title: remove or append a kexalgorithms or a hostkeyalgorithms in "/etc/ssh/sshd_config"
body: <p>I need to modify the default list of kexalgorithms or a hostkeyalgorithms in &quot;/etc/ssh/sshd_config&quot; by explicitly mentioning both the not required algos as well as the required ones.</p>
  <p><a href="http://manpages.ubuntu.com/manpages/bionic/man5/sshd_config.5.html" rel="nofollow noreferrer">http://manpages.ubuntu.com/manpages/bionic/man5/sshd_config.5.html</a>  tells:-
  if the specified value begins with a ‘+’ character, then the specified methods will be appended to the default set instead of replacing them.  If the specified value begins with a ‘-’ character, then the specified methods (including wildcards) will be removed from the default set instead of replacing them.</p>
  <p>For eg: I need to remove just the diffie-hellman* from the default list, so in &quot;/etc/ssh/sshd_config&quot; i tried these 3 syntax individually</p>
  <pre><code>KexAlgorithms -diffie-hellman*
  KexAlgorithms -&quot;diffie-hellman*&quot;
  KexAlgorithms &quot;-diffie-hellman*&quot;
  </code></pre>
  <p>However none of these syntax is working..</p>