SSH pubkey on a NetScaler Application Switch

I like to take a backup of all my device configurations on a regular basis. Its usually pretty straight-forward, simply add a scp command to cron, but with the NetScaler there's a little gotcha.

The default location of the authorized_keys file is in '/flash/nsconfig/ssh'. After you append your public key into the file, you'll need to copy the 'authorized_keys' file to '/root/.ssh/'.

This filecopy will need to be done after every reboot of the NetScaler because the / mount point is on volatile media.

If you want to script this action, or any other post-boot commands on a NetScaler device, create or edit the file '/flash/nsconfig/rc.netscaler', set the perms on the file to 755, and start adding commands to the file.

 

Using PKI with SSH

If you're concerned about the global increase in brute-force SSH login attempts, you can use PKI to prohibit successful unauthorized authentication through password guessing.

Generate key pair
# keygen -b 1024 -t rsa -f ./rsa_id_clientname

Add/append public key to ~/.ssh/authorized_keys file on the target

Add/append a few lines to ~/.ssh/config on the client
Host
User
IdentityFile ~/.ssh/

Attempt new SSH session