Connecting to SQL Server Through a Proxy Server
To deter unauthorized access to your private network, connections to an instance of SQL Server can be mediated by Microsoft Internet Security and Acceleration (ISA) Server, a stand-alone program that provides secured access to data. ISA Server helps to protect your sensitive data by controlling the permissions and accesses to the listening port. You can block access to restricted sites by ranges of IP addresses, domains, or individual users, to regulate access to the Internet by your users.
For more information about Local Address Table (LAT) configuration in the context of remote listen and accept calls, see the ISA Server documentation.