Soldiers sometimes detect the presence of tripwires by spraying the area with Silly String.
In his book The Yom Kippur War: The Epic Encounter That Transformed the Middle East, historian Abraham Rabinovich posits that the Bar-Lev line was a blunder — too lightly manned to be an effective defensive line and too heavily manned to be an expendable tripwire.
Among notable software designed and/or supervised by Spafford include the freeware Tripwire tool coded by his student Gene Kim (Spafford was later the chief external technical advisor to the Tripwire company during their first few years), and the freeware COPS tool coded by his student Dan Farmer.