Duplicate ping

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Pratapa
Posts: 144
Joined: Tue Oct 01, 2019 1:33 am

Duplicate ping

Post by Pratapa »

Hi,

We are using Nagios XI.

When we ping a host from Nagios XI GUI duplicate ping is appearing. Sample output is shown below.

PING 10.62.88.45 (10.62.88.45) 56(84) bytes of data.
64 bytes from 10.35.88.23: icmp_seq=1 ttl=246 time=143 ms
64 bytes from 10.35.88.23: icmp_seq=1 ttl=246 time=144 ms (DUP!)
64 bytes from 10.35.88.23: icmp_seq=2 ttl=246 time=142 ms
64 bytes from 10.35.88.23: icmp_seq=2 ttl=246 time=143 ms (DUP!)
64 bytes from 10.35.88.23: icmp_seq=3 ttl=246 time=136 ms
64 bytes from 10.35.88.23: icmp_seq=3 ttl=246 time=143 ms (DUP!)
64 bytes from 10.35.88.23: icmp_seq=4 ttl=246 time=136 ms
64 bytes from 10.35.88.23: icmp_seq=4 ttl=246 time=136 ms (DUP!)
64 bytes from 10.35.88.23: icmp_seq=5 ttl=246 time=136 ms

The device is an Access point and no ping service is configured for this device.

What could be the reason for duplicate ping(DUP!)

Pratap
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pbroste
Posts: 1288
Joined: Tue Jun 01, 2021 1:27 pm

Re: Duplicate ping

Post by pbroste »

Hello Pratap,

Typically we see this when a device with the same IP address (with a different MAC address) is hitting it. Other reasons include incorrect load balancing, proxy, or redundancy setup. Also, note that this is expected behavior if you are pinging a multicast group.

Several options to take a look at to see what is going on.
  • Use TCPDUMP command and import to Wireshark to see if anything of concern is going on.
  • Increase the ping -t value to 60 to see if (dup) goes away, could be false feedback or noise.
Thanks,
Perry
Pratapa
Posts: 144
Joined: Tue Oct 01, 2019 1:33 am

Re: Duplicate ping

Post by Pratapa »

Thank you for the response. You may close this.

Regards,
Pratap
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