I work for a company with a pretty standard internet presence. One dedicated webserver and one dedicated database server colocated at a datcenter. We are a MS house running Windows Server 2k3 and SQL Server 2k5

While most of our communication is from WebApp to DB server and back, we have one legacy VB.net Uberapplication that won't go away and it is now causing a problem with security.

It makes a connection directly with our offsite SQL server, and because it runs on our employees machines and some clients, we can't firewall off the SQL Server port or install a white-list because of ever changing client IPs.

I am hoping for some kind of Firewall where we can somehow send it an authentication packet and it will allow that IP to access the port, while still blocking non-authenticated IPs.


Can you configure a VPN, and then only allow access to the SQL server from authenticated hosts?


you can try dyndns on your client's and allows those dyndns in your firewall. did you think that could work ?


There is a technique called "portknocking" which allows a host to send a series of connection attempts to various ports as an almost PIN (like you have on your bank ATM cards). The portknocking daemon watches for these connection attempts and when a correct series is detected, an action is taken.

Although it might be a little convoluted, this technique might also work for you, especially considering the last component of your question.

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