Date: Wed, 2 Aug 2000 19:49:01 +0300 From: Ruslan Ermilov <ru@FreeBSD.ORG> To: Archie Cobbs <archie@whistle.com> Cc: Charles Mott <cmott@scientech.com>, Erik Salander <erik@whistle.com>, net@FreeBSD.ORG, Julian Elischer <julian@elischer.org>, Brian Somers <brian@Awfulhak.org>, Eivind Eklund <perhaps@yes.no> Subject: Re: Improved PPTP support for libalias(3) Message-ID: <20000802194901.D36141@sunbay.com> In-Reply-To: <200008021625.JAA81509@bubba.whistle.com>; from archie@whistle.com on Wed, Aug 02, 2000 at 09:25:13AM -0700 References: <20000802112458.B38876@sunbay.com> <200008021625.JAA81509@bubba.whistle.com>
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On Wed, Aug 02, 2000 at 09:25:13AM -0700, Archie Cobbs wrote: > 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 > > > <sourceIP, CallID>. 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. > Sorry, I misinterpreted your explanation. But I still do not understand why there is such a limitation in PPTP, can you see any sense here? -- Ruslan Ermilov Oracle Developer/DBA, ru@sunbay.com Sunbay Software AG, ru@FreeBSD.org FreeBSD committer, +380.652.512.251 Simferopol, Ukraine http://www.FreeBSD.org The Power To Serve http://www.oracle.com Enabling The Information Age To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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