacific>; from reto.trachsel@netmodule.com on Fri, Jan 18, 2002 at 11:28:12AM %2B0100 References: <F58DFF990DB0D411841D000102A7CD70090C04@tigris.pacific>
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On Fri, Jan 18, 2002 at 11:28:12AM +0100, Reto Trachsel (NetModule) wrote:
> Problem 1
> ---------
>
> If i'm doing a ping to an external address, on the router machine i can see
> two ICMP request packets:
>
> 10:41:33.868478 172.16.224.24 > 157.161.7.7: icmp: echo request
> 10:41:33.868501 172.16.224.24 > 157.161.7.7: icmp: echo request
> 10:41:34.878624 172.16.224.24 > 157.161.7.7: icmp: echo request
> 10:41:34.878664 172.16.224.24 > 157.161.7.7: icmp: echo request
> 10:41:35.890321 172.16.224.24 > 157.161.7.7: icmp: echo request
> 10:41:35.890361 172.16.224.24 > 157.161.7.7: icmp: echo request
I doubt this is a problem. Run tcpdump(1) with '-e'. One packet is
from 172.16.224.24 and the other is the one the router is generating
to forward.
> On the BSDClient it looks all right. Every ICMP request gets a reply
>
> 10:41:28.973126 172.16.224.24 > 157.161.7.7: icmp: echo request
> 10:41:28.994275 157.161.7.7 > 172.16.224.24: icmp: echo reply
> 10:41:29.978672 172.16.224.24 > 157.161.7.7: icmp: echo request
> 10:41:29.989218 157.161.7.7 > 172.16.224.24: icmp: echo reply
> 10:41:30.988690 172.16.224.24 > 157.161.7.7: icmp: echo request
> 10:41:31.004373 157.161.7.7 > 172.16.224.24: icmp: echo reply
You have not given us a clear picture of your network setup, but
again, run with '-e'. My guess is the client sees its own ping, it
_doesn't_ see the one the router forwards (a switched LAN?), and then
gets the ping back. The routing is probably asymmetric so the pongs
don't go by the above router.
But again, I don't see any problems here. Or at least this all seems
consistent.
> Problem 2
> ---------
>
> If the router isn't the default router, the ICMP Redirect will be send. But
> this ICMP Redirect Packets are not acceptet (don't create a routing table
> entry with Flag M or D) by the Hosts (Windows and BSD). Both hosts work with
> a RedHat Routing Machine.
>
> tcpdump on the Router:
> 10:57:58.838278 172.16.224.24 > 172.24.0.100: icmp: echo request
> 10:57:58.838330 172.16.224.24 > 172.24.0.100: icmp: echo request
> 10:57:58.838357 172.16.1.12 > 172.16.224.24: icmp: redirect 172.24.0.100 to
> host
> 172.16.1.252
> 10:57:59.848649 172.16.224.24 > 172.24.0.100: icmp: echo request
> 10:57:59.848683 172.16.224.24 > 172.24.0.100: icmp: echo request
> 10:57:59.848707 172.16.1.12 > 172.16.224.24: icmp: redirect 172.24.0.100 to
> host
> 172.16.1.252
You still didn't provide the info for the BSDHost. My best guess is
that it is ignoring the redirects because it does not believe that the
other host, 172.16.1.252 is local.
If this isn't the problem, I'm not sure what else to look for.
--
Crist J. Clark | cjclark@alum.mit.edu
| cjclark@jhu.edu
http://people.freebsd.org/~cjc/ | cjc@freebsd.org
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