a password to brwse internet but not for other services

Hi all.
I want to insert an rb750 from my lan and the gateway.
I need to force users to insert a password for inernet browsing but the rb must be transparent for other services (voip, rdp, dns, etc).
How could I do ?

thanks

dns is part of browsing, you can’t separate these 2

Try Mikrotik Hotspot…

Thanks.
How can I use hotspot ?
Is it possible to bypass all traffic except port 80 to be hotspotted ?

Yes it is possible to bypass all traffic except port 80.

Normally, Hotspot feature requires Level 4 or above license.

you can search more wiki links related to Hotspot.

http://wiki.mikrotik.com/wiki/Manual:IP/Hotspot

It isn’t a reliable solution because eg. if you have established a pptp (vpn) connexion between an external ip and that pc which you want to request password for, that pc could pass even port 80 traffic through that tunnel
I have managed to do that in such conditions when all my egress traffic of port 80 is redirected by the isp to a page like hotspot or restricted acces.