Date: Wed, 18 Mar 1998 03:38:20 -0500 (EST) From: Robert Watson <robert@cyrus.watson.org> To: hackers@FreeBSD.ORG Subject: need a reference: data link layer packet transmission Message-ID: <Pine.BSF.3.96.980318033148.410A-100000@thithle.watson.org>
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For performance testing and bug catching, I would like to be able to "replay" tcpdump captured packet streams that were promiscuously sniffed off of a network. Using the existing tcpdump to do this is ideal, as it timestamps, etc. However, I need to be able to resend the packets over the network, and not all of the packets of interest are IP-packets. So I need to be able to manually ship these packets to the link layer for delivery (on a specific device). I know that bpf can be used for transmission as well as reception (bpfwrite), but have had a hard time finding sample source code that uses this transmission; bpf is primarily intended for listening and not deliver. The Stevens UNIX Network Programming book referred me to the rarp source code, and indeed there is a somewhat obfuscated creation of rarp replies there, but I was hoping for something a little more tutorial-like. Similarly, the man pages are not particularly talkative about the functions associated with BPF (although they due cover the structures fairly well). I do not currently have a copy of the original BPF paper, but was wondering if it was available online, or if there were other software packages I could look at for further information. While I am willing to delve into kernel source to find the answer, I would rather see some text or a package that does similar things to what I want to write. Alternatively, if such a package exists that already does what I describe, a URL to that would be great! Thanks in advance, Robert N Watson Carnegie Mellon University http://www.cmu.edu/ SafePort Network Services http://www.safeport.com/ robert@fledge.watson.org http://www.watson.org/~robert/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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