Q:

MySQL Workbench with Debian Jessie - TCP/IP over SSH does not work

I use to connect with Windows 7 Pro x64 to my MySQL server hosted on a Debian Wheezy with the MySQL Workbench client using the "TCP/IP over SSH" but it does not work on my new server on Debian Jessie, why ? 

MySQL Workbench config:
Connection Name: TEST
Connection Method: Standard TCP/IP over SSH

SSH Hostname: x.x.x.x:22
SSH Username: root
SSH Password: myRootPa$$word
SSH Key File: <NOT-USING-KEYFILE>

MySQL Hostname: 127.0.0.1
MySQL Server Port: 3306
Username: root
Password: myMySQLPa$$word

I have double check the IP address/hostname, username and password...

Debian Wheezy server config:
root@debian:~# cat /etc/debian_version
7.8

mysql> select version();
+------------------+
| version()        |
+------------------+
| 5.5.40-0+wheezy1 |
+------------------+
1 row in set (0.00 sec)

root@debian:~# cat /etc/ssh/sshd_config
Port 22
Protocol 2
HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_dsa_key
HostKey /etc/ssh/ssh_host_ecdsa_key
UsePrivilegeSeparation yes

KeyRegenerationInterval 3600
ServerKeyBits 768
SyslogFacility AUTH
LogLevel INFO
LoginGraceTime 120
PermitRootLogin yes
StrictModes yes
RSAAuthentication yes
PubkeyAuthentication yes

IgnoreRhosts yes
RhostsRSAAuthentication no
HostbasedAuthentication no
PermitEmptyPasswords no
ChallengeResponseAuthentication no

X11Forwarding yes
X11DisplayOffset 10
PrintMotd no
PrintLastLog yes
TCPKeepAlive yes

AcceptEnv LANG LC_*
Subsystem sftp /usr/lib/openssh/sftp-server
UsePAM yes

Debian Jessie server config:
root@debian:~# cat /etc/debian_version
8.0

mysql> select version();
+-----------------+
| version()       |
+-----------------+
| 5.5.43-0+deb8u1 |
+-----------------+
1 row in set (0.00 sec)

root@debian:~# cat /etc/ssh/sshd_config
Port 22
Protocol 2
HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_dsa_key
HostKey /etc/ssh/ssh_host_ecdsa_key
HostKey /etc/ssh/ssh_host_ed25519_key
UsePrivilegeSeparation yes

KeyRegenerationInterval 3600
ServerKeyBits 1024
SyslogFacility AUTH
LogLevel INFO
LoginGraceTime 120
PermitRootLogin yes
StrictModes yes
RSAAuthentication yes
PubkeyAuthentication yes

IgnoreRhosts yes
RhostsRSAAuthentication no
HostbasedAuthentication no
PermitEmptyPasswords no
ChallengeResponseAuthentication no

X11Forwarding yes
X11DisplayOffset 10
PrintMotd no
PrintLastLog yes
TCPKeepAlive yes

AcceptEnv LANG LC_*
Subsystem sftp /usr/lib/openssh/sftp-server
UsePAM yes

So the man difference is the ServerKeyBits between the two sshd_config file...

The error MySQL Workbench 6.3.3 give me when I try to connect to the Debian Jessie server:
Could not connect the SSH Tunnel
Authentication error, unhandled exception caught in tunnel manager, please refer to logs for details

The log file:
10:00:04 [INF][     SSH tunnel]: Starting tunnel
10:00:04 [INF][     SSH tunnel]: Existing SSH tunnel not found, opening new one
10:00:07 [INF][     SSH tunnel]: Opening SSH tunnel to 10.232.50.15:22
10:00:07 [WRN][sshtunnel.py:_connect_ssh:287]: IOError, probably caused by file C:\Users\myUser\AppData\Roaming\MySQL\Workbench\ssh\known_hosts not found, the message was: [Errno 2] No such file or directory: u'C:\\Users\\myUser\\AppData\\Roaming\\MySQL\\Workbench\\ssh\\known_hosts'
10:00:07 [ERR][sshtunnel.py:notify_exception_error:233]: Traceback (most recent call last):
  File "C:\Program Files\MySQL\MySQL Workbench 6.3 CE\sshtunnel.py", line 297, in _connect_ssh
    look_for_keys=has_key, allow_agent=has_key)
  File "C:\Program Files\MySQL\MySQL Workbench 6.3 CE/python/site-packages\paramiko\client.py", line 301, in connect
    t.start_client()
  File "C:\Program Files\MySQL\MySQL Workbench 6.3 CE/python/site-packages\paramiko\transport.py", line 461, in start_client
    raise e
SSHException: Incompatible ssh peer (no acceptable kex algorithm)

10:00:07 [INF][     SSH tunnel]: TunnelManager.wait_connection authentication error: Authentication error, unhandled exception caught in tunnel manager, please refer to logs for details
10:00:07 [ERR][     SSH tunnel]: Authentication error opening SSH tunnel: Authentication error, unhandled exception caught in tunnel manager, please refer to logs for details

More infos:
The folder "ssh" is not present in:
C:\Users\myUser\AppData\Roaming\MySQL\Workbench

Firewall rules on both servers:
root@debian:~# iptables -vnL

Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination

I can connect with SSH (KiTTY) on both server...

I have tried two different version of MySQL Workbench:
Version 6.3.3.0 build 592 (64 bits)
Version 6.0.9.11421 build 1170 (32 bits)

These two version works with Debian Wheezy but not with Debian Jessie. 
What am I missing? 

A:

According to https://bugs.mysql.com/bug.php?id=74658 the issue presents itself when using openssh 6.7 the python libraries shipped with MySql workbench.  While adding the "KexAlgorithms" to the sshd config works, you can update the python libraries that come with MySql Workbench.   This may be handy if you don't have control over the sshd config...
If you scroll down in the bug report, there are instructions to download and copy the paramiko and ecdsa libraries.  

A:

I have found the solution. 
I added this line to my /etc/ssh/sshd_config file:
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-group1-sha1

and restarted ssh:
systemctl restart ssh
as suggested by this post: 
https://stackoverflow.com/questions/26577494/aptana-sftp-key-exchange

