From owner-freebsd-net Sun Mar 5 9:32:33 2000 Delivered-To: freebsd-net@freebsd.org Received: from binky.de.uu.net (binky.de.uu.net [192.76.144.28]) by hub.freebsd.org (Postfix) with ESMTP id 85AF937BA8B for ; Sun, 5 Mar 2000 09:32:15 -0800 (PST) (envelope-from hartung@zkom.de) Received: from zkom.de (pec-82.au1.do2.uunet.de [149.228.53.82]) by binky.de.uu.net (5.5.5/5.5.5) with ESMTP id SAA14478 for ; Sun, 5 Mar 2000 18:32:09 +0100 (MET) Message-ID: <38C299CA.E3C47051@zkom.de> Date: Sun, 05 Mar 2000 18:30:50 +0100 From: Michael Hartung Organization: ZKOM X-Mailer: Mozilla 4.08 [de] (WinNT; I) MIME-Version: 1.0 To: freebsd-net@FreeBSD.ORG Subject: Re: Answer keep-alive requests References: <38C23F61.853FEE66@zkom.de> <20000305161540.A22005@pingoo.ifn.fr> Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org Rémi Guyomarch schrieb: > On Sun, Mar 05, 2000 at 12:05:05PM +0100, Michael Hartung wrote: > > Hi Folks, > > > > a customers hardware (fucking S7 CP from Siemens) loves to emit > > keep-alive packets once a TCP-connection is established. No chance to > > turn this off (Siemens doesn’t care about RFC1122). How can I force our > > FreeBSD 3.4 system to answer these packets. Probably a switch in > > /sys/netinet/tcp_timer.c...? Compile the kernel and everything is > > fine...? > > If I read /usr/src/sys/netinet/tcp* correctly, you shouldn't have to do > anything to answer keepalive messages. In fact keepalive messages are just 0 > bytes packets which repeat the last ack sent to the peer. > > There is a few sysctl variables which allow you to customize the rate your > system *sends* those keepalive messages, but none to answer them, because > the answer is part of the normal TCP processing. > > Am I right ? :-) > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-net" in the body of the message Hi again, sounds very reasonable. Are the following tcpdumped packets keep-alive packets (Siemens says they are)? 10.64.60.100 – 103 are the Siemens S7 CPs, 10.64.60.104 is our FreeBSD 3.4 server. After a couple of these packets, not replied by 10.64.60.104, the S7 CP resets the connection. The wrong packet length (for example 0028) is a result of ethernet frame padding. Michael Hartung . . . 10:57:15.975984 10.64.60.103.callbook > 10.64.60.104.globe: . win 0 4500 0028 0194 0000 7806 b3ed 0a40 3c67 0a40 3c68 07d0 07d2 0291 2200 07fe 974e 5000 0000 4f16 0000 b6ff ffff 1011 10:57:16.078589 10.64.60.101.callbook > 10.64.60.104.globe: . win 0 4500 0028 02a3 0000 7806 b2e0 0a40 3c65 0a40 3c68 07d0 07d2 0291 21f1 07ff 303f 5000 0000 b635 0000 b6ff ffff 1011 10:57:16.080035 10.64.60.101.dc > 10.64.60.104.globe: . win 0 4500 0028 02a4 0000 7806 b2df 0a40 3c65 0a40 3c68 07d1 07d2 034b a5a8 07ff b1d0 5000 0000 b031 0000 b6ff ffff 1011 10:57:16.080885 10.64.60.100.globe > 10.64.60.104.globe: . win 0 4500 0028 03c3 0000 7806 b1c1 0a40 3c64 0a40 3c68 07d2 07d2 0428 e651 0800 8439 5000 0000 9c41 0000 b6ff ffff 1011 10:57:16.093227 10.64.60.102.callbook > 10.64.60.104.globe: . win 0 4500 0028 0196 0000 7806 b3ec 0a40 3c66 0a40 3c68 07d0 07d2 0291 2200 0801 74b3 5000 0000 71af 0000 b6ff ffff 1011 10:57:18.481166 10.64.60.100.callbook > 10.64.60.104.globe: . 337956829:337956833(4) win 0 4500 002c 03c4 0000 7806 b1bc 0a40 3c64 0a40 3c68 07d0 07d2 1424 cfdd 098e c49c 5000 0000 a9c6 0000 b6ff ffff 1011 10:57:18.482608 10.64.60.100.dc > 10.64.60.104.globe: . 357566179:357566183(4) win 0 4500 002c 03c5 0000 7806 b1bb 0a40 3c64 0a40 3c68 07d1 07d2 1550 06e3 098f b75c 5000 0000 7ed3 0000 b6ff ffff 1011 10:57:34.778487 10.64.60.103.callbook > 10.64.60.104.globe: . 43065856:43065860(4) win 0 4500 002c 0195 0000 7806 b3e8 0a40 3c67 0a40 3c68 07d0 07d2 0291 2200 07fe 974e 5000 0000 9812 0000 b6ff ffff 1011 10:57:34.881053 10.64.60.101.callbook > 10.64.60.104.globe: . 43065841:43065845(4) win 0 4500 002c 02a5 0000 7806 b2da 0a40 3c65 0a40 3c68 07d0 07d2 0291 21f1 07ff 303f 5000 0000 ff31 0000 b6ff ffff 1011 10:57:34.882509 10.64.60.101.dc > 10.64.60.104.globe: . 55289256:55289260(4) win 0 4500 002c 02a6 0000 7806 b2d9 0a40 3c65 0a40 3c68 07d1 07d2 034b a5a8 07ff b1d0 5000 0000 f92d 0000 b6ff ffff 1011 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message