Listen 172.19.128.68:3128
<VirtualHost 172.19.128.68:3128>
  ProxyRequests On
  ProxyVia On

  ErrorLog /var/log/httpd/nl.wirelessleiden.proxy-error.log
  CustomLog /var/log/httpd/nl.wirelessleiden.proxy-access.log combinedio
  
  <Proxy *>
    Order deny,allow
    Deny from all
    Allow from 172.16.4.46
    Allow from 172.17.169.67
    Allow from 172.19.128.68
  </Proxy> 
</VirtualHost>