Application silently applies rules for 3G network to a wired USB connection

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What steps will reproduce the problem?
1. Setup a whitelist configuration which enables some apps to go through WiFi
interfaces only (don't allow 3G networking to any app)
2. Enable firewall
3. Connect USB cable and set to use internet over usb

What is the expected output? What do you see instead?
No app is able to access network with ICMP Port Unreachable result. As long as
WiFi is obviously a less expensive way of internet access, it implies USB
networking to be definitely free. So why is it applied with rules from a more
restricted communications channel?

What version of the product are you using? On what operating system?
1.5.7

Please provide any additional information below.
I'd better suggest to add a third column of checkboxes for USB connection or at
least add a switch into settings so the user be able to select which bearer's
rules are to be aplied to USB conenction
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Original issue reported on code.google.com by `Bob...@gmail.com` on 20 Dec 2011 at 6:53