I am trying to setup to secure a redirect public port to a private port

Question

I i am trying to setup to secure a redirect public port to a private port to a Microsoft server exchange
A user coming from the outside(Untrusted security level 0) will connect to IIS server in the DMZ(Trusted security level 50) with a port 443 to a PIX 515 , the IIS server has a application called Detour Service(Service transparently reroutes any TCP connection from one IP Port to any other IP Port) will initiate a connection to Microsoft server exchange to the inside(trusted security level 100).
Do you think it is the right solution I term of security?yes or no, are do you have a better solutution
Thanks
User port destination 443(outside)>>>>>> IIS server port destination 9999(DMZ)>>>>>>>>>>> Microsoft server exchange(inside)

Answer 1

Actually the connection from lower security level to higher security level is blocked. You can apply an access list to limit traffic from inside to outside, or allow traffic from outside to inside. For transparent firewall mode, you can also apply an EtherType access list to allow non-IP traffic.