Home page redirection, done at default router or use dummy DNS

Hi,
Imagine a user in a hotspot, when he comes to the hotspot and tries
to load a webpage (on the internet), he would automatically redirected
to login page.
I believe the following is to be done.
There should be a DHCP server setup which gives the arriving clients
IP, default router address etc.

Where should the homepage redirection be done,
1. It could be done at the default router, the clients who haven't
authenticated would be given IP from a fixed address pool, and if the
IP packets are from that address pool the default router sends the
packet to the login webserver with a change in the destination IP
address (to the login server). Now this involves configuring the
router, does the standard routers allow this kinda configuration
without significant hacking of the system. Here after successfully
logging in the user is given a different DHCP config info.

2. In DHCP configuration information, a system in their domain is
claimed as DNS, so when the user tries to load a page the DNS server
gives the IP of the login webserver as IP of all the webservers any
user is trying to access. Are there any problems in this. Ofcourse, the
client side stores that IP for all the pages the user tries to login,
however, the user would not try to load another page once (or utmost
twice) the page is redirected to login page. So, this doesn't seem to
be a problem at all. What should be used here as DNS, should a specific
application be written for this purpose or is there any widely used
software component that provides this functionality.
Here after the user successfully authenticates, she is provided with
new DHCP settings (DNS, IP address etc)

Is there any other way to do this redirection
-shar.

(E-Mail Removed) wrote:
> Hi,
> Imagine a user in a hotspot, when he comes to the hotspot and tries
> to load a webpage (on the internet), he would automatically redirected
> to login page.
> I believe the following is to be done.
> There should be a DHCP server setup which gives the arriving clients
> IP, default router address etc.
>
> Where should the homepage redirection be done,
> 1. It could be done at the default router, the clients who haven't
> authenticated would be given IP from a fixed address pool, and if the
> IP packets are from that address pool the default router sends the
> packet to the login webserver with a change in the destination IP
> address (to the login server). Now this involves configuring the
> router, does the standard routers allow this kinda configuration
> without significant hacking of the system. Here after successfully
> logging in the user is given a different DHCP config info.
>
> 2. In DHCP configuration information, a system in their domain is
> claimed as DNS, so when the user tries to load a page the DNS server
> gives the IP of the login webserver as IP of all the webservers any
> user is trying to access. Are there any problems in this. Ofcourse, the
> client side stores that IP for all the pages the user tries to login,
> however, the user would not try to load another page once (or utmost
> twice) the page is redirected to login page. So, this doesn't seem to
> be a problem at all. What should be used here as DNS, should a specific
> application be written for this purpose or is there any widely used
> software component that provides this functionality.
> Here after the user successfully authenticates, she is provided with
> new DHCP settings (DNS, IP address etc)
>
> Is there any other way to do this redirection
> -shar.
>

Yes port forwarding with iptables like transparent proxy

--
Weill Philippe - Administrateur Systeme et Reseaux
CNRS Service Aeronomie - Universite Pierre et Marie Curie -
Tour 45/46 3e Etage B302 - 4 Place Jussieu - 75252 Paris Cedex 05 - FRANCE
Email(E-Mail Removed) | tel:+33 0144274759 Fax:+33 0144273776