[KARAF-3656] SSH message channel closed too early

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 3.0.3, 2.4.1, 2.3.10, 4.0.0.M2
• Fix Version/s: 2.4.2, 3.0.4, 2.3.12, 4.0.0.M3
• Component/s: karaf
• Assignee: Guillaume Nodet
• Reporter: Jan-Peter Nilsson
• Created: 10/Apr/15 21:38
• Updated: 15/Sep/18 16:35
• Resolved: 16/Apr/15 09:35

Description

Using SSH exec with Karaf 2.3.10 SSH_MSG_CHANNEL_SUCCESS is sent after SSH_MSG_CHANNEL_CLOSE in the response.
This causes problems when trying to use the Paramiko SSH client library as it will close the channel on receiving SSH_MSG_CHANNEL_CLOSE and considers it a failure if SSH_MSG_CHANNEL_SUCCESS was not received.

reproduce.py

#!/usr/bin/python
import paramiko
client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
client.load_system_host_keys()
client.connect('localhost', port=8101, username="karaf", password="karaf")
client.exec_command('help')
# Throws SSHException "Channel closed." for affected versions.

The reason SUCCESS and CLOSE come out of order seems to be that start in the ShellCommand class does not spawn a separate thread but calls the onExit callback from within the same thread, see SSHD-295 and the Apache MINA SSHD API.