Microsoft SQL Server Resolution Protocol (SSRP)

SSRP

Microsoft SQL Server Resolution Protocol

SSRP is a service that enables SQL Server clients to locate and connect to SQL Server instances on a network.

Port: 1434 UDP  |  RFC: N/A

OSI Layer: 7 (Application Layer)

Cyber Security Stance: Low

Designed by Vivekanand Padala

Protocol Overview

The SSRP service listens on UDP port 1434 for requests from clients. When a request is received, the SSRP service parses the request and uses the information provided to locate the SQL Server instance that the client wants to connect to. The SSRP service then responds to the client with the necessary connection information, such as the TCP/IP port number and the server name.

The SSRP protocol is used in conjunction with the Tabular Data Stream (TDS) protocol, which is used for client-server communication between SQL Server clients and instances. When a client receives the connection information from the SSRP service, it uses the TDS protocol to establish a connection to the SQL Server instance.

The SSRP protocol includes the following message types:

• Request message: Sent by a client to request information about a SQL Server instance.
• Response message: Sent by the SSRP service in response to a request message, containing information about the SQL Server instance.

SSRP workflow

1. A client sends a request message to the SSRP service on UDP port 1434. The request message contains the name of the SQL Server instance that the client wants to connect to.
2. The SSRP service receives the request message and parses it to extract the name of the SQL Server instance.
3. The SSRP service then searches its database to locate the SQL Server instance. If the instance is found, the SSRP service responds with a response message containing the necessary connection information, such as the TCP/IP port number and the server name.
4. The client receives the response message and uses the connection information to establish a connection to the SQL Server instance using the Tabular Data Stream (TDS) protocol.
5. If the SSRP service cannot locate the requested SQL Server instance, it may send a broadcast message to the network to try to locate the instance. This is known as the "browse" mechanism.
6. If the instance is still not located, the SSRP service may respond with an error message to the client, indicating that the requested SQL Server instance cannot be found.