From owner-freebsd-net Wed May 12 6: 4:39 1999 Delivered-To: freebsd-net@freebsd.org Received: from mailhub.scl.ameslab.gov (mailhub.scl.ameslab.gov [147.155.137.127]) by hub.freebsd.org (Postfix) with ESMTP id 461D714BFE for ; Wed, 12 May 1999 06:04:37 -0700 (PDT) (envelope-from ghelmer@scl.ameslab.gov) Received: from demios.ether.scl.ameslab.gov ([147.155.137.54]) by mailhub.scl.ameslab.gov with esmtp (Exim 1.90 #1) id 10hYhP-0007QH-00; Wed, 12 May 1999 08:05:23 -0500 Date: Wed, 12 May 1999 08:04:34 -0500 From: Guy Helmer To: boards yan Cc: freebsd-net@FreeBSD.ORG Subject: Re: Why not response? In-Reply-To: <19990512025000.29712.rocketmail@web706.mail.yahoo.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Tue, 11 May 1999, boards yan wrote: > hi, > In a program, I have to implement a function. > That is, (not a hacker's idea) > > A--------------R----------------B > 1,A tries to make a tcp connection to B. > 2,R is A's default router. > 3,When R receive A's ip packet, it just changes the ip source address > by the address of itself. > Then R sends the packets. > R pretends that it is him that wants to establish a tcp connection > with B. > 4,B receives the packets, and responds to R... > > The issue is B does response icmp packets(ping), > but does not response tcp packets > as if it regards them illegal packets and therefore discards them. This sounds a lot like what the FreeBSD natd (network address translation daemon) can do... I think we could use the output from tcpdump running on B to help you diagnose this problem. Guy Guy Helmer, Ph.D. Candidate, Iowa State University Dept. of Computer Science Research Assistant, Ames Laboratory --- ghelmer@scl.ameslab.gov Research Assistant, Dept. of Computer Science --- ghelmer@cs.iastate.edu http://www.cs.iastate.edu/~ghelmer To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message