Whose LAN am I on? Is this LAN mine? (Laptop networking query)

Discussion in 'Linux Networking' started by Mark Hobley, Jun 30, 2008.

  1. Mark Hobley

    Mark Hobley Guest

    I have a laptop computer that I use at home and on public networks. I am
    wondering if there is some conventional tool (maybe using DHCP or some other
    type of service) that identifies the network that I am on.

    I need to know whether the laptop is on my home LAN, or an alien LAN.

    I configured a Debian computer on a remote LAN last week, and it
    automatically obtained a machine name (STUDENT-23). I don't know how it
    obtained this, I certainly did not key it (There must be some sort of
    automatic allocation of machine names (Is this an extension to DHCP?).

    I was thinking of setting up a similar service on my home LAN.

    I was thinking of configuring a custom service on a specific port, and
    then using a query from the client, to obtain a "markhobley.yi.org"
    respose for the local network, but I don't want to reinvent the wheel,
    if services already provide LAN identification.

    Please advise.

    Mark Hobley, Jun 30, 2008
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  2. Mark Hobley

    Sarah Guest

    It *is* DHCP. You can configure networking so that it assigns a constant
    hostname. I don't know how to do this on Debian.
    ISC dhcp is the "standard" package, but I think dnsmasq is much easier
    to configure.

    Sarah, Jul 1, 2008
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  3. Mark Hobley

    Mark Hobley Guest

    Wow! I looked at the DHCP related documents, and you are right. It does
    provide the option to set the hostname. Interestingly in the early days
    of Microsoft Windows '95, I encountered a problem that required me to
    study the DHCP telemetry. I found a problem with the hostname not being
    available in the telemetry from the Unix based network. The
    organizations affected by the problem took the decision to install a Microsoft
    Windows NT based servers alongside their existing Unix networks to
    manage their hosts. Interestingly, when I obtained that "STUDENT-23"
    hostname, I was on a Microsoft Windows NT based network.

    On my LAN, DHCP is provided by a Netgear router. It allows for a
    hostname to be entered against manually entered IP addresses. I am interested
    now to see if this can be used by my Debian based laptop.

    If so, this means that my laptop will be able to recognize my home LAN
    from the provided hostname. (Damn! I hope it works.)


    Mark Hobley, Jul 2, 2008
  4. Mark Hobley

    Baho Utot Guest

    Mark Hobley wrote:

    Why wouldn't it work? This is Linux where all things are possible :)
    Baho Utot, Jul 3, 2008
  5. Mark Hobley

    Rikishi 42 Guest

    Why not simply recognise the IP range that your LAN uses ?
    Or even the - fixed - address ?
    Rikishi 42, Jul 3, 2008
  6. Mark Hobley

    Mark Hobley Guest

    Yeah. I do actually dynamically allocate fixed addresses on my LAN, but
    I cannot guarantee that these addresses would not be allocated on a
    foreign network. However, I am sure that my hostname is only meaningful
    on my LAN. Certainly the fully qualified domain name is, but I am not
    sure whether this is obtainable via DHCP, (and I don't think my netgear
    router can provide a fully qualified domain name to its clients.)

    Mark Hobley, Jul 3, 2008
  7. Or the SSID of the network itself?

    - Andrew
    Andrew Gideon, Jul 6, 2008
  8. Mark Hobley

    Mark Hobley Guest

    My network is not wireless, and I have no wireless devices. I currently carry
    an ethernet cable with me. (Damn! I am so old fashioned.)

    Mark Hobley, Jul 6, 2008
  9. Wow. Shows my bias that I assumed wireless, eh?


    - Andrew
    Andrew Gideon, Jul 6, 2008
  10. Mark Hobley

    Mark Hobley Guest

    That is not really an issue here. The networks that I visit are known.
    The reason that I need to know if the network is mine is so that
    localized outgoing mail on the laptop can be transferred to the "outbox" on
    the IMAP server.

    Mark Hobley, Jul 20, 2008
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