on my beaglebone i have installed hostapd, iscdhcp and lighttpd so i can build a router and webserver.
let say my network is not secured so every on can be connected to it, and will get an ip-address from the beaglebone-server. 
After the person is connected to the network and he starts a browser he should be redirected to a homepage to give his password, if he is not authenticated yet.
do i need a webframe-work (like django) for this purpose?? if not what else??
i am familiar with programming in python, php, html and java. 
thanks
You can use any of these framework since the have authetications nativly implemented but you don't need to, you can build your own authentication system: You will need a database/file to store credentails and a authentication program verifying credentials against this given storage in any language your webserver can use.
However I would strongly recommend you to use an established framework for authetication.
authentication on webserver