Microsoft Technology Licensing, LLC

Microsoft Corporation

Nk Srinivas

Sanjay N Kaniyar

Abolade Gbadegesin

Jameel Hyder

James T Pinkerton

Vadim Eydelman

Art Shelest

Kyle E Brandon

Venkataraman Ramanathan

Alireza Dabagh

Sanjay Anand

Costin Hagiu

Sriram Sampath

Ashwin Palekar

Arvind M Murching

Peter Sewall Ford

Rod N Gamache

Bhupinder Singh Sethi

Shaun David Cox

Olga Ivanova

Huei Chung Wang

Rouslan Beletski

Rajat Mishra

Alan T G Jowett

Scott K Holden

Seema J Lukose

Kyle Brandon

Techniques are disclosed for virtualizing internet protocol (IP) addresses in terminal server sessions. A client component comprises a layer service provider (LSP) and a name service provider (NSP) that intercept a socket call to associate a port with a socket for a terminal server session. The client component queries a server component for a virtual IP address, and the server component determines whether the terminal server session can use a virtual IP address. Where the session can use a virtual IP address, the server returns a virtual IP address and the client component binds the socket call to the virtual IP address. Where the session cannot use a virtual IP address, the server returns an indication of that, and the client component acts as a proxy for that socket call and any future calls for that socket.

Internet protocol (IP) address virtualization for terminal server sessions

An error tracing analysis tool applies static code analysis to software source code to identify error paths in the code and determine how many of these error paths have trace statements.

Tracing errors in software

An initial sequence number generator is provided that prevents the local server from being attacked while maintaining reliable data transfer. A random intermediate value is created that is unique to each connection identifier and is combined with a random value created from a global counter to generate the initial sequence number. The counter capable of monotonically increasing by both a fixed and variable amount for ensuring that the same connection identifier does not have data collisions from competing sequence numbers within a predetermined period of time, and also to ensures randomness of the initial sequence number on a per connection basis for preventing attacks on the local server.

Secure ISN generation

Offloading specific processing tasks that would otherwise be performed in a computer system's processor and memory, to a peripheral device. The computing task is then performed by the peripheral, thereby saving computer system resources for other computing tasks. In one preferred embodiment, the disclosed method is utilized in a layered network model, wherein computing tasks that are typically performed in network applications are instead offloaded to the network interface card (NIC) peripheral.

Method and computer program product for offloading processing tasks from software to hardware

A system and method are presented that enhance the performance of single and multiple-processor servers by taking advantage of the half-duplex nature of many HTTP requests. Upon receipt of an HTTP Get resource request, a single send and disconnect IRP is generated. The semantics of the send and disconnect IRP completion recognizes the half-duplex nature of the transaction by indicating a graceful close of the TCP/IP connection. This send and disconnect IRP is also completed without a queuing stage (queuelessly) on the processor that serviced the client request. To further enhance performance, the server FIN message to the client is included in the last data frame transmitted to the server. The invention also contemplates transmission of a single HTTP get and disconnect request by a client to allow acknowledgementless disconnection of the TCP/IP connection once a requested resource has been sent.

System and method of enhancing web server throughput in single and multiple processor systems

A method and system are directed at automatically tuning a TCP receive window (RWIN). The size of the RWIN may be determined by attributes of a network card. One attribute used to size the RWIN is the speed of the adapter card. The adapter speed is readily available by polling the network card. Once the speed is known, the size of the RWIN is selected from a table and is automatically set. Alternatively, the size of the RWIN may be determined by a formula.

Method for automatic tuning of TCP receive window based on a determined bandwidth

A method of enhancing a server's ability to withstand a SYN flood type denial of service attack is presented. Modifications to the TCP/IP layer of a server reduce the amount of system resources that are allocated, and the amount of CPU overhead that is required to process a connection request until the TCP/IP three-way handshake is completed to verify the presence of a legitimate client. Specifically, the TCP/IP layer allocates a small TCP control block (TCB) of a size sufficient only to service the connect request upon receipt of the SYN packet. A full TCB is not allocated until the connection is completed. Further, the TCP/IP layer delays notification to the socket layer of the receipt of the SYN packet until after the connection is completed. Finally, the route information of the connection is not cached until after the connection is completed.

System and method for enhancing a server's ability to withstand a 'SYN flood' denial of service attack

A system and method to improve server throughput is presented. This system and method stores only selected information from the server's TCP/IP Transmission Control Block (TCB) in the time-wait state. This allows for the release of a portion of the non-paged pool (NPP) memory that was used by the TCB to previously service the now closing connection. This newly released NPP memory may then be used by the server to service additional TCP/IP connections, thus improving the throughput of the server. This small time-wait TCB (TWTCB) stores only an amount of information necessary to uniquely identify the connection to which it relates. Information that was stored to allow servicing of an active connection, but that is not needed to merely identify the connection, is not kept in the TWTCB. By maintaining information that allows for a unique identification of a closing connection, late routed packets for that connection are prevented from establishing a new connection with the server. By minimizing the amount of information to accomplish this unique identification, additional connections to new client may be established without reaching a NPP memory limit.

System and method of enhancing server throughput by minimizing timed-wait TCP control block (TWTCB) size

A method to offload a network stack connection is presented. A request, which includes a list of resource requirements from each software layer in the stack, to offload the network stack connection is sent through the stack to the peripheral device. The device allocates resources for the list and sends a handle to each of the software layers for communication with the device. The state for each layer is sent to the device that includes state variables that are classified as a constant, a cached variable handled by the CPU, or a delegated variable handled by the device.

Method to offload a network stack

A method to synchronize and upload an offloaded network stack connection between a host network stack and processing device is presented. A state object for each layer in the stack is sent to the device that includes state variables that are classified as a constant, a cached variable handled by the host, or a delegated variable handled by the device. State that must be updated by the network stack and the processing device is cleanly divided. For example, statistics are tracked by the host, the device, or the host and the device. A statistic tracked by both the host and processing device is divided into non-overlapping portions and combined to produce the statistic. Once an upload is initiated, the device achieves a consistent state and hands delegated states to the stack. Each layer in the stack takes control of its delegated state and resources at the device are freed.

Method to synchronize and upload an offloaded network stack connection with a network stack

A mapping between virtual processing units and physical processing units allows for an increase or decrease in the number of physical processing units installed in a computing device without disrupting the computing device's network communications. At startup, each of the virtual processing units can be allocated the necessary network communication management structures for supporting network communication. The networking subsystem can continue to use the virtual processing units as it would physical processing units, namely packets can be routed through the appropriate processing unit. However, because the networking subsystem is only aware of the virtual processing units, the mapping between the virtual processing units and the physical processing units can continually adjust for changes in the number of physical processing units installed, allowing the number of installed physical processing units to be modified without affecting the operation of the networking subsystem or ongoing network communications.

Dynamic TCP partitioning

A new communications connection timer management framework for handling network communications protocol timers is disclosed. The timer management framework separates transmission control blocks (TCBs) having scheduled actions from the set of all TCBs maintained by a server. The TCBs having scheduled actions are referenced by a time-space partitioned data structure having time-slots corresponding to a current protocol timer 'tick' value. The active TCBs are placed within particular ones of the time-space partitions based upon their expiration times. During each timer check sequence (e.g., once every 100 millisecond timer tick for TCP protocol timers), the timer management framework accesses a partition associated with a current timer value and checks the TCBs referenced within the current partition.

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Issaquah, WA, United States of America

Nk Srinivas