See also network
With Posix servers already running an SSH server, xpra sessions can be accessed without any extra configuration. ie:
xpra attach ssh://USERNAME@HOST/DISPLAY
(the DISPLAY value may be omitted if the user only has a single active session)
Similarly, it is possible to start new sessions and connect to them in one command:
xpra start ssh://USERNAME@HOST/ --start=xterm
The sessions do not require any specific bind command line options: the default xpra configuration will already create unix domain sockets which are forwarded to the client by the SSH transport. Those sockets can be seen with xpra list on the server.
This mode can be used to enable SSH connections on servers that do not include an SSH server by default (ie: MS Windows servers), or to use SSH authentication and encryption but without allowing full shell logins via SSH on the server system. (as the connection can only be used to connect to the xpra server)
This mode can be used with plain TCP sockets which end up being upgraded to SSH. The server also supports the bind-ssh option: these sockets will only allow SSH connections. ie:
xpra start --bind-ssh=0.0.0.0:10000 --start=xterm
The client can then connect to this port using ssh:
xpra attach ssh://HOST:10000/
The SSH server's private key must be accessible to the user running the xpra server. The filenames can be configured using the OpenSSH IdentityFile option or the XPRA_SSH_DEFAULT_KEYFILES environment variable. Otherwise, the server will try to open key files found in ~/.ssh/)
Regular TCP sockets can also be upgraded to SSH.
For details, see #1920, use the -d ssh debug logging flag.
The client can either use the builtin ssh client (based on paramiko), or an external tool.
This can be configured using the ssh command line option. The default setting is auto which will use paramiko if it is present and fallback to the platform's default external tool when it is not.
On most platforms the default external tool is the ssh command, but on MS Windows it is putty plink.
This mechanism relies on openssh on Posix systems, optionally using sshpass to supply passwords via the command line or connection files.
On MS Windows, the installer will bundle the tortoisesvn version of PuTTY plink which includes a more user friendly GUI for host key confirmation and password input.
Since this mechanism relies on executing the ssh client program, you can use the same command line options as you normally would and / or use the openssh configuration files for using tunnels, restricting ciphers, etc.
ie: --ssh="ssh -x -c blowfish-cbc"
The --exit-ssh switch controls whether the SSH transport is killed when the client terminates, this can be useful if openssh is setup to use connection sharing. (see #203 for details)
This backend is built into the client connection code and provides better diagnostics (using the --debug=ssh switch), and it provides a GUI for confirming host keys, entering key passphrases or passwords.
The downside is that since it does not use OpenSSH at all, it does not have the same flexibility, it may require re-confirmation of known hosts and it may not support all the configuration options normally used with OpenSSH.
You can specify the password to use on the command line URI:
xpra attach ssh://USERNAME:PASSWORD@HOSTNAME/
But this exposes the password in the process list: obfuscate passwords