We currently use SBS2k3 premium with ISA server.  I am getting ready to install a Cisco 5505 firewall between the server and our DSL modem.  I am planning to continue to use the SBS as the DHCP server and no the firewall.

 

I believe I know which ports to make sure are open so I can continue to use the services we currently use (OWA, RWW, etc.).  Can anyone tell me if I am likely to run into conflicts between ISA rules and the firewall.  I am not sure if I should disable my custom rules in ISA and just use the firewall to control or both.  My understanding from my ISP is that once I clear the DSL modem then it basically acts as a bridge and all traffic is forwarded straight to the firewall.  I am a little nervous about this and want to try to anticipate any problems that might arise. 

 

Any thoughts or suggestions on any of the above would be much appreciated.  Thanks.

Hi Lianne,

 

What kind of custom ISA rules do you have? ISA will work with 2 nics and a Cisco firewall. You will just have to forward the ports to the external nic from the Cisco that you want to use, like 25 for SMTP, 443, 4125. If you want Companyweb accessible from outside, add 444.

Hi Marina,

 

Many of our rules are old ones that came over with ISA 2000 and are outdated.  We also have rules for WSUS and Trend.  But mostly the rules are ones created by SBS.  I have never spent much time adding/removing or customizing the existing rules.  I am thinking that as long as I forward the same ports from the Cisco to the external NIC that I had our ISP open for us that we should be ok.

 

Thanks.