SBS bascially requires the following ports:
21 FTP Enables external and internal file transfer
25 Exchange Server Enables incoming and outgoing SMTP mail
80 (http://) IISEnables all nonsecure browser access, including: internal access to IIS Webs including the company Web, Windows SharePoint Web, Windows SharePoint administration Web, and server monitoring and usage reports Enables internal access to Exchange by OWA and OMA clients
110 POP3 Enables Exchange to accept incoming POP3 mail
123 (UDP port) NTP Enables the system to synchronize time with an external Network Time Protocol (NTP) server
143 IMAP4 Enables Exchange to accept incoming IMAP4-compliant messages
220 IMAP3 Enables Exchange to accept incoming IMAP3-compliant messages
443 (https://) Outlook Enables all secure browser access, including external access to Exchange for Outlook 2003, OWA, and OMA clients; required for external access to server monitoring and usage reports
444 Windows Share Point Services Enables internal and external access to the SharePoint Web
500 IPSec Enables external VPN connections by using IPSec
1701 L2TP clients Enables external L2TP VPN connections
1723 PPTP clients Enables external PPTP VPN connections
3389 Terminal Services Enables internal and external Terminal Services client connections
4125 (Note: you can change this port in RRAS) Remote Web Workplace Enables external OWA access to Exchange, plus internal and external HTTPS access to the client Web site
4500 IPSec Internet Key Exchange (IKE) Network Address Translation (NAT) traversal
If you need access to Sharepoint .... you MUST go through port 444
as per http://msmvps.com/blogs/bradley/archive ... 33537.aspx