tcpdump/bpf and seeing .1q tags

Charlie Schluting charlie at schluting.com
Wed Mar 9 12:30:54 PST 2005


Charles Swiger wrote:
> On Mar 9, 2005, at 2:22 PM, Charlie Schluting wrote:
>> More importantly, I'm trying to figure out if a bpf read will see them 
>> as well. Any insight on this?
> 
> 
> Yes, or it will if you use promisc mode and an appropriate BPF filter:
> 

So promisc is enabled in my case.

This seems to imply that the bpf will always see the vlan tags. (I don't want 
to.. that was the point of my question)

I believe this is starting to make sense. Thanks for your reply.

-Charlie


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