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Remote Servers

Remote servers are supported in SQL Server for backward compatibility only. New applications should use linked servers instead. For more information, see Linked Servers (Database Engine).

A remote server configuration allows for a client connected to one instance of SQL Server to execute a stored procedure on another instance of SQL Server without establishing a separate connection. Instead, the server to which the client is connected accepts the client request and sends the request to the remote server on behalf of the client. The remote server processes the request and returns any results to the original server. This server in turn passes those results to the client. When you set up a remote server configuration, you should also consider how to establish security.

If you want to set up a server configuration to execute stored procedures on another server and do not have existing remote server configurations, use linked servers instead of remote servers. Both stored procedures and distributed queries are allowed against linked servers; however, only stored procedures are allowed against remote servers.

Remote servers are set up in pairs. To set up a pair of remote servers, configure both servers to recognize each other as remote servers.

Most of the time, you should not have to set configuration options for remote servers. SQL Server Set sets the defaults on both the local and remote computers to allow for remote server connections.

For remote server access to work, the remote access configuration option must be set to 1 on both the local and remote computers. (This is the default setting.) remote access controls logins from remote servers. You can reset this configuration option by using either the Transact-SQL sp_configure stored procedure or SQL Server Management Studio. To set the option in SQL Server Management Studio, on the Server Properties Connections page, use Allow remote connections to this server. To reach the Server Properties Connections page, in Object Explorer, right-click the server name, and then click Properties. On the Server Properties page, click the Connections page.

From the local server, you can disable a remote server configuration to prevent access to that local server by users on the remote server with which it is paired.

To enable remote procedure calls (RPC) against a remote server, you must set up login mappings on the remote server and possibly on the local server that is running an instance of SQL Server. RPC is disabled by default in SQL Server. This configuration enhances the security of your server by reducing its attackable surface area. Before using RPC you must enable this feature. For more information see sp_configure (Transact-SQL).

Setting Up the Remote Server

Remote login mappings must be set up on the remote server. Using these mappings, the remote server maps the incoming login for an RPC connection from a specified server to a local login. Remote login mappings can be set up by using the sp_addremotelogin stored procedure on the remote server.

Note Note

The trusted option of sp_remoteoption is not supported in SQL Server.

Setting Up the Local Server

For SQL Server authenticated local logins, you do not have to set up a login mapping on the local server. SQL Server uses the local login and password to connect to the remote server. For Windows authenticated logins, set up a local login mapping on a local server that defines what login and password are used by an instance of SQL Server when it makes an RPC connection to a remote server.

For logins created by Windows Authentication, you must create a mapping to a login name and password by using the sp_addlinkedservlogin stored procedure. This login name and password must match the incoming login and password expected by the remote server, as created by sp_addremotelogin.

Note Note

When possible, use Windows Authentication.

Remote Server Security Example

Consider these SQL Server installations: serverSend and serverReceive. serverReceive is configured to map an incoming login from serverSend, called Sales_Mary, to a SQL Server authenticated login in serverReceive, called Alice. Another incoming login from serverSend, called Joe, is mapped to a SQL Server authenticated login in serverReceive, called Joe.

The following Transact-SQL code example configures serverSend to perform RPCs against serverReceive.

--Create remote server entry for RPCs 
--from serverSend in serverReceive.
EXEC sp_addserver 'serverSend';
GO

--Create remote login mapping for login 'Sales_Mary' from serverSend
--to Alice.
EXEC sp_addremotelogin 'serverSend', 'Alice', 'Sales_Mary';
GO
--Create remote login mapping for login Joe from serverReceive 
--to same login.
--Assumes same password for Joe in both servers.
EXEC sp_addremotelogin 'serverSend', 'Joe', 'Joe';
GO

On serverSend, a local login mapping is created for a Windows authenticated login Sales\Mary to a login Sales_Mary. No local mapping is required for Joe, because the default is to use the same login name and password, and serverReceive has a mapping for Joe.

--Create a remote server entry for RPCs from serverReceive.
EXEC sp_addserver 'serverReceive';
GO
--Create a local login mapping for the Windows authenticated login.
--Sales\Mary to Sales_Mary. The password should match the
--password for the login Sales_Mary in serverReceive.
EXEC sp_addlinkedsrvlogin 'serverReceive', false, 'Sales\Mary',
   'Sales_Mary', '430[fj%dk';
GO

You can use the xp_msver extended stored procedure to review server attributes for local or remote servers. These attributes include the version number of SQL Server, the type and number of processors in the computer, and the version of the operating system. From the local server, you can view databases, files, logins, and tools for a remote server. For more information, see xp_msver (Transact-SQL).

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