A system and method for simulating network connection characteristics by alteration of a network packet. In general, the method of the invention includes providing a driver that is capable of accessing all outgoing and incoming network packets and altering a network packet to simulate a connection characteristic of the network. In particular, the method of the invention includes receiving a network packet, assigning a new, simulated network address to the network packet and performing modification of the network packet to simulate certain network connection characteristics (including, for example, transmission delay, limited bandwidth, packet dropping, packet fragmentation, packet duplication and packet reordering). The system of the invention includes a modification module for altering certain characteristics of a packet. The modification module is capable of mapping a new, simulated network address to a network packet, modifying a propagation characteristic of the network connection, and altering an additional packet characteristic.