You might have seen something like this when running inzider:
Checked C:\Program Files\Internet Explorer\IEXPLORE.EXE (PID=1244)
- Found UDP port 1056 bound at 127.0.0.1 [UDP client]
This line refers to a UDP socket allocated by IE. It is bound at the
loopback address 127.0.0.1 and at a dynamically allocated port in the range
1024-5000. As the note at the end of the line says, this is a UDP client,
and so one naturally asks "where is the server?". I have received a few
mails from people who were worried that this might be a way for Microsoft to
collect information from their computers while they browse the web with IE.
But in fact the server is not located at Microsoft, but in your own
computer - in IE itself. IE simply sends UDP packets from this port, through
the loopback address, and back to the same port. The packets never go out on
the Internet, and the port is not visible from the outside since it is only
bound at the loopback address. IE sends one byte large packets to itself
this way more or less constantly while you browse, and the purpose is most likely some kind of diagnostics.