To use any Warcraft 3 Lan Emulator you need to unblock port 6112, this is easy to say but not easy to do for som computer users.
When You Start Lancraft or other Wc3 Lan Emulator Windows Firewall shout ask You to allow it in Firewall.
If it doesn't use next:
To enter Windows Firewall go to Control Panel
Start>Control Panel
Then enter "System and Security" category
And enter Windows Firewall
Go to "Allow programs or feature through Windows Firewall" click "Allow another program..." button and add lancraft.exe
When You add lancraft.exe (or battle.net.exe if You are using Battle.net) check "Home/Work (Private)" and "Public" than click OK
*This manual is from Windows 7 but it shout work in Windows Vista.
