A computer performs dynamic address isolation. The computer comprises an application associated with an application address, a network interface coupled to receive incoming data packets from and transmit outgoing data packets to an external network, a network address translation engine configured to translate between the application address and a public address, and a driver for automatically forwarding the outgoing data packets to the network address translation engine to translate the application address to the public address, and for automatically forwarding the incoming data packets to the network address translation engine to translate the public address to the application address. The computer may communicate with a firewall configured to handle both network-level security and application-level security.