This is almost a copy and paste of the http probe.
Probe definition:
Name: Google through proxy
Type: TCP
Port: 8080 (this may change at your company)
Connect Only UNCHECKED
First Receive, Then Send UNCHECKED
Send: GET
http://www.google.com/ HTTP/1.0\r\n\r\n
Receive: HTTP/1.1 200 OK