How can I determine which interface a specific mac address or ip address is using on my UTM9?

Question

Hi, I have three ISPs on my Sophos utm9. Each is configured as its own interface. How can I tell which interface a client on my network is using? I have their IP 10.x.x.x. and their mac address. I know if it were a computer i could just visit whatismyip.com and cross ref the public ip of the interface but I cannot access the computer to do this. Is there a way I can figure this out on the Sophos? 
 thanks!

sachingurung · Answer

Hi John, 
 If you have Uplink Balancing enabled on the UTM then your requirement is nearly impossible to figure out, as the outgoing traffic will be balanced equally through all the active WAN interfaces. However, if you want to route the outgoing traffic from specific source addresses, primarily through a particular WAN interface then configure a multipath route definition. Take a look at the following KB article for more information. 
 Sophos UTM: Uplink Balancing and Multipath rule 
 Hope that helps. 
 PS- Please move this thread in the Sophos UTM forum, you might need to subscribe the group before you can move the thread.