From owner-freebsd-net Sun Jan 13 9: 1:38 2002 Delivered-To: freebsd-net@freebsd.org Received: from smtpzilla5.xs4all.nl (smtpzilla5.xs4all.nl [194.109.127.141]) by hub.freebsd.org (Postfix) with ESMTP id C05C237B402 for ; Sun, 13 Jan 2002 09:01:34 -0800 (PST) Received: from grand.canyon.xs4all.nl (canyon.xs4all.nl [194.109.195.185]) by smtpzilla5.xs4all.nl (8.12.0/8.12.0) with ESMTP id g0DH1X3l018352 for ; Sun, 13 Jan 2002 18:01:33 +0100 (CET) Received: by grand.canyon.xs4all.nl (Postfix, from userid 1000) id E37955FA9; Sun, 13 Jan 2002 18:01:32 +0100 (CET) Received: from meander.tcja.nl (localhost [127.0.0.1]) by grand.canyon.xs4all.nl (Postfix) with ESMTP id AC4E05DB2 for ; Sun, 13 Jan 2002 18:01:32 +0100 (CET) Date: Sun, 13 Jan 2002 18:01:35 +0100 Mime-Version: 1.0 (Apple Message framework v480) Content-Type: text/plain; charset=US-ASCII; format=flowed Subject: Filtering packets received through an ipsec tunnel From: Rene de Vries To: net@freebsd.org Content-Transfer-Encoding: 7bit Message-Id: <3386757E-0847-11D6-882A-00039357FA7A@canyon.xs4all.nl> X-Mailer: Apple Mail (2.480) Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org Hello, > This message was already posted to hackers@freebsd.org, but with > limited success. I'm hoping that someone on net@freebsd.org can give me > some more information. By experimenting with ipsec and looking at the source of "ip_input.c" a co-worker and I found the following out. When a ipsec tunnel packet is received this (protocol 50/51) packet is passed through ip-filter (& co). After filtering and when it has been determent that the current host is the destination (tunnel end-point), this packet is decrypted/verified. The decrypted packet is then pushed back into the queue that leads to ip_input(...). So far so good.... But once in ip_input(...) the filtering code is skipped and we were wondering why. I know that ipsec has some handles to be able to filter on address, protocol and/or port. But for more complex situations this is not enough. In these situations it would be nice to be able to use ip-filter (& co) on traffic from the tunnel (and also for traffic going into the tunnel). I was wondering why this is implemented the way it is. Maybe someone on this list could shed a light on this? Rene -- Rene de Vries To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message