Message-ID: <52147A34.7050406@...1227...> Date: Wed, 21 Aug 2013 10:28:36 +0200 From: Arne Schwabe MIME-Version: 1.0 References: <51C77F12.1090802@...515...> <5210B1EB.7000409@...1227...> <20130821072739.GG16543@...1296...> In-Reply-To: <20130821072739.GG16543@...1296...> Subject: Re: [Openvpn-devel] [PATCH] TLS versioning List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit To: Gert Doering Cc: James Yonan , "openvpn-devel@lists.sourceforge.net" -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Am 21.08.13 09:27, schrieb Gert Doering: > Hi, > > On Sun, Aug 18, 2013 at 01:37:15PM +0200, Arne Schwabe wrote: >> Am 24.06.13 01:04, schrieb James Yonan: >>> This is the TLS versioning patch as discussed in last Thursday's IRC >>> meeting. > [..] >> OpenVPN for Android already ships this change and there seem some >> incompatibility. I have a report from a user which reports that against >> his OpenVPN server (Tomato Router Firmware - OpenVPN 2.2.2): > > So if I understand the issue right, it's caused by OpenSSL 0.96 on the > server side (which is ancient, but obviously still shipping). > > I think we have three options now, and need to decide > > - tell users "this is how it is, your server side is a gaping security > hole due to ancient OpenSSL (do we have facts to back that?), get > your server upgraded!" > - not overly nice, especially if the user has no real control about > what router firmware bundlers ship > > - back out the change > - I'd rather not do that, as 2.3.x will be around for a long time, and > we *want* to be able to use higher TLS versions if possible > > - introduce a new option > --talking-to-old-server-disable-tls-nego-yes-stupid-I-know > that will run-time disable TLS negotiation, falling back to the old > code path that only does TLS 1.0 > - while making our code even more complex and adding even more option, > this would give us "higher TLS version" security, and a knob to get > back compatibility for those setups where OpenSSL on either side > is too broken to handle TLS 1.1 or 1.2 > - we could name this option "--tls-max-version", to complement the > existing --tls-min-version option to leave negotiation enabled, but > set bounds - from some other project, I have learned that there are > combinations of OpenSSL versions where TLS 1.0 and 1.1 negotiate > fine, but 1.2 fails (just hangs) - so that might be a more clean > approach. Add big warning to the log if used .-) > > I can neither comment on the problem nor write the code, so I can only > try to get the discussion going to fix this. > Well I am not really sure what is going on on the Tomato firmware. I build a OpenSSL 0.9.7e (0.9.7e-3sarge3 to be exact, might already have some fixes in it, Tomato has 0.9.8d) on amd64 + OpenVPN 2.2.2 and that worked against 2.4-master. Before backing out the change or adding a backward fix I would like to understand what the real problem here is. Arne Arne -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.13 (Darwin) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iEYEARECAAYFAlIUejQACgkQe8+cMNS4zRdYwACguUMi+4kMLDuKfgLVH3BScQLa Z4YAn0EItxf2cOsxKyf6deQYEbo8VAfH =0r25 -----END PGP SIGNATURE-----