Skip site navigation (1)Skip section navigation (2)
Date:      Fri, 30 Apr 1999 13:04:32 -0400 (EDT)
From:      Robert Watson <robert@cyrus.watson.org>
To:        current@freebsd.org
Subject:   dummynet: weird icmp behavior
Message-ID:  <Pine.BSF.3.96.990430125915.21181B-100000@fledge.watson.org>

next in thread | raw e-mail | index | archive | help

I have a -current install from just before egcs and am using DummyNet to
experiment with network protocols.  I've been applying the rules to the
loopback device so as to prevent other interference.  It seems to work
well, except that ICMP seems not to be working for me.  At one point in
the past, I am certain that it did work.  Here is the ruleset: 

sleipnir:/homea/robert# ipfw list
00001 pipe 5 ip from 127.0.0.1 to 127.0.0.1
00100 allow ip from any to any via lo0
00200 deny ip from any to 127.0.0.0/8
65000 allow ip from any to any
65535 deny ip from any to any

The pipe is configured:
sleipnir:/homea/robert# ipfw pipe 5 config bw 10Mbit/s delay 150ms

And ping localhost simply doesn't get any response, except once in a blue
moon when a 600ms packet turns up.
Tcpdump indicates that packets are going out but not being responded to:

tcpdump: listening on lo0
13:02:09.201061 127.0.0.1 > 127.0.0.1: icmp: echo request
13:02:10.211104 127.0.0.1 > 127.0.0.1: icmp: echo request
13:02:11.221089 127.0.0.1 > 127.0.0.1: icmp: echo request
13:02:12.231110 127.0.0.1 > 127.0.0.1: icmp: echo request
13:02:13.241125 127.0.0.1 > 127.0.0.1: icmp: echo request

When I load up tcpdump, I see:

Apr 30 13:02:28 sleipnir last message repeated 19 times
Apr 30 13:02:29 sleipnir /kernel: lo0: promiscuous mode enabled
Apr 30 13:02:29 sleipnir /kernel: looutput: af=0 unexpected

Normal UDP/TCP/etc all seem to get there fine, just not any ICMP (or at
least not pings).  For example, the ICMP port unreachable packet for
telneting to an invalid port also disappears.

Any advice here would be quite welcome :)

  Robert N Watson 

robert@fledge.watson.org              http://www.watson.org/~robert/
PGP key fingerprint: AF B5 5F FF A6 4A 79 37  ED 5F 55 E9 58 04 6A B1

Carnegie Mellon University            http://www.cmu.edu/
TIS Labs at Network Associates, Inc.  http://www.tis.com/
Safeport Network Services             http://www.safeport.com/



To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-current" in the body of the message




Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.BSF.3.96.990430125915.21181B-100000>