UDP Traceroute in Wireshark
Used by UNIX(and derivatives e.g Linux) systems
(windows uses ICMP outbound). UDP is sent to destination on ports 33434 to 33464. 3 UDP packets sent with same IP TTL. This enables the trace route app calculate the average RTT.
Initial TTL=1 and incremented with each Time exceeded message received. Final destination sends Port unreachable message back.