From owner-freebsd-net Wed Aug 2 9:25:18 2000 Delivered-To: freebsd-net@freebsd.org Received: from bubba.whistle.com (bubba.whistle.com [207.76.205.7]) by hub.freebsd.org (Postfix) with ESMTP id 6FDDD37B5A6; Wed, 2 Aug 2000 09:25:15 -0700 (PDT) (envelope-from archie@whistle.com) Received: (from archie@localhost) by bubba.whistle.com (8.9.3/8.9.3) id JAA81509; Wed, 2 Aug 2000 09:25:13 -0700 (PDT) (envelope-from archie) From: Archie Cobbs Message-Id: <200008021625.JAA81509@bubba.whistle.com> Subject: Re: Improved PPTP support for libalias(3) In-Reply-To: <20000802112458.B38876@sunbay.com> from Ruslan Ermilov at "Aug 2, 2000 11:24:58 am" To: Ruslan Ermilov Date: Wed, 2 Aug 2000 09:25:13 -0700 (PDT) Cc: Archie Cobbs , Charles Mott , Erik Salander , net@FreeBSD.ORG, Julian Elischer , Brian Somers , Eivind Eklund X-Mailer: ELM [version 2.4ME+ PL68 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org Ruslan Ermilov writes: > > > > Is this a limitation of a specific server implementation, or > > > > a limitation of the PPTP standard? > > > > > > It's simply a limitation in our address translation module for PPTP. > > > There's nothing implied wrong with the standard itself or the server > > > implementation. > > > > > > This limitation could be eliminated with more coding, but it's > > > somewhat ugly (you have to make two TCP streams appear as one). > > > > Sorry, I may have misinterpreted your question... > > > > It is inherent in the PPTP standard that there be at most ONE > > PPTP TCP control connection between any two IP addresses. > > > > If you think about it for a second you can see why: when a machine > > receives a GRE packet, it identifies the call using the pair > > . That means that there can be at most ONE entity > > living at sourceIP doling out CallID's for calls to the local > > machine/IP address.. otherwise CallID's would not be guaranteed > > to be unique. > > This is all right, except libalias(3) is supposed to intercept > outgoing PPTP call requests messages and alias CallID to be unique, > see AliasHandlePptpOut(). Sorry, I don't understand your point... libalias already does this fine, that's not the problem. The problem is that two internal clients connecting to the same external server at the same time will result in two TCP connections to the same server seeming to come from the same IP address, which violates the protocol. -Archie ___________________________________________________________________________ Archie Cobbs * Whistle Communications, Inc. * http://www.whistle.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message