I teach computer networking and the latest assignment I gave my students was to use Python and Scapy to emmulate traceroute. The code is simple: - send an ICMP packet with TTL = 1 which will fail but return the first hop address - continue sending ICMP packets - each time increasing the TTL to get the next hop - if the ICMP reply is NOT an error, we have arrived.
None of my student submissions worked, which was strange, so I tried my own code which I know is correct. It also did not work. The error messages arrive for each hop, but it seems that the NO ERROR message (when the destination is reached) is not arriving. I also checked with Wireshark and see error replies (as I should) for each hop, but then (when I assume I have reached the destination) there is no reply. I then tried disconnecting my computer from my ISP and connected via a Hotspot on my phone - PROBLEM SOLVED. So this seems to be a problem with my ISP (019) blocking some traffic. But I don't know what the next step is. If I call customer service, I'm sure no-one will understand what I want. BTW - ping and the "real" traceroute work fine. I also looked at router settings, but did not find anything suspicious. Can anyone suggest how to explain my problem to my ISP? ALSO - if there is anyone using 019, I would be happy to send my code for testing to verify that this is really a problem with 019. -- Shlomo Solomon http://the-solomons.net Claws Mail 4.0.0 - KDE Plasma 5.24.7 - Kubuntu 22.04 _______________________________________________ Linux-il mailing list -- linux-il@cs.huji.ac.il To unsubscribe send an email to linux-il-le...@cs.huji.ac.il
