client denied by server configuration: proxy:ajp://your_host:8009/ on a Debian server

To suppress the client denied by server configuration error with ajp and Apache (I suppose you already did a a2enmod proxy_ajp), just change the Proxy setting from Deny all to Deny none in /etc/apache2/mods-enabled/proxy.conf :

<Proxy *>
  AddDefaultCharset off
  Order deny,allow
  Deny from none
  #Allow from