Frequent Ping Unreachable but Manual Pinging Works Fine

[yyiinn1]

I have a host that frequently reports 'ping unreachable,' and packet captures confirm no response. However, manual pinging works fine at the same time.

unreachable icmp packet sequence
1:
Sequence Number (BE): 0 (0x0000)
Sequence Number (LE): 0 (0x0000)
2:
Sequence Number (BE): 2 (0x0002)
Sequence Number (LE): 512 (0x0200)
3:
Sequence Number (BE): 4 (0x0004)
Sequence Number (LE): 1024 (0x0400)

at the same time
use fping -C3 -i0 ipaddress
sequence is 0 1 2 3 4 5 ...

I'm not sure if the switch has any issues, but based on the feedback from the network administrator, the device should be operating normally.

[Alexander J]

Does the host you are pinging have a firewall setup?

It's common for prefab firewalls, like CSF for example, to set limits on the number of icmp messages per second.

This could be the issue.

[yyiinn1]

Thank you, this situation is possible. I will ask the network administrator for help in checking.

[yyiinn1]

I using iptables. The issue hasn't occurred again after I restarted the OS. It's a bit strange that I wasn't able to capture and analyze packets from the switch side at that time.