Revision #3

Author: Dinakar Nethi

Contributors: Michael Thomassy, Dustin Fraser

Technical Reviewers: Tony Petrossian

Summary
SQL Azure Database is a cloud database service from Microsoft. SQL Azure provides web-facing database functionality as a utility service. Cloud-based database solutions such as SQL Azure can provide many benefits, including rapid provisioning, cost-effective scalability, high availability, and reduced management overhead. This document provides an overview of security guidelines for customers connecting to SQL Azure Database, and building secure applications on SQL Azure.

Security Guidelines for SQL Azure

This document provides basic requirements for both server-side as well as client-side settings to enable connectivity to Microsoft SQL Azure.

The Tabular Data Stream protocol is used by all SQL Server and SQL Azure tools and client libraries to connect to the server. The SQL Azure service is only accessible through the default port of TCP/1433 used by the TDS protocol. Customers need to configure their environment to allow outbound TCP connections over port TCP/1433 to enable applications and tools to connect to SQL Azure.

Connecting to Microsoft SQL Azure involves multiple steps:

· The networks must allow computers that need to connect to SQL Azure to establish outbound connections on port 1433. Usually, customer sites disallow outgoing TCP/1433 connections by default; however, consuming the SQL Azure service requires customer to allow outgoing connections to the SQL Azure service IP addresses. Network firewall and other security devices may prevent computers on the customer networks from establishing outbound connection to SQL Azure. Inbound connections are not required or recommended.

· Proxy servers may need to be adjusted to allow the outbound TDS protocol over port 1433. Client-side proxy software such as Microsoft ISA client may be needed to allow client computers to use proxy servers for outbound connections.

· Use the SQL Azure portal to configure SQL Azure firewall settings to allow connections from your computer(s) and/or Windows Azure. More details on configuring the firewall can be found here – How to configure firewall and SQL Azure firewall

· Always use the loginname@Servername format for the login since certain tools implement TDS differently. For example, if your server name is mv2abek9r7.database.windows.net and your administrator login is testsa, use testsa@mv2abek9r7 as the login.

· Create appropriate logins on your SQL Azure server. After the SQL Azure server has been provisioned, create the administrator user that has admin privileges on the server, connect to your master database on your SQL Azure server via SQL Server Management Studio R2, and use the CREATE LOGIN scripts to create users and roles. More detailed information on managing logins is available at Managing databases and logins in SQL Azure

· Developers and database users can now use the logins created above to connect to SQL Azure.

· Optional: If you have on-premises SQL Servers that need to communicate with SQL Azure for data synchronizations or other reasons you must ensure that your servers have an internet routable IPs.

Allowing outbound traffic for TCP/1433 to the SQL Azure Virtual IP for each location is sufficient for connecting to SQL Azure.

Customers may also need to explicitly allow return traffic from Microsoft’s VIP back into their network, depending on how strict their policies are.  In other words, if a customer allows outbound TCP/1433 traffic to SQL Azure IPs, they also need to allow the return traffic coming from SQL Azure IPs (source port of TCP/1433) back into their network.  Some networks allow all return traffic for any connection initiated internally, but other more restrictive networks also restrict return traffic to explicit access control lists. The use of the “established” tag for outbound ACLs, such as in the examples below, will return traffic for customer sites to connections established within the customer site. In other words, traffic will not be allowed unless the connections are initiated within the customer site. 

“Outbound” and “inbound” refers to direction of traffic with reference to the router.

It may be more convenient for customers to allow TCP/1433 connections to the range of Microsoft’s public network addresses instead of a specific SQL Azure location. This will allow for greater flexibility; as SQL Azure adds more locations, the need to revisit customer access control lists will be reduced.

For example, the TDS endpoint for the SQL Azure North Central US data center is data.ch1-1.database.windows.net, with an IP address of 207.46.203.22. Performing a lookup of http://ws.arin.net/whois/?queryinput=207.46.203.22 reveals Microsoft’s entire scope for this IP is 207.46.0.0/16.

The following is an example ACL setting to allow connections to the entire range of possible IP addresses for Microsoft SQL Azure Service.

Other guidelines:

· When connecting to SQL Azure, use the most current version of tools and libraries for best experience

· Configure your firewall to allow connections only to specific IP addresses.

· Prevent SQL injection vulnerabilities by using parameterized queries.

· SQL Azure server is just a logical grouping of databases. It is not a physical SQL Server. Hence creating multiple servers will not provide any performance benefit. You can create multiple servers if you want to group sets of databases into logical unit(s) or if you want to have a separate billing for certain database(s).

References:

· SQL Azure Firewall

· Managing Databases and Logins in SQL Azure

· How to Configure SQL Azure Firewall

· Troubleshooting SQL Azure

· SQL Azure Portal

· SQL Azure Developer Center

· SQL Azure Team Blog