A method of modifying network identifiers at data servers is disclosed. A virtual private network (VPN) gateway server generates a Hypertext Transfer Protocol (HTTP) request. The HTTP request not only requests data from a data server that is within a VPN, but also instructs the data server to modify (“mangle”) URLs that are contained within the requested data so that the URLs refer to the VPN gateway server. The VPN gateway server sends the HTTP request toward the data server. As a result, the data server modifies the URLs so that the VPN gateway server does not need to. When such a modified URLs is selected in a web browser, the web browser generates an HTTP request that is directed to the VPN gateway server's URL, which, unlike the unmodified URLs, can be resolved by domain name servers that are outside of the VPN.