An unintuitive application using ICMP

  • Works by sending packets with small TTLs
  • When TTL hits 0, router will respond with ICMP Time Exceeded message
  • Use these Time Exceeded messages to identify routers
  • So TTL=1 will result in a message from the first router, TTL=2 will result in a message from the second router, and so on
  • Keep incrementing TTL until you hit destination

Covered in lecture 11, but the slides aren’t super useful