The principle of traceroute and tracert

The principle of traceroute:

The 1.traceroute host sends UDP packets to the trace host, and the destination port is the port with a higher number (such as port 33434).

two。 The TTL value and port number of the packet after the first packet TTL=1,Dport=33434; are added by 1

3. How to tell if you have arrived at your destination

Generally speaking, the destination will not open any service on a port as large as UDP33434, so after the packet arrives at the destination, the destination will find that the local host has not opened the corresponding port and will reply to the port unreachable message. Of course, this is limited to UDP.

In the case of TCP service, the local host will reply resert if the corresponding TCP service is not enabled.

The principle of tracert:

The principle of 1.tracert is relatively simple, sending echo reauest directly

two。 When you receive the echo reply from the destination, you will arrive at the destination.

Notes from my own study, if there are mistakes I hope to spend, we will make progress together, thank you.