Only I can connect to control panel

[lucky777]

im the only one who can connect to http://localhost:14534/slogin.html

[Thomas]

"localhost" is a symbol for your local machine.

So everyone else who browse to "localhost" will browse to his machine, so if he runs a TeamSpeak-Server too, he will find his webinterface.

Other users outside your lan have to use your WAN IP (http://www.whatismyip.com). For those you need to forward port 14534 TCP to your machine (if you have a router).
Users inside your LAN can use your LAN IP (see Windows app "ipconfig.exe" (2000 and XP; older: "winipconfig.exe").