Firewall box test

[ramamonjisoa @ bnetd . sita . net (Ramamonjisoa Charles Emile)]

    Hello,
    After some months of investigation in term of securing our
LAN, it's for us now to set up our firewall box.

    Configuration

                Intranet ( Servers, Workstations, ... )
------------ router ------------- ISP ( leased line )
                            (Web, mail, news, ...)

                NB : We have not access the router configuration.
                        A minimum policy is already defined for
the intranet security.

    Questions

               1- How is the best place to put my firewall box (
Win NT ) ? The best configuration ?
               2- During my testing period, I need to have the
Internet access from the Intranet functionning normally ( web
access, mails, ... ) : how can I configure the system without
DISTURBING my 300 users.
    I suggest the following schema :

                    Intranet -------- Firewall box ------- router
------- ISP
                    < ---Subnet 1-->              <-- Subnet 2 -->


                    I'll disturb the system functionnality during
my testing period.

    Thanks for your response.

R. Charles Emile
BNETD / DOTI
ramamonjisoa @
 bnetd .
 sita .
 net