Authentication keys can be generated for securely accessing a Cumulus Linux switch with the ssh-keygen component of the Secure Shell (SSH) protocol. Cumulus Linux uses the OpenSSH package to provide this functionality. The section below covers how to generate a SSH key pair.


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Generate an SSH Key Pair

  1. Run the ssh-keygen command, and follow the prompts, to generate the key pair:

    Configure a Passwordless System

    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/
    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. Run the ssh-copy-id command, and follow the prompts, to copy the generated public key to the desired location:

    cumulus@leaf01:~$ ssh-copy-id -i /home/cumulus/.ssh/ cumulus@leaf02
    The authenticity of host 'leaf02 (' 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 will not work if the username on the remote switch is different to the local switch. To work around this issue, use the scp command instead:

    cumulus@leaf01:~$ scp .ssh/ cumulus@leaf02:.ssh/authorized_keys
    Enter passphrase for key '/home/cumulus/.ssh/id_rsa':
  3. Connect to the remote switch to confirm the authentication keys are in place:

    cumulus@leaf04:~$ ssh cumulus@leaf02
    Welcome to Cumulus VX (TM)
    Cumulus VX (TM) is a community supported virtual appliance designed for
    experiencing, testing and prototyping Cumulus Networks' latest technology.
    For any questions or technical support, visit our community site at:
    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
    Last login: Thu Sep 29 16:56:54 2016

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