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Access to the relay server is protected by SSH private key authentication. The authentication process is hidden from vlab module users by the authorisation file mechanism:
    auth = vlab.loadAuthorisation("vluser.key")
    vlf = vlab.VlabClientFactory(auth)
The authorisation file encapsulates all of the data required to connect to the relay server, i.e. user name, private key, and host name. This data is stored in a Python dict object, pickled, zlib-compressed, then base64 encoded. It is not encrypted. The public key and recommended board server name are also stored.

Using an SSH client

If you want to connect to VL2 using an SSH client, or using something other than the vlab module, then you will need to recover the private key from the authorisation file. This can be done using the following Python program fragment:
    import vlab
    file("pkey", "wt").write(vlab.loadAuthorisation("vluser.key").private_key)
to recover the SSH private key in "vluser.key" and write it to "pkey". You can give this to SSH to connect to the VL2 relay server. You will need to know your VL2 user name and the host name of the relay server. Here is an example:
    ssh -i pkey -l username virtuallab.cs.york.ac.uk

Authorisation files are created as described on the VL2 administrator's manual page. For each authorisation file, there is a matching "/home/username/.ssh/authorized_keys" file on the relay server.

  Copyright (C) Jack Whitham 1997-2011