title: How to fix "Service [XXX]: SSL server needs a certificate" on an Stunnel server?
body: <p>I had an Stunnel server configuration that was working fine last week. It seems that after a <code>sudo apt-get update &amp;&amp; sudo apt-get upgrade</code> that is not the case anymore.</p>
  
  <p>Version:</p>
  
  <pre><code>$ ls -la /usr/bin/stunnel
  ?????????? 1 root root 8 Xxx XX  2016 /usr/bin/stunnel -&gt; stunnel4
  $ stunnel -version
  stunnel 5.30 on x86_64-pc-linux-gnu platform
  Compiled with OpenSSL 1.0.2e 3 Dec 2015
  Running  with OpenSSL 1.0.2g  1 Mar 2016
  Update OpenSSL shared libraries or rebuild stunnel
  </code></pre>
  
  <p>And this is my server <code>stunnel.conf</code></p>
  
  <pre><code>verify = 2
  debug = 7
  output = stunnel.log
  options = NO_SSLv3
  
  [XXX]
  client = no
  verify = 0
  accept = 9888
  connect = localhost:9879
  key = path/to/file.key
  CAfile = path/to/ca.pem
  </code></pre>
  
  <hr>
  
  <p>What was working before, now gives to following error:</p>
  
  <pre><code>$ sudo stunnel stunnel.conf
  [ ] Initializing service [XXX]
  [!] Service [XXX]: SSL server needs a certificate
  </code></pre>
  
  <hr>
  
  <p>Why do I need a certificate now? Isn't this a server? I already provided a private key and CA certificate and thought that was enough.</p>
  
  <p>Please correct me if I'm wrong, but I think an Stunnel server doesn't need the clients' certs on the configuration in order to start a session to listen on.</p>
  
  <p>Whatever the issue is. I appreciate any help.</p>