Troubleshoot an SSH connection

The remoting functionality for XL Deploy and XL Release uses the Overthere framework to manipulate files and execute commands on remote hosts. SSH is supported for connectivity to Unix, Microsoft Windows, and z/OS hosts. These are configuration errors that can occur when using XL Deploy or XL Release with the SSH protocol.

Cannot start a process on an SSH server because the server disconnects immediately

If the terminal type requested using the allocatePty property or the allocateDefaultPty property is not recognized by the SSH server, the connection will be dropped. Specifically, the dummy terminal type configured by allocateDefaultPty property, will cause OpenSSH on AIX and WinSSHD to drop the connection. Try a safe terminal type such as vt220 instead.

To verify the behavior of your SSH server with respect to PTY allocation, you can manually execute the ssh command with the -T (disable PTY allocation) or -t (force PTY allocation) flags.

Connecting to AIX over SSH returns timeout error

When connecting over SSH to an IBM AIX system, you may see a ConnectionException: Timeout expired error. To prevent this, set the allocatePty default to an empty value (null). If you do not want to change the default for all configuration items (CIs) of the overthere.SshHost type, create a custom CI type to use for connections to AIX. For example:

<type type="overthere.AixSshHost" extends="overthere.SshHost">
    <property name="allocatePty" kind="string" hidden="false" required="false" default="" category="Advanced" />
</type>

Command executed using SUDO or INTERACTIVE_SUDO fails with the message sudo: sorry, you must have a tty to run sudo

The sudo command requires a tty to run. Set the allocatePty property or the allocateDefaultPty property to ask the SSH server allocate a PTY.

Command executed using SUDO or INTERACTIVE_SUDO appears to hang

This may be caused by the sudo command waiting for the user to enter his password to confirm his identity. There are several ways to solve this:

  • Use the NOPASSWD tag in your /etc/sudoers file, or
  • Use the INTERACTIVE_SUDO connection type instead of the SUDO connection type

If you are already using the INTERACTIVE_SUDO connection type and you still get this error, please verify that you have correctly configured the sudoPasswordPromptRegex property. If you cannot determine the proper value for the sudoPasswordPromptRegex property, set the log level for the com.xebialabs.overthere.ssh.SshInteractiveSudoPasswordHandlingStream category to TRACE and examine the output.