title: Fail2ban failed to match date format
body: <p>I'm currently optimizing my fail2ban filter. </p>
  
  <p>Before my regex was this :</p>
  
  <pre><code>&lt;HOST&gt; \- \- \[.*\] \"(GET|POST) .+ HTTP\/\d\.\d\" 40\d \d{2,5} \"(.*)\" \"(.*)\"$
  </code></pre>
  
  <p>and it was working for every line that contains a 404 error like this :</p>
  
  <pre><code>&lt;HOST&gt; - - [16/Aug/2017:14:02:33 +0200] "GET /favicon.ico HTTP/1.1" 404 6494 "-" "Mozilla/5.0 (Windows NT 6.1; Win64; x64; Trident/7.0; rv:11.0) like Gecko"
  </code></pre>
  
  <p>After that I changed the :</p>
  
  <pre><code>\[.*\]
  </code></pre>
  
  <p>By</p>
  
  <pre><code>\[[0-9]{2}\/.{3}\/[0-9]{4}\:([0-9]{2}\:){2}[0-9]{2} \+[0-9]{4}\]
  </code></pre>
  
  <p>But now it doesn't match anymore with fail2ban whereas website like regex101 still recognize the correct patern ! (don't mind the \HOST if i didn't put the \ the word was not appearing).</p>
  
  <p>I tried to change <strong>\d</strong> by <strong>[0-9]</strong> <strong>/</strong> by <strong>\/</strong> <strong>:</strong> by <strong>\:</strong>
  Fail2ban always miss the lines and I don't know why..</p>
  
  <p>Is someone having the same problem ? thanks ! :)</p>