dhcp config for 200 users via single file

Nick Urbanik nicku at nicku.org
Sat Jan 12 21:04:16 UTC 2008

Dear Syed,

I do not understand your problem completely; I am trying to clarify it

On 12/01/08 20:24 +0000, AA Inter.Network Services / SYED JAHANZAiB wrote:

>I am running internet cable.net setup in my local area with around
>200+ users.

Is only one cable modem involved with these 200 users, or are there
200 cable modems involved?

>I have created a linux birgde which only allow specific mac address
>/etc/mac.allowed to pass from the bridge to server ,I want that this
>Bridge should also act as a DHCP server too with MAC to IP
>MATCH.binding, so that only specific mac should get the specific ip
>address, and if the user tries to change the ip or mac, he should get

So you mean that the DHCP server should only provide a specific IP
address for any given MAC address and not respond to other requests?

Or do you mean that you want to firewall out any users who have
manually set their IP address?

If the first, fixed records could be generated from a file.

The second is much harder; if each user has their own cable modem, and
you are provisioning that cable modem, then you would use docsis to
authenticate the cable modem MAC addresses.

If there is only one cable modem shared between 200, then you can use
iptables or the like to restrict access to your range of fixed IP
addresses; I am not quite sure what your setup is.

>All other unknown clients shouldn't get any ip or some fake ip with
>fake gateway.

Easily achieved with fixed records.  I made a system many years ago
that used an Excel spreadsheet shared out by Samba from the DHCP/name
server that would generate DHCP/name server records for the
address/MAC/name mappings in the spreadsheet.  Details are at
http://nicku.org/snm/dhcp-dns-system/  (The code now makes me wince.)

>I have the MAC to IP binding script.

I'm not sure what this does.

>but how can i setup mac ip entry in a file and tell dhcp to pick
>entries from there and provide macs the fix ips. How can this be done
>in simple way, because I have to allow/modify/deny various users on
>daily basis, so is there a way I can edit any single file lets say
>/etc/macallowed , and there entries should be like, 00-08-74-4D-74-DE
> # John B-303 Sunview Appartments00-02-74-D2-74-F3 #
>Arnold 402 Aone BunglowsAnd so on . . .

Still not totally clear on what you need.  It should be quite simple
to write a program that generates /etc/dhcpd.conf and restarts the
dhcp server when your MAC/IP mapping file changes.  But perhaps you
are aiming for something else; please help us understand your
Nick Urbanik   RHCE         http://nicku.org        nicku at nicku.org
GPG: 7FFA CDC7 5A77 0558 DC7A 790A 16DF EC5B BB9D 2C24 ID: BB9D2C24
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