Get IP from DHCP - Ubuntu

For example if the wrong dhcp server is 195.249.186.30 you can configure your dhcp client addng this line to dhclient.conf :

reject 195.249.186.30

reject ip-address; The reject statement causes the DHCP client to reject offers from servers who use the specified address as a server identifier. This can be used to avoid being configured by rogue or misconfigured DHCP servers, although it should be a last resort - better to track down the bad DHCP server and fix it.