A trace detector prevents network mapping and tracing by detecting an initial packet containing an initial time to live value that meets a first predetermined threshold range. The trace detector identifies a source address of the initial packet and adjusts a threshold time to live range for detection of at least one subsequent trace route or response packet associated with the source address of the initial packet. In response to detecting the subsequent packet(s), the trace detector processes the subsequent packet(s) associated with the source address of the initial packet according to a security policy to prevent a trace process originating the initial packet from tracing a network using the at least one subsequent packet.