# DUP! in ping replies to or from server



## ProServ (Dec 17, 2012)

Hi,
I have not seen this before and am hoping someone on the FreeBSD Forums has.

When ping out from a Server I see quite a few


```
64 bytes from 107.6.50.74: icmp_seq=0 ttl=56 time=5.707 ms
64 bytes from 107.6.50.74: icmp_seq=1 ttl=56 time=5.404 ms
64 bytes from 107.6.50.74: icmp_seq=1 ttl=56 time=5.529 ms (DUP!)
64 bytes from 107.6.50.74: icmp_seq=2 ttl=56 time=10.788 ms
64 bytes from 107.6.50.74: icmp_seq=3 ttl=56 time=12.424 ms
64 bytes from 107.6.50.74: icmp_seq=3 ttl=56 time=12.549 ms (DUP!)
```

Same when ping the Server:


```
64 bytes from 68.179.122.137: icmp_seq=0 ttl=56 time=5.067 ms
64 bytes from 68.179.122.137: icmp_seq=1 ttl=56 time=5.151 ms
64 bytes from 68.179.122.137: icmp_seq=2 ttl=56 time=5.048 ms
64 bytes from 68.179.122.137: icmp_seq=2 ttl=56 time=5.083 ms (DUP!)
64 bytes from 68.179.122.137: icmp_seq=3 ttl=56 time=5.950 ms
64 bytes from 68.179.122.137: icmp_seq=4 ttl=56 time=5.299 ms
64 bytes from 68.179.122.137: icmp_seq=5 ttl=56 time=4.983 ms
64 bytes from 68.179.122.137: icmp_seq=5 ttl=56 time=5.047 ms (DUP!)
```

The network configuration is pretty simple:
Server -> Switch -> wireless network (company has wireless connection to the internet).

Any help would greatly be appreciated.

Thanks.


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## throAU (Dec 17, 2012)

Without knowing your network setup, hard to tell you exactly what it is, but this isn't a FreeBSD specific issue (i don't think anyway), FreeBSD is just reporting duplicate ping responses.

Haven't seen it myself, but this is FreeBSD reporting that it received a packet back for an echo request that already had a response.


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## bbzz (Dec 17, 2012)

My first guess would be a card issue, as I've seen this on some of the bad GE cards I used. 
But like throAU said, hard to tell without more information.

Why don't you test with large payload, say 1400 bytes, see if you get dups again.


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## Rudy (Dec 21, 2012)

I don't get DUP's when I ping those IPs.  

An odd loop in the network topography between point a and b could kick out a DUP.

A couple of years ago, the Netgear GS105 switches would pass packets fine, but DUP some ICMP packets... firmware upgrade fixed that.

When I see DUP's on a local network, I install arping 

```
pkg_add -r arping
```
and 'arping' the IP.  That returns all the MAC addresses that are responding to that IP.


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## m6tt (Dec 22, 2012)

Yes, the GS105E would reply to every ping. They're not bad other than the silly way of configuring them...the GS108E is probably a better device for not much more (both cheap for managed gig-e, but not really great devices).

Easiest test is to plug a cable between the server and a laptop (if possible, obviously constant production use may prevent this) and see if you get the DUPs then. If you don't it's a route issue, a vlan issue, or is a egotistical device that has to get a word in 

Are you running spanning tree or any other redundant route stuff?


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## m6tt (Dec 22, 2012)

Rudy said:
			
		

> When I see DUP's on a local network, I install arping
> 
> ```
> pkg_add -r arping
> ...



arp-scan is pretty awesome too...I usually impress the MCSE types when I can find their IP before they can


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