[Bug 1254085] Re: ssh fails to connect to VPN host - hangs at 'expecting SSH2_MSG_KEX_ECDH_REPLY'

[fhsm]

I'm running into hung ssh connection and it is crazy making because I'm
getting inconsistent behavior across 16.10 boxes.

I've got two newly installed 16.10 boxes ($ ssh -V: OpenSSH_7.3p1
Ubuntu-1, OpenSSL 1.0.2g  1 Mar 2016). I'll call them Box1 and Box2.
They are in in adjacent ports on switch that has not had any changes in
years and on which all other systems are functioning.

I've got four clients: one OS X 10.9 (OpenSSH_6.2p1,OSSLShim 0.9.8r 8
Dec 2011), OS X 10.11 (OpenSSH_6.9p1, LibreSSL 2.1.8), Box1, and Box2.

I can connect to Box1 from the other three clients without any problem.
Works as expected.

I can ONLY connect to Box2 from OS X 10.9 and itself (i.e. ssh
me at localhost). I cannot get to it from Box1, I cannot get to it from OS
X 10.11. I have swapped the two OS X boxes around on the network and
also the two 16.10 boxes such that I'm confident that the ability to
connect is a function of the client-server combination not the network
link between them. ssh -vvv into Box2 from all of the failing clients
hangs as above, expecting SSH2_MSG_KEX_ECDH_REPLY.

This behavior / bug is so perplexing I'm unsure of it's relevance. I see two factors of interest:
 - Two ubuntu 16.10 sshds are behaving differently despite stock config across the two;
 - The ubuntu 16.10 is unable to connect to an sshd that one of two OS X ssh clients is able to connect two.

Since the two just got installed they haven't had much time to diverge.
The only differences between box1 and box2 are: (1) box2 is a few
updates behind and (2) although both have LXD installed only box2 has
had a container launched on it. Unfortunately prior to racking only the
10.9 system had ssh-ed into these boxes.

I'm going to sit on this for now in case someone interesting in trying
to get the Ubuntu ssh client to function - or - someone curious about
the divergent behavior of the Ubuntu sshd can give guidance on how to
turn this from a odd +1 report into something more useful. If not I'll
do a little more troubleshooting (install the pending updates
[initramfs-tools initramfs-tools-bin initramfs-tools-core isc-dhcp-
client isc-dhcp-common libglib2.0-0 libglib2.0-data liblxc1 lxc-common],
purge LXD) to see if I stumble onto something useful and failing that
nuke and pave.

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to openssh in Ubuntu.
https://bugs.launchpad.net/bugs/1254085

Title:
  ssh fails to connect to VPN host - hangs at 'expecting
  SSH2_MSG_KEX_ECDH_REPLY'

Status in openssh package in Ubuntu:
  Invalid

Bug description:
  ssh -vvv <host> is failing for me where <host> is a VPN system.

  VPN is configured and connected via network-manager. Last messages
  from ssh (hangs forever):

  debug2: kex_parse_kexinit: none,zlib at openssh.com
  debug2: kex_parse_kexinit: none,zlib at openssh.com
  debug2: kex_parse_kexinit: 
  debug2: kex_parse_kexinit: 
  debug2: kex_parse_kexinit: first_kex_follows 0 
  debug2: kex_parse_kexinit: reserved 0 
  debug2: mac_setup: found hmac-md5
  debug1: kex: server->client aes128-ctr hmac-md5 none
  debug2: mac_setup: found hmac-md5
  debug1: kex: client->server aes128-ctr hmac-md5 none
  debug1: sending SSH2_MSG_KEX_ECDH_INIT
  debug1: expecting SSH2_MSG_KEX_ECDH_REPLY

  
  = Workaround =

  $ sudo apt-get install putty
  $ putty <host>

  This works perfectly.

  ProblemType: Bug
  DistroRelease: Ubuntu 14.04
  Package: openssh-client 1:6.4p1-1
  ProcVersionSignature: Ubuntu 3.12.0-3.8-generic 3.12.0
  Uname: Linux 3.12.0-3-generic i686
  NonfreeKernelModules: nvidia
  ApportVersion: 2.12.7-0ubuntu1
  Architecture: i386
  CurrentDesktop: Unity
  Date: Fri Nov 22 15:37:18 2013
  InstallationDate: Installed on 2010-10-21 (1128 days ago)
  InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release i386 (20101007)
  RelatedPackageVersions:
   ssh-askpass       1:1.2.4.1-9
   libpam-ssh        N/A
   keychain          2.7.1-1
   ssh-askpass-gnome 1:6.4p1-1
  SSHClientVersion: OpenSSH_6.4p1 Ubuntu-1, OpenSSL 1.0.1e 11 Feb 2013
  SourcePackage: openssh
  UpgradeStatus: Upgraded to trusty on 2013-11-01 (20 days ago)

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/1254085/+subscriptions