Cannot ping subnet hosts

[Lars Kruse]

Hello Davide,


Am Thu, 24 May 2018 17:50:50 +0200
schrieb Davide L <davide.lovreglio at gmail.com>:

> I don't know how to solve the problem.

Maybe you want to check, where exactly the packet disappears?

The following could be helpful to be run on one of the hosts along the way of
the packet:

  tcpdump -npi any icmp and host PEER_IP

* meanwhile run a "ping" from the source to the target
* PEER_IP could be either the source or the target IP
* "any" could also be replaced with a specific network interface
  Hint: "any" will cause the same packet to be listed twice by "tcpdump"
  (once on the incoming and a few milliseconds later on the outgoing interface)

Just follow the path of the packet forward and then the path of the reply
packet backwards.

Somewhere along the way you will notice, that there is no packet. The previous
host is the culprit (routing or firewall rules).
Regarding routing: "ip route get TARGET_IP" could be useful (on the problematic
host).

Have fun!

Cheers,
Lars