Traceroute
A simple command-line tracert implementation in Python 3 using ICMP packets
Details
Traceroute is a networking tool designed for tracing the movement of packets across a network. In this Python 3 implementation, ICMP 'ping' packets are used, much like the Windows tracert.exe program (and unlike Unix tracert which typically uses UDP packets).
The application sends a sequence of ICMP packets to the host, initially with the Time-To-Live field set to 1. As the packet travels across the network to its final destination, each node it passes through will decrement the TTL field by 1. When the field reaches zero the node will respond by saying that the packet could not reach its destination.
+------+ +--------+
| | TTL = 1 | |
| | --------> | |
| HOST | | node 1 |
| | timeout | |
| | <-------- | |
+------+ +--------+
Having now identified the first node that the packet passes through, tracert now sends another ICMP packet with TTL set to 2, which will timeout when it reaches the second node, and so on.
+------+ +--------+ +--------+
| | TTL = 2 | | TTL = 1 | |
| | --------> | | --------> | |
| HOST | | node 1 | | node 2 |
| | timeout | | timeout | |
| | <-------- | | <-------- | |
+------+ +--------+ +--------+
+------+ +--------+ +--------+ +--------+
| | TTL = 3 | | TTL = 2 | | TTL = 1 | |
| | --------> | | --------> | | --------> | |
| HOST | | node 1 | | node 2 | | node 3 |
| | timeout | | timeout | | timeout | |
| | <-------- | | <-------- | | <-------- | |
+------+ +--------+ +--------+ +--------+
Eventually, an ICMP packet will be sent with a sufficiently large TTL value that it can reach the final destination, at which point the process is complete.
+------+ +--------+ +--------+ +--------+ +--------+
| | TTL = 4 | | TTL = 3 | | TTL = 2 | | TTL = 1 | |
| | --------> | | --------> | | --------> | | --------> | |
| HOST | | node 1 | | node 2 | | node 3 | | TARGET |
| | success | | success | | success | | success | |
| | <-------- | | <-------- | | <-------- | | <-------- | |
+------+ +--------+ +--------+ +--------+ +--------+
1 Dec 14, 2021
1 Oct 17, 2021
0 Dec 15, 2021
10 Dec 29, 2022
55 Nov 15, 2022
16 Sep 25, 2022
15 Feb 26, 2022
471 Dec 15, 2022
5 Apr 12, 2022
38 May 26, 2022
20 Dec 22, 2022
12 Jan 29, 2022
4.8k Dec 30, 2022
22 Dec 05, 2022
3 Aug 03, 2022
2 Nov 27, 2022
215 Dec 19, 2022
1 Jan 03, 2022
3 Oct 26, 2022
68 Dec 30, 2022