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"pinging loopback" response on all PC's.

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by dan m.

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I recently upgraded all of my 30+ PC's in the office to Windows XP Pro. They all have static private class "C" (192.168.1.x) addresses and unique hostnames. I also have a Netware server and each PC has the CSNW.

Just the other day I noticed in my firewall traffic log (a PC running SonicWall's ViewPoint) that most of the traffic is coming from a host named "loopback". As it turns out, the PC that is logging this information thinks that many of the PC's on the network are "loopback".

After discovering this I pinged most of the PC's on the network by IP address on a few different PC's. Some XP some 2K. The some of them result in "pinging loopback [192.168.1.x] with 32 bytes of data". However, if I ping by hostname it responds with the correct IP address.

I have a WINS server but it doesn't make a difference if WINS is setup in the client or not.

One last thing....when I browse the network neighborhood, I can see all the proper NetBIOS names.

Any thoughts on this would be appreciated.

Thanks in advance.

Dan

2 replies

by bfilmfan

I assume that you are NATing those non-routable subnets back to the client systems at the firewall? Is the firewall also serving as a DNS server for the local network?

Since you can resolve via the WINS server, it is a definite DNS issue. Check to see there are A records in DNS for those host system names.

by choppit

'Loopback' refers to a range of addresses 127.0.0.x assigned to 'localhost' by the OS. This allows software to connect to ports on itself as if they were external hosts. Applying this to your firewall host would suggect that the traffic is originating from itself. If you look at the types of traffic (ports etc) this should yield some clues as to why.

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