These devices regulate IP traffic data between the internal network and the external Internet. Traffic from the inside is rerouted to the external router, after the sending address in the IP packet has been changed from the address of the workstation to the address of the firewall. Traffic from the outside is likewise rerouted to the internal router, with the destination address in the IP packet rewritten from that of the firewall to the private address of the appropriate internal host. Whether such IPX translation takes place or not, the data in the body of these packets is not generally parsed. However, external machines, such as the subscription service's server, cannot know the workstation IP address.
Data packets travel with the source address of the firewall.
Only the firewall knows the original source address. How Subscription Services Work with the Bess Proxy Server Bess proxy servers do parse the data in the body of packets for web page requests. After being read, this data is largely left as is. Unlike a firewall, Bess does not hinder subscription services, because the original source IP address travels with the web page request. However, if the proxy is used in conjunction with, and on the outside of, a firewall, the proxy will read the firewall address as the original source IP address.