MySQL Bugs: #49419: Test Connection for SSH connection locks up entire app

Bug #49419	Test Connection for SSH connection locks up entire app
Submitted:	3 Dec 2009 20:44	Modified:	15 Jan 2010 11:25
Reporter:	Kolbe Kegel	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Workbench	Severity:	S1 (Critical)
Version:	5.2.11	OS:	Linux (mysql-workbench-oss-5.2.10-1ubu804-amd64.deb)
Assigned to:	Alfredo Kojima	CPU Architecture:	Any

Description:
"Test Connection" locks up Workbench if using "Standard TCP/IP over SSH" connection.

How to repeat:
1) New Connection
2) Connection Method: "Standard TCP/IP over SSH"
3) Enter host, user, and password details
4) Hit Test Connection
5) App locks up

Console output:

18743 INFO Connecting to SSH server at 127.0.0.1:22...
Unhandled exception in thread started by <bound method Tunnel._threadloop of <__main__.Tunnel instance at 0x9acea8>>

I can abort the connection attempt with ctrl-c at the console, but the interface is non-responsive to mouse input. Esc will close the New Connection wizard, but application behavior at this point is inconsistent and app will sometimes close unexpectedly.

Suggested fix:
It should of course be possible to successfully Test Connection with "Standard TCP/IP over SSH" connections.

I can not repeat this. Also looking at the code, one of the possible causes of the issue has already been fixed. Please reopen with a copy/paste of console output if you can still repeat in latest release.

Reproduced as described in 5.2.11 on Ubuntu 8.04.

Starting thread...
Thread started
19579 INFO Connecting to SSH server at 127.0.0.1:22...
19579 INFO Internal error in tunnel manager: AttributeError("'module' object has no attribute 'WarningPolicy'",)
Traceback (most recent call last):
  File "/usr/share/mysql-workbench/sshtunnel.py", line 109, in _threadloop
    self._actual_work(password, keyfile)
  File "/usr/share/mysql-workbench/sshtunnel.py", line 117, in _actual_work
    if not self._connect_ssh(password, keyfile):
  File "/usr/share/mysql-workbench/sshtunnel.py", line 85, in _connect_ssh
    self.client.set_missing_host_key_policy(paramiko.WarningPolicy())
AttributeError: 'module' object has no attribute 'WarningPolicy'

What version of the python-paramiko package do you have installed?

Package: python-paramiko
Version: 1.6.4-1.1

This is caused by old paramiko in Ubuntu 8.04 and is only repeatable in that specific Ubuntu version.
Fixed by adding the missing class.

Patch for fix:

--- library/sshtunnel/sshtunnel.py	2009-12-10 15:28:33 +0000
+++ library/sshtunnel/sshtunnel.py	2010-01-04 21:20:59 +0000
@@ -18,6 +18,14 @@
 # timeout for closing an unused tunnel
 TUNNEL_TIMEOUT = 60
 
+# paramiko 1.6 didn't have this class
+if hasattr(paramiko, "WarningPolicy"):
+    WarningPolicy = paramiko.WarningPolicy
+else:
+    class WarningPolicy(paramiko.MissingHostKeyPolicy):
+        def missing_host_key(self, client, hostname, key):
+            print 'WARNING: Unknown %s host key for %s: %s' % (key.get_name(), hostname, hexlify(key.get_fingerprint()))
+
 
 class Tunnel:
     def __init__(self, q, tunnel_manager, server, username, target, threaded=True):
@@ -82,7 +90,7 @@
     def _connect_ssh(self, password, keyfile):
         self.client = paramiko.SSHClient()
         self.client.load_system_host_keys()
-        self.client.set_missing_host_key_policy(paramiko.WarningPolicy())
+        self.client.set_missing_host_key_policy(WarningPolicy())
 
         try:
             self.client.connect(self.server[0], self.server[1], username=self.username, key_filename=keyfile, password=password)

fix will be included in 5.2.12

An entry has been added to the 5.2.12 changelog:

Clicking the Test Connection button in the Manage DB Connections dialog caused MySQL Workbench to lock up. The error generated on the console was:

18743 INFO Connecting to SSH server at 127.0.0.1:22...
Unhandled exception in thread started by <bound method Tunnel._threadloop of
<__main__.Tunnel instance at 0x9acea8>>

Copy and paste error. This paragraph was also part of the changelog entry:

This happened for the connection method Standard TCP/IP over SSH.