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How to change host's IP address over a VPN connection ?

Discussion in 'BlackHat Lounge' started by imobilec, Aug 8, 2009.

  1. imobilec

    imobilec Registered Member

    Dec 14, 2006
    Likes Received:
    I am using a VPN connection to connect to my Home computer.
    The home computer has dynamic DSL connection and can change IP address
    easily using router configuration. so while changing IP address the internet connection is dropped.

    I have configured my home computer as a VPN server to allow incoming connection. I am using dyndns's service to point a alias to my dynamic IP and their software on my computer automatically updates any change in my IP in their servers. So that I can use it as a VPN host.

    I use a VPN connection from my work computer to my home computer.
    So on my client computer(say at work) uses my home internet connection
    to browse the internet. But I need to know how can I access the router settings of my home computer via the client without disconnection.
    Simply put I need a way to change the IP address of my home computer via the client without disconnecting from the VPN..
    I am able to access the router settings of my home connection from this client but when I reset the IP. the client's connection is lost and I need someone to reboot the router at my home to get connected again.

    So is there a simple way to change the IP of my home computer without someone else's help at home,,
    Is there a software that runs on the host and I can change IP address every 5-10 mins ?

    Any help/insights into this is highly appreciated.
  2. zorba

    zorba Newbie

    Jun 18, 2009
    Likes Received:
    Sorry, it can't be done.

    When you create the VPN connection, you create an encrypted tunnel from your work PC's IP address to the home PC's IP address. If your home connection changes IP, that will always sever the connection with any VPN protocol.

    However, you shouldn't have to reboot the router to get connected again. When your home system changes IP, then you should be able to reconnect your VPN client to the new IP. I think the problem is DNS propagation -- i.e. your home router changes IP, but it takes a while for the software to notice and notify dyndns. Once it does, dyndns updates its DNS server, but DNS has multiple layers of caching, so it can take minutes or even hours for your work computer to know the new IP.

    You could write up some software on either the home PC or the router to change the IP every 5-10 mins... but every time it does it, you're going to cut the VPN connection (unavoidably) and have the propagation delay before you can connect again. I suppose maybe you could have it email you the new IP whenever it changes it and connect that way to get around the DNS issue.