Slackみたいな無料のオープンショースチャットサーバ

https://rocket.chat/docs/installation/manual-installation/centos/

14 Let's Encrypt無料のSSL証明書を設定して、後はリバースプロキシ設定すればOK

<VirtualHost _default_:443>
  ServerName chat01.fl8.jp
   SSLEngine on
   SSLProtocol all -SSLv2 -SSLv3
   SSLCipherSuite ALL:!ADH:!EXPORT:!SSLv2:RC4+RSA:+HIGH:+MEDIUM:+LOW
   SSLCertificateFile /etc/letsencrypt/live/chat01.fl8.jp/cert.pem
   SSLCertificateKeyFile /etc/letsencrypt/live/chat01.fl8.jp/privkey.pem
   SSLCACertificateFile /etc/letsencrypt/live/chat01.fl8.jp/chain.pem
  # Rochet.Chat
  SSLOptions +StrictRequire
  ProxyPreserveHost On
  ProxyPass /websocket ws://localhost:3000/websocket
  ProxyPassMatch ^/sockjs/(.*)/websocket ws://localhost:3000/sockjs/$1/websocket
  ProxyRequests Off
  ProxyPass / http://127.0.0.1:3000/
  ProxyPassReverse / http://127.0.0.1:3000/
</VirtualHost>