Re: only outbound traffic

[Andrej van der Zee <andrejvanderzee () gmail com>]

Hi,

> I have a ProCurve J9021A Switch 2810-24G and configured port A to be
> mirrored to port B. When I run tcpdump on port B, I can only see the
> outgoing traffic on port A, but no incoming traffic at all! The
> configuration menu of the switch does not have any options for egress
> and/or ingress. According to the manual, it is supposed to do both at
> all times. I also turned off all Firewalls, but still no luck. What am
> I forgetting?

Well, I experienced VLAN-tags for the first time... This solved my
problem for listening on port 3306:

tcpdump -i eth1  "(port 3306) or (vlan and port 3306)"

Is there any documentation on how libpcap/tcpdump/BPF deal with VLAN
tags? Its still a bit of a mystery to me...

Thank you,
Andrej
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