SSH for Remote Access

You can generate authentication keys to access a Cumulus Linux switch securely with the ssh-keygen component of the Secure Shell (SSH) protocol. Cumulus Linux uses the OpenSSH package to provide this functionality. This section describes how to generate an SSH key pair.

Generate an SSH Key Pair

1. To generate the SSH key pair, run the ssh-keygen command and follow the prompts:

   To configure a completely passwordless system, do not enter a passphrase when prompted in the following step.

   cumulus@leaf01:~$ ssh-keygen
   Generating public/private rsa key pair.
   Enter file in which to save the key (/home/cumulus/.ssh/id_rsa):
   Enter passphrase (empty for no passphrase):
   Enter same passphrase again:
   Your identification has been saved in /home/cumulus/.ssh/id_rsa.
   Your public key has been saved in /home/cumulus/.ssh/id_rsa.pub.
   The key fingerprint is:
   5a:b4:16:a0:f9:14:6b:51:f6:f6:c0:76:1a:35:2b:bb cumulus@leaf04
   The key's randomart image is:
   +---[RSA 2048]----+
   |      +.o   o    |
   |     o * o . o   |
   |    o + o O o    |
   |     + . = O     |
   |      . S o .    |
   |       +   .     |
   |      .   E      |
   |                 |
   |                 |
   +-----------------+
   

2. To copy the generated public key to the desired location, run the ssh-copy-id command and follow the prompts:

   cumulus@leaf01:~$ ssh-copy-id -i /home/cumulus/.ssh/id_rsa.pub cumulus@leaf02
   The authenticity of host 'leaf02 (192.168.0.11)' can't be established.
   ECDSA key fingerprint is b1:ce:b7:6a:20:f4:06:3a:09:3c:d9:42:de:99:66:6e.
   Are you sure you want to continue connecting (yes/no)? yes
   /usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
   /usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
   cumulus@leaf01's password:
   
   Number of key(s) added: 1
   

   ssh-copy-id does not work if the username on the remote switch is different from the username on the local switch. To work around this issue, use the scp command instead:

   cumulus@leaf01:~$ scp .ssh/id_rsa.pub cumulus@leaf02:.ssh/authorized_keys
   Enter passphrase for key '/home/cumulus/.ssh/id_rsa':
   id_rsa.pub
   

3. Connect to the remote switch to confirm that the authentication keys are in place:

   cumulus@leaf01:~$ ssh cumulus@leaf02
   
   Welcome to Cumulus VX (TM)
   
   Cumulus VX (TM) is a community supported virtual appliance designed for
   experiencing, testing and prototyping the latest technology.
   For any questions or technical support, visit our community site at:
   http://community.cumulusnetworks.com
   
   The registered trademark Linux (R) is used pursuant to a sublicense from LMI,
   the exclusive licensee of Linus Torvalds, owner of the mark on a world-wide basis.
   Last login: Thu Sep 29 16:56:54 2016