How to learn a router's latest dynamic IP address when I'm outside its LAN?

Posted on 2004-11-19
Last Modified: 2013-11-30
I have a client who has two computers behind a Linksys BEFSR41 router and a DSL modem that receives a dynamic IP, sometimes quite frequently.  

The people who work on the computers are completely incompetent. Thus, I need to be able to administer the systems externally.  To do this, I have to know the IP address of the router.

Since none of the computers inside the router are aware of when the IP address changes, how can I have the latest IP address reported to me?  Is there a way to have an internal system cue the router for this info and report it to me?
Question by:fuze44
    LVL 49

    Assisted Solution

    I am sure this can help you

    Nice idea by Lucf in there.

    Let us know if that doesnot help you
    LVL 41

    Accepted Solution

    I use (free) and they have clients that you can download and setup that will check it periiodically and update the dyndns records
    LVL 2

    Assisted Solution

    There is one simple solution I often use for my clients...
    There is no aditional configuration required.
    Let them send you e-mail (might be blank) and you look at the properties of the recieved mail
    and you can find their originating IP address.
    Example in outlook express - right-click recieved email then go to properties then details and now you will see IP in "Received: from" section. For first try get their IP address before you look at the mail - it is easyer to find where to search, next time you'll know exactly where to look.
    Mail must be sent from one local computer that uses outlook... outlook express... or some other mail client that uses smtp.

    Some ISP's mask their originating IP's. If that is the case try using different smtp (outgoing) server.

    Hope this helps.
    LVL 1

    Assisted Solution

    I usually set a batch file that telnet's (or any other program) to my server/firewall and run it as a schedule task on one of the clients machine's as often as you want. Since my firewall does not allow telnet I get a log producded and can find out what the originating address is.

    The good thing about this is that you don't need anyone on site just a computer turned on.

    Good Luck
    LVL 4

    Assisted Solution

    I'm with stevenlewis on this one, although I use the service. a client runs as a windows service, which the user can't interupt, and simply updates the DNS entry for that DSL/cable connection. I have a whole list of clients and I can remote control their boxes from here via I've even got one company using PCanywhere that i have four computers set up to respond to non-standard ports and thier linksys router forwards the appropriate ports to their PC so I can connect to all four boxes based on which port i use. All based on dynamic IPs
    LVL 4

    Expert Comment

    Is this still current or should it be marked as resolved? if resolved which answer was used?

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