LARTC - Jul 2006 - Hello New MAC / DHCP Request - How to spot the presents of a new MAC address...

Hi All,

How do I find out about new new DHCP connections as they appear?

I want to write a script that will do some stuff based on a new ip
request from a machine on my lan.

ie - new user connects to the lan, DHCP server on my Linux (debian)
gateway gives them an IP, my script is run automatically to change the
firewall rules and start recording their presents, or if it''s an
unknown
user it will add their MAC to a list of unknown users.

More details of the application can be seen here:
http://www.tcn.bowenvale.co.nz/component/option,com_wrapper/Itemid,23/


Cheers Don
-- 
Don Gould
www.thinkdesignprint.co.nz - www.tcn.bowenvale.co.nz -
www.bowenvale.co.nz - SkypeMe:  ThinkDesignPrint
Upcoming events:  Software Freedom Day - 16 September 2006 -
www.softwarefreedomday.org




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On Friday 07 July 2006 15:21, Don Gould wrote:
> ie - new user connects to the lan, DHCP server on my Linux (debian)
> gateway gives them an IP, my script is run automatically to change
> the firewall rules and start recording their presents, or if it''s
an
> unknown user it will add their MAC to a list of unknown users.
I''m sure you could engineer something really impressive, but you could 
probably get away with a lot less effort by simply tailing whatever 
dhcpd logs to (possibly /var/log/messages).

Ciao,
Sheldon.
-- 
Sheldon Hearn
IT Director
Clue Technologies (PTY) Ltd

Web:		http://www.clue.co.za/
Mail:		sheldonh@clue.co.za
Office:		+27-21-913-8840
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Sheldon Hearn wrote:
> I''m sure you could engineer something really impressive, but you
could
> probably get away with a lot less effort by simply tailing whatever 
> dhcpd logs to (possibly /var/log/messages).
Yes, that discussion has been had some where...

Some research in to dnsmasq and a few emails to the guy who wrote it
showed up the answer...
> You may not need to make any source changes at all: dnsmasq will call a
custom script whenever a DHCP lease is created or destroyed: see the
--dhcp-script flag in the manpage for details. The MAC address and IP address
and name of the host are passed to the script.

-- 
Don Gould
www.thinkdesignprint.co.nz - www.tcn.bowenvale.co.nz -
www.bowenvale.co.nz - www.hearingbooks.co.nz - SkypeMe:  ThinkDesignPrint