Thanks for your replies. So, - without --tls-auth - with tcp as the transport if we want to make openvpn purely SSL then are these the complete set of things to take care of?: 1. Move all P_CONTROL_* messages to be encapsulated in SSL 2. Stop adding reliability layer over SSL
Let's say, theoretically, that the above 2 steps are taken care of (easier said than don, for sure). Will the resulting VPN setup then pass through transparent SSL proxies unbroken? Thanks, Vineet On Fri, Mar 11, 2011 at 1:35 AM, David Sommerseth <openvpn.l...@topphemmelig.net> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On 11/03/11 10:04, Gert Doering wrote: > | Hi, > | > | On Thu, Mar 10, 2011 at 05:04:48PM -0800, Vineet Kumar wrote: > |> Also, doesn't this make openvpn different from other SSL VPNs which > |> advertise the fact that they are truly SSL? > | > | Well, OpenVPN is "truly SSL", but it's not "using https as a browser would > | do to hide the fact that there is a VPN inside"... > > Kind of. Gert is basically correct. But it is important to understand that > OpenVPN doesn't use the SSL wire protocol directly, like the majority of SSL > applications does. So all the SSL packets from OpenVPN are encapsulated in > a > kind of OpenVPN container. Which is why some strict proxies or deep packet > inspection firewalls might not allow OpenVPN traffic. > > The reason for this is that OpenVPN is primarily written for the UDP > protocol. > ~ While SSL itself is very TCP oriented. To my knowledge, there are no UDP > transport support in OpenSSL. So OpenVPN uses OpenSSL differently, > intercepting the network connections and sending the data through OpenVPN's > own network socket infrastructure. If OpenVPN's HMAC support (--tls-auth) > is > enabled, some extra bytes are added on top of the SSL packet itself. > > Of course, it would probably be possible (I have not investigated this) to > add > a feature which restricts OpenVPN to use the core SSL protocol, without > this > encapsulation on top of the SSL packets. However, when such a feature is > enabled, it would restrict the usage of TCP. In addition, the --tls-auth > feature would not be useful in at all. > > > kind regards, > > David Sommerseth > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.10 (GNU/Linux) > Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/ > > iEYEARECAAYFAk157MQACgkQDC186MBRfrqQdgCdGKarB9OcdlKSQaTxLXZIZnou > qmoAn0G/9cfGHx6+NeWk2v0agOjRJCI9 > =SOiC > -----END PGP SIGNATURE----- >
