#472 - Upgrade SSH key exchange and message authentication code from SHA1 to SHA2

X2Go Bug report logs - #472
Upgrade SSH key exchange and message authentication code from SHA1 to SHA2

Reported by: Aurélien Grosdidier <aurelien.grosdidier@gmail.com>

Date: Thu, 3 Apr 2014 14:35:02 UTC

Severity: important

Found in version 4.0.1.3-1

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Date: Fri, 17 Oct 2014 08:37:41 +0000
Message-ID: <20141017083741.Horde.RkoCCGaWBHPsVWlZz-8Rcg1@mail.das-netzwerkteam.de>
From: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>
To: Michael DePaulo <mikedep333@gmail.com>
Cc: Oleksandr Shneyder <o.shneyder@phoca-gmbh.de>, 472@bugs.x2go.org, Alex
 DEKKER <bugs@ale.cx>, o.schneyder@phoca-gmbh.de
Subject: Re: [X2Go-Dev] Bug#472: Bug#472: Debian now has
 diffie-hellman-group1-sha1 disabled
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Hi Alex, hi Mike#2, On Mo 13 Okt 2014 21:33:15 CEST, Michael DePaulo wrote: > On Mon, Oct 13, 2014 at 9:34 AM, Oleksandr Shneyder > <o.shneyder@phoca-gmbh.de> wrote: >> And why is it a problem for X2Go? Is libssh not working any more? Then >> it should be fixed in libssh, not in x2go? >> >> Am 11.10.2014 22:48, schrieb Mike Gabriel: >>> Control: severity -1 important >>> >>> HI Alex (DEKKER), hi Alex (Schneyder), >>> >>> On Sa 11 Okt 2014 13:07:00 CEST, Alex DEKKER wrote: >>> >>>> As of Version: 1:6.7p1-1 of openssh-server, it appears that Debian >>>> [and presumably upstream]'s sshd now has diffie-hellman-group1-sha1 >>>> disabled. This means that connections from x2goclient will fail. >>>> >>>> I was able to work around this by adding: >>>> >>>> KexAlgorithms >>>> curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1 >>>> >>>> >>>> to /etc/ssh/sshd_config, but obviously at some point support for >>>> diffie-hellman-group1-sha1 is going to go away completely, rather than >>>> just being disabled by default. >>> >>> Thanks for bringing this up. Did not realize so far. >>> >>> @Alex Schneyder: do you think you can find a fix for this. This actually >>> is a release blocker of 4.0.3.0... And it endangers the status of X2Go >>> Client in Debian, as well. >>> >>> Mike > [...] > > Looking through the libssh git logs, it appears that libssh 0.6 was > the first version to add support for a non-sha1 key exchange method, > ecdh_sha2_nistp256 [1]. > > 0.6 also added support for curve25519-sha256@libssh.org [1]. > > In a few hours or so, I will test if using a libssh 0.6.x linked > version of x2goclient fixes this bug. > > Jessie does include libssh 0.6.3 (Thanks to our DD, Mike#1)[2]. > > -Mike#2 The issue is a non-issue on distributions with libssh 0.6.x provided. See yesterday's post of mine to x2go-user [1]. Mike [1] http://permalink.gmane.org/gmane.linux.terminal-server.x2go.user/2368 -- DAS-NETZWERKTEAM mike gabriel, herweg 7, 24357 fleckeby fon: +49 (1520) 1976 148 GnuPG Key ID 0x25771B31 mail: mike.gabriel@das-netzwerkteam.de, http://das-netzwerkteam.de freeBusy: https://mail.das-netzwerkteam.de/freebusy/m.gabriel%40das-netzwerkteam.de.xfb

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X2Go Bug report logs - #472 Upgrade SSH key exchange and message authentication code from SHA1 to SHA2

X2Go Bug report logs - #472
Upgrade SSH key exchange and message authentication code from SHA1 to SHA2