title: Ruby on Rails: Permission denied - bind(2) for "0.0.0.0" port 80 (Errno::EACCES)
body: <h3>Steps to reproduce</h3>
  
  <ol>
  <li>I created my database and migrated.</li>
  <li>I ran <code>rails server</code>.</li>
  </ol>
  
  <p>This was the result:</p>
  
  <pre class="lang-none prettyprint-override"><code>[3957] Puma starting in cluster mode...
  [3957] * Version 3.10.0 (ruby 2.5.1-p57), codename: Russell's Teapot
  [3957] * Min threads: 5, max threads: 5
      [3957] * Environment: development
      [3957] * Process workers: 4
      [3957] * Preloading application
      [3957] * Listening on tcp://0.0.0.0:80
      Exiting
      Traceback (most recent call last):
              22: from bin/rails:4:in `&lt;main&gt;'
              21: from bin/rails:4:in `require'
              20: from /home/my_username/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.0/lib/rails/commands.rb:18:in `&lt;top (required)&gt;'
              19: from /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.0/lib/rails/command.rb:46:in `invoke'
              18: from /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.0/lib/rails/command/base.rb:65:in `perform'
              17: from /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.20.0/lib/thor.rb:387:in `dispatch'
              16: from /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.20.0/lib/thor/invocation.rb:126:in `invoke_command'
              15: from /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/thor-0.20.0/lib/thor/command.rb:27:in `run'
              14: from /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.0/lib/rails/commands/server/server_command.rb:142:in `perform'
              13: from /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.0/lib/rails/commands/server/server_command.rb:142:in `tap'
              12: from /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.0/lib/rails/commands/server/server_command.rb:147:in `block in perform'
              11: from /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/railties-5.2.0/lib/rails/commands/server/server_command.rb:53:in `start'
              10: from /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/rack-2.0.5/lib/rack/server.rb:297:in `start'
               9: from /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/puma-3.10.0/lib/rack/handler/puma.rb:69:in `run'
               8: from /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/puma-3.10.0/lib/puma/launcher.rb:183:in `run'
               7: from /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/puma-3.10.0/lib/puma/cluster.rb:397:in `run'
               6: from /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/puma-3.10.0/lib/puma/runner.rb:144:in `load_and_bind'
               5: from /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/puma-3.10.0/lib/puma/binder.rb:88:in `parse'
               4: from /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/puma-3.10.0/lib/puma/binder.rb:88:in `each'
               3: from /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/puma-3.10.0/lib/puma/binder.rb:105:in `block in parse'
               2: from /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/puma-3.10.0/lib/puma/binder.rb:270:in `add_tcp_listener'
               1: from /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/puma-3.10.0/lib/puma/binder.rb:270:in `new'
      /home/my_usernam/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/puma-3.10.0/lib/puma/binder.rb:270:in `initialize': Permission denied - bind(2) for "0.0.0.0" port 80 (Errno::EACCES) 
  </code></pre>