Date: Wed, 27 Oct 2010 14:37:05 +0100 From: David Evans <dave.evans55@googlemail.com> To: FreeBSD Net <freebsd-net@freebsd.org> Subject: Re: Bridge problems, possibly due to proxy arp on Parallels Desktop Message-ID: <4CC82B01.5030404@googlemail.com>
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[ posted to freebsd-net@freebsd.org 2010-10-27 ]
More weirdness. Pinging from 192.168.0.2 (Mac OS X) to 192.168.0.220
(VPN client) and monitoring em0 on 192.168.0.8 (the VPN server bridge), I find
that each ping request generates two ICMP echo replies to two different
ethernet addresses. Here is the tcpdump:
------
Script started on Wed Oct 27 13:41:29 2010
tcpdump -i em0 -ne icmp
tcpdump: WARNING: em0: no IPv4 address assigned
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on em0, link-type EN10MB (Ethernet), capture size 96 bytes
13:43:05.556768 00:1d:4f:fa:f4:a0 > 00:bd:e5:22:02:00,
ethertype IPv4 (0x0800), length 98: 192.168.0.2 > 192.168.0.220:
ICMP echo request, id 50437, seq 0, length 64
13:43:05.557318 00:bd:e5:22:02:00 > 00:1c:42:01:3f:6c,
ethertype IPv4 (0x0800), length 98: 192.168.0.220 > 192.168.0.2:
ICMP echo reply, id 50437, seq 0, length 64
13:43:05.557318 00:bd:e5:22:02:00 > 00:1d:4f:fa:f4:a0,
ethertype IPv4 (0x0800), length 98: 192.168.0.220 > 192.168.0.2:
ICMP echo reply, id 50437, seq 0, length 64
3 packets captured
4 packets received by filter
0 packets dropped by kernel
Script done on Wed Oct 27 13:43:51 2010
---------
I don't have a rational explanation for this, but I think I may be chasing
two bugs. Bug 1. The FreeBSD bridge assigns the ethernet address for the
VPN client to the wrong interface unless told to do otherwise with a static
assignment. Bug 2. The Desktop bridge changes the destination ethernet
address of arp replies coming from NICs on the other side of the bridge
that are connected to a physical network ( the NICs that are plugged into
the Netgear router.) Normally this would not matter.
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