Re: tcpdump on tap100: no packets shown, even though they arrive/get replied to

[Robert Swindells <rjs%fdy2.demon.co.uk@localhost>]

Hugo Silva wrote:
>Just noticed this;
>
>15:18:05.215970 00:16:3e:be:ef:03 f2:0b:a4:63:80:03 0800 98:
>172.16.99.203 > 172.16.99.133: icmp: echo request
>15:18:05.216021 f2:0b:a4:63:80:03 00:16:3e:be:ef:03 0800 98:
>172.16.99.133 > 172.16.99.203: icmp: echo reply
>
>That's on machine B.
>
>On machine A (the one replying to the ping), # tcpdump -peni tap100
>
>tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
>listening on tap100, link-type EN10MB (Ethernet), capture size 65535 bytes
>
>machine A is a 5.99.55 kernel+world built  Tue Aug 23 12:05:48 UTC 2011,
>tap100 is on bridge3 which is passed as an interface to machine B (a Xen
>domU).

What are the ifconfig outputs on the "machines" in question ?

>Shouldn't the ping reply appear on tap100 @ the host ?

Nope.

You *really* don't want to send any packets that use the ethernet
address of the tap device itself, they will not get bridged to
anywhere that a socket is listening.

Both tap(4) and bridge(4) do work correctly.

Robert Swindells