Prevent User from being able to change IP

[Suhas!]

Hi all,

We have dhcpd server running on RHEL AS 4. If on a client, user sets a static IP and then sets it to be a dynamic, his machine gets the same IP from the DHCP server rather than what it was given before by the DHCP server.

e.g.

Step 1 :

Machine set to Dynamic, IP Obtained: 192.168.0.100

Step 2 :

Machine assigned a static IP : 192.168.0.200

Step 3:

Machine set back to Dynamic, Obtained IP : 192.168.0.200


In this scenario, in the third step a machine should have got the old one IP i.e. 192.168.0.100 but it didnt get that one. Why is it so? This allows user to have whatever IP he wants. (It is very serious issue when Internet access is given on the IP addresses )

What setting can I do on this, as users having administrative rights can easily change their dynamic IP.

(I am not looking for the solution through Group Policy in Windows Domain Environment.)

Please suggest.......

[mechdave]

Why don't you configure DHCPd to assign ip addresses based on the MAC address of the machine that is requesting the lease? Eg: As taken directly from Peter's page http://www.linuxhomenetworking.com/wiki/index.php/Quick_HOWTO_:_Ch08_:_Configuring_the_DHCP_Server

<snip>
   # You can also assign specific IP addresses based on the clients'
   # ethernet MAC address as follows (Host's name is "laser-printer":

  host laser-printer {
      hardware ethernet 08:00:2b:4c:59:23;
     fixed-address 192.168.1.222;
   }
</snip>

This will only assign the address 192.168.1.222 and no other address to the printer. Change this to reflect your own MAC address and host name in your servers dhcp.conf (usually in /etc/ ). Also make sure users cannot change their MAC address on the machine they are using!

Cheers,
Mechdave