From owner-freebsd-net@FreeBSD.ORG Fri May 26 20:40:08 2006 Return-Path: X-Original-To: freebsd-net@freebsd.org Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id E66C516A4CB for ; Fri, 26 May 2006 20:40:08 +0000 (UTC) (envelope-from amit.freebsd@gmail.com) Received: from py-out-1112.google.com (py-out-1112.google.com [64.233.166.183]) by mx1.FreeBSD.org (Postfix) with ESMTP id E9CC843D46 for ; Fri, 26 May 2006 20:40:07 +0000 (GMT) (envelope-from amit.freebsd@gmail.com) Received: by py-out-1112.google.com with SMTP id 39so303318pyu for ; Fri, 26 May 2006 13:40:06 -0700 (PDT) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:mime-version:content-type; b=l6tftJvryb0CGjysVo4QwIQFFuMy3HXd2p2JJC/c6DT6R5RpBSlVhjaMUplvYFVjZ9zhSX6Hh/mSpvHnSX+DyFCShtv8wuSSvbu9QfKEzcm21SL5Var9MmAM7gwyvlzwqtTY/i6OziXhhu4L9O5e4YXc6dT6nI1+f/U6vVZFQV0= Received: by 10.35.112.3 with SMTP id p3mr1217317pym; Fri, 26 May 2006 13:40:06 -0700 (PDT) Received: by 10.35.99.6 with HTTP; Fri, 26 May 2006 13:40:06 -0700 (PDT) Message-ID: Date: Fri, 26 May 2006 15:40:06 -0500 From: "Amit Mondal" To: freebsd-net@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Subject: TCP checksum X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 26 May 2006 20:40:13 -0000 Hi, Could anyone pls tell me the function freebsd provides for calculating TCP checksum. What I am doing, I am sniffing packet using divert packet and changing the destination address of the packet. Now, since TCP checksum calculation include Pseudo head (src dest IP ....) I need to recalculate TCP checksum. Is there any way to recalculate the checksum incrementally. Thanks in advance. Rgds -Amit