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 Oct 17, 2021
414 Jan 06, 2023
0 Jan 29, 2022
1 Oct 30, 2021
3.2k Jan 09, 2023
17.1k Jan 04, 2023
1 Jan 03, 2022
222 Jan 03, 2023
3 Jan 19, 2022
83 Dec 26, 2022
161 Dec 26, 2022
2 Nov 10, 2022
181 Dec 23, 2022
13 Jan 13, 2022
64 Dec 28, 2022
1.9k Jan 05, 2023
4 Aug 18, 2022
0 May 17, 2022
16 Apr 25, 2022
23 Jun 10, 2022