We are currently a cisco house (with sonicwall firewall) and I would like to implement somthing (NOT ISA SERVER) which will prevent users bringing in laptops from home and setting static ip's to connect to our network. We have had a problem in the past where a user plugged in a laptop that had the same address as our firewall which took our network down for a while until we could trace source. I am implementing VLAN's and also will be doing port security which will prevent this, HOWEVER, i will not be done with segmentation project for some time. I need an interim solution which will prevent users on a FLAT network from taking up either our SWITCH ip's or FIREWALL ip. I need recommendations on something i can implement which is FREE. Thanks in advance for all of your responses.