@tomdlgns:
i used this command in the dd-wrt router to intercept DNS that client machines were trying to use.
I suspect an equivalent in pfSense would be to set up a port forward rule on the LAN interface as follows:
On Firewall -> NAT, Port Forward tab click "+" at the bottom to add the rule (default values not specified here): Interface=LAN, Protocol=TCP/UDP, Destination=(not box ticked, Type=(Address=LAN address, Destination port range from: DNS)), Redirect target IP = <pfsense lan="" ip="" address="">Click Save then go to Diagnostics -> States, click on Reset States tab, read the explanation then click on the Reset button and test the new port forward rule.
I haven't tested this. I expect it would forward any TCP/UDP access to port 53 (DNS) on an address other than the LAN IP address to the LAN IP address.</pfsense>