SSH Access: Accessing the installer via “ssh”

This mode is supported with debug level set to 2

When ssh access to the installer is enabled, the admin can login into the installer through:

For RHEL, the installation won’t halt, just login into the installer with ssh root@<node>.
For SLES, the installation will halt after the ssh server is started, the console output looks like:
```
***  sshd has been started  ***


***  login using 'ssh -X root@<node>'  ***
***  run 'yast' to start the installation  ***
```
xCAT configures the SLES installer with the temporary root password cluster. This password is used only by the installer; it is not the installed system’s root password from the passwd table.

To use a different temporary installer password, add the SUSE SSH parameters to the node’s kernel command line and regenerate its boot configuration:
```
chdef -t node -o <node> addkcmdline="ssh=1 ssh.password=<temporary-password>"
nodeset <node> osimage=<osimage>
```
The temporary password is stored in the generated boot configuration and is visible in the kernel command line. Do not reuse the installed system’s root password. Restore the node’s previous addkcmdline value after debugging and run nodeset again.

The admin can open 2 sessions and run ssh -X root@<node> with the temporary installer password, then run yast to continue installation in one session and inspect the installation process in the other session.

After the installation is finished, the system requires a reboot. The installation will halt again before the system configuration, the console output looks like:
```
*** Preparing SSH installation for reboot ***
*** NOTE: after reboot, you have to reconnect and call yast.ssh ***
```
Just as the message above suggests, the admin should run ssh -X root@<node> to access the installer and run yast.ssh to finish the installation.

Note: For sles12, during the second stage of an SSH installation YaST freezes. It is blocked by the SuSEFirewall service because the SYSTEMCTL_OPTIONS environment variable is not set properly. Workaround: When logged in for the second time to start the second stage of the SSH installation, call yast.ssh with the --ignore-dependencies as follows:
```
SYSTEMCTL_OPTIONS=--ignore-dependencies yast.ssh
```

For UBT, the installation will halt on the message in the console similar to:

┌───────────┤ [!!] Continue installation remotely using SSH ├───────────┐
│                                                                       │
│                               Start SSH                               │
│ To continue the installation, please use an SSH client to connect to  │
│ the IP address <node> and log in as the "installer" user. For         │
│ example:                                                              │
│                                                                       │
│    ssh installer@<node>                                               │
│                                                                       │
│ The fingerprint of this SSH server's host key is:                     │
│ <SSH_host_key>                                                        │
│                                                                       │
│ Please check this carefully against the fingerprint reported by your  │
│ SSH client.                                                           │
│                                                                       │
│                              <Continue>                               │
│                                                                       │
└───────────────────────────────────────────────────────────────────────┘

Just as the message above suggests, the admin can run ssh installer@<node> with the password “cluster” to login into the installer, the following message shows on login:

┌────────────────────┤ [!!] Configuring d-i ├─────────────────────┐
│                                                                 │
│ This is the network console for the Debian installer. From      │
│ here, you may start the Debian installer, or execute an         │
│ interactive shell.                                              │
│                                                                 │
│ To return to this menu, you will need to log in again.          │
│                                                                 │
│ Network console option:                                         │
│                                                                 │
│                Start installer                                  │
│                Start installer (expert mode)                    │
│                Start shell                                      │
│                                                                 │
└─────────────────────────────────────────────────────────────────┘

The admin can open 2 sessions and then select “Start installer” to continue installation in one session and select “Start shell” in the other session to inspect the installation process in the installer.