A system and method for restricting packet transfer to a computer across a network, wherein the computer includes a network interface device coupled to the network and wherein the network interface device includes a packet filter. A security server is connected to the network. A packet is received at the network interface device and the network interface device determines if the packet is an authorized transaction. If the packet is not an authorized transaction, the packet is routed to the security server, where the security server determines whether the packet is an authorized transaction. If the security server determines that the packet is an authorized transaction, the network interface device is configured to accept similar transactions.