Abstract:
A method and device for detecting and halting specified peer-to-peer (“P2P”) and/or Internet Relay Chat (“IRC” communication sessions based on a priori defined templates is described. Network packets are intercepted and inspected for patterns (defined by the templates) that identify them as definitely, likely or not being associated with one of the specified P2P and/or IRC protocols. Those packets identified as definitely belonging to one of the specified protocols are prevented from reaching their target destination. Those packets identified as only likely belonging to one of the specified protocols are permitted to continue toward their target destination after select information about the particular session/packet is recorded for later use. Those packets identified as not belonging to one of the specified protocols are permitted to continue to their target destination.

Description:
BACKGROUND 
       [0001]    The invention relates generally to network monitoring devices and methods for the protection of intellectual property and more particularly, but not by way of limitation, to the detection and halting of peer-to-peer communications between computer systems. 
         [0002]    A peer-to-peer (“P2P”) computer network is a network that relies primarily on the collective computing power and bandwidth of the network&#39;s individual nodes rather than concentrating it&#39;s computational power in a relatively few dedicated systems or servers. P2P networks are typically used for connecting nodes via largely ad hoc connections for sharing files (e.g., audio and video data files) and realtime data (e.g., Internet telephony traffic). 
         [0003]    Because of its decentralized nature, ease of use and wide-spread distribution, P2P technology has become one of the principal means by which Internet users share and distribute information. Organizations (e.g., businesses and academic institutions) have recognized the danger unregulated use of P2P operations pose to the function of their networks. These dangers include, but are not limited to, exposing the organization&#39;s network to the introduction of viruses (programs that are loaded onto a user&#39;s computer without their knowledge and that usually perform malicious actions), spyware (software that covertly gathers user information and transmits that information to an unknown third party) and malware (software that is intentionally included or inserted in a system for a harmful purpose), the excessive use of network storage facilities, the loss of proprietary data (e.g., trade secrets) and the liability associated with their users (e.g., employees and students) sharing and distributing copyrighted material without the owners consent. 
         [0004]    Current attempts to limit or prevent use of P2P technology (and related technologies such as, for example, “IRC” or Internet Relay Chat) rely on published “rules” that users must agree to for the privilege of using an organization&#39;s network and/or network administrator-based monitoring. In the former, one&#39;s agreement to forgo use of P2P technology does not in itself prevent such use. In the latter, it is incumbent upon the network&#39;s administrator (and their staff) to police, detect and enforce the organization&#39;s P2P policies. The rapid and acknowledged use of P2P technology for the widespread distribution of copyrighted and other proprietary material attests to the limited ability of these approaches to satisfactorily deal with the use of P2P networks. Thus, it would be beneficial to provide a mechanism to automatically detect and halt peer-to-peer communications to, or from, an organization&#39;s network. 
       SUMMARY 
       [0005]    In one embodiment the invention provides a method to effectively block one or more a priori specified communication sessions. The method includes intercepting a network packet in route from a source to a destination, analyzing the network packet and preventing the network packet from arriving at the destination if it is determined (during the act of analyzing) to be associated with one of a specified plurality of peer-to-peer and/or Internet relay chat protocols. In one embodiment, the act of analyzing includes comparing selected portions of the network packet against a plurality of predefined templates, wherein each template identifies a forensically determined signature (i.e., a specified data pattern, its location and, perhaps, a length). In addition, each template specifies an action to take if the packet matches its signature. For example, one action may be to simply prevent the packet from reaching its destination. Another action may be to record information about the packet in a system state table for comparison to subsequently received packets and then either drop the packet or permit it to reach its destination. The former action is appropriate where the template&#39;s signature does not definitively identify the packet as belonging to a prohibited protocol while the latter may be more appropriate where two or more packets in a communication session are needed to make this determination. 
         [0006]    In another embodiment, methods in accordance with the invention may be stored in any media that is readable and executable by a computer system. In one such embodiment, the invention provides a device including memory (for storing instructions in accordance with the invention) and a processing unit (for executing said instructions) that may be used to analyze network traffic. Such a device may be placed between two networks (e.g., a private network and a public network or between two private networks). 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0007]      FIG. 1  shows, in flowchart format, a network monitoring method in accordance with one embodiment of the invention. 
           [0008]      FIG. 2  shows, in flowchart format, one method in accordance with the invention for determining if a current network packet is related to a prior identified transaction. 
           [0009]      FIG. 3  shows, in flowchart format, one method in accordance with the invention for classifying network packets. 
           [0010]      FIG. 4  shows, in flowchart format, one method in accordance with the invention for checking packets against known protocols. 
           [0011]      FIGS. 5A and 5B  show, in block diagram format, a network monitoring and intellectual property management system in accordance with various embodiments of the invention. 
           [0012]      FIG. 6  shows, in block diagram format, a network monitoring and intellectual property management device in accordance with one embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    The following descriptions are presented to enable any person skilled in the art to make and use the invention as claimed and are provided in the context of the particular examples discussed below, variations of which will be readily apparent to those skilled in the art. Accordingly, the claims appended hereto are not intended to be limited by the disclosed embodiments, but are to be accorded their widest scope consistent with the principles and features disclosed herein. 
         [0014]    In one embodiment of the invention, a network monitoring and intellectual property protection method inspects network packets into and out of a given network (e.g., an organization&#39;s local area network) to determine if the packet is part of a prohibited transaction (e.g., a P2P or IRC communication stream). In another embodiment of the invention, a network device is configured to perform the aforementioned network monitoring and intellectual property protection operations. 
         [0015]    Referring to  FIG. 1 , network monitoring and intellectual property protection process  100  in accordance with one embodiment of the invention begins when network packet  105  is received. If the packet is irrelevant (the “Yes” prong of block  110 ), it is released, that is, allowed to propagate toward its destination (block  115 ). In one particular embodiment, irrelevant network packets include non-Ethernet and non-Internet Protocol (“IP”) packets. If packet  105  is relevant (the “No” prong of block  110 ), a check is made to determine if the packet belongs to a prior inspected transaction (block  120 ). If this is so, and interrogation of packet  105  confirms it is part of a prohibited transaction (e.g., a P2P or IRC transaction), packet  105  is dropped. Otherwise, packet  105  is classified as belonging to one of a plurality of relevant packet types (block  125 ). By way of example, relevant network packets include, but are not limited to, Transport Control Protocol (“TCP”) stream packets, User Datagram Protocol (“UDP”) announcements and Hyper Text Transfer Protocol (“HTTP”) request packets. Once classified, certain characteristics of packet  105  are checked against known prohibited protocol characteristics (block  130 ). During the acts of block  130 : if packet  105  is identified as belonging to a prohibited protocol, it is dropped; if packet  105  is identified as not being associated with a prohibited protocol it is released (allowed to propagate toward its destination); and if packet  105  cannot be definitively identified as either belonging or not belonging to a prohibited transaction, information concerning the packet is retained for evaluating subsequently received data packets (e.g., during the acts of block  120 ) and released. 
         [0016]    One illustrative technique to determine if the current packet is related to a prior received packet is shown in  FIG. 2  (i.e., block  120 ). It will be recognized that for efficiency, each received packet may be “filtered” to obtain the information necessary for tracking and identifying the packet as belonging to a prohibited protocol. Such information can include any data or value included in or encoded within the packet such as, for example, packet sequence number, packet direction (e.g., into or out of a given network), header byte length, packet type, source IP address, destination IP address, source port identifier, destination port identifier, frame number, packet length, payload byte length, SYN (request for information) and ACK (information acknowledgement) flags, checksum and window size values—that is, information retained in a packet&#39;s layer 1, 2 or 7 structure. As used herein, layers 1, 2 and 7 refer to layers as defined in the Open Systems Interconnection (“OSI”) Reference Model, a communications standard sponsored by the International Standards Organization (“ISO”). Illustrative packet types include, but are not limited to, those used in TCP, UDP, HTTP, ARP (Address Resolution Protocol), SSDP (Simple Service Discovery Protocol), NBNS NetBIOS Name Server) and POP (Post Office Protocol) protocols. Packet information obtained in this manner will be referred to as a “captured element” or “captured characteristic.” In an embodiment implemented for the Linux® operating system, packet filtering may be based the Linux netfilter packet filtering framework. (LINUX is a registered trademark of Linus Torvalds.) 
         [0017]    In the embodiment illustrated in  FIG. 2 , for example, packet information  200  is used to access three system state tables to determine if the current packet is related to a prior received network packet. In a first system state table look-up operation, one or more of the current packet&#39;s captured characteristics (see discussion above) are combined (e.g., concatenated) and used as a key into a first system state table (block  205 ). If an entry is found and its value indicates the packet should be dropped (the “Yes” prong of block  210 ), the packet is dropped (block  235 ). If there is no entry associated with the key or the entry&#39;s value indicates that the packet should not be dropped (the “No” pong of block  210 ), a second system state table look-up operation is performed (block  215 ). In this second system state table look-up, a different collection of one or more of the current packet&#39;s captured characteristics are used as a key. If an entry is found and its value indicates the packet should be dropped (the “Yes” prong of block  220 ), the packet is dropped (block  235 ). If there is no entry associated with the key or the entry&#39;s value indicates that the packet should not be dropped (the “No” pong of block  220 ), a third system state table look-up operation is performed (block  225 ). In this third system state table look-up, yet another collection of one or more of the current packet&#39;s captured characteristics are used as a key. Again, if an entry is found and its value indicates the packet should be dropped (the “Yes” prong of block  230 ), the packet is dropped (block  235 ). If there is no entry associated with the key or the entry&#39;s value indicates that the packet should not be dropped (the “No” pong of block  230 ), processing continues in accordance with block  125 . By way of example, each of the system state tables accessed during the acts of block  120  ( FIG. 2 ) may be implemented as arrays, database tables, linear lists or the like. The type of information that may be retained in the system state tables include: one or more captured characteristics; a protocol identifier (a unique identifier assigned to each protocol being analyzed); a match-block-action value that indicates whether the associated packet should be dropped (e.g., BLOCK) or not dropped (e.g., NON_BLOCK); a timestamp (to indicate the time the entry was last used); and any protocol specific information necessary to allow two or more sequentially received packets to be logically identified as part of a common communications session such as some or all of the packet&#39;s payload data (in binary or ASCII format), a forensically determined protocol signature and protocol DNA. 
         [0018]    Generally speaking, if no system state table entry is found during the acts of block  205 ,  215  or  225 , either the communication session to which the current packet belongs has not been seen before or the packet belongs to a session that should not be blocked. If a system state table entry is found and its match-block-action value (or a functionally equivalent value) indicates that it should not be dropped, this implies that while one or more packets in the packet&#39;s communication session has been seen before, additional processing is needed to conclusively determine if the packet belongs to a prohibited communications session (e.g., a P2P or IRC session). Finally, if a system state table entry is found and its match-block-action value indicates that it should be dropped, this implies that the current packet belongs to a prior-seen session and provides the information necessary to conclusively determine the packet belongs to a prohibited communications session. 
         [0019]    Referring to  FIG. 3 , packet classification in accordance with block  125  inspects packet information  300  (e.g., network packet  105 ) to determine if the current packet is a TCP packet (the “Yes” prong of block  305 ), a UDP packet (the “Yes” prong of block  310 ) or an HTTP packet (the “Yes” prong of block  315 ). If the current packet is not any of these types (e.g., is not relevant—see discussion above regarding block  110  in  FIG. 1 ), the packet is released (block  115 ). It will be recognized that identification of packet type typically involves the inspection of the packet&#39;s header and/or payload information. For example, it is known that TCP and UDP packets are explicitly identified as such in their headers. It is further known that HTTP packets are TCP type packets whose first four bytes in their layer-7 (“payload”) segment are GET_, HEAD, PUSH or POST (where “_” can be any value). As used herein, layer-7 corresponds to the application layer as defined in the Open Systems Interconnection (“OSI”) Reference Model, a communications standard sponsored by the International Standards Organization (“ISO”). In addition, in one embodiment the following information is extracted or recorded for packets identified as HTTP type packets: argument offset; host offset; and user agent offset (also typically found in the packet&#39;s layer-7 segment). 
         [0020]    Referring again to  FIG. 1 , if the current packet has not been dropped or released in accordance with the acts of blocks  110 ,  120  or  125 , the packet is compared against protocol templates to ascertain whether the packet should be dropped (because it is part of a prohibited transaction), released (because it is not part of a prohibited transaction) or if information should be retained so that future packets can be analyzed in accordance with the acts of block  120 . 
         [0021]    In general, a template encapsulates the rules by which a packet is determined to be part of a specified protocol (e.g., WinMX, Kademilia or Myster) and an indication of the action to take if such determination is made. In one embodiment, each protocol being screened is associated with one or more templates. Each template, in turn, specifies one or more data patterns (“forensic signatures” or, more simply, “signatures”) within a packet that may be used to identify that packet as part of a communication session of that protocol&#39;s type and where (e.g., as an offset into the packet&#39;s layer-7 payload segment) the data pattern may be found within the packet. Some templates may also include a “length” characteristic which, when combined with the forensic signature, may also be used to uniquely associate a packet with a P2P or IRC protocol. As used here, the term “length” refers to the size of the packet&#39;s layer-7 payload segment. In addition, each template has an assigned protocol-ID (unique across all protocols), a template-ID (unique within a given protocol), a protocol type identifier (e.g., TCP or UDP) and an action function identifier designating what action to take if the current packet matches the template&#39;s signature. 
         [0022]    Template signatures are based on a forensic a priori analysis of packets from those protocols being screened. That is, multiple packets from each protocol to be blocked are obtained and analyzed to determine the unique characteristics that identify it as part of a communication session for a prohibited protocol. It will be appreciated that the large number of P2P and IRC protocols combined with the fact that each protocol may exhibit multiple variations (transmitted using one or more protocols, e.g., TCP, HTTP and UDP), can make the task of developing signatures time-consuming. Nevertheless, such work would be within the skill of one of ordinary skill in the art of network security and programming having the benefit of this disclosure. 
         [0023]    In general, template action functions place an entry in one or more of the system state tables corresponding to the current packet and set that entries match-block-action value to BLOCK or NON_BLOCK. The table entry is set to BLOCK if the template&#39;s signature match indicates that the packet is strongly related to a prohibited protocol (e.g., definitively identifies the packet as belonging to a prohibited communication protocol) and to NON_BLOCK if the template&#39;s signature match indicates that the packet is weakly related to a prohibited protocol (e.g., does not definitively identify the packet as belonging to a prohibited communication protocol). The exact value (BLOCK or NON_BLOCK) has been found to be a function of the specific protocol being checked and, as a result, is dependent upon how well or conclusively the template&#39;s signature uniquely identifies the packet as being associated with a given protocol. As a result, this information varies form protocol to protocol and, even, over time as the specific P2P/IRC protocols evolve. Nevertheless, one of ordinary skill in the art would be able to determine these differences given the present teaching. 
         [0024]    In one embodiment, four different types of templates are used which are referred to herein as: instant kill templates, kill identification templates, protocol identification templates and source templates. Generally speaking, instant kill templates are applied when a signature definitively identifies a packet as belonging to a prohibited protocol. Kill identification, protocol identification and source templates (collectively referred to as response kill templates), on the other hand, are applied when one or more packets in the communication session are required to definitively identify the use of a prohibited protocol. 
         [0025]    Referring to  FIG. 4 , once classified as belonging to one of a specified plurality of protocol types in accordance with the acts of block  125  (see  FIGS. 1 and 3 ), packet information  400  is compared against a series of template types. For example, instant kill (block  405 ), kill identification (block  415 ), protocol identification (block  425 ) and source templates (block  435 ). If a match is found during any one of these matching operations (the “Yes” prong of blocks  410 ,  420 ,  430  and  440 ), the action function specified in the template is performed (block  445 ). If no match is found (the “No” prong of blocks  410 ,  420 ,  430  and  440 ), the packet is released (block  450 ). 
         [0026]    For efficiency, it has been found beneficial to perform template matching operations on a packet-type basis wherein only those templates applicable to the current packet&#39;s type are checked. For example, if the current packet is a UDP type packet, then only those instant kill templates applicable to UDP packets are checked during the acts of block  405 . This same approach may be applied during the template matching operations of blocks  415 ,  425  and  435 . It has also been found beneficial to check templates in a most-used to least-used order (i.e., blocks  405 ,  415 ,  425  and  435 ). That is, if the current packet is a TCP type packet and protocol-1 is the most widely used TCP-based P2P/IRC protocol, templates associated with protocol-1 are matched first. Additional templates would be checked in descending order of their use. It will be recognized that the prevalence of a given protocol may vary from time to time, and that this determination may be made by observing network traffic for each of the targeted protocols. 
         [0027]    One use of the network monitoring and intellectual property protection technology described herein is to prevent P2P and/or IRC communication sessions between users of a private or internal network (e.g., a corporate or educational network) and an external network such as, for example, the Internet. By way of example, consider  FIG. 5A  in which network monitoring and intellectual property protection system  500  in accordance with one embodiment of the invention includes external network  505  (e.g., the Internet), external router  510 , network monitoring device  515 , firewall  520 , internal router  525  and one or more internal networks  530  and  535  (e.g., local area networks, “LANs”). 
         [0028]    In another embodiment, network monitoring device  515  may be used to automatically detect and halt P2P and IRC communications between an external network and a private or household network. Referring to  FIG. 5B , in this version of network monitoring and intellectual property protection system  540 , external network  505  is coupled to home network  545  via cable or DSL modem  550  and internal router  555 . 
         [0029]    In still another embodiment, network monitoring device  515  may be used to prevent P2P and/or IRC communication sessions between users within a common network. Referring to  FIG. 5A , for example, digital monitoring device  515  may be positioned in the communication path between users of internal network  1   530  and internal network  2   535 . 
         [0030]    Referring to  FIG. 6 , in one embodiment network monitoring device  515  includes communication ports  600  and  605 , memory  610 , processor  615  and storage unit  620 . Communication ports  600  and  605  may couple directly to networks  625  and  630  or indirectly as illustrated in  FIG. 5 . Although not required by the claimed invention, in the described embodiments network monitoring device  515  captures/monitors network packets in a bidirectional manner. That is, packets are analyzed as they move from external network  625  toward internal network  630 , and as they move from internal network  630  toward external network  625 . Memory  610  generally comprises random access memory (“RAM” and may be volatile, non-volatile or a combination of volatile and non-volatile memories. For example, one portion of memory  610  may comprise volatile RAM for use in storing network packets (e.g., packet  105 ) during analysis in accordance with the invention. Another portion of memory  610  may comprise non-volatile memory for storing program code that controls the overall operation, or supports the overall operation, of network monitoring device  515 . In one embodiment, all templates are retained in volatile RAM  610  (during operation) while non-volatile memory  610  may retain program code that facilitates remote management of network monitoring device  515 . Processor  615  comprises a programmable control device and may be a conventional computer processor (e.g., a reduced or complex instruction set central processing unit), a special purpose processor (e.g., a digital signal processor, “DSP”), a plurality of processors coupled by a communications link or a custom designed state machine. Custom designed state machines may be embodied in a hardware device such as an integrated circuit including, but not limited to, application specific integrated circuits (“ASICs”) or field programmable gate array (“FPGAs”). Storage unit  620  may comprise any long-term storage device such as, for example, one or more of the following: Storage devices suitable for tangibly embodying program instructions include, but are not limited to: magnetic disks (fixed, floppy, and removable); magnetic tape; and optical media such as CD-ROMs and digital video disks (“DVDs”). 
         [0031]    Various changes in the materials, components, circuit elements, as well as in the details of the illustrated operational methods are possible without departing from the scope of the following claims. By way of example, while network monitoring and intellectual property protection systems  500  and  540  show network monitoring device  515  as a stand-alone unit, this is not required. In one embodiment the functionality associated with network monitoring device  515  may be wholly (or partially) provided by a general purpose computer system programmed to perform one or more acts illustrated in of  FIG. 1 . In addition, while the invention has been described in the context of a single processing flow, it will be recognized by those of ordinary skill in the art that a “threaded” approach may also be implemented. In such implementations, two or more threads (each analyzing one or more network packets) may operate concurrently. In addition, classification operations in accordance with block  125  ( FIGS. 1 and 3 ) do not need to be performed. That is, once a packet passes through processing in accordance with block  120  (i.e., is not dropped or released), processing could continue directly to block  130  ( FIGS. 1 and 4 ).