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School “destination unreachable”.

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Hi all

I'm new to Wireshark. I managed to set up Wireshark to record on the routers mirroring port.

I then recorded 3 minutes of not being able to connect to websites..... It seems like its not possible for local ip's to reach the router (192.168.0.1). It says "destination unreachable".

Why could that be? Could you help me point me in some direction at what to look for, when trying to troubleshoot with Wireshark? I believe i got a good log at the failure, but i'm not sure how to figure out, what causes the "destination unreachable".

Best regard Mike Kristensen Denmark

asked 02 Oct '16, 03:02

Mikethk's gravatar image

Mikethk
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accept rate: 0%

From your description I guess that you have connected your PC only to the mirroring port of your switch. Is that true?

(02 Oct '16, 03:09) sindy

If the local devices could ping the routers ip before. Some / one of your changes is incorrect.

So how did you set up the mirror port at the router? Have you changed some routes?

(02 Oct '16, 14:30) Christian_R

One Answer:

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Hi, Mike -

Not sure I understand completely your situation. IMCP Unreachable destination message can mean, in routing, there's no route active/defined to the IP/subnet. Are you trying to troubleshoot not being able to get to a website? It could be good to take a trace from the source PC in that case. If you want to work your way across the net, you could open a command window and ping your machine IP, then the router IP, and then the FQDN of the target website. This should be a test of each stage of the process, including the DNS resolution of the FQDN to an IP. Hope this helps.

answered 02 Oct '16, 13:42

packetlevel's gravatar image

packetlevel
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accept rate: 0%