For an Internet Access Gateway operative between an area network and a public network, managing dynamic network sessions therebetween whereby a primary server on the public network in a primary session with a client of the area network initiates an additional session with an additional server on the public network, for which an unexpected data packet received at the gateway from the additional server is associated with the primary session, and accordingly allowed access to the area network through the gateway, provided the gateway received the data packet at an input port exceeding 1023, the additional session comprises a pre-defined Session Triggering Event, and at least one internal network component of the area network indicates willingness to receive the data packet. Wherefore, a preferred Application Level Gateway is thereby provided for firewall and NAT implementations to enhance network security.