if your using Framework 2.0 to compile this app you have to make any changes to files on your system
you have to change machine.config IF Framework 2.0 is installed and your using it to compile this app.
I am using VS2005 and need to make any changes.
If you did't changed machine.config . then you compile this using Framework 2.0 you will get a warning message for one line of code in both the server and client code.
warning message
warning CS0618: 'System.Net.Sockets.Socket.SupportsIPv6' is obsolete: 'SupportsIPv6 is obsoleted for this type, please use OSSupportsIPv6 instead. http://go.microsoft.com/fwlink/?linkid=14202'
if(!Socket.SupportsIPv6)
I changed it to this
if(!Socket.OSSupportsIPv6)
This code appears in both the server and client