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==== SSH Tunneling

A common need is to connect to some resource on the testbed as if it were local. SSH provides this functionality. Go to the [wiki:tutorials/ssh_tunnel Configuring SSH Tunnels tutorial] to learn how to configure these.
  

==== Common SSH issues
===== If you deleted the "@internal1" key from your profile

As long as you have at least one public key configured in your profile, use your SSH client to connect to {{{gw.orbit-lab.org}}} and run the following commands there. You do not need to make a reservation in the scheduler for this.

{{{
rm ~/.ssh/id_rsa
rm ~/.ssh/id_rsa.pub
ssh-keygen -t rsa -C "@internal1"
}}}

Press 'Enter' at every prompt so that the default filename (id_rsa) and no password is used.

Then type the following command:

{{{
cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
}}}

The internal key should now be restored.


===== Common ssh options for nodes

We'd like to do a few things for convenience:

1. log into nodes as root by default
1. allow forwarding of X11 applications
1. Suppress annoying host key warnings

First, log into any console, or gw.orbit-lab.org

After logging in, create or modify the file at {{{~/.ssh/config}}}

Add the following to the file

{{{
Host sdr?-md* sdr?-s?-lg* srv?-co* srv?-lg* node?-* node??-*
  User root
  UserKnownHostsFile /dev/null
  StrictHostKeyChecking no
  ForwardX11 yes
}}}

* Host: The Host line matches common naming conventions for nodes within the testbed
* User: root is set to match the common default for baseline
* !UserKnownHostsFile: is set to /dev/null to prevent saving new host keys for nodes
* !StrictHostKeyChecking: disables the warning message. SSH complains when host keys for a dns name change. This is a useful security feature, but is inconvenient within the testbed, where the operating system on a trusted machine changes frequently. Do not set it as a wildcard default for public endpoints, or you will be vulnerable to spoofing or man in the middle attacks.
* ForwardX11: allows the forwarding of graphical applications running the X11 protocol from a node back to your machine