From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.2 Received: from minnie.tuhs.org (minnie.tuhs.org [45.79.103.53]) by inbox.vuxu.org (OpenSMTPD) with ESMTP id d0c72e0e for ; Fri, 13 Sep 2019 22:31:03 +0000 (UTC) Received: by minnie.tuhs.org (Postfix, from userid 112) id 8A87F9BA3F; Sat, 14 Sep 2019 08:31:02 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 93FBC947CD; Sat, 14 Sep 2019 08:30:49 +1000 (AEST) Received: by minnie.tuhs.org (Postfix, from userid 112) id 1C1E5947CD; Sat, 14 Sep 2019 08:30:47 +1000 (AEST) Received: from viclamta21p.bpe.bigpond.com (viclamta21p.bpe.bigpond.com [203.38.21.85]) by minnie.tuhs.org (Postfix) with ESMTPS id 3059B947C7 for ; Sat, 14 Sep 2019 08:30:45 +1000 (AEST) Received: from smtp.telstra.com ([10.10.26.4]) by viclafep21p-svc.bpe.nexus.telstra.com.au with ESMTP id <20190913223043.OXRB15610.viclafep21p-svc.bpe.nexus.telstra.com.au@smtp.telstra.com> for ; Sat, 14 Sep 2019 08:30:43 +1000 X-RG-Spam: Unknown X-RazorGate-Vade: gggruggvucftvghtrhhoucdtuddrgedufedrtdekgddtiecutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfupfevtfgpvffgnffuvffttedpqfgfvfenuceurghilhhouhhtmecugedttdenucenucfjughrpeffhffvufgjkfhffgggtgesthdttddttdervdenucfhrhhomhepffgrvhgvucfjohhrshhfrghllhcuoegurghvvgeshhhorhhsfhgrlhhlrdhorhhgqeenucfkphepuddutddrudeguddrudelfedrvdeffeenucfrrghrrghmpehhvghloheprghnvghurhhinhdrhhhorhhsfhgrlhhlrdhorhhgpdhinhgvthepuddutddrudeguddrudelfedrvdeffedpmhgrihhlfhhrohhmpeeouggrvhgvsehhohhrshhfrghllhdrohhrgheqpdhrtghpthhtohepoehtuhhhshesthhuhhhsrdhorhhgqeenucevlhhushhtvghrufhiiigvpedt X-RazorGate-Vade-Verdict: clean 0 X-RazorGate-Vade-Classification: clean X-RG-VS-CLASS: clean Received: from aneurin.horsfall.org (110.141.193.233) by smtp.telstra.com (5.8.335) id 5D48A28706EF0F2A for tuhs@tuhs.org; Sat, 14 Sep 2019 08:30:43 +1000 Received: from aneurin.horsfall.org (localhost [127.0.0.1]) by aneurin.horsfall.org (8.15.2/8.15.2) with ESMTP id x8DMUgX2029926 for ; Sat, 14 Sep 2019 08:30:42 +1000 (EST) (envelope-from dave@horsfall.org) Received: from localhost (dave@localhost) by aneurin.horsfall.org (8.15.2/8.15.2/Submit) with ESMTP id x8DMUgS7029923 for ; Sat, 14 Sep 2019 08:30:42 +1000 (EST) (envelope-from dave@horsfall.org) X-Authentication-Warning: aneurin.horsfall.org: dave owned process doing -bs Date: Sat, 14 Sep 2019 08:30:42 +1000 (EST) From: Dave Horsfall To: The Eunuchs Hysterical Society In-Reply-To: <1568412078.22454.for-standards-violators@oclsc.org> Message-ID: References: <1568412078.22454.for-standards-violators@oclsc.org> User-Agent: Alpine 2.21.9999 (BSF 287 2018-06-16) X-GPG-Public-Key: http://www.horsfall.org/gpgkey.pub X-GPG-Fingerprint: 05B4 FFBC 0218 B438 66E0 587B EF46 7357 EF5E F58B X-Home-Page: http://www.horsfall.org/ X-Witty-Saying: "chmod 666 the_mode_of_the_beast" MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Subject: Re: [TUHS] [SPAM] Re: SCCS X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" On Fri, 13 Sep 2019, Norman Wilson wrote: > UDP (and TCP) checksums are nearly useless against the sort of > corruption Larry described. Since they are a simple addition with carry > wraparound, you can insert or remove any number of word-aligned pairs of > zero octets without the checksum changing. I was thinking of an intermediate router (probably one that you never knew about) corrupting the checksum-less UDP packet, recalculating the Ethernet checksum, and your kernel happily accepting it; you now have an application that fails for some unknown reason. Never seen it in practice, but I've heard of it happening. -- Dave