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

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.

--
Mark Hobley,
393 Quinton Road West,
Quinton, BIRMINGHAM.
B32 1QE.

Mark Hobley wrote:
> 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?).

It *is* DHCP. You can configure networking so that it assigns a constant
hostname. I don't know how to do this on Debian.

> 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.

ISC dhcp is the "standard" package, but I think dnsmasq is much easier
to configure.

Sarah

Sarah <(E-Mail Removed)> wrote:

> It *is* DHCP. You can configure networking so that it assigns a constant
> hostname. I don't know how to do this on Debian.

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.)

Cheers,

Mark.

--
Mark Hobley,
393 Quinton Road West,
Quinton, BIRMINGHAM.
B32 1QE.

Mark Hobley wrote:

[putolin]

> 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.)
>

Why wouldn't it work? This is Linux where all things are possible

--
Tayo'y mga Pinoy

On 2008-07-02, Mark Hobley <(E-Mail Removed)> wrote:

> 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.)

Why not simply recognise the IP range that your LAN uses ?
Or even the - fixed - address ?


--
The sand remembers once there was beach and sunshine
but chip is warm too
-- haiku from Effector Online, Volume 1, Number 6

Rikishi 42 <(E-Mail Removed)> wrote:

> Why not simply recognise the IP range that your LAN uses ?
> Or even the - fixed - address ?

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.

--
Mark Hobley,
393 Quinton Road West,
Quinton, BIRMINGHAM.
B32 1QE.

On Thu, 03 Jul 2008 19:55:31 +0200, Rikishi 42 wrote:

> Why not simply recognise the IP range that your LAN uses ? Or even the -
> fixed - address ?

Or the SSID of the network itself?

- Andrew

Andrew Gideon <(E-Mail Removed)> wrote:

> Or the SSID of the network itself?

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.

--
Mark Hobley,
393 Quinton Road West,
Quinton, BIRMINGHAM.
B32 1QE.

On Sun, 06 Jul 2008 21:07:30 +0100, Mark Hobley wrote:

>> Or the SSID of the network itself?
>
> My network is not wireless,

Wow. Shows my bias that I assumed wireless, eh?

<Laugh>

- Andrew

Jim Talbut <www.spudsoft.co.uk> wrote:
> I don't know if this matters, but be aware that none of the ideas suggested
> here are secure - they could all be spoofed.

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.

--
Mark Hobley,
393 Quinton Road West,
Quinton, BIRMINGHAM.
B32 1QE.