proxy help

[danilo lujambio <danilo@tau.org.ar>]

Hi:

I am working in a scope plenty of MS windows, we have the oportunity to
start to replace some of them by linux. 

We need to solve this problem :


                                

        PC 1             default                
        MS win ---------   gw     ----------- gateway
                           PC1                  |
                                                |
                                                |
                                              Linux
                                                BOX
                                                |
                                                | ip public
                                           ---------------
                                                INTERNET

in the linux box we have a proxy squid , it authenticate against PDC (
MS win NT) , everything works OK (with samba , winbindd ) . An user from
PC1 can acced to internet using Linux as a proxy and authenticating
itsel against PDC.

But the user in PC1 wants to use MSN and netmeeting :-)

I tryed to configure netmeeting to use HTTP proxy pointing to Linux Box
and in the linux box put 

/sbin/iptables -t nat -A PREROUTING -i eth1 -p tcp --dport 1863 -j
REDIRECT --to-port 3128 

when the user tun MSN , it ask userid and password (this does not happen
when it uses a browser because it is authenticated directly against the
PDC) , when the user introduce de userid  and password , the squid give
tcp denied , and the user can not connect.

Surely I am doing some mistake , can anybody help me ?

thanks

dl
Argentina