Masquerading for connections or traffic initiated from inside a network. Consider reading for details on handling inbound traffic or connections. Masquerading has been supported under the linux kernel since before kernel 2.0. The technique of masquerading

Though SNAT and masquerading perform the same fundamental function, mapping one address space into another one, the details differ slighly. Most noticeably, masquerading chooses the source IP address for the outbound packet from the IP bound to the interface through which the packet will exit.