From owner-freebsd-hackers@FreeBSD.ORG  Thu Jul 10 14:13:52 2003
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Date: Wed, 09 Jul 2003 12:18:01 +0300
From: Alin-Adrian Anton <aanton@reversedhell.net>
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Subject: tcp raw socket programming recvfrom()
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Hey folks,

I wrote my piece of code to play with, and it uses raw sockets to send 
TCP packets. It sends packets okay, everything tested with a sniffer, 
everything is really really fine, but it seems I cannot recvfrom 
anything. I mean, it just keeps waiting and doesn't see the reply the 
server is actually sending (can be seen with a sniffer). I read that the 
freebsd kernel does not duplicate any incoming TCP/UDP packets to any of 
the opened raw sockets. Is that true? So the only solution is to use the 
interface in promiscuous mode and sniff like a sniffer for the expected 
packet? Is there any other way?

PS: ICMP gets received well with recvfrom (tested).

On Linux, it does work for tcp/udp too with recvfrom.


I was also wondering if anyone could help me understand why this 
behaviour in freebsd? (or *BSD)

Thanks!

Best Regards,
Alin.