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I am out of town, and dyndns droped my account and deleted my ip address. I set up a new dyndns account, but I really need the ip address of my home modem. Is there any way for me to retrieve it? Shouldn't the ISP know that type of thing?

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closed as off topic by Michael Hampton, Scott Pack, Magellan, Mathias R. Jessen, mfinni Dec 21 '12 at 23:33

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Logmein is a nice for when this happens. You can even get the IP without logging in by looking at the summary of one of the machines on your home network. –  Glen Nov 24 '11 at 21:39
    
@mailq, more like, the ISP tech doesn't know how to find it. I had to walk him through pinging the modem and using whois to get my ip. Eventually, we got it. –  Jonathan Henson Nov 24 '11 at 21:50

4 Answers 4

up vote 8 down vote accepted

What do you have handy? If you have any emails from yourself, sent from home, the full headers will contain your IP address (maybe only if sent from a desktop client, not sent by webmail).

Can you login to your ISP account page and find it?

Do you have any servers you can connect into, and find "last logged in from {home IP}" in a logfile somewhere? Or forum posts (Wikipedia edits?) which log IPs?

Did you setup a DynDns client on your modem with a username and password? If you sign up for DynDns with the same details, it might continue connecting and put the new IP in.

Is there anything you have, e.g. DropBox, which automatically connects out from your home to somewhere?

Otherwise, you'll have to ask someone at home to visit http://www.whatismyip.com or similar and tell you the address.

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This is the stuff I was asking about thanks! I couldn't find any in the email headers. I tried logging into the ISP account, they didn't have anything. All of my dyndns entries had been deleted without a trace--that is why I couldn't find the ip. I did call my ISP and explain my situation. He told me that it wasn't possible to retrieve it so I told him to ping my modem and tell me that address. Of course, that was a 10.100 ... address so that had to be their internal network. Eventually he was able to retrieve my public IP. This is great advice though. Thanks! –  Jonathan Henson Nov 24 '11 at 21:48

If you have someone at home who would be willing to cooperate, you could just ask her or him to ping your current IP address while performing a network trace with Wireshark. Looking at the source address of the incoming ICMP packets within the trace will get you to the address of your home router.

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If I had that, I wouldn't be asking the question. :) –  Jonathan Henson Nov 24 '11 at 21:52
    
I could also just have him log into my router and read it there. Anyways, there is no one there. –  Jonathan Henson Nov 24 '11 at 21:54

Yes, your ISP knows. But he is not telling you, probably. Ask someone at home. Otherwise your chances for guessing are 1:2^32. Or depending on the AS range of your provider "only" 1:2^16?

And the shortest way to get the current IP (at home!) is http://ix.de/ip

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more like, the ISP tech doesn't know how to find it. I had to walk him through pinging the modem and using whois to get my ip. Eventually, we got it. –  Jonathan Henson Nov 24 '11 at 21:52
    
@JonathanHenson Yeah, but probably they can't even verify your identity and therefore don't hand out this secret information. –  mailq Nov 24 '11 at 21:59
    
Well, they verified my account number, address, and birthday. I guess they figured that was enough. Thanks for the help. –  Jonathan Henson Nov 24 '11 at 22:06

ok is really easy, go to command prompt and type the next: ipconfig /release

then press enter and then type the next command ipconfig /renew

that will release the ip adress for internal and external ips and renew them, to know your ip address afterwork jus type the next command ipconfig then press enter and it should show you allot of information, so scroll up and look for ipv4 then and ip address thats your ip for your computer, there you will also see the netmask and ip address and subnet mask.

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And how does one do that while not at the machine? You really should read and understand the question before attempting to answer it. –  Michael Hampton Dec 21 '12 at 21:04

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