Ethereal-users: Re: [Ethereal-users] http content capture filter

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From: Guy Harris <gharris@xxxxxxxxx>
Date: Tue, 08 Feb 2005 12:07:27 -0800
NOEL, ANDRE wrote:

Is there any way to do a capture filter based on the HTTP data content ? I want to capture Every packet that contains the word CONNECT.

There's no general "string match" instruction in the BPF pseudo-machine used for capture filters, nor are there any backwards branches in the BPF pseudo-machines in various OS kernels (so that you can't load a pseudo-program that can loop infinitely), so there's no way to look for CONNECT at any arbitrary offset in the packet.

You can look for it at a *specific* offset in the packet, although it's not easy to construct the expression:

	http://home.insight.rr.com/procana/#Payload