A form of filtering in which packets from one machine to the outside world have their headers rewritten so that they appear to come from an intermediate machine. That intermediate machine then passes responses back to the originating machine. The net effect is that an entire network of machines can appear to use a single IP number, that of the masquerading host, for the purpose of outgoing connections.

In the WatchGuard Firebox System, masquerading sets up addressing so that a Firebox presents its IP address to the outside world in place of the private IP addresses of the hosts protected by the Firebox. See also NAT.

Masquerading is a type of attack where the attacker poses as someone they are not.

when one person uses the identity of another to gain access to a computer