How does FortiProxy Self-Test work?

[#1]

Description
How does FortiProxy Self-Test work?
Solution

When FortiClient is installed and running, you will see FortiProxy.exe process opening multiple connections from a PC going to 1.1.1.1 IP address (refer to FortiProxy_SelfTest.PNG). These packets are generated by FortiClient's proxy self test code and the frequency of the self test is one packet per 30 seconds for each port that FortiClient is monitoring.

The purpose of this is to detect if the proxy can work properly. The logic is as follows:

1. FortiProxy.exe sends packets to 1.1.1.1:80 (for HTTP).

2. FortiRdr.exe (the proxy driver) will see this packet and redirect back to FortiProxy.exe. The destination port will be changed from port 80 to a port which FortiProxy.exe is listening on.

3. If FortiProxy.exe successfully receives back the test packet, it will simply drop it (close connection).

4. If for some reason the redirected packets cannot reach FortiProxy.exe, it will disable itself if the test fails.

This test is helpful if the MS Windows or another Firewall/Antivirus installation disabled the FortiProxy from working, which will cause outage in the Internet connection. The FortiClient avoids this case by simply disabling the FortiProxy to allow the PC to access the Internet.