System and method for an adaptive TCP SYN cookie with time validation

- A10 NETWORKS, INC.

Provided is a method and system for TCP SYN cookie validation. The method includes receiving a session SYN packet by a TCP session setup module of a host server, generating a transition cookie including a time value representing the actual time, sending a session SYN/ACK packet, including the transition cookie, in response to the received session SYN packet, receiving a session ACK packet, and determining whether a candidate transition cookie in the received session ACK packet comprises a time value representing a time within a predetermined time interval from the time the session ACK packet is received.

Skip to: Description  ·  Claims  ·  References Cited  · Patent History  ·  Patent History
Description
CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation reissue application of U.S. Pat. No. 7,675,854 and claims benefit under 35 U.S.C. 120 as a continuation of application Ser. No. 13/413,191 filed on Mar. 6, 2012, which is an application for reissue of U.S. Pat. No. 7,675,854, originally issued on Mar. 9, 2010.

BACKGROUND OF THE INVENTION

When a TCP (Transmission Control Protocol) connection starts, a destination host receives a SYN (synchronize/start) packet from a source host and sends back a SYN ACK (synchronize acknowledge). The destination host normally then waits to receiver an ACK (acknowledge) of the SYN ACK before the connection is established. This is referred to as the TCP “three-way handshake.”

While waiting for the ACK to the SYN ACK, a connection queue of finite size on the destination host keeps track of connections waiting to be completed. This queue typically empties quickly since the ACK is expected to arrive a few milliseconds after the SYN ACK is sent.

A TCP SYN flood attack is a well known denial of service attack that exploits the TCP three-way handshake design by having an attacking source host generate TCP SYN packets with random source addresses toward a victim host. The victim destination host sends a SYN ACK back to the random source address and adds an entry to the connection queue, or otherwise allocates server resources. Since the SYN ACK is destined for an incorrect or non-existent host, the last part of the “three-way handshake” is never completed and the entry remains in the connection queue until a timer expires, typically, for example, for about one minute. By generating phony TCP SYN packets from random IP addresses at a rapid rate, it is possible to fill up the connection queue and deny TCP services (such as e-mail, file transfer, or WWW) to legitimate users. In most instances, there is no easy way to trace the originator of the attack because the IP address of the source is forged. The external manifestations of the problem may include inability to get e-mail, inability to accept connections to WWW or FTP services, or a large number of TCP connections on your host in the state SYN_RCVD.

A malicious client sending high volume of TCP SYN packets without sending the subsequent ACK packets can deplete server resources and severely impact the server's ability to serve its legitimate clients.

Newer operating systems or platforms implement various solutions to minimize the impact of TCP SYN flood attacks. The solutions include better resource management, and the use of a “SYN cookie”.

In an exemplary solution, instead of allocating server resource at the time of receiving a TCP SYN packet, the server sends back a SYN/ACK packet with a specially constructed sequence number known as a SYN cookie. When the server then receives an ACK packet in response to the SYN/ACK packet, the server recovers a SYN cookie from the ACK packet, and validates the recovered SYN cookie before further allocating server resources.

The effectiveness of a solution using a SYN cookie depends on the method with which the SYN cookie is constructed. However, existing solutions using a SYN cookie typically employ a hash function to construct the SYN cookie, which can lead to a high percentage of false validations of the SYN cookie, resulting in less than satisfactory protection again TCP SYN flood attack.

Therefore, there is a need for a better system and method for constructing and validating SYN cookies.

SUMMARY OF THE INVENTION

An aspect of the present invention provides a system for TCP SYN cookie validation. The system includes a host server including a processor and memory. The processor is configured for receiving a session SYN packet, generating a transition cookie, the transition cookie comprising a time value representing the actual time, sending a session SYN/ACK packet, including the transition cookie, in response to the received session SYN packet, receiving a session ACK packet, and determining whether a candidate transition cookie in the received session ACK packet comprises a time value representing a time within a predetermined time interval from the time the session ACK packet is received.

One aspect of the invention includes the system above in which the processor is further configured for regarding the received session ACK packet as valid if the candidate transition cookie in the received session ACK packet comprises a time value representing a time within a predetermined time interval from the time the session ACK packet is received.

In another aspect of the invention, the predetermined time interval is in the range of one to six seconds.

In one aspect of the invention, the predetermined time interval is three seconds.

In another aspect of the invention, the step of generating the transition cookie includes the use of data obtained from the session SYN packet.

In one aspect of the invention, the data obtained from the session SYN packet comprises the source IP address of an IP header associated with the session SYN packet.

In another aspect of the invention, the data obtained from the session SYN packet comprises the sequence number of a TCP header associated with the session SYN packet.

In another aspect of the invention, the data obtained from the session SYN packet comprises a source port associated with the session SYN packet.

In another aspect of the invention, the data obtained from the session SYN packet comprises a destination port associated with the session SYN packet.

Another aspect of the present invention provides a method for TCP SYN cookie validation. The method includes receiving a session SYN packet by a TCP session setup module, generating a transition cookie by the TCP session setup module, the transition cookie comprising a time value representing the actual time, sending a session SYN/ACK packet, including the transition cookie, in response to the received session SYN packet, receiving a session ACK packet, and determining whether a candidate transition cookie in the received session ACK packet comprises a time value representing a time within a predetermined time interval from the time the session ACK packet is received.

In an aspect of the invention, the method further includes indicating the received session ACK packet comprises a valid candidate transition cookie if the time value of the candidate transition cookie is within a predetermined time interval of the time the session ACK packet is received.

In another aspect of the invention, the step of generating the transition cookie includes the use of data obtained from the session SYN packet.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a host server including a TCP session setup module and a client server, in accordance with an embodiment of the present invention;

FIG. 2 is a schematic diagram of a TCP/IP handshake in accordance with an embodiment of the present invention;

FIG. 3a illustrates a method including steps for generating a transition cookie data element by a transition cookie generator 245, in accordance with an embodiment of the present invention;

FIG. 3b illustrates a method including steps for generating a transition cookie secret key by a transition cookie generator 245 based on data obtained from the received session SYN packet, in accordance with an embodiment of the present invention;

FIG. 3c illustrates a method including steps for generating a transition cookie based on a transition cookie data element, a transition cookie secret key, and data obtained from a received session SYN packet in accordance with an embodiment of the present invention;

FIG. 4a illustrates steps for generating a candidate encrypted data element by a transition cookie validator 275 based on data obtained from a received session ACK packet, in accordance with an embodiment of the present invention;

FIG. 4b illustrates a method including steps for generating a candidate transition cookie secret key by a transition cookie validator 275 based on data obtained from a received session ACK packet and a candidate sequence number, in accordance with an embodiment of the present invention;

FIG. 4c illustrates a method including steps for generating a candidate transition cookie data element by a transition cookie validator 275 based on a candidate encrypted data element and a candidate transition cookie secret key, in accordance with an embodiment of the present invention;

FIG. 4d illustrates a method including the steps for validating a candidate transition cookie data element, in accordance with an embodiment of the present invention; and

FIG. 5 illustrates a method including steps for generating information based on a validated candidate transition cookie data element, in accordance with an embodiment of the present invention.

 DETAILED DESCRIPTION

In the following description, for purposes of explanation, specific numbers, materials and configurations are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one having ordinary skill in the art, that the invention may be practiced without these specific details. In some instances, well-known features may be omitted or simplified so as not to obscure the present invention. Furthermore, reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in an embodiment” in various places in the specification are not necessarily all referring to the same embodiment.

Transmission Control Protocol (“TCP”) is one of the main protocols in TCP/IP networks. Whereas the Internet Protocol (“IP”) deals only with packets, TCP enables two hosts to establish a connection and exchange streams of data. TCP guarantees delivery of data and also guarantees that packets will be delivered in the same order in which they were sent.

The terms “host server” and “client server” referred to in the descriptions of various embodiments of the invention herein described are intended to generally describe a typical system arrangement in which the embodiments operate. The “host server” generally refers to any computer system interconnected to a TCP/IP network, including but not limited to the Internet, the computer system comprising at a minimum a processor, computer memory, and computer software. The computer system is configured to allow the host server to participate in TCP protocol communications over its connected TCP/IP network. Although the “host server” may be a single personal computer having its own IP address and in communication with the TCP/IP network, it may also be a multi-processor server or server bank. The “client server” is similar to the “host server”, although it is understood that the “client server” may, in fact, be a single personal computer attached to the TCP/IP network. The only difference between the client and the host server for the purposes of the present invention is that the host server receives the SYN from the client server, sends a SYN ACK to the client server, and waits for the ACK from the client server.

FIG. 1 is a schematic diagram illustrating an embodiment of the present invention. A host server 102 may include a TCP session module 104. The TCP session setup module 104 can engage in a TCP handshake 108, such as described above, with a client server 106. In an embodiment, the TCP session setup module 104 is a software component of the host server 102. In one embodiment, the TCP session setup module 104 is implemented in an Application Specific Integrated Circuit (“ASIC”) or a Field Programmable Gate Array (“FPGA”). It is the TCP session setup module that handles the “3-way handshake” 108 between the host server 102 and the client server 106. The TCP session setup module may itself also incorporate modules for sending and receiving TCP session packets. These modules may include but are not limited to a session SYN packet receiver, a session SYN/ACK packet sender, and a session ACK packet receiver, which are all known to those of ordinary skill in the computer arts.

The TCP sessions setup module 104 may itself be embedded in one or more other host server modules (not shown). The TCP session setup module may alternatively comprise a hardware or firmware component. For example, the software which handles the TCP handshake 108 on behalf of the host server 102 may be programmed onto a externally programmable read-only memory (“EPROM”) (not shown), and the EPROM may then be integrated into the host server. In another example, the ASIC or FPGA is integrated into the host server.

FIG. 2 illustrates a TCP session setup module 104 processing TCP/IP segments (not shown), such as session SYN packet 210, session SYN/ACK packet 220, and session ACK packet 230.

A TCP/IP segment includes a TCP header and an IP header as described in IETF RFC 793 “Transmission Control Protocol” section 3.1 “Header Format”, incorporated herein by reference. A TCP header optionally includes a sack-permitted option as described in IETF RFC 2018 “TCP Selective Acknowledgement Options” section 2 “Sack-Permitted Option”, incorporated herein by reference. A session SYN packet 210 is a TCP/IP segment with the SYN control bit in the TCP Header set to “1”. A session SYN/ACK packet 220 is a TCP/IP segment with the SYN control bit and the ACK control bit in the TCP header set to “1”. A Session ACK Packet 230 is a TCP/IP segment with the ACK control bit in the TCP header set to “1”.

Referring to FIG. 2, in an embodiment, the TCP session setup module 104 receives a session SYN packet 210, obtains data from a session SYN packet 210, such as but not limited to the source IP address of the IP header, or the sequence number of the TCP header, and uses the data to generate a transition cookie 250. The transition cookie 250 is preferably a 32-bit data element. In response to the session SYN packet 210, the TCP session setup module 104 creates and sends out a session SYN/ACK packet 220 in accordance with IETF RFC 793 “Transmission Control Protocol” section 3.4 “Establishing a connection”, incorporated herein by reference. The TCP session setup module 104 preferably includes the transition cookie 250 as the sequence number of the TCP header in the session SYN/ACK packet 220.

After the TCP session setup module 104 has sent out the session SYN/ACK packet 220, it waits for receipt of a responding session ACK packet 230. In an embodiment, when a session SYN/ACK packet 230 is received, the TCP session setup module 104 generates a 32-bit candidate transition cookie 270 such that the sum of candidate transition cookie 270 and a value of “1” equal the acknowledgement number of the TCP header in the session ACK packet 230. For example, if the acknowledgement number is “41B4362A” in hexadecimal format the candidate transition cookie 270 is “41B43629” in hexadecimal format; the sum of “41B43629” and a value of “1” equals “41B4362A”. In another example, if the acknowledgement number is “00A30000” in hexadecimal format the candidate transition cookie 270 is “00A2FFFF” in hexadecimal format; the sum of “00A2FFFF” and a value of “1” equals “00A30000”. In another example, if the acknowledgement number is “00000000” in hexadecimal format the Candidate Transition Cookie 270 is “FFFFFFFF” in hexadecimal format; the sum of “FFFFFFFF” and a value of “1” equals “00000000”, with the most significant bit carried beyond the 32-bit boundary. The TCP session setup module 104 may thus validate the candidate transition cookie 270 in this manner. If the TCP session setup module 104 determines that the candidate transition cookie 270 is thus valid, the session ACK packet 230 is also valid. In this case, the TCP session setup module 104 obtains data from the validated session ACK packet 230 and sends the data and information generated during the validation of candidate transition cookie 270 to a computing module (not shown) for further processing.

In order to generate and validate transition cookies 250, 270, the TCP session setup module 104 may include a transition cookie generator 245 and a transition cookie validator 275, respectively. Alternatively, the generation and validation may be performed directly by the TCP session setup module 104. In the descriptions herein, references to the TCP and transition cookie validator 275 are understood to include any of the alternative embodiments of these components.

A transition cookie generator 245 includes the functionality of generating a transition cookie based on the data obtained from a session SYN 210 packet received by the TCP session setup module 104.

A transition cookie validator 275 includes the functionality of validating a candidate transition cookie 270 generated based on data obtained from a session ACK packet 230 received by the TCP session setup module 104.

In exemplary operation, a transition cookie generator 245 is software or firmware that generates a transition cookie 250 based on data obtained from a session SYN packet 210 received by the TCP session setup module 104. An exemplary method for generating a transition cookie 250 by a transition cookie generator 245 includes multiple steps as illustrated in FIGS. 3a-3c.

FIG. 3a illustrates exemplary steps for generating a transition cookie data element 330 by a transition cookie generator 245. A transition cookie generator 245 includes a clock 305 indicating the current time of day in microseconds in a 32-bit format.

The transition cookie data element 330 is preferably a 32-bit data element, generated by the transition cookie generator 245 based on the selective ACK 321, the MSS index 324 and the 32-bit current time of day indicated by clock 305. Selective ACK 321 is a 1-bit data element which is set to a value of “1” by transition cookie generator 245 if a TCP header in a received session SYN packet 210 includes an optional sack-permitted option, or to “0” if a TCP header in a received session SYN packet 210 does not include an optional sack-permitted option.

Maximum Segment Size (“MSS”) 322 is the maximum number of bytes that TCP will allow in an TCP/IP packet, such as session SYN packet 210, session SYN/ACK packet 220, and session ACK packet 230, and is normally represented by an integer value in a TCP packet header. If a TCP header in a received session SYN packet 210 includes a maximum segment size option, the transition cookie generator 245 sets the MSS 322 to equal the maximum segment size option data of the maximum segment size option. Otherwise, if the TCP header in a received session SYN packet 210 does not include a maximum segment size option, the transition cookie generator 245 sets the MSS 322 to a default value, for example, such as integer “536”. The MSS index 324 is a 4-bit data element set by the transition cookie generator 245 based on the MSS 322. The transition cookie generator 245 preferably includes an MSS table 307, which maps an MSS 322 to an MSS index 324. The transition cookie generator 245 maps a MSS 322 with the MSS table 307 to set the value of MSS index 324. For example, MSS 322 has an integer value of “1460”. After the mapping, MSS index 324 has a value of “4” as represented in hexadecimal format. In an alternative embodiment, means other than an MSS table 307 may be employed to determine the MSS index 324 value, such as the use of a mapping algorithm.

In generating a transition cookie data element 330, the transition cookie generator 245 sets a transition cookie data element 330 to equal the 32-bit current time of day indicated by clock 305. For example, the 32-bit current time of day may be “A68079E8” as represented in hexadecimal format, so the transition cookie data element 330 has a value of “A68079E8”.

Next, the transition cookie generator 245 replaces the least significant 4 bits (bit 0-3) of transition cookie data element 330 with the MSS index 324, and replaces bit 4 of a transition cookie data element 330 with selective ACK 321. For example, if a transition cookie data element 330 has been set to a value of “A68079E8”, selective ACK 321 has a value of “1”, and MSS index 324 has a value of “4” as represented in hexadecimal format, after the replacements, transition cookie data element 330 has a value of “A68079F4” in hexadecimal format.

FIG. 3b illustrates exemplary steps for generating a transition cookie secret key 360, such as by a transition cookie generator 245 based on data obtained from a received session SYN packet 210. The data used in generating the transition cookie secret key 360 may include at least the source IP address 312 of an IP header, a destination port 314, a source port 316 and a sequence number 318 of a TCP header in a received session SYN packet 210. In generating a transition cookie secret key 360, a transition cookie generator 245 forms a 96-bit data element, a first data item 340, by concatenating a source IP address 312, a sequence number 318, a source port 316, and a destination port 314. For example, if the source IP address 312 is 192.168.1.134, the hexadecimal representation being “C0A80186”, the sequence number 318 is “9A275B84”, the source port 316 is 4761, the hexadecimal representation being “1299”, and the destination port 314 is 240, the hexadecimal representation being “00F0”, then, after the concatenation, the first data item 340 has a hexadecimal value of “C0A801869A275B84129900F0”.

Next, since the transition cookie secret key 360 is a 128-bit data element, the transition cookie generator 245 may use a hash function to generate the transition cookie secret key 360 from the first data item 340. Further, the transition cookie generator 245 may use a secret key offset 301, which may be a 6-bit integer value, to select a 6-bit non-negative integer from first data item 340 starting at the bit indicated by secret key offset 301. For example, if the secret key offset 301 has a value of “12” and the first data item 340 has a hexadecimal value of “C0A801869A275B84129900F0”, the transition cookie generator 245 selects a 6-bit non-negative integer from the first data item 340 starting at bit 12 (bit 12-17). The selected non-negative integer is of this example is thus “16”. The transition cookie generator 245 then uses the selected non-negative integer to select 64 bits of data from the first data item 340, starting at the bit indicated by the selected non-negative integer, to generate the second data item 350, which has 64 bits.

For example, if the selected non-negative integer is “8” and the first data item 340 has a hexadecimal value of “C0A801869A275B84129900F0”, the transition cookie generator 245 selects 64 bits (bit 8-71) of the first data item 340 to generate a second data item 350, having a hexadecimal value of “869A275B84129900”. In another example, if the selected non-negative integer is “52”, and the transition cookie generator 245 selects 64 bits (bit 52-95 and bit 0-19) of the first data item 340 in a wrap-around fashion, bits 52-95 have a hexadecimal value of “C0A801869A2”, and bit 0-19 have a hexadecimal value of “900F0”, so the generated second data item 350 has a hexadecimal value of “900F0C0A801869A2”. The transition cookie generator 245 then generates a transition cookie secret key 360 by storing the second data item 350 in the least significant 64 bits (bit 0-63) of the transition cookie secret key 360 and setting the most significant 64 bits (bit 64-127) to “0”. For example, if the second data item 350 has a hexadecimal value of “869A275B84129900”, the transition cookie secret key 360 has a hexadecimal value of “0000000000000000869A275B84129900”.

FIG. 3c illustrates exemplary steps for generating a transition cookie 250 based on a transition cookie data element 330, a transition cookie secret key 360, and data obtained from a received session SYN packet 210, including a sequence number 318 of a TCP header in a received session SYN packet 210. To generate a transition cookie 250, a transition cookie generator 245 applies a cryptographic method 308 on the transition cookie secret key 360 and the transition cookie data element 330, such as an RC5 algorithm described in IETF RFC 2040 “The RC5, RC5-CBC, RC5-CBC-Pad, and RC5-CTS Algorithms” section 1 “Overview”, and sections 2-8 with detailed explanations, incorporated herein by reference. The RC5 algorithm takes a 32-bit plaintext input and a 128-bit encryption key to generate a 32-bit ciphertext output. The transition cookie generator 245 uses the transition cookie data element 330 as the plaintext input to the RC5 algorithm, and the transition cookie secret key 360 as the encryption key input to the RC5 algorithm. The transition cookie generator 245 stores the resulting 32-bit ciphertext output of the RC5 algorithm in the encrypted data element 370.

Next, the transition cookie generator 245 performs an unsigned binary addition on an encrypted data element 370 and the sequence number 318, and stores the result in the transition cookie 250. For example, if the encrypted data element 370 has a value of “0025BC83” in hexadecimal format, and the sequence number 318 has a value of “0743BD55” in hexadecimal format, the result of the addition is hexadecimal “076979D8”. After the addition, the transition cookie 250 has a value of “076979D8” in hexadecimal. In another example, if the encrypted data element 370 has a value of “BE43D096” in hexadecimal format, and the sequence number 318 has a value of “9A275B84” in hexadecimal format, the result of the addition, and the value of transition cookie 250 is hexadecimal “1586B2C1A”, with the most significant bit carried beyond the 32-bit boundary.

In another embodiment, a transition cookie generator 245 may use different steps to generate a transition cookie secret key 360. For example, a secret key offset 301 may be an integer of a different bit length, such as a 4-bit integer value, a 3-bit integer value, or a 5-bit integer value. Also, a transition cookie generator 245 may use a secret key offset 301 to select a non-negative integer value of a different bit length from a first data item 340. For example, a transition cookie generator 245 may select a 4-bit non-negative integer value, a 7-bit non-negative integer value, or a 5-bit non-negative value from a first data item 340.

In other embodiments, a transition cookie generator 245 may store a second data item 350 in the least significant 64 bits (bit 0-63) of a transition cookie secret key 360 or store second data item 350 in the most significant 64 bits (bit 64-127) of a transition cookie secret key 360.

A transition cookie generator 245 may also perform an exclusive-or operation on the most significant 48 bits (bit 0-47) of a first data item 340 and the least significant 48 bits (bit 48-95) of a first data element 340 to form a 48-bit temporary data element (not shown). Similarly, in another embodiment, a transition cookie generator 245 may perform an exclusive-or operation on the 48 even bits (bit 0, 2, 4, . . . 90, 92, 94) and the 48 odd bits (bit 1, 3, 5, . . . 93, 95, 97) to form a 48 bit temporary data element. In yet another embodiment, a transition cookie generator 245 may store a 48-bit temporary data element in the least significant 48 bits (bit 0-47) and the most significant 48 bits (bit 80-127) of a transition cookie secret key 360, and set bit 48-79 to “0”, or store a 48-bit temporary data element in the least significant 48 bits (bit 0-47) of a transition cookie secret key 360, and set the most significant 80 bits (bit 48-127) of a transition cookie secret key 360 to “0”.

In other embodiments of the invention, a transition cookie generator 245 may use an encryption algorithm to generate a transition cookie secret key 360 from the first data item 340.

In another embodiment, a transition cookie generator 245 includes a secret key and an encryption algorithm, and uses a first data element 340 as a plaintext input, and a secret key as an encryption key input to the encryption algorithm to generate a 128-bit ciphertext output. Next, a transition cookie generator 245 generates a transition cookie secret key 360 as a 128-bit ciphertext output. Alternatively, the ciphertext output may be a 96-bit data element, and a transition cookie generator 245 stores a 96-bit ciphertext output in the least significant 96 bits (bit 0-95) of a transition cookie secret key 360, and sets the most significant 32 bits (bit 96-127) to “0”. In another alternative, a transition cookie generator 245 stores the least significant 32 bits (bit 0-31) of a 96-bit ciphertext output in the most significant 32 bits (bit 96-127) of a transition cookie secret key 360.

As seen in FIG. 2, a transition cookie validator 275 validates a candidate transition cookie 270 generated from a session ACK packet 230 received by the TCP session setup module 104. An exemplary method for validating a candidate transition cookie 270 by a transition cookie validator 275 may include multiple steps as illustrated in FIGS. 4a-4d.

FIG. 4a illustrates exemplary steps for generating a candidate encrypted data element 470 by a transition cookie validator 275 based on data obtained from a received session ACK packet 230. The candidate encrypted data element 470 may be a 32-bit data element generated based on the sequence number 418 of the TCP header in the received session ACK packet 230, and the candidate transition cookie 270 generated from the received session ACK packet 230 as illustrated in FIG. 2.

The candidate sequence number 428 may be a 32-bit data element generated by a transition cookie validator 275 such that the sum of candidate sequence number 428 and a value of “1” equals the sequence number 418.

The candidate encrypted data element 470 is generated by the transition cookie validator 275 such that the result of performing an unsigned binary addition of the candidate encrypted data element 470 and the candidate sequence number 428 equals the candidate transition cookie 270.

FIG. 4b illustrates exemplary steps for generating a candidate transition cookie secret key 460 by the transition cookie validator 275 based on data obtained from the received session ACK packet 230 and a candidate sequence number 428. The data used for generating the candidate transition cookie secret key 460 may include at least a source IP address 412 of the IP header in a received session ACK packet 230, a destination port 414 and a source port 416 of the TCP header in a received session ACK packet 230. In the process, a 96-bit first data item 440 is formed by a transition cookie validator 275 by concatenating a source IP address 412, a candidate sequence number 428, a source port 416, and a destination port 414. For example, if the source IP address 412 is 192.168.1.134, having a hexadecimal representation of “C0A80186”, the candidate sequence number 428 is hexadecimal “9A275B84”, the source port 416 is 4761, having a hexadecimal representation of “1299”, and the destination port 414 is 240, having a hexadecimal representation of “00F0”, after the concatenation, the first data item 440 has a hexadecimal value of “C0A801869A275B84129900F0”.

Next, the 128-bit candidate transition cookie secret key 460 is generated from a first data item 440 by a transition cookie validator 275 using a hash function. In an embodiment, a transition cookie validator 275 uses a 6-bit secret key offset 401 to select a 6-bit non-negative integer from a first data item 440 starting at a bit indicated by secret key offset 401. For example, if the secret key offset 401 has a value of “12” and the first data item 440 is “C0A801869A275B84129900F0”, the transition cookie validator 275 selects a 6-bit non-negative integer from the first data item 440 starting at bit 12 (bits 12-17), selecting the non-negative integer “16”. The transition cookie validator 275 then generates a 64-bit second data item 350 by using the selected non-negative integer to select 64 bits of data from the first data item 440, starting at the bit indicated by the selected non-negative integer.

For example, if the selected non-negative integer is “8” and the first data item 440 has a hexadecimal value of “C0A801869A275B84129900F0”, the transition cookie validator 275 selects 64 bits (bit 8-71) of the first data item 440 to generate a second data item 450 having a hexadecimal value of “869A275B84129900”. In another example, if the first data item 440 has a hexadecimal value of “C0A801869A275B84129900F0”, and the selected non-negative integer is “52”, the transition cookie validator 275 selects 64 bits (bit 52-95 and bit 0-19) in a wrap-around fashion. Bits 52-95 have a hexadecimal value of “C0A801869A2”, and bits 0-19 have a hexadecimal value of “900F0”, so the generated second data item 450 has a hexadecimal value of “900F0C0A801869A2”.

Next, the transition cookie validator 275 generates a candidate transition cookie secret key 460 by storing the second data item 450 in the least significant 64 bits (bit 0-63) of the candidate transition cookie secret key 460 and setting the most significant 64 bits (bit 64-127) to “0”. For example, if the second data item 450 has a hexadecinmal value of “869A275B84129900”, the candidate transition cookie secret key 460 has a hexadecimal value of “0000000000000000869A275B84129900”.

FIG. 4C illustrates exemplary steps for generating a candidate transition cookie data element 430 by a transition cookie validator 275 based on a candidate encrypted data element 470 and a candidate transition cookie secret key 460.

In an embodiment, a transition cookie validator 275 applies a cryptographic method 408 on a candidate transition cookie secret key 460 and a candidate encrypted data element 470. An exemplary cryptographic method 408 is an RC5 algorithm described in IETF RFC 2040 “The RC5, RC5-CBC, RC5-CBC-Pad, and RC5-CTS Algorithms” section 1 “Overview”, and sections 2-8 with detailed explanations, incorporated herein by reference. The RC5 algorithm takes a 32-bit ciphertext input and a 128-bit decryption key to generate a 32-bit plaintext output. A transition cookie validator 275 uses a candidate encrypted data element 470 as a ciphertext input to the RC5 algorithm, and a candidate transition cookie secret key 460 as a decryption key input to the RC5 algorithm, to generate a 32-bit candidate transition cookie data element 430 as the plaintext output of the RC5 decryption algorithm.

FIG. 4d illustrates exemplary steps by a transition cookie validator 275 of validating a candidate transition cookie data element 430. In an embodiment, a transition cookie validator 275 includes a clock 305. The clock 305 indicates the current time of day, preferably in microseconds in a 32-bit format. The modified current time 409 is a 32-bit data element set by a transition cookie validator 275 sets to the current time indicated by clock 305. A transition cookie validator 275 then sets the least significant 5 bits (bit 0-4) of the modified current time 409 to “0”. For example, if the modified current time 409 has a value of “89AE03F6” in hexadecimal format, after setting the least significant 5 bits to “0”, the modified current time 409 has a hexadecimal value of “89AE03E0”.

Next, a transition cookie validator 275 sets a 32-bit adjusted candidate transition cookie data element 431 to equal the candidate transition cookie data element 430, and then sets the least significant 5 bits (bit 0-4) of the adjusted candidate transition cookie data element 431 to “0”. For example, if the adjusted candidate transition cookie data element 431 has a hexadecimal value of “89DB468F”, after setting the least significant 5 bits to “0”, the adjusted candidate transition cookie data element 431 has a hexadecimal value of “89DB4680”.

The transition cookie validator 275 may then determine if the candidate transition cookie data element 430 is valid by determining if the adjusted candidate transition cookie data element 431 is within a time margin of 3 seconds of the modified current time 409. In an embodiment, in order to determine if the adjusted candidate transition cookie data element 431 is within a time margin of 3 seconds of the modified current time 409, the transition cookie stores the modified current time 409 in the least significant 32 bits (bit 0-31) of a first 33-bit time data element, sets the most significant bit (bit 32) to “0”, and adds 6 seconds to the first 33-bit time data element. Adding 6 seconds is to add 6,000,000 micro seconds as represented by “5B8D80” in hexadecimal format. For example, if before the addition, the first 33-bit time data element has a hexadecimal value of “0FFFFFAE2”, After the addition of “5B8D80”, the first 33-bit time data element has a hexadecimal value of “1005B8862”. The transition cookie validator 275 stores the adjusted candidate transition cookie data element 431 in the least significant 32 bits (bit 0-31) of a second 33-bit time data element, sets the most significant bit (bit 32) to “0”, and adds 3 seconds to the second 33-bit time data element. Adding 3 seconds is to add 3,000,000 micro seconds as represented by hexadecimal “2DC6C0”. The transition cookie validator 275 stores the modified current time 409 in the least significant 32 bits (bit 0-31) of a third 33-bit time data element, and sets the most significant bit (bit 32) to “0”. If the second 33-bit time data element is smaller than the first 33-bit time data element and the second 33-bit time data element is larger than the third 33-bit time data element, the transition cookie validator 275 determines that the adjusted candidate transition cookie data element 431 is within 3 seconds of the modified current time 409, and thus that the candidate transition cookie data element 430 is valid.

FIG. 5 illustrates exemplary steps of generating information based on a validated candidate transition cookie data element 430. In an embodiment, candidate MSS 522 is an integer. A transition cookie validator 275 includes a reversed MSS table 507, which includes information that maps a 4-bit data element to a candidate MSS 522. A transition cookie validator 275 extracts the least significant 4-bit (bit 0-3) data from candidate transition cookie data element 430, maps the extracted 4-bit data to a reversed MSS table 507, and stores the result in a candidate MSS 522. A transition cookie validator 275 may then generate a maximum segment size option as described in IETF RFC 793 “Transmission Control Protocol” section 3.1 “Header Format”, incorporated herein by reference, and sets a maximum segment size option data of the maximum segment size option to equal a candidate MSS 522. A transition cookie validator 275 may further examine bit 4 of a candidate transition cookie data element 430. If bit 4 of candidate transition cookie data element 430 has a value of “1”, a transition cookie validator 275 may generate a sack-permitted option as described in IETF RFC 2018 “TCP Selective Acknowledgement Options” section 2, incorporated herein by reference. A TCP session setup module 104 may then send a sack-permitted option, a maximum segment size option, and data obtained from a received session ACK packet 230 to a computing module (not shown) for further processing.

There are many different encryption algorithms that use encryption keys of different bit lengths, such as, for example, 56-bit, 64-bit, 96-bit, 128-bit. These may generate ciphertext outputs of different bit lengths, for example, 96-bit, 64-bit, 128-bit, or 32-bit. Persons of ordinary skill in the cipher arts will be able to apply different methods, for example a hash function, to generate the transition cookie secret key 360 from the ciphertext output.

A transition cookie validator 275 may also use different steps to generate a candidate transition cookie secret key 460. The steps used by a transition cookie validator 275 to generate a candidate transition cookie secret key 460 are similar to the steps used by a transition cookie generator 245 to generate a transition cookie secret key 360.

Alternative embodiments of the invention may employ a different algorithm for the cryptographic methods 308, 408. In one example, the different algorithm is an RC2 algorithm described in IETF RFC 2268 “A Description of the RC2(r) Encryption Algorithm” section 1 “Introduction” and section 2-4 with detailed explanation, incorporated herein by reference. In another example, the different algorithm is a Blowfish algorithm. In one other example, the different algorithm is a Data Encryption Standards (“DES”) algorithm based on Federal Information Processing Standards Publication “Data Encryption Standard (DES) FIPS PUB 46-3”, which is incorporated herein by reference in its entirety. Other algorithms are also usable.

Also, a transition cookie validator 275 may use different time margins of modified current time 409 to determine if the candidate transition cookie data element is valid. Different time margins include but are not limited to 1 second, 4 seconds, 6 seconds, 2 seconds, or 11 seconds.

In an embodiment, the method of generating a transition cookie includes MD5 signature option information in the TCP options field. When this method is used, the method of validating a candidate transition cookie 270 correspondingly includes the MD5 signature option information in the TCP options field.

In another embodiment, transition cookie generator 245 may include a plurality of transition cookie generation methods for generating transition cookie 250. For example, the secret key offset 301 may have a different value, such as an integer value of different bit length, such as 4-bit, or 8-bit. In other examples, the selected non-negative integer from first data item 340 may be of different bit length, such as 8-bit, or 10-bit, the cryptographic method 308 may be a different algorithm than RC5, or the generating of transition cookie data element 330 may include MD5 signature option information in the TCP options field of session SYN packet 210. A transition cookie generation method may include steps different from the steps in the exemplary method illustrated in FIGS. 3a-3c.

In an embodiment, the transition cookie generator 245 may selects method to generate transition cookie 250 based on random data.

The random data may include time. In one embodiment, transition cookie generator 245 selects a method based on the time of day. Alternatively, the transition cookie generator 245 may select a method after a time period, such as 10 seconds, 30 seconds, 2 minutes or 3 hours.

In another embodiment, the random data may include a source IP address in session SYN packet 210, or a destination IP address in session SYN packet 210.

The random data may include the network interface at which a TCP session setup module 104 receives a session SYN packet 210, or a Virtual Local Area Network (VLAN) information associated with a session SYN packet 210.

In one embodiment, transition cookie validator 275 includes a plurality of transition cookie validation methods for validating candidate transition cookie 270. A transition cookie validation method may include steps different from the steps in the exemplary method illustrated in FIGS. 4a-4d. A transition cookie validator 275 may select a method to validate candidate transition cookie 270 based on random data.

In these embodiments it is understood to be preferred that the transition cookie validator 275 selects a complementary method to the method selected by transition cookie generator 245.

Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims

1. A system for TCP SYN cookie validation at a host server comprising:

a session SYN packet receiver for receiving a session SYN packet;
a transition cookie generator operating to generate a transition cookie with the use of a transition cookie secret key, the transition cookie comprising a time value representing the actual time, wherein the transition cookie generator generates the transition cookie secret key based on data obtained from the received session SYN packet, the data obtained from the SYN packet including at least one of a source IP address of an IP header, a destination port, a source port, and a sequence number of a TCP header in the received session SYN packet, wherein the transition cookie generator concatenates the obtained data from the session SYN packet to generate a first data item of the generator and the transition cookie generator uses a first hash function to generate the transition cookie secret key from the first data item of the generator;
a session SYN/ACK packet sender for sending the transition cookie in response to the received session SYN packet;
a session ACK packet receiver for receiving a session ACK packet, the session ACK packet including a candidate transition cookie; and
a transition cookie validator, for determining whether the candidate transition cookie in the received session ACK packet comprises a time value representing a time within a predetermined time interval from the time the session ACK packet is received, wherein the transition cookie validator generates a candidate transition cookie secret key based on data obtained from the received session ACK packet, the data obtained from the ACK packet including at least one of a source IP address of the IP header, a destination port, and a source port, wherein the transition cookie validator concatenates the obtained data from the session ACK packet to generate a first data item of the validator and the transition cookie validator uses the first or another hash function to generate the candidate transition cookie secret key from the first data item of the validator,
wherein at least one of:
the transition cookie generator uses a secret key offset to select one or more bits of data from the first data item of the generator in order to generate a second data item of the generator, and
the transition cookie validator uses a candidate secret key offset to select one or more bits of data from the first data item of the validator in order to generate a second data item of the validator.

2. The system according to claim 1, in which the transition cookie validator determines that the received session ACK packet is valid if the candidate transition cookie in the received session ACK packet comprises a time value representing a time within a predetermined time interval from the time the session ACK packet is received.

3. The system according to claim 1, in which the predetermined time interval is in the range of one to six seconds.

4. The system according to claim 1, in which the predetermined time interval is three seconds.

5. The system according to claim 1, in which the generating of the transition cookie includes the use of random data.

6. The system according to claim 1, in which the generating of the transition cookie includes the use of data obtained from the session SYN packet.

7. A system for TCP SYN cookie validation at a host server comprising:

a session SYN packet receiver for receiving a session SYN packet;
a transition cookie generator operating to generate a transition cookie with the use of a transition cookie secret key, the transition cookie comprising a time value representing the actual time, wherein the transition cookie generator generates the transition cookie by (i) generating an encrypted data element of the generator by applying a cryptographic method on the transition cookie secret key and a transition cookie data element, (ii) performing an unsigned binary addition on the encrypted data element of the generator and a sequence number of a TCP header in the received session SYN packet, and (iii) storing the result in the transition cookie;
a session SYN/ACK packet sender for sending the transition cookie in response to the received session SYN packet;
a session ACK packet receiver for receiving a session ACK packet, the session ACK packet including a candidate transition cookie; and
a transition cookie validator, for determining whether the candidate transition cookie in the received session ACK packet comprises a time value representing a time within a predetermined time interval from the time the session ACK packet is received.

8. The system according to claim 7, wherein the transition cookie data element comprises data based on at least one of: a selective ACK, an MSS index, and a 32-bit current time of day indicated by a clock.

9. A system for TCP SYN cookie validation at a host server comprising:

a session SYN packet receiver for receiving a session SYN packet;
a transition cookie generator operating to generate a transition cookie with the use of a transition cookie secret key, the transition cookie comprising a time value representing the actual time;
a session SYN/ACK packet sender for sending the transition cookie in response to the received session SYN packet;
a session ACK packet receiver for receiving a session ACK packet, the session ACK packet including a candidate transition cookie; and
a transition cookie validator, for determining whether the candidate transition cookie in the received session ACK packet comprises a time value representing a time within a predetermined time interval from the time the session ACK packet is received, wherein the transition cookie validator generates:
a candidate sequence number such that a sequence number of a TCP header in the received session ACK packet equals the sum of the candidate sequence number and a value of 1,
a candidate encrypted data element such that the result of performing an unsigned binary addition of the candidate encrypted data element and a candidate sequence number equals the candidate transition cookie, and
a candidate transition cookie data element by applying a cryptographic method on a candidate transition cookie secret key and the candidate encrypted data element.

10. The system according to claim 9, wherein the transition cookie validator validates the candidate transition cookie data element by adjusting the candidate transition cookie data element to generate, and determining if the adjusted candidate transition cookie data element is within a predetermined time margin of a modified current time.

11. A system for TCP SYN cookie validation at a host server, the system comprising: wherein:

at least one processor and a memory storing:
a session SYN packet receiver, wherein when the session SYN packet receiver is executed by the at least one processor, the session SYN packet receiver causing the at least one processor to receive a session SYN packet;
a transition cookie generator, the transition cookie generator being executed by the at least one processor to generate a transition cookie with the use of a transition cookie secret key, the transition cookie comprising a time value representing the actual time;
a session SYN/ACK packet sender, the session SYN/ACK packet sender being executed by the at least one processor to send the transition cookie in response to the received session SYN packet;
a session ACK packet receiver, the session ACK packet receiver being executed by the at least one processor to receive a session ACK packet, the session ACK packet including a candidate transition cookie; and
a transition cookie validator, the transition cookie validator being executed by the at least one processor to determine whether the candidate transition cookie in the received session ACK packet comprises a time value representing a time within a predetermined time interval from the time the session ACK packet is received; and
the transition cookie generator is executed by the at least one processor to generate the transition cookie secret key based on data obtained from the received session SYN packet;
the transition cookie validator is executed by the at least one processor to generate a candidate transition cookie secret key based on data obtained from the received session ACK packet;
the transition cookie generator is executed by the at least one processor to concatenate the obtained data from the session SYN packet to generate a first data item of the generator;
the transition cookie validator is executed by the at least one processor to concatenate the obtained data from the session ACK packet to generate a first data item of the validator;
the transition cookie generator is executed by the at least one processor to use a secret key offset to select one or more bits of data from the first data item of the generator in order to generate a second data item of the generator, and
the transition cookie validator is executed by the at least one processor to use a candidate secret key offset to select one or more bits of data from the first data item of the validator in order to generate a second data item of the validator.

12. The system according to claim 11, wherein:

when the transition cookie secret key is generated based on data obtained from the received session SYN packet, the obtained data includes at least one of: a source IP address of an IP header, a destination port, a source port, and a sequence number of a TCP header in the received session SYN packet, and
when the candidate transition cookie secret key is generated based on data obtained from the received session ACK packet, the obtained data includes at least one of:
a source IP address of the IP header, a destination port, and a source port.

13. The system according to claim 11, wherein at least one of:

the transition cookie generator is executed by the at least one processor to use a first hash function to generate the transition cookie secret key from the first data item of the generator, and
when the transition cookie validator is executed by the at least one processor to use the first or another hash function to generate the candidate transition cookie secret key from the first data item of the validator.

14. The system according to claim 11, in which the transition cookie validator is executed by the at least one processor to determine that the received session ACK packet is valid if the candidate transition cookie in the received session ACK packet comprises a time value representing a time within a predetermined time interval from the time the session ACK packet is received.

15. The system according to claim 11, in which the predetermined time interval is in the range of one to six seconds.

16. The system according to claim 11, in which the predetermined time interval is three seconds.

17. The system according to claim 11, in which the generating of the transition cookie includes the use of random data.

18. The system according to claim 11, in which the generating of the transition cookie includes the use of data obtained from the session SYN packet.

19. A system for TCP SYN cookie validation at a host server, the system comprising:

at least one processor and a memory storing:
a session SYN packet receiver, wherein the session SYN packet receiver is executed by the at least one processor to receive a session SYN packet;
a transition cookie generator, wherein the transition cookie generator is executed by the at least one processor to generate a transition cookie with the use of a transition cookie secret key, the transition cookie comprising a time value representing the actual time;
a session SYN/ACK packet sender, wherein the session SYN/ACK packet sender is executed by the at least one processor to send the transition cookie in response to the received session SYN packet;
a session ACK packet receiver, wherein when the session ACK packet receiver is executed by the at least one processor to receive a session ACK packet, the session ACK packet including a candidate transition cookie; and
a transition cookie validator, wherein the transition cookie validator is executed by the at least one processor to determine whether the candidate transition cookie in the received session ACK packet comprises a time value representing a time within a predetermined time interval from the time the session ACK packet is received; and wherein:
the transition cookie generator is executed by the at least one processor to generate the transition cookie by (i) generating an encrypted data element of the generator by applying a cryptographic method on the transition cookie secret key and a transition cookie data element, (ii) performing an unsigned binary addition on the encrypted data element of the generator and a sequence number of a TCP header in the received session SYN packet, and (iii) storing the result in the transition cookie.

20. The system according to claim 19, wherein the transition cookie data element comprises data based on at least one of: a selective ACK, an MSS index, and a 32-bit current time of day indicated by a clock.

21. The system according to claim 19, in which the transition cookie validator is executed by the at least one processor to determine that the received session ACK packet is valid if the candidate transition cookie in the received session ACK packet comprises a time value representing a time within a predetermined time interval from the time the session ACK packet is received.

22. The system according to claim 19, in which the predetermined time interval is in the range of one to six seconds.

23. The system according to claim 19, in which the predetermined time interval is three seconds.

24. The system according to claim 19, in which the generating of the transition cookie includes the use of random data.

25. The system according to claim 19, in which the generating of the transition cookie includes the use of data obtained from the session SYN packet.

26. A system for TCP SYN cookie validation at a host server, the system comprising:

at least one processor and a memory storing:
a session SYN packet receiver, wherein the session SYN packet receiver is executed by the at least one processor to receive a session SYN packet;
a transition cookie generator, wherein the transition cookie generator is executed by the at least one processor to generate a transition cookie with the use of a transition cookie secret key, the transition cookie comprising a time value representing the actual time;
a session SYN/ACK packet sender, wherein the session SYN/ACK packet sender is executed by the at least one processor to send the transition cookie in response to the received session SYN packet;
a session ACK packet receiver, wherein the session ACK packet receiver is executed by the at least one processor to receive a session ACK packet, the session ACK packet including a candidate transition cookie; and
a transition cookie validator, wherein the transition cookie validator is executed by the at least one processor to determine whether the candidate transition cookie in the received session ACK packet comprises a time value representing a time within a predetermined time interval from the time the session ACK packet is received; and to generate: a candidate sequence number such that a sequence number of a TCP header in the received session ACK packet equals the sum of the candidate sequence number and a value of 1, a candidate encrypted data element such that the result of performing an unsigned binary addition of the candidate encrypted data element and a candidate sequence number equals the candidate transition cookie, and a candidate transition cookie data element by (i) applying a cryptographic method on a candidate transition cookie secret key and the candidate encrypted data element.

27. The system according to claim 26, wherein the transition cookie validator is executed by the at least one processor to validate the candidate transition cookie data element by adjusting the candidate transition cookie data element to generate, and determining if the adjusted candidate transition cookie data element is within a predetermined time margin of a modified current time.

28. The system according to claim 26, in which when the transition cookie validator is executed by the at least one processor to determine that the received session ACK packet is valid if the candidate transition cookie in the received session ACK packet comprises a time value representing a time within a predetermined time interval from the time the session ACK packet is received.

Referenced Cited
U.S. Patent Documents
5218602 June 8, 1993 Grant et al.
5774660 June 30, 1998 Brendel et al.
5862339 January 19, 1999 Bonnaure et al.
5875185 February 23, 1999 Wang et al.
5935207 August 10, 1999 Logue et al.
5958053 September 28, 1999 Denker
5995981 November 30, 1999 Wikstrom
6003069 December 14, 1999 Cavill
6047268 April 4, 2000 Bartoli et al.
6075783 June 13, 2000 Voit
6131163 October 10, 2000 Wiegel
6219706 April 17, 2001 Fan et al.
6259705 July 10, 2001 Takahashi et al.
6321338 November 20, 2001 Porras et al.
6374300 April 16, 2002 Masters
6456617 September 24, 2002 Oda et al.
6459682 October 1, 2002 Ellesson et al.
6483600 November 19, 2002 Schuster et al.
6535516 March 18, 2003 Leu et al.
6578066 June 10, 2003 Logan et al.
6587866 July 1, 2003 Modi et al.
6600738 July 29, 2003 Alperovich et al.
6658114 December 2, 2003 Farn et al.
6748414 June 8, 2004 Bournas
6772205 August 3, 2004 Lavian et al.
6772334 August 3, 2004 Glawitsch
6779017 August 17, 2004 Lamberton et al.
6779033 August 17, 2004 Watson et al.
6804224 October 12, 2004 Schuster et al.
6952728 October 4, 2005 Alles et al.
7010605 March 7, 2006 Dharmarajan
7013482 March 14, 2006 Krumel
7058718 June 6, 2006 Fontes et al.
7069438 June 27, 2006 Balabine et al.
7076555 July 11, 2006 Orman et al.
7143087 November 28, 2006 Fairweather
7167927 January 23, 2007 Philbrick et al.
7181524 February 20, 2007 Lele
7218722 May 15, 2007 Turner et al.
7228359 June 5, 2007 Monteiro
7234161 June 19, 2007 Maufer et al.
7236457 June 26, 2007 Joe
7254133 August 7, 2007 Govindarajan et al.
7269850 September 11, 2007 Govindarajan et al.
7277963 October 2, 2007 Dolson et al.
7301899 November 27, 2007 Goldstone
7308499 December 11, 2007 Chavez
7310686 December 18, 2007 Uysal
7328267 February 5, 2008 Bashyam et al.
7334232 February 19, 2008 Jacobs et al.
7337241 February 26, 2008 Boucher et al.
7343399 March 11, 2008 Hayball et al.
7349970 March 25, 2008 Clement et al.
7370353 May 6, 2008 Yang
7373500 May 13, 2008 Ramelson et al.
7391725 June 24, 2008 Huitema et al.
7398317 July 8, 2008 Chen et al.
7423977 September 9, 2008 Joshi
7430755 September 30, 2008 Hughes et al.
7463648 December 9, 2008 Eppstein et al.
7467202 December 16, 2008 Savchuk
7472190 December 30, 2008 Robinson
7492766 February 17, 2009 Cabeca et al.
7506360 March 17, 2009 Wilkinson et al.
7509369 March 24, 2009 Tormasov
7512980 March 31, 2009 Copeland et al.
7533409 May 12, 2009 Keane et al.
7552323 June 23, 2009 Shay
7584262 September 1, 2009 Wang et al.
7584301 September 1, 2009 Joshi
7590736 September 15, 2009 Hydrie et al.
7610622 October 27, 2009 Touitou
7613193 November 3, 2009 Swami et al.
7613822 November 3, 2009 Joy et al.
7673072 March 2, 2010 Boucher et al.
7675854 March 9, 2010 Chen et al.
7703102 April 20, 2010 Eppstein et al.
7707295 April 27, 2010 Szeto et al.
7711790 May 4, 2010 Barrett et al.
7733866 June 8, 2010 Mishra
7747748 June 29, 2010 Allen
7765328 July 27, 2010 Bryers et al.
7792113 September 7, 2010 Foschiano et al.
7808994 October 5, 2010 Vinokour et al.
7826487 November 2, 2010 Mukerji et al.
7881215 February 1, 2011 Daigle et al.
7948952 May 24, 2011 Hurtta et al.
7965727 June 21, 2011 Sakata et al.
7970934 June 28, 2011 Patel
7979694 July 12, 2011 Touitou
7983258 July 19, 2011 Ruben et al.
7990847 August 2, 2011 Leroy et al.
7991859 August 2, 2011 Miller et al.
7992201 August 2, 2011 Aldridge et al.
8019870 September 13, 2011 Eppstein et al.
8032634 October 4, 2011 Eppstein et al.
8081640 December 20, 2011 Ozawa et al.
8090866 January 3, 2012 Bashyam et al.
8099492 January 17, 2012 Dahlin et al.
8116312 February 14, 2012 Riddoch et al.
8122116 February 21, 2012 Matsunaga et al.
8151019 April 3, 2012 Le et al.
8179809 May 15, 2012 Eppstein et al.
8185651 May 22, 2012 Moran et al.
8191106 May 29, 2012 Choyi et al.
8224971 July 17, 2012 Miller et al.
8261339 September 4, 2012 Aldridge et al.
8266235 September 11, 2012 Jalan et al.
8296434 October 23, 2012 Miller et al.
8312507 November 13, 2012 Chen et al.
8379515 February 19, 2013 Mukerji
8499093 July 30, 2013 Grosser et al.
8539075 September 17, 2013 Bali et al.
8554929 October 8, 2013 Szeto et al.
8559437 October 15, 2013 Mishra
8560693 October 15, 2013 Wang et al.
8584199 November 12, 2013 Chen et al.
8595791 November 26, 2013 Chen et al.
RE44701 January 14, 2014 Chen et al.
8675488 March 18, 2014 Sidebottom et al.
8681610 March 25, 2014 Mukerji
8750164 June 10, 2014 Casado et al.
8782221 July 15, 2014 Han
8813180 August 19, 2014 Chen et al.
8826372 September 2, 2014 Chen et al.
8879427 November 4, 2014 Krumel
8885463 November 11, 2014 Medved et al.
8897154 November 25, 2014 Jalan et al.
8965957 February 24, 2015 Barros
8977749 March 10, 2015 Han
8990262 March 24, 2015 Chen et al.
9094364 July 28, 2015 Jalan et al.
9106561 August 11, 2015 Jalan et al.
9137301 September 15, 2015 Dunlap et al.
9154577 October 6, 2015 Jalan et al.
9154584 October 6, 2015 Han
9215275 December 15, 2015 Kannan et al.
9219751 December 22, 2015 Chen et al.
9253152 February 2, 2016 Chen et al.
9270705 February 23, 2016 Chen et al.
9270774 February 23, 2016 Jalan et al.
9338225 May 10, 2016 Jalan et al.
9350744 May 24, 2016 Chen et al.
9356910 May 31, 2016 Chen et al.
9386088 July 5, 2016 Zheng et al.
9531846 December 27, 2016 Han et al.
20010042200 November 15, 2001 Lamberton
20010049741 December 6, 2001 Skene et al.
20020026515 February 28, 2002 Michielsens et al.
20020032777 March 14, 2002 Kawata et al.
20020032799 March 14, 2002 Wiedeman et al.
20020078164 June 20, 2002 Reinschmidt
20020091844 July 11, 2002 Craft et al.
20020103916 August 1, 2002 Chen et al.
20020133491 September 19, 2002 Sim et al.
20020138618 September 26, 2002 Szabo
20020141386 October 3, 2002 Minert et al.
20020143991 October 3, 2002 Chow et al.
20020178259 November 28, 2002 Doyle et al.
20020188678 December 12, 2002 Edecker et al.
20020191575 December 19, 2002 Kalavade et al.
20020194335 December 19, 2002 Maynard
20020194350 December 19, 2002 Lu et al.
20030009591 January 9, 2003 Hayball et al.
20030014544 January 16, 2003 Pettey
20030023711 January 30, 2003 Parmar et al.
20030023873 January 30, 2003 Ben-Itzhak
20030035409 February 20, 2003 Wang et al.
20030035420 February 20, 2003 Niu
20030061506 March 27, 2003 Cooper et al.
20030091028 May 15, 2003 Chang et al.
20030131245 July 10, 2003 Linderman
20030135625 July 17, 2003 Fontes et al.
20030195962 October 16, 2003 Kikuchi et al.
20040010545 January 15, 2004 Pandya
20040062246 April 1, 2004 Boucher et al.
20040073703 April 15, 2004 Boucher et al.
20040078419 April 22, 2004 Ferrari et al.
20040078480 April 22, 2004 Boucher et al.
20040103315 May 27, 2004 Cooper et al.
20040111516 June 10, 2004 Cain
20040128312 July 1, 2004 Shalabi et al.
20040139057 July 15, 2004 Hirata et al.
20040139108 July 15, 2004 Tang et al.
20040141005 July 22, 2004 Banatwala et al.
20040143599 July 22, 2004 Shalabi et al.
20040187032 September 23, 2004 Gels et al.
20040199616 October 7, 2004 Karhu
20040199646 October 7, 2004 Susai et al.
20040202182 October 14, 2004 Lund et al.
20040210623 October 21, 2004 Hydrie et al.
20040210663 October 21, 2004 Phillips et al.
20040213158 October 28, 2004 Collett et al.
20040250059 December 9, 2004 Ramelson et al.
20040268358 December 30, 2004 Darling et al.
20050005207 January 6, 2005 Herneque
20050009520 January 13, 2005 Herrero et al.
20050021848 January 27, 2005 Jorgenson
20050027862 February 3, 2005 Nguyen et al.
20050036501 February 17, 2005 Chung et al.
20050036511 February 17, 2005 Baratakke et al.
20050039033 February 17, 2005 Meyers et al.
20050044270 February 24, 2005 Grove et al.
20050074013 April 7, 2005 Hershey et al.
20050080890 April 14, 2005 Yang et al.
20050102400 May 12, 2005 Nakahara et al.
20050125276 June 9, 2005 Rusu
20050163073 July 28, 2005 Heller et al.
20050198335 September 8, 2005 Brown et al.
20050213586 September 29, 2005 Cyganski et al.
20050240989 October 27, 2005 Kim et al.
20050249225 November 10, 2005 Singhal
20050259586 November 24, 2005 Hafid et al.
20050281190 December 22, 2005 McGee et al.
20060023721 February 2, 2006 Miyake et al.
20060036610 February 16, 2006 Wang
20060036733 February 16, 2006 Fujimoto et al.
20060041745 February 23, 2006 Parnes
20060064478 March 23, 2006 Sirkin
20060069774 March 30, 2006 Chen et al.
20060069804 March 30, 2006 Miyake et al.
20060077926 April 13, 2006 Rune
20060092950 May 4, 2006 Arregoces et al.
20060098645 May 11, 2006 Walkin
20060112170 May 25, 2006 Sirkin
20060164978 July 27, 2006 Werner et al.
20060168319 July 27, 2006 Trossen
20060187901 August 24, 2006 Cortes et al.
20060190997 August 24, 2006 Mahajani et al.
20060209789 September 21, 2006 Gupta et al.
20060230129 October 12, 2006 Swami
20060233100 October 19, 2006 Luft et al.
20060251057 November 9, 2006 Kwon et al.
20060277303 December 7, 2006 Hegde et al.
20060280121 December 14, 2006 Matoba
20070019543 January 25, 2007 Wei et al.
20070022479 January 25, 2007 Sikdar et al.
20070076653 April 5, 2007 Park et al.
20070086382 April 19, 2007 Narayanan et al.
20070094396 April 26, 2007 Takano et al.
20070118881 May 24, 2007 Mitchell et al.
20070124502 May 31, 2007 Li
20070156919 July 5, 2007 Potti et al.
20070165622 July 19, 2007 O'Rourke et al.
20070180119 August 2, 2007 Khivesara et al.
20070185998 August 9, 2007 Touitou et al.
20070195792 August 23, 2007 Chen et al.
20070230337 October 4, 2007 Igarashi et al.
20070242738 October 18, 2007 Park et al.
20070243879 October 18, 2007 Park et al.
20070245090 October 18, 2007 King et al.
20070248009 October 25, 2007 Petersen
20070259673 November 8, 2007 Willars et al.
20070283429 December 6, 2007 Chen et al.
20070286077 December 13, 2007 Wu
20070288247 December 13, 2007 Mackay
20070294209 December 20, 2007 Strub et al.
20080016161 January 17, 2008 Tsirtsis et al.
20080031263 February 7, 2008 Ervin et al.
20080076432 March 27, 2008 Senarath et al.
20080101396 May 1, 2008 Miyata
20080109452 May 8, 2008 Patterson
20080109870 May 8, 2008 Sherlock et al.
20080120129 May 22, 2008 Seubert et al.
20080134332 June 5, 2008 Keohane et al.
20080162679 July 3, 2008 Maher et al.
20080225722 September 18, 2008 Khemani et al.
20080228781 September 18, 2008 Chen et al.
20080250099 October 9, 2008 Shen et al.
20080253390 October 16, 2008 Das et al.
20080263209 October 23, 2008 Pisharody et al.
20080271130 October 30, 2008 Ramamoorthy
20080282254 November 13, 2008 Blander et al.
20080291911 November 27, 2008 Lee et al.
20080298303 December 4, 2008 Tsirtsis
20090024722 January 22, 2009 Sethuraman et al.
20090031415 January 29, 2009 Aldridge et al.
20090049198 February 19, 2009 Blinn et al.
20090070470 March 12, 2009 Bauman et al.
20090077651 March 19, 2009 Poeluev
20090092124 April 9, 2009 Singhal et al.
20090106830 April 23, 2009 Maher
20090138606 May 28, 2009 Moran et al.
20090138945 May 28, 2009 Savchuk
20090141634 June 4, 2009 Rothstein et al.
20090164614 June 25, 2009 Christian et al.
20090172093 July 2, 2009 Matsubara
20090213858 August 27, 2009 Dolganow et al.
20090222583 September 3, 2009 Josefsberg et al.
20090227228 September 10, 2009 Hu et al.
20090228547 September 10, 2009 Miyaoka et al.
20090262741 October 22, 2009 Jungck et al.
20090271472 October 29, 2009 Scheifler et al.
20090285196 November 19, 2009 Lee et al.
20090313379 December 17, 2009 Rydnell et al.
20100008229 January 14, 2010 Bi et al.
20100023621 January 28, 2010 Ezolt et al.
20100036952 February 11, 2010 Hazlewood et al.
20100042869 February 18, 2010 Szabo et al.
20100054139 March 4, 2010 Chun et al.
20100061319 March 11, 2010 Aso et al.
20100064008 March 11, 2010 Yan et al.
20100082787 April 1, 2010 Kommula et al.
20100083076 April 1, 2010 Ushiyama
20100094985 April 15, 2010 Abu-Samaha et al.
20100095018 April 15, 2010 Khemani et al.
20100098417 April 22, 2010 Tse-Au
20100106833 April 29, 2010 Banerjee et al.
20100106854 April 29, 2010 Kim et al.
20100128606 May 27, 2010 Patel et al.
20100162378 June 24, 2010 Jayawardena et al.
20100205310 August 12, 2010 Altshuler et al.
20100210265 August 19, 2010 Borzsei et al.
20100217793 August 26, 2010 Preiss
20100217819 August 26, 2010 Chen et al.
20100223630 September 2, 2010 Degenkolb et al.
20100228819 September 9, 2010 Wei
20100235507 September 16, 2010 Szeto et al.
20100235522 September 16, 2010 Chen et al.
20100235880 September 16, 2010 Chen et al.
20100238828 September 23, 2010 Russell
20100265824 October 21, 2010 Chao et al.
20100268814 October 21, 2010 Cross et al.
20100293296 November 18, 2010 Hsu et al.
20100312740 December 9, 2010 Clemm et al.
20100318631 December 16, 2010 Shukla
20100322252 December 23, 2010 Suganthi et al.
20100330971 December 30, 2010 Selitser et al.
20100333101 December 30, 2010 Pope et al.
20110007652 January 13, 2011 Bai
20110019550 January 27, 2011 Bryers et al.
20110023071 January 27, 2011 Li et al.
20110029599 February 3, 2011 Pulleyn et al.
20110032941 February 10, 2011 Quach et al.
20110040826 February 17, 2011 Chadzelek et al.
20110047294 February 24, 2011 Singh et al.
20110060831 March 10, 2011 Ishii et al.
20110083174 April 7, 2011 Aldridge et al.
20110093522 April 21, 2011 Chen et al.
20110099403 April 28, 2011 Miyata et al.
20110099623 April 28, 2011 Garrard et al.
20110110294 May 12, 2011 Valluri et al.
20110145324 June 16, 2011 Reinart et al.
20110149879 June 23, 2011 Noriega et al.
20110153834 June 23, 2011 Bharrat
20110178985 July 21, 2011 San Martin Arribas et al.
20110185073 July 28, 2011 Jagadeeswaran et al.
20110191773 August 4, 2011 Pavel et al.
20110196971 August 11, 2011 Reguraman et al.
20110276695 November 10, 2011 Maldaner
20110276982 November 10, 2011 Nakayama et al.
20110289496 November 24, 2011 Steer
20110292939 December 1, 2011 Subramaian et al.
20110302256 December 8, 2011 Sureshehandra et al.
20110307541 December 15, 2011 Walsh et al.
20120008495 January 12, 2012 Shen et al.
20120023231 January 26, 2012 Ueno
20120026897 February 2, 2012 Guichard et al.
20120030341 February 2, 2012 Jensen et al.
20120066371 March 15, 2012 Patel et al.
20120084419 April 5, 2012 Kannan et al.
20120084460 April 5, 2012 McGinnity et al.
20120106355 May 3, 2012 Ludwig
20120117382 May 10, 2012 Larson et al.
20120117571 May 10, 2012 Davis et al.
20120144014 June 7, 2012 Natham et al.
20120144015 June 7, 2012 Jalan et al.
20120151353 June 14, 2012 Joanny
20120170548 July 5, 2012 Rajagopalan et al.
20120173759 July 5, 2012 Agarwal et al.
20120179770 July 12, 2012 Jalan et al.
20120191839 July 26, 2012 Maynard
20120215910 August 23, 2012 Wada
20120239792 September 20, 2012 Banerjee et al.
20120240185 September 20, 2012 Kapoor et al.
20120290727 November 15, 2012 Tivig
20120297046 November 22, 2012 Raja et al.
20120311116 December 6, 2012 Jalan et al.
20130046876 February 21, 2013 Narayana et al.
20130058335 March 7, 2013 Koponen et al.
20130074177 March 21, 2013 Varadhan et al.
20130083725 April 4, 2013 Mallya et al.
20130100958 April 25, 2013 Jalan et al.
20130124713 May 16, 2013 Feinberg et al.
20130135996 May 30, 2013 Torres et al.
20130136139 May 30, 2013 Zheng et al.
20130148500 June 13, 2013 Sonoda et al.
20130166762 June 27, 2013 Jalan et al.
20130173795 July 4, 2013 McPherson
20130176854 July 11, 2013 Chisu et al.
20130191486 July 25, 2013 Someya et al.
20130198385 August 1, 2013 Han et al.
20130250765 September 26, 2013 Ehsan et al.
20130258846 October 3, 2013 Damola
20130282791 October 24, 2013 Kruglick
20140012972 January 9, 2014 Han
20140089500 March 27, 2014 Sankar et al.
20140164617 June 12, 2014 Jalan et al.
20140169168 June 19, 2014 Jalan et al.
20140207845 July 24, 2014 Han et al.
20140258465 September 11, 2014 Li
20140258536 September 11, 2014 Chiong
20140269728 September 18, 2014 Jalan et al.
20140286313 September 25, 2014 Fu et al.
20140298091 October 2, 2014 Carlen et al.
20140330982 November 6, 2014 Jalan et al.
20140334485 November 13, 2014 Jain et al.
20140359052 December 4, 2014 Joachimpillai et al.
20150026794 January 22, 2015 Zuk et al.
20150039671 February 5, 2015 Jalan et al.
20150156223 June 4, 2015 Xu et al.
20150215436 July 30, 2015 Kancherla
20150237173 August 20, 2015 Virkki et al.
20150244566 August 27, 2015 Puimedon
20150281087 October 1, 2015 Jalan et al.
20150281104 October 1, 2015 Golshan et al.
20150296058 October 15, 2015 Jalan et al.
20150312092 October 29, 2015 Golshan et al.
20150312268 October 29, 2015 Ray
20150333988 November 19, 2015 Jalan et al.
20150350048 December 3, 2015 Sampat et al.
20150350379 December 3, 2015 Jalan et al.
20160014052 January 14, 2016 Han
20160014126 January 14, 2016 Jalan et al.
20160036778 February 4, 2016 Chen et al.
20160042014 February 11, 2016 Jalan et al.
20160043901 February 11, 2016 Sankar et al.
20160044095 February 11, 2016 Sankar et al.
20160050233 February 18, 2016 Chen et al.
20160088074 March 24, 2016 Kannan et al.
20160105395 April 14, 2016 Chen et al.
20160105446 April 14, 2016 Chen et al.
20160119382 April 28, 2016 Chen et al.
20160156708 June 2, 2016 Jalan et al.
20160173579 June 16, 2016 Jalan et al.
20170048107 February 16, 2017 Dosovitsky et al.
20170048356 February 16, 2017 Thompson et al.
Foreign Patent Documents
1372662 October 2002 CN
1449618 October 2003 CN
1473300 February 2004 CN
1529460 September 2004 CN
1575582 February 2005 CN
1714545 December 2005 CN
1725702 January 2006 CN
1910869 February 2007 CN
101004740 July 2007 CN
101094225 December 2007 CN
101163336 April 2008 CN
101169785 April 2008 CN
101189598 May 2008 CN
101193089 June 2008 CN
101247349 August 2008 CN
101261644 September 2008 CN
101442425 May 2009 CN
101495993 July 2009 CN
101682532 March 2010 CN
101878663 November 2010 CN
102123156 July 2011 CN
102143075 August 2011 CN
102546590 July 2012 CN
102571742 July 2012 CN
102577252 July 2012 CN
102918801 February 2013 CN
103533018 January 2014 CN
103944954 July 2014 CN
104040990 September 2014 CN
104067569 September 2014 CN
104106241 October 2014 CN
104137491 November 2014 CN
104796396 July 2015 CN
102577252 March 2016 CN
102918801 May 2016 CN
1209876 May 2002 EP
1770915 April 2007 EP
1885096 February 2008 EP
02296313 March 2011 EP
2577910 April 2013 EP
2622795 August 2013 EP
2647174 October 2013 EP
2760170 July 2014 EP
2772026 September 2014 EP
2901308 August 2015 EP
2760170 December 2015 EP
1182560 November 2013 HK
1183569 December 2013 HK
1183996 January 2014 HK
1189438 June 2014 HK
1198565 May 2015 HK
1198848 June 2015 HK
1199153 June 2015 HK
1199779 July 2015 HK
1200617 August 2015 HK
39/2015 September 2015 IN
CHE2014 July 2016 IN
H09-097233 April 1997 JP
1999096128 April 1999 JP
H11-338836 October 1999 JP
2000276432 October 2000 JP
2000307634 November 2000 JP
2001051859 February 2001 JP
2001298449 October 2001 JP
2002091936 March 2002 JP
2003141068 May 2003 JP
2003186776 July 2003 JP
2005141441 June 2005 JP
2006332825 December 2006 JP
2008040718 February 2008 JP
2009500731 January 2009 JP
2013528330 July 2013 JP
2014504484 February 2014 JP
2014143686 August 2014 JP
2015507380 March 2015 JP
5855663 December 2015 JP
5906263 March 2016 JP
5913609 April 2016 JP
10-0830413 May 2008 KR
1020120117461 August 2013 KR
101576585 December 2015 KR
269763 February 1996 TW
425821 March 2001 TW
444478 July 2001 TW
WO2001013228 February 2001 WO
WO2001014990 March 2001 WO
WO2001045349 June 2001 WO
WO2003103237 December 2003 WO
WO2004084085 September 2004 WO
WO2006098033 September 2006 WO
WO2008053954 May 2008 WO
WO2008078593 July 2008 WO
WO2011049770 April 2011 WO
WO2011079381 July 2011 WO
WO2011149796 December 2011 WO
WO2012050747 April 2012 WO
WO2012075237 June 2012 WO
WO2012083264 June 2012 WO
WO2012097015 July 2012 WO
WO2013070391 May 2013 WO
WO2013081952 June 2013 WO
WO2013096019 June 2013 WO
WO2013112492 August 2013 WO
WO2014031046 February 2014 WO
WO2014052099 April 2014 WO
WO2014088741 June 2014 WO
WO2014093829 June 2014 WO
WO2014138483 September 2014 WO
WO2014144837 September 2014 WO
WO2014179753 November 2014 WO
WO2015153020 October 2015 WO
WO2015164026 October 2015 WO
Other references
  • Cardellini et al., “Dynamic Load Balancing on Web-server Systems”, IEEE Internet Computing, vol. 3, No. 3, pp. 28-39, May-Jun. 1999.
  • Spatscheck et al., “Optimizing TCP Forwarder Performance”, IEEE/ACM Transactions on Networking, vol. 8, No. 2, Apr. 2000.
  • Kjaer et al. “Resource allocation and disturbance rejection in web servers using SLAs and virtualized servers”, IEEE Transactions on Network and Service Management, IEEE, US, vol. 6, No. 4, Dec. 1, 2009.
  • Sharifian et al. “An approximation-based load-balancing algorithm with admission control for cluster web servers with dynamic workloads”, The Journal of Supercomputing, Kluwer Academic Publishers, BO, vol. 53, No. 3, Jul. 3, 2009.
  • Hunt et al. NetDispatcher: A TCP Connection Router, IBM Research Report RC 20853 May 19, 1997.
  • Noguchi, “Realizing the Highest Level “Layer 7” Switch”= Totally Managing Network Resources, Applications, and Users =, Computer & Network LAN, Jan. 1, 2000, vol. 18, No. 1, p. 109-112.
  • Takahashi, “The Fundamentals of the Windows Network: Understanding the Mystery of the Windows Network from the Basics”, Network Magazine, Jul. 1, 2006, vol. 11, No. 7, p. 32-35.
  • Ohnuma, “AppSwitch: 7th Layer Switch Provided with Full Setup and Report Tools”, Interop Magazine, Jun. 1, 2000, vol. 10, No. 6, p. 148-150.
  • Koike et al., “Transport Middleware for Network-Based Control,” IEICE Technical Report, Jun. 22, 2000, vol. 100, No. 53, pp. 13-18.
  • Yamamoto et al., “Performance Evaluation of Window Size in Proxy-based TCP for Multi-hop Wireless Networks,” IPSJ SIG Technical Reports, May 15, 2008, vol. 2008, No. 44, pp. 109-114.
  • Abe et al., “Adaptive Split Connection Schemes in Advanced Relay Nodes,” IEICE Technical Report, Feb. 22, 2010, vol. 109, No. 438, pp. 25-30.
  • Gite, Vivek, “Linux Tune Network Stack (Buffers Size) To Increase Networking Performance,” accessed Apr. 13, 2016 at URL: «http://www.cyberciti.biz/faq/linux-tcp-tuning/», Jul. 8, 2009, 24 pages.
  • “Tcp—TCP Protocol”, Linux Programmer's Manual, accessed Apr. 13, 2016 at URL: «https://www.freebsd.org/cgi/man.cgi?query=tcp&apropos=0&sektion=7&manpath=SuSE+Linux%2Fi386+11.0&format=asci», Nov. 25, 2007, 11 pages.
  • “Enhanced Interior Gateway Routing Protocol”, Cisco, Document ID 16406, Sep. 9, 2005 update, 43 pages.
  • Crotti, Manuel et al., “Detecting HTTP Tunnels with Statistical Mechanisms”, IEEE International Conference on communications, Jun. 24-28, 2007, pp. 6162-6168.
  • Haruyama, Takahiro et al., “Dial-to-Connect VPN System for Remote DLNA Communication”, IEEE Consumer Communications and Networking Conference, CCNC 2008. 5th IEEE, Jan. 10-12, 2008, pp. 1224-1225.
  • Chen, Jianhua et al., “SSL/TLS-based Secure Tunnel Gateway System Design and Implementation”, IEEE International Workshop on Anti-counterfeiting, Security, Identification, Apr. 16-18, 2007, pp. 258-261.
  • “EIGRP MPLS VPN PE-CE Site of Origin (SoO)”, Cisco Systems, Feb. 28, 2006, 14 pages.
Patent History
Patent number: RE47296
Type: Grant
Filed: Jan 9, 2014
Date of Patent: Mar 12, 2019
Assignee: A10 NETWORKS, INC. (San Jose, CA)
Inventors: Lee Chen (Saratoga, CA), Ronald Wai Lun Szeto (San Francisco, CA), Shih-Tsung Hwang (San Jose, CA)
Primary Examiner: David E England
Application Number: 14/151,803
Classifications
Current U.S. Class: Policy (726/1)
International Classification: G01R 31/08 (20060101); H04L 12/801 (20130101); H04L 29/06 (20060101);