1 - Abstract

There As there are two different things needed to setup the certificate authentification.

user certificates: There are N user certifiactes, one for each public key provided for signing.

helloworld-1234567890-1-cert.pub
helloworld-1234567890-2-cert.pub
...
helloworld-1234567890-N-cert.pub

types of certificates, there are two individual tasks to setup a client.

• Host Certificate
• Client Certificate

If one would like to use only one certificate, execute the corresponding subtask.

host certificate public key: There is one public key to authenticate servers.

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Configuration paths

There are two different options to tell the ssh daemon about the certificate: 'user based' (recommended)  or 'global'


• 'user based': The certificate is valid for one specific

  user on the client.'global': The certificate is valid for each

  user on the client.

user based

• Code Block
  language bash
  SSH_CERTIFICATES=$HOME/.ssh/netdef SSH_CONFIG=$HOME/.ssh/config SSH_KNOWNHOSTS=$HOME/.ssh/known_hosts

...

• 
  

• 'global': The certificate is valid for each user on the client.

  Code Block
  language bash
  SSH_CERTIFICATES=/etc/ssh/netdef SSH_CONFIG=/etc/ssh/ssh_config SSH_KNOWNHOSTS=/etc/ssh/ssh_known_hosts

  
  

2 - Client Certificate

Step 1 - Sign client's public key

The instructions how to singed a clients public key can be found here.

The CA provides a zip file where all signed keys are stored.

helloworld-1234567890-1

...

-cert.pub
helloworld-1234567890-2-cert.pub
...
helloworld-1234567890-N-cert.pub

Step 2 - Copy all certificates to netdef folder

Copy all certificates that can be found in the provided tar file to the folder '$SSH_CERTIFICATES'.

mkdir -p $SSH_CERTIFICATES
cp *cert.pub $SSH_CERTIFICATES

Step

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3 -

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Edit the config file

Add the following lines to '$SSH_CONFIG'. The name of the certificate as well as '$SSH_CERTIFICATES' must be replaced with the correct file name and the correct path to the folder respectively.

Host *.netdef.org
	CertificateFile `$SSH_CERTIFICATES`/helloworld-1234567890-1-cert.pub
	CertificateFile `$SSH_CERTIFICATES`/helloworld-1234567890-2-cert.pub 
	... 
	CertificateFile `$SSH_CERTIFICATES`/helloworld-1234567890-N-cert.pub

Step 3 - edit known hosts file.

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.pub

...

@cert-authority *.netdef.org `yubikeyX.pub`