Patent Publication Number: US-2011078283-A1

Title: Service providing system, filtering device, filtering method and method of confirming message

Description:
TECHNICAL FIELD 
     The present invention relates to a filtering method carried out in upper layer protocol, and particularly, the present invention relates to technique to eliminate unwilled information and ensure a communication band for an IP (Internet Protocol) network path. 
     BACKGROUND ART 
     Recently, phone services using IP networks become popular rapidly. In a communication service using an IP network, there are various services such as a video phone, video communication, automatic acquisition of information and content delivery in addition to an voice telephone call by a phone service. In order to achieve such services and provide well services, development in various kinds of technique has been carried out. The services as described above have been realized, but they have room of further improvement, and in particular, improvement of a security aspect is desired. 
     As technique related to security, filtering by a port number carried out in a network layer such as a router, filtering by a MAC (Media Access Control) address carried out in a lower layer, and the like are mentioned. By carrying out these kinds of filtering, unwanted information and unusual information is to be eliminated. However, there is unwanted information and unusual information that the filtering by ports or filtering by MAC addresses cannot keep out. For example information, which can slip through a filter transmitted from a malicious person, wrong information transmitted by a legitimate user by incorrectly operating an information processing device, wrong information due to a trouble or incorrect setting of the information processing device, are mentioned. In order to establish a secure service or system, elimination of information as described above becomes important. 
     Conventionally, in order to select and eliminate the information as described above, various approaches have been made. 
     For example, in Patent Literature 1, a system that carries out filtering by a packet in protocol such as HTTP is disclosed. For more details, a filtering system analyzes and compares received packets in a lower layer, based the system using a declarative protocol of an upper layer and an actually used protocol described in a request line, and eliminates it if they are in discord with each other is described. 
     In Patent Literature 2, a method of filtering in order to eliminate unwanted information for a VoIP (Voice over Internet Protocol) system by analyzing header information of a session control protocol to be used and determining whether or not it is a communications partner to be permitted on the basis of an caller phone number and an IP address is disclosed. 
     In Patent Literature 3, as one example a gateway for eliminate information from a malicious person and slips through a lower layer filter. A gateway to count up the number of reception from a specific terminal for a method of session establishment and to eliminate it if it is a threshold value or more in order to eliminate terminals that unnecessarily transmits a large number of methods of session establishment for a session control protocol is disclosed. 
     In Patent Literature 4, a packet filtering device is disclosed that, in order to eliminate information transmitted from a malicious person to eluding a lower layer filter, stores specific operations carried out using a session control protocol as malicious operations and eliminates a packets in which a message method predicted as malice carries out a specific operation.
     Patent Literature 1: Japanese Patent Application Publication No. 2004-145583   Patent Literature 2: Japanese Patent Application Publication No. 2006-173731   Patent Literature 3: Japanese Patent Application Publication No. 2004-343580   Patent Literature 4: Japanese Patent Application Publication No. 2006-100873   

     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     As the systems of providing a communication service, the techniques described in Patent Literatures described above has tried to eliminate unwanted information using various methods. 
     Patent Literatures 2 and 3 of those as described above are described as technique to defense a so-called DoS (Denial of Services) attack and a DDoS (Distributed Denial of Service) attack frequently used as a malicious attack. On the other hand, Patent Literature 4 describes a defense for a so-called single-ring-and-hang-up solicitation call in addition to the above attacks. The DoS attack and the DDoS attack are known as a method of attacking a Web server, and a single-ring-and-hang-up solicitation call is known as a method of an attack against a phone service server. 
     Namely, a system for providing a new service requires countermeasures for an attacking method known in the prior art such as a DoS attack, a DDoS attack and a single-ring-and-hang-up solicitation call. Moreover, it is also necessary to again take matters that have not been a problem conventionally as a new problem with advancement, speeding up and high quality of the system. 
     This is because new problems may occur in the case where a new system and new service is established in the IT (information Technology) industry whose technical innovations are marked. This occurring problem is often a matter that has not been thought conventionally. In addition, there is a need to again take a new problem and countermeasures for matters that have not been taken as a problem conventionally with advancement, speeding up and high quality of the system. 
     It is therefore an object of the present invention to resolve the problems anticipatorily by focusing on a service system that carries out band guarantee using QoS (Quality of Service) technique utilized in video delivery and audio communication. In addition, it is another object to provide a service and a system capable of secure band guarantee by which unwanted information can be eliminated. 
     Means for Solving the Problems 
     A service providing system according to the present invention is characterized to be a service providing system for providing a service, the service providing system being connected to a user terminal via a network, the service providing system transmitting requested data in response to a request of the user terminal, the service providing system comprising: a filtering function which subjects a request message to filtering, the request message which is transmitted by the user terminal to request desired data and which is described with an upper layer protocol exceeding three layers, wherein the filtering function acquires to the request message to analyze a body portion of the request message, and the filtering function subjects the request message to a predefined process in the case where unwanted information and/or unusual information is included as a request content. 
     EFFECTS OF THE INVENTION 
     According to the present invention, it is possible to provide a service and a system in which a filter is set up in a band guaranteed type service system using QoS (Quality of Service) technique and secure band guarantee allowing to eliminate unwanted information is carried out. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram schematically showing a content delivery system according to embodiment; 
         FIG. 2  is a flowchart showing processes of an information-processing device; 
         FIG. 3  is a flowchart showing an operation of a filtering function of a filtering device; 
         FIG. 4  is a flowchart showing an operation of the entire content delivery system; 
         FIG. 5  is a flowchart showing an operation in which the filtering function subjects an SIP (Session Initiation Protocol) to filtering; and 
         FIG. 6  is a flowchart showing an operation in which the filtering function subjects RTSP to filtering. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Hereinafter, the present invention will be described using embodiment. Further, the embodiment will be described on the basis of  FIG. 1  to  FIG. 6 . 
       FIG. 1  is a block diagram for schematically showing a content delivery system using a filtering method according to the present invention. 
     A content delivery system  10  delivers contents in response to a request of a user terminal  20  used by a service beneficiary who wishes given content at a service provided destination of a content delivery service. In the content delivery system  10  shown in the drawing, a portal server  200  managing services and providing a beneficiary with a service, a delivery server  300  that stores contents and delivers content data in response to a request, and a band guarantee network  100  that controls and ensures a band of a communication path for the content data are included. 
     The user terminal  20  is a personal computer, for example. The user terminal  20  has, in addition to a control section, a ROM, a RAM, an input/output section, a storage device and a network control section, and is connected to a network. The user terminal  20  may have any configuration so long as it can enjoy the delivery service, and may be a cellular phone, PDA (Personal Digital Assistants) and the like, for example, in addition to the personal computer. 
     The band guarantee network  100  is schematically constructed from, a session control server  400  for control session establishment and so on, a network device  500  configured by a router and the like carrying out session establishment for transferring or discarding data, a filtering device  600  for filtering various protocol messages, and a band control device  700  that carries out band control such as band ensuring and band release to the network device  500  in response to a band control request from the session control server  400 . 
     The portal server  200  is a group of servers built up by a general Web server, a database and the like, and is connected to the network. The portal server  200  receives a content request (request regarding viewing, acquisition and the like of content) from the user terminal  20 , and carries out a setup of an access right to content and permission of an access right. 
     The delivery server  300  is a group of servers built up by a database server and the like to store a large number of content data, and is connected to the network. The content data are video files, music files, application files, text files and the like, and are defined by type of content delivery service. 
     The session control server  400  is capable of recognizing session control protocols such as an SIP, and carries out address resolution and session control. In the present embodiment, it carries out an instruction of band ensuring for the band control device  700 . Further, it also communicates with the delivery server  300  to transmit information on the user terminal  20  thereto. 
     The network device  500  is an assembly of network segments such as a router, a bridge and a hub. The network device  500  has a QoS control function of communication data via the network device  500 , and is capable of ensuring a communication band of the route on which the content data flows. 
     The filtering device  600  is a server on which an application server capable of recognizing various protocols is mounted. The filtering device  600  receives and analyzes a session control message from the user terminal  20 , and transmits the content to the session control server  400  or the like. The filtering device  600  shown in the drawing is cooperated with the portal server  200 , receives the session control message for content request from the user terminal  20 , analyzes the message, and carries out operations such as discarding, error transmission and transfer if needed. The filtering device  600  will be described later using  FIG. 2 . 
     The band control device  700  is an application server capable of QoS control (band control); receives a band ensuring request from the session control server  400 ; and carries out band ensuring (port ensuring, port open/close and the like), QoS control (ToS value change/priority control) and the like against the network device  500 . In this regard, in order to carry out control of Layers 2 to 4, it may be built up by a blade server implemented in relation to Advanced TCA (next-generation carrier grade platform). 
     In this regard, although it is omitted in the above explanation, each of the servers and devices has a control section, a ROM, a RAM, a storage device (database) and the like, and carries out Information processing and communicate via the network. 
     Further, arrows shown in  FIG. 1  indicate that devices indicated by the arrow can communicate via the network. Each of the servers and devices is connected to the network such as the Internet, and can communicate at least between the devices for which the arrows are described. 
       FIG. 2  is a block diagram showing a schematic configuration of the filtering device  600 . 
     The filtering device  600  is an information-processing device configured by a control section, a ROM, a RAM, an auxiliary storage device  610 , an input section, an output section, a network interface and the like. 
     A hub function and router function is provided in the case where needed in the filtering device  600 , and the filtering device  600  can carry out filtering with two layers (data link layer) and three layers (network layer). 
     The auxiliary storage device  610  may be such as an HDD, a flash ROM, so long as it can store information. 
     In the auxiliary storage device  610  stores an OS and various application software, for achieve various functions. Similarly, the auxiliary storage device  610  functions as a database. And the auxiliary storage device  610  stores as malicious user information, information of user terminals which carries out malicious actions against services to be provided. And the auxiliary storage device  610  stores as content information such as a bandwidth suitable for identifiers and reproduction of the content as content information. Further, in the auxiliary storage device  610 , the content information delivered from the portal server  200 , addresses of various devices, an operating situation of the system and the like are stored if needed. 
     In this regard, it is desirable that all devices including the auxiliary storage device and the control section have a redundant configuration. 
       FIG. 3  is a flowchart showing an operation of a filtering function of the filtering device  600 . 
     The control section of the filtering device  600  extracts a message (packet, data string), which is a subject of filtering, received via the network in accordance with a program (Step S 301 ). 
     The control section of the filtering device  600  analyses the extracted message, and acquires the content of the message (Step S 302 ). 
     The control section of the filtering device  600  analyzes an origin of the message, and acquires the malicious user information recorded in the database. In the case where it is a message from the user terminal  20  recorded in malicious user information, it discards the message (Step S 303 ). 
     The control section of the filtering device  600  acquires various kinds of information in addition to band information recorded in a database, and determines whether there is an error in the content of the message. In the case where it is an error message, it discards the message (Step S 304 ). 
     The control section of the filtering device  600  transmits the message after filtering to a next device (Step S 305 ). 
     Here, a feature of the filtering carried out by the filtering device  600  is to carry out filtering at a layer of a session layer (five layers) or more. Namely, feature is to acquire a message (packet, data string) of the session layer or more, to analyze content, and eliminate an unwanted message such as a message coming from a malicious user and an error message generated due to an incorrect operation or trouble. In this regard, to carry out filtering at a lower layer (two to four layers) in addition thereto is more effective. 
     In this regard, as examples of the messages to be filtered, an SIP message method (INVITE message method) that is a message for session establishment and the like are mentioned. Further, there is also contains Re INVITE and UPDATE. 
     Similarly, as examples of message content to be filtered, an identifier (URL, an extension, a file name and the like) contained in a header portion, and a type of content service, request content, a request bandwidth, a port number contained in the body portion, and combination, thereof are mentioned. The body portion corresponds to a portion described by SDP (Session Description Protocol), case of an INVITE message method. 
     In this regard, in the content delivery service, it is particularly important to filtering whether an identifier of request content (URL, an extension, a file name and the like) and a predefined bandwidth suitable for transfer and reproduction of the request content is accurate or not. 
     In such a configuration, the content delivery system  10  according to embodiment of the present invention can securely provide a content delivery service to which band guarantee is carried out. 
     An operation of the entire content delivery system  10  will be described using  FIG. 4  to  FIG. 6 . 
       FIG. 4  is a flowchart showing an operation of the entire content delivery system  10 . 
     The content delivery system  10  is connected to a user terminal  20  used by a service user who acquires content via a network. 
     The user terminal  20  can access the portal server  200  via the network, and can access a Web server function that the portal server, using HTTP or the like. 
     The portal server  200  discloses content and the like that can be delivered to the service user using the Web server function, and the service user can select content using a browsing function of the user terminal  20 . 
     The delivery server  300  operates as a data server for storing a large number of content. The delivery server  300  is allowed to follow the permission of the portal server  200  to permit access of the user terminal  20 , and to deliver content in response to a request for the content. 
     The band guarantee network  100  exchanges information with the portal server  200  and delivery server  300 , and ensures a band of a connection to be used to deliver content between the user terminal  20  and the delivery server  300 . 
     In the explanation of this operation, the user terminal  20  accesses the portal server  200 ; acquires information on desired content (content A); and accesses the delivery server  300  using the information. Moreover, the user terminal  20  and the delivery server  300  use the SIP for establishment of a session, and use an RTSP (Real Time Streaming Protocol) and an RTP (Real time Transport Protocol) for delivery of content. 
     The information on content contains at least a route to access the delivery server  300  and a request band width to define for each of content and service to be delivered to be provided suitably, and is delivered to the user terminal  20 . 
     The user terminal  20  tries to access the content A stored in the delivery server in accordance with the information on the content A acquired from the portal server  200  (Step S 401 ). 
     The filtering device  600  constituting the band guarantee network  100  acquires a message transmitted by the user terminal  20  for accessing the content A (Step S 402 ). 
     In this regard, the message transmitted from the user terminal  20  is dividing to packets, but it may be acquired as a state of packets without coupling to the message. 
     The filtering device  600  analyzes a header portion and a body portion of the acquired message (Step S 403 ). 
     This analysis may be carried out at a state of packets without synthesizing them to a message (packet filtering). As one example, information on packets may be added to the information on the content that the user terminal  20  acquires from the portal server  200 . 
     The filtering device  600  compares an analysis result of the message with the malicious user information stored in the included database (auxiliary storage device  610 ). In the case where it is any user terminal  20  described in the malicious user information, the whole message is discarded. The filtering device  600  compares information on the content A which has already been acquired in advance from the portal server  200  recorded in the database, with information on the content A transmitted from the user terminal  20 . In the case where there is an error, it discards the whole message. In the case where the compared message is valid, the filtering device  600  transmits a message for accessing the content A to the session control server  400  (Step S 404 ). 
     In this regard, the comparison carried out by the filtering device  600  is carried out by comparing the information delivered from the portal server  200  to the user terminal  20  with information acquired by the filtering device  600  from the portal server  200  to confirm that it is not modified intentionally by the user terminal  20  and is not changed into information that causes a defect to occurs due to a trouble or the like. Namely, by comparing the content information, which is to be the same information, acquired via the user terminal  20  with the content information acquired from a trusted route other than it, it is possible to eliminate unwanted information. 
     In this regard, filtering is not necessary to restrict to cancellation of a message, and filtering can be registered with error transmission and/or malicious user information. 
     Referring also to  FIG. 1 , the session control server  400  receives the message for accessing the content A transmitted from the filtering device  600 , acquires content of the message, and instructs the band control device  700  to ensure the band in accordance with the acquired message. The band control device  700  receiving the instruction to ensure the band controls the network device  500  for reserving the instructed band. The network device  500  carries out open/close of ports and distribution of the resource to ensure the band (Step S 405 ). 
     The session control server  400  transmits the message for accessing the content A to the delivery server  300  (Step S 406 ). 
     The delivery server  300  receives the message for accessing the content A; analyzes the content; and carries out establishment of the session with the user terminal  20  (Step S 407 ). 
     The user terminal  20  carries out establishment of a session with the delivery server  300  (Step S 408 ). 
     The delivery server  300  transmits the content A to the user terminal  20  (Step S 409 ). 
     The user terminal  20  acquires the content A received from the delivery server  300 , and carries out reproduction or the like if needed (Step S 410 ). 
     In this regard, the band guarantee network  100  is providing the band-guarantee of the route at Step S 405 , and the route which contents A transmitted at Step S 409  pass is secured so that transmission of contents A may not be made to generate a band problem. 
     Thus, the content delivery service  10  that provides a content delivery service can deliver content in response to a request of the user  20 . 
     Moreover, the content delivery service  10  can carry out filtering in the case where there is a modification in the message transmitted from the user terminal  20 . 
     In order to explain the filtering of a message carried out by the band guarantee network  100  in detail, an SIP and an RTSP will be illustrated and explained in detail. 
       FIG. 5  is a flowchart showing an operation in which the filtering function subjects an SIP to filtering. 
     The filtering function analyzes a message (packet, data string) transmitted via the network, extracts and acquires an INVITE message that is a predefined message (Step S 501 ). 
     The filtering function analyzes and acquires a header (transmitting terminal information, address information and the like) and a body portion (content described with SDP) of the extracted INVITE message (Step S 502 ). 
     The filtering function compares the transmitting terminal information and the like recorded in the header with the malicious user information. In the case where it is any transmitting terminal recorded in the malicious user information, the message is discarded (Step S 503 ). 
     The filtering function compares the various kinds of information (band information and type (extension)) recorded in the body portion with proper information that has already been acquired in advance. In the case where there is an error or the like, a process to discard or modify the message is carried out (Step S 504 ). 
     In the case where there is no problem in the message, the filtering function transmits the INVITE message to a next device (SIP server) (Step S 505 ). 
     In the case where it is determined at Steps S 503  and  5504  described above that the transmitting terminal of the message is any malicious user, a sending terminal of the message is identified with the malicious user, and malicious user information is recorded. 
     Moreover, as operations to recognize that there is an error in a message the case where malice is recognized, that is, the case where a user terminal that repeatedly transmits similar messages is recognized; the case where an instruction of an operation suggestive of an attack is described in a body portion of a message; the case where an unusual bandwidth is requested; the case where a similar process is requested from a plurality of user terminals at the same time; the case where band ensuring and release are repeatedly requested so that a session cutoff request is transmitted immediately after the band ensuring is carried out normally; the case where a message is received via an illegal server (via an illegal terminal); and the like are mentioned. 
       FIG. 6  is a flowchart showing an operation in which the filtering function subjects RTSP to filtering. 
     The filtering function analyzes a message (packet, data string) transmitted from a network device  500 , extracts and acquires an RTSP message that is a predefined message (Step S 601 ). 
     The filtering function analyzes and acquires a header (transmitting terminal information, address information and the like) and a body portion (content described with SDP) of the extracted RTSP message (Step S 602 ). 
     The filtering function compares the information and the like (URL, port number and the like) recorded in the header and transmitted by the user terminal  20  with the malicious user information and the like. In the case where the content of the SDP is illegal, discarding of the message, transmission of an error and the like are carried out (Step S 603 ). 
     The filtering function compares various kinds of information (band information and type (extension)) and the like recorded in the body portion as the SDP with proper information that has already been acquired in advance. In the case where there is an error or the like, a process to discard or modify the message is carried out timely (Step S 604 ). 
     In the case where there is no problem in the RTSP message, the filtering function transmits the RTSP message to a next device (network device  500 ) (Step S 605 ). 
     Here, in the case where the system is established so that an RTSP message is communicated between the user terminal  20  and the delivery server  300  not via the filtering device  600 , the network device  500  and the filtering device  600  work together to confirm whether there is an error or an injustice in the content of the RTSP message. As the method of confirmation, the filtering device  600  confirms it by acquiring, from the network device  500 , the content of the RTSP message transmitted by the user terminal  20 ; carrying out filtering of the content; and timely carrying out an operation such as an instruction of cutoff of the line and update of the malicious user information in the case where there is an error or an injustice. 
     In such a filtering function, the filtering device  600  can filter a session control message transmitted from a malicious user. 
     Moreover, by filtering a session control message, it is possible to establish a system in which an unwanted message is not transmitted to the band control device  700 . Namely, it is possible to prevent the band control device  700  from carrying out band ensuring more than necessary. 
     Further, by filtering the session control message, it is possible to eliminate unwanted information and unusual information. Namely, it is possible to eliminate information transmitted by a malicious person, which can slip through a filter, wrong information transmitted by a legitimate user by incorrectly operating an information processing device, and wrong information due to a trouble or incorrect setting of the information processing device. 
     Namely, by using the filtering device  600  according to the present invention, it is possible to carry out filtering of a message containing an illegal band ensuring request. 
     Moreover, since a malicious session control message cannot arrive at the delivery server  300  by carrying out the filtering according to the present invention, it is possible to establish a system that does not need an unnecessary service resource. 
     Further, in the present invention, it is possible to establish a system in which a finite communication band for the network is not consumed wastefully. 
     Moreover, it is possible to provide a system capable of a defense against a DOS attack, a DDoS attack and a single-ring-and-hang-up solicitation call. 
     Moreover, it is possible to provide a system that can resolve an attack against the system using the QoS technique. 
     Namely, secure services and secure systems can be provided. 
     In this regard, the message explained in the present embodiment indicates a message method of an upper layer protocol. Namely, the filtering can also be adapted to HTTP, SMTP, FTP and the like in addition to exemplification of the SIP and the RTSP. 
     In addition, content information (URL, band information and the like) that the filtering device  600  acquires from the portal server  200  may be acquired from the delivery server  300 , or acquired from other server. Namely, it may be acquired from a legitimate information source. 
     In this regard, although the video content delivery system has been described as an example in the present embodiment, the present invention can be applied to one that delivers audio contents. Further, it can also be adapted to other services. 
     Moreover, although the SIP message and the RTSP message have been described as examples in the filtering device  600 , to carry out filtering has an effect so long as they are protocols used by a system to provide a service. Namely, it may be changed to a message, a protocol, a packet or the like to be subjected to filtering if needed. 
     Further, although the present invention has been described with reference to the embodiment described above, the present invention is not limited to the embodiment described above. Various modifications in a configuration and details of the present invention, which can be understood by those skilled in the art, can be made within the claims of the present invention. 
     This application claims priority based on Japanese patent application No. 2007-220502, filed Aug. 28, 2007, the disclosure of which is incorporated herein in its entirety by reference.