From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Just Keijser Date: Thu, 13 Jan 2011 01:47:06 +0000 Subject: Re: ppp / open vpn Message-Id: <4D2E599A.5030301@gmail.com> List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ppp@vger.kernel.org James Carlson wrote: > On 01/12/11 16:17, Jan Just Keijser wrote: > >> James Carlson wrote: >> >>> The whole point of a point-to-point interface (of any type; PPP, tunnel, >>> or otherwise) is that it connects two distinct IP nodes. Distinct. Not >>> one IP node to itself! >>> >>> >>> >> This is another trick of OpenVPN to assign "linear addresses" to clients >> while using a PtP (tun) interface. It is enabled in OpenVPN 2.1 (and >> openvpnas, which is based on 2.1) by using the >> topology subnet >> directive. >> > > That's simply frightening. Thanks for the update; I had no idea anyone > was relying on that sort of undocumented OS feature. > > Good luck getting a routing protocol to work reliably with that ... > > actually, this mode is not used in combination with routing protocols. 'topology subnet' is used primarily when multiple clients are connecting to a single server. OpenVPN also support a "point-to-point" mode (for lack of a better term), which does follow the regular PtP semantics. Running a routing protocol in that mode is just as easy as running one over a ppp-based link. HTH, JJK