1. A method of testing a firewall comprising: transmitting session termination signals used to terminate established communications sessions; monitoring to determine port closing delays, said port closing delays being a delay in time between the time a session termination signal is transmitted and the time a port in said firewall is closed in response to the transmitted session termination signal; transmitting session termination signals at an increased rate through said firewall to cause the closing of ports in said firewall; and measuring the effect of said increased rate of session termination signals on closing delay times associated with closing ports in response to transmitted session termination signals.