From owner-freebsd-questions Mon Apr 10 14:37:29 1995 Return-Path: questions-owner Received: (from majordom@localhost) by freefall.cdrom.com (8.6.10/8.6.6) id OAA07265 for questions-outgoing; Mon, 10 Apr 1995 14:37:29 -0700 Received: from wcarchive.cdrom.com (wcarchive.cdrom.com [192.216.191.11]) by freefall.cdrom.com (8.6.10/8.6.6) with ESMTP id OAA07227 for ; Mon, 10 Apr 1995 14:37:17 -0700 Received: from protools.com (agate.protools.ngc.com [161.69.133.118]) by wcarchive.cdrom.com (8.6.11/8.6.6) with ESMTP id OAA11514 for ; Mon, 10 Apr 1995 14:37:11 -0700 Received: from dot.protools.com (dot.protools.com [161.69.134.64]) by protools.com (8.6.9/8.6.9) with SMTP id KAA02115 for ; Mon, 10 Apr 1995 10:34:15 -0700 Received: from localhost by dot.protools.com (4.1/CF5.2L) id AA16157; Mon, 10 Apr 95 10:32:15 PDT Message-Id: <9504101732.AA16157@dot.protools.com> To: freebsd-questions@wcarchive.cdrom.com Subject: Does BSD implement TCP/IP incorrectly? Date: Mon, 10 Apr 1995 10:32:15 PDT From: Brian Smith Sender: questions-owner@FreeBSD.org Precedence: bulk I saw this in an article about the capture of Mitnick done by Simson Garfinkle. Here is the relavant excerpt: The attacker who perpetrated the initial break-in of Shimomura's machine did so with a technique called IP spoofing. Using IP spoofing, an attacking computer can masquerade as another. It is also possible, using spoofing, for an attacking computer to com- mandeer an existing connection between two computers. Although IP spoofing sounds like a new technique, it has actually been recognized and openly discussed for years. There are special provisions in the TCP/IP (Transmission Control Protocol/Internet Protocol) standard used by the Internet that are designed to make IP spoofing difficult. The problem is that the IP stack distri- buted with Berkeley Unix (and now used by most of the computer industry) doesn't implement the TCP/IP correctly. I have read the IP, UDP, and TCP RFC's and cannot recall any chunks of functionality missing in BSD TCP/IP implementation relevant to IP spoofing. Mr. Garfinkle makes it sound as if BSD TCP/IP is severely flawed. He admits that he is the not a proponent of UNIX: Face it: Unix sucks. It's a research operating system that never should have escaped from the lab. Unix is a lot of fun for hack- ers (I enjoy it myself from time to time), but it shouldn't be inflicted on millions of innocent users. It shouldn't be the basis for mission-critical operations, and it shouldn't make up the backbone of the Internet or commercial Internet providers. You might think this point of view biased. I am, after all, the editor in chief of The UNIX-HATERS Handbook. But the fact is, most IP-spoofing attacks wouldn't work if Unix implemented the IP protocols properly. Unix is an insecure operating system. We can work to make it more secure, but many ongoing computer security problems result from fundamental flaws in Unix. I really can't agree with him on his conclusion about releasing UNIX :), but I am curious about this alleged TCP/IP security hole. Any ideas? Brian (The only really secure computer is is a dysfunctional computer. I still like using computers. QED I must be a security breach. :) /-------------------------------------------------------\ | #include | brians@ngc.com | | #undef COMPANY_REPRESENTATIVE | brians@mandor.dev.com | \-------------------------------------------------------/