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Hi, i m just wondering if there is a way to set an ip address on a computer remotely. Here's my issue : Have a debian computer (plug computer) on ...
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  1. #1
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    Set ip address remotely


    Hi,
    i m just wondering if there is a way to set an ip address on a computer remotely.
    Here's my issue :
    Have a debian computer (plug computer) on which, after upgrade, i m not able to
    log in back anymore.
    At the moment it seems i have no chanche to connect something like a monitor but i m pretty sure the computer it boots up cause wireless is on and i can see ssid and mac address of the ap.

    I ve tried to assign an ip to the mac address (from my laptop) by arp and in the table it shows the link between the mac and ip, but i m unable to ping the ip after that.

    I was trying to think of maybe set up a dhcp server from my laptop and see if the plugcomputer gets an ip automatically, but i m not sure if it is working and at the moment i have little experience on set up a dhcp server on linux (sabayon).

    Do you think is it possible to manage the network card of my plug computer by eth/wlan from my laptop?

    Thank you

  2. #2
    Linux Engineer Kloschüssel's Avatar
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    ve tried to assign an ip to the mac address (from my laptop) by arp and in the table it shows the link between the mac and ip, but i m unable to ping the ip after that.
    That would solve problems where your laptop doesn't know how to route to the other host. But the other host won't accept your requests as he doesn't believe he is the one you're talking to (wrong IP).

    I was trying to think of maybe set up a dhcp server from my laptop and see if the plugcomputer gets an ip automatically, but i m not sure if it is working and at the moment i have little experience on set up a dhcp server on linux (sabayon).
    If it's a blackbox to you and you cannot physically access this host but you know the MAC, you can indeed let a dhcp server assign a static ip to that host. Once the hosts dhcp timeout has passed or is rebooted, it should request a new ip.

    Do you think is it possible to manage the network card of my plug computer by eth/wlan from my laptop?
    Yes, if you are able to log into the other host from your laptop. Otherwise: NO.

    If you're in the same subnet as the other host but just don't know its IP, you may want to try "nmap" and scan the subnet for hosts. nmap knows several methods to find/uncover hosts, open ports and other stuff like OS guessing. It may tell you that either the host is up and listening on a specific IP (hooray!) or that the networking on that host is down (ouch!) which would mean you have to plug in a monitor and a keyboard to that host.

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    First of all, thank you for your answer.
    I can try to scan ranges 192.x.x.x and 10.x.x.x, maybe even 169.254.x.x and 172.x.x.x
    I could nmap and see what happens but i do not know where to start from, cause i believe there is no ip address assigned to that nic.

    The connection is direct by a cross cable.

    Other chanche is with dhcp server but my question is:
    Is NIC automatically configured to use dhcp or it could be disabled by default?

  4. #4
    Linux Engineer Kloschüssel's Avatar
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    Is NIC automatically configured to use dhcp or it could be disabled by default?
    Can't tell. That changes from distro to distro, but usually the configuration defaults to DHCP as that can be seen as the standard nowadays.

    I would attach the device to a LAN whose IP addresses are managed by a DHCP server and see what appears in the DHCP server logs / nmap the DHCP subnet (i.e. 10.10.10.0/24).

    EDIT: Does this host of yours support the SNMP protocol?
    EDIT2: this link may be of help, as I understood it this software uses the DHCP protocol to determine the IP of another host by resending DHCP requests with a fake MAC address
    EDIT3: another method would be to bring the network card into promisc mode, do broadcast pings, capture all the data for later analysis and observe the local ARP table.. if you're lucky the arp table reveals the other host, otherwise you may need to further mine the captured data for the mac address and send a prayer to your favorite god
    Last edited by Kloschüssel; 03-21-2011 at 03:51 PM.

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