About a decade ago I worked at a small web-hosting company where I installed the LaBrea tarpit software (http://labrea.sourceforge.net/Intro-History.html http:/

About a decade ago I worked at a small web-hosting company where I installed the LaBrea tarpit software (http://labrea.sourceforge.net/Intro-History.html http://labrea.sourceforge.net/Intro-History.html) on an otherwise unused system and had our routers route all non-allocated IPs to said system. The intent was to use that to track IPs that were attacking (since otherwise, no legitimate traffic would hit that server) and then block them at the router level. Sadly, source level routing on routers is slow, and even if it wasn't, I wasn't sure how to automatically block said IPs at the router level.