Open display error

[Andrew Stribblehill]

The way forwarding works is this:

ssh (client) run on 'smallbox' is asked to connect to 'bigbox'. It
looks at /etc/ssh/ssh_config then at the ~/.ssh/config file
(allowing the latter to override the former's defaults).

It connects to 'bigbox'.

If ssh (client) has X forwarding enabled, it tries to open an
encrypted tunnel from smallbox:0.0 to bigbox:10.0. (If this is
used, it tries :11 etc). This will only work if bigbox allows X
forwarding (it looks in /etc/ssh/sshd_config). Assuming bigbox
lets it have bigbox:10.0, the connection has $DISPLAY set to
bigbox:10.0.

If in this new window, you run 'xterm', it makes a connection with
bigbox:10.0 which is tunnelled through to smallbox's display.

Disclaimer: I'm not very familiar with SSH internals so this is
just partially-educated guesswork.

Cheerio,

Andrew Stribblehill
Systems Programmer, IT Service, University of Durham, England