need an starting point from which i can figure out how a game's network connection works

#1 from which class all the network connection begins?
i think from: NetConnection Class (SimObject->SimSet->SimGroup->NetConnection)
am i right?
if yes,then may be it's callback function can be a good starting place?

is there any other class before NetConnection in class hiearcy that does any other network related tasks?

#2 Greetings!

If you want to see where the raw packets are handled, start with the Net struct defined in platformNet.h. The Net::process() method reads in the data, looks up the source's address and port, and triggers a packet receive event. The Net struct is also used to open a port, performs sendTo(), etc.

Then the NetInterface responds to the packet event in NetInterface::processPacketReceiveEvent(). [This event hook up is done in StandardMainLoop::init()] Within there the given address and port is used to look up the appropriate NetConnection that will handle the packet.

NetInterface also handles the handshaking required to allow a client to connect in the first place. You can poke around the various send and handle methods.

I hope that helps!

- Dave

#3 sorry for late answer.i did not had net connection.

actually i was asking for a script side point.
and i thinks i have found.
ChooseLevelDlg->ChooseLevelDlgGoBtn's
function ChooseLevelDlgGoBtn::onMouseUp( %this )
and
JoinServerDlg->JS_joinServer.command=JoinServerDlg.join();

but thanks for your answer.it will help me in future.