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Can I use WireShark to see the handshake data exchange between my router/modem and my ISP's server at first logon?

asked 20 Sep '15, 05:27

Jonnyc's gravatar image

accept rate: 0%

No, you can't because the link between your router and your ISP is (most certainly) not Ethernet. I guess it's either a DSL link or a cable link (DOCSIS). For both, you would need (very expensive) hardware protocol analyzers.

But maybe I'm misunderstanding your question. In that case, please add more details what you expect to see in that first few packets between your router and the ISP.


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answered 20 Sep '15, 13:08

Kurt%20Knochner's gravatar image

Kurt Knochner ♦
accept rate: 15%

Hi Kurt. Thanks for your answer to my dumb question! What I'm trying to do is to configure a modem/router to be a standby for the ISP's box. We get a lot of thunderstorms here in Central France, and when the last one took out the box I was without I/net and phone for the week it took them to replace it. PITA! I called and asked them for some required parameters (VPI/VCI, Registrar address Etc.) but they refused to give them. So I'm looking for a way to read this information at first logon. I'm hoping maybe someone has already done this and save me "re-discovering the wheel"! I'm completely new to this so ANY help would much appreciated. TNX.


(20 Sep '15, 17:49) Jonnyc

P.S. How do I "cast my vote"?


(20 Sep '15, 17:54) Jonnyc

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(21 Sep '15, 05:28) grahamb ♦

So I'm looking for a way to read this information at first logon.
I called and asked them for some required parameters (VPI/VCI,

VPI/VCI sounds like it's a DSL modem/router. In that case, you can't capture that traffic with Wireshark, as I have explained. The protocol between the modem/router and and your ISP is not ethernet. It's not even anything close to anything you can capture with Wireshark. So, I'm sorry for you! Unless you are able to capture that information IN the modem/router, you'll have to rely on the ISP to hand over that information. Alternatively you could (politely) ask them to send you a second pre-configured box as a "cold standby" device. Other than that I don't see a solution for you.

You might be able to find some information on the internet how to open the modem/router and how to access the internal JTAG interface. Sometimes it's possible to "root" a modem/router via that way, but that's certainly beyond the scope of this site!

Some general hints, NOT related to your modem/router, as you did not mention the brand/model!!

(21 Sep '15, 09:56) Kurt Knochner ♦
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question asked: 20 Sep '15, 05:27

question was seen: 880 times

last updated: 21 Sep '15, 09:56

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