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Ask HN: Two IPv4 hosts on the internet cannot ping each other
1 point by Ecco on June 2, 2021 | hide | past | favorite | 3 comments
Hi! I have to machines connected to consumer-grade fiber at major ISPs. One in France on the Orange network, and one in the US on ATT.

Each of them have perfectly fine internet access: they can ping and be pinged by every other machine I have access to.

But, very surprisingly, they cannot ping each other. I also have web servers running on both, and neither can curl a web page from the other.

I suspect something is broken in the overall routing.

How can I diagnose what's going on and who do I report this to?



https://en.m.wikipedia.org/wiki/Traceroute


You could also use tcpdump to record packet captures on both machines (to see if the ICMP packets are sent properly or arrive properly). This can confirm that the problem is somewhere in the middle, rather than a firewall rule or something on one host or the other.


I remember reading something about AT&T consumer DSL and Fiberoptic having ping disabled to prevent ping floods. Maybe Orange does the same thing?




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