Out-of-band keep-alive mechanism for clients associated with network address translation systems

• US 20080209068A1
• Filed: 02/28/2007
• Published: 08/28/2008
• Est. Priority Date: 02/28/2007
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Hagman, Marie, Herzog, Shai
• Granted Patent: US 7,881,318 B2
• Time in Patent Office: Days
• US Class Current: 709/232
• CPC Class Codes: H04L 61/2514 between local and global IP addresses
• CPC Class Codes: H04L 61/2553 Binding renewal aspects, e.g. using keep-alive messages
• CPC Class Codes: H04L 63/02 for separating internal from external traffic, e.g. firewalls
• CPC Class Codes: H04L 67/14 Session management for real-time applications in data packet communications networks H04L65/1066
• CPC Class Codes: H04L 67/142 Managing session states for stateless protocols; Signalling session states; State transitions; Keeping-state mechanisms
• CPC Class Codes: H04L 69/28 Timers or timing mechanisms used in protocols

Abstract

Architecture for maintaining connection state of network address translation (NAT) devices by employing an out-of-band (OOB) technique externally to application connections without imposing additional requirements on the underlying native application(s). The OOB solution can be applied to arbitrary connections without requiring modification to an application protocol and works with TCP and UDP. A keep-alive (KA) application is employed as an OOB mechanism that injects KA packets that appear to the NAT device to be coming from the native connection. These injected packets fool the NAT device into resetting the inactivity timer for that connection, but do not fool or confuse the native application, which is oblivious to the spoofing. Accordingly, the connection will not terminate due to NAT timeouts, and therefore, a client/server protocol, for example, will not need to generate fake activity packets to keep the connection alive.

Claims

1. A computer-implemented system that facilitates connection management, comprising:

a connection component for providing an arbitrary communications connection between software entities; and

a keep-alive component for sending out-of-band (OOB) signals to the connection component to maintain the connection.

2. The system of claim 1, wherein the arbitrary communications connection accommodates a transport layer connection-oriented end-to-end protocol.

3. The system of claim 1, wherein the arbitrary communications connection accommodates a transport layer connection-less protocol.

4. The system of claim 1, wherein the connection component includes a network address translation (NAT) device that facilitates connection of a private network with a public network.

5. The system of claim 1, wherein the OOB signals are keep-alive packets that are inserted by the keep-alive component into the connection between the software entities.

6. The system of claim 1, wherein the keep-alive component is an application distinct from the software entities, which application generates and facilitates insertion of the OOB signals into the connection between the software entities based on table activity of a TCP/IP system table.

7. The system of claim 1, wherein the keep-alive component monitors a timeout period of the connection component, employs a keep-alive refresh period based on the timeout period and, based on the refresh period, generates and inserts the OOB signals into the connection.

8. The system of claim 1, wherein the software entities between which the connection is established reside correspondingly on a client and a server.

9. The system of claim 8, wherein the keep-alive component comprises a server-based keep-alive application and a client-based keep-alive application, the server-based and client-based keep-alive applications communicating keep-alive packets through the connection component to maintain the connection.

10. The system of claim 1, wherein the keep-alive component removes the OOB signals after the OOB signals are processed by the connection component.

11. A computer-implemented method of managing a connection, comprising:

establishing a NAT connection between native applications of disparate systems; and

automatically inserting keep-alive packets into the connection OOB in order to maintain the connection.

12. The method of claim 11, further comprising automatically inserting the keep-alive packets into the connection based upon a predetermined connection policy.

13. The method of claim 11, wherein NAT connection is facilitated via a transmission control protocol (TCP) communications transport technology.

14. The method of claim 11, further comprising launching corresponding keep-alive applications for the native applications, the keep-alive applications intercommunicating OOB and automatically inserting the keep-alive packets into the connection to maintain the connection based on a new entry in a TCP/IP system table.

15. The method of claim 14, wherein the keep-alive applications monitor corresponding system tables associated with the native applications for connection state, and discontinue sending the keep-alive packets based on the connection state.

16. The method of claim 11, further comprising:

discovering a tuple that includes at least two of a protocol number, a source IP address, a source port number, a destination IP address, or a destination port number associated with at least one of the native applications; and

resetting a NAT timer based on keep-alive packets that utilize the tuple.

17. The method of claim 11, further comprising removing the keep-alive packets before the keep-alive packets reach the native applications.

18. The method of claim 11, further comprising automatically launching a keep-alive application based on in-band activity of at least one of the native applications.

19. The method of claim 11, further comprising automatically launching one or more keep-alive applications and inserting the keep-alive packets via the one or more keep-alive applications based on a type of transport protocol employed.

20. A computer-implemented system, comprising:

computer-implemented means for automatically establishing a NAT connection between native applications;

computer-implemented means for automatically launching corresponding keep-alive applications of the native applications;

computer-implemented means for monitoring the connection for inactivity based on a system table; and

computer-implemented means for automatically inserting keep-alive packets into the connection in response to sensing the inactivity, the keep-alive packets inserted from both keep-alive applications based on TCP packets or inserted from one of the keep-alive applications based on UDP packets.