title: why do I have to DNS.1 = localhost in my certificate SAN for chrome to accept it
body: <p>We are creating a CA signed certificate for us to talk to some embedded controller via HTTPS </p>
  
  <p>If we just include a common name, Chrome flags it as insecure, but allows us to click through.</p>
  
  <p>However if we add the following SAN entries in a config file</p>
  
  <pre><code>[alt_names] 
  IP.1   = 192.168.61.30 
  IP.2   = 192.168.61.31 
  IP.3   = 192.168.61.32
  </code></pre>
  
  <p>Chrome complains that information is not consistent with the server and therefore it is unsafe to access the server page. </p>
  
  <p>We got around it by adding another SAN entry as follows</p>
  
  <pre><code>[alt_names]
  DNS.1 = localhost
  IP.1   = 192.168.61.30
  IP.2   = 192.168.61.31
  IP.3   = 192.168.61.32
  </code></pre>
  
  <p>Then Chrome accepts the certificate and we can access the web page with no errors</p>
  
  <p>What is the DNS.1 entry doing and why is it needed?</p>