# sites-enabled/site
NameVirtualHost *:80
<VirtualHost *:80>
ServerName site.com
</VirtualHost>
# sites-enabled/proxy
<VirtualHost *:80>
#ServerName not important
ProxyRequests On
</VirtualHost>
When using Debian style sites-enabled, make sure Proxy site goes BEFORE actual site in alpha order, i.e. 00proxy vs site
Reason:
Proxy requests having "Host" field set to destination site, i.e. google.com or anything. This will result in matching none of the VirtualHosts' ServerName, and will go to First VirtualHost regardless of ServerName settings.