Patent Publication Number: US-7225461-B2

Title: Method for updating security information, client, server and management computer therefor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   The present application claims priority upon Japanese Patent Application No. 2002-259190 filed on Sep. 4, 2002, which is herein incorporated by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a method for updating security information, and to a client, a server and a management computer for use in the method. 
   2. Description of the Related Art 
   As shown in  FIG. 7 , a client that is connected to a server through a network comprises a CPU, a memory, a network interface, and a storage (local disk device) constituted by a hard disk device. An OS (Operating System), security software, and an application program are deployed in the memory. Various files are stored in the storage. These various files are a file group making up the OS, a policy file group, and a group of other files. The group of other files includes security software, an application program, data files (referred to simply as files as appropriate), and a file system. Various file management information, such as respective file attributes and a file allocation table, are described in the file system (e.g., see Yasuharu Murase, Nyumon MS-DOS kaitei shinpan (“Introduction to MS-DOS, Newly Revised Edition”), ASCII Corporation, Aug. 11, 1991, pp. 63–64). 
   As shown in  FIG. 8 , under the typical OS control, when the application program requests access to a file (S 10 ), the file system is referenced by a file access control function, and it is determined whether or not access is to be permitted (S 20 ). When access is permitted by this determination, the application program can access the file by a drive (S 30 -&gt;S 40 ). The file that the application program accesses also includes files of the server connected through the network. That is, files of the server connected through the network are accessed by a network drive and a network card (S 50 -&gt;S 60 -&gt;S 70 ). 
   Examples of the content of the file system stored in the storage include file attributes (see  FIG. 2 ; e.g., see Yasuharu Murase, Nyumon MS-DOS kaitei shinpan (“Introduction to MS-DOS, Newly Revised Edition”), ASCII Corporation, Aug. 11, 1991, pp. 131–132), an allocation table (see  FIG. 3 ), and a cluster (see  FIG. 4 ). As shown in the file attributes of  FIG. 2 , attributes such as file names, path names, owners, and group names are made to correspond to each file. Particularly in relation to access to the respective files by users, such as the owners, groups, and the outside, respective headings of read (“read” in  FIG. 2 ), write (“write” in  FIG. 2 ), and implementation are disposed. Attributes relating to access columns of permitted (“permitted” in  FIG. 2 ) and not permitted (“not permitted” in  FIG. 2 ) are made to correspond to each of these headings. 
   The security software shown in  FIG. 7  is software that is added to the OS and strengthens the access control function. The security software provides precise access control to further raise security on the basis of access control information described in the policy file. Detailed attributes, such as users, applications, and periods of time, are specified in the policy file as conditions permitting access to files. 
   A virus pattern file and a signature file are included in the policy file. The virus pattern file is used in virus countermeasure software called anti-virus software. The signature file is used in network attack countermeasure software called a host intrusion detection system. The anti-virus software inspects files, periodically or while a file is open, for the presence of computer virus infections on the basis of a pattern indicative of the characteristics of a computer virus, and appropriately takes necessary action. The host intrusion detection system identifies a network packet called a signature, detects attacks through the network, monitors e.g., a log file that the implemented application program outputs, and detects attacks. 
   The policy (security policy) referred to herein is security information generically naming limitations relating to use of a computer. In other words, the policy includes not only information for prohibiting the implementation of specific applications and preventing changes to settings, but also various kinds of software. 
   Next, the updating of the policy file in the network environment will be described. As shown in  FIG. 9 , first, when power is turned on and the client starts up (S 100 ), the OS thereof is activated (S 110 ). Services resulting from a network connection and various pieces of software are started up (S 120 ) by a control of the activated OS, whereby the transmission and reception of data via the network become possible. The updating function of the policy file is started up by the implementation of the security software (S 130 ), and the client receives updates of the policy file from a management computer through the network. That is, the client receives the latest version of the policy file from the management computer (S 140 ). Thus, the client is allowed to implement various processing corresponding to operational inputs by a user (S 150 ). 
   In the above conventional technology, the policy file is stored in a storage equipped with the client. Thus, the policy file naturally cannot be updated while the operation of the client is stopped. For this reason, access control, virus countermeasures, etc., cannot be conducted in the latest state during the period of time until the policy file is updated. 
   As shown in the flow chart of  FIG. 9 , because the policy file of the client is updated after start-up, the client is operated with the old version of the security information during the period of time from start-up until the security information is updated. In particular, network-infecting viruses attack devices connected to the network. Thus, the client is ordinarily in a state in which it is vulnerable to attack during the period of time from start-up until the security information is updated. 
   Moreover, in relation to updating of the policy, updating of the policy must be implemented with regard to each of a plurality of clients, and the entire management burden of each client becomes enormous. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide a method for updating security information even when operation of the client is stopped. 
   In order to accomplish the above and other objects, according to a first aspect of the present invention, there is provided a method for updating information on security, in which the client is connected with a server through a network, with the server including a storage device that is managed by the client, the storage device storing security information of the client, the method comprising updating the security information of the client stored in the storage device that the client manages in the server. 
   According to a second aspect of the present invention there is provided a client connected to a server through a network, the server including a storage device, comprising means for managing the storage in the server, the storage device storing security information, the security information being updated without operation of the client, and means for referencing the security information of the client. 
   According to a third aspect of the present invention there is provided a server connected to a client through a network comprising means for communicating with the client through the network, and a storage device that is managed by the client, the storage device storing security information to be updated. 
   According to a fourth aspect of the present invention there is provided a management computer connected through a network to a server, the server including a storage device that is managed by a client, the storage device storing security information of the client, comprising means for communicating with the server through the network, and means for updating the security information. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings wherein: 
       FIG. 1  is a system block diagram showing an embodiment according to the present invention; 
       FIG. 2  is a chart showing file attributes in the embodiment according to the present invention; 
       FIG. 3  is a chart showing an allocation table in the embodiment according to the present invention; 
       FIG. 4  is a chart showing the structure of a cluster in the embodiment according to the present invention; 
       FIG. 5  is a flow chart showing a policy update sequence in the embodiment according to the present invention; 
       FIG. 6  is a flow chart showing additional access control of a file in the embodiment according to the present invention; 
       FIG. 7  is a block diagram showing the structure of a client in the embodiment according to the present invention; 
       FIG. 8  is a flow chart showing control of access to a file by a conventional client; and 
       FIG. 9  is a flow chart showing updating of a policy file by a conventional client. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   At least the following matters will be made clear by the explanation in the present specification and the description of the accompanying drawings. 
   A client is constituted by a so-called diskless computer that does not include a local hard disk device. In the present embodiment, this client will be called a “diskless client.” 
   As shown in  FIG. 1 , one or a plurality of diskless clients  100  are connected through a network to a server  200  referred to as a “storage server.” A management computer  300  is connected through the network to the server  200 . It should be noted that the management computer  300  may be omitted by having the server  200  include the function(s) of the management computer  300 . 
   Similar to convention, the diskless client  100  is equipped with a CPU  110 , a memory  120 , and a network interface  130 . An OS  121 , security software  122 , an application program  123 , and a network storage driver  124  are read out from the server  200  and deployed in the memory  120 . The diskless client  100  gives to the server  200  the function of a storage device as disk images  230 . 
   That is, the diskless client  100  does not include a local disk device, but is mounted with a hard disk device (storage, storage device) of the server  200 . The network storage driver  124  of the diskless client  100  controls the disk of the mounted server  200  via the network. 
   The server  200  includes a network interface  210  and a CPU  220 , and also includes a plurality of hard disk devices that each diskless client  100  manages. The server  200  may also operate on, for example, a RAID (Redundant Array of Inexpensive Disks) format. The disk images  230  that the diskless client  100  uses are stored in the hard disk device. There is a disk image  230  present for each diskless client  100 . The disk images  230  are file groups that are the same as the ones stored in the storage (hard disk device) of the conventional client shown in  FIG. 7 . 
   That is, the disk images  230  that the diskless client  100  uses are an OS configuration file group  231  relating to the configuration of the OS, a policy file group  232 , and a group  233  of other files. Security information that is the same as that of the aforementioned conventional technology is included in these file groups  231  to  233 . 
   That is, the policy file  232  is constituted by the aforementioned access control information, the virus pattern file, the signature file, and the like. The group  233  of other files includes the application program  123 , data files that software and/or programs use, and the network storage driver  124 . Additionally, various file management information shown in  FIGS. 2 to 4 , such as file attributes and a file allocation table, is included as a file system in the group  233 . 
   The management computer  300  includes a CPU  310 , a memory  330 , a network interface  320 , and a storage  340  that is constituted by a hard disk device. An OS  331 , management software  332 , and an application program  333  are deployed in the memory  330 . Various file groups  341  to  343 , such as an OS, management software, an application program, and data files, are stored in the storage  340 . The management software  332  uses the management software file group  342  to update the content of the various file groups  341  to  343  in the disk images  230  of the server  200 , i.e., the security information, to update them to the latest versions. 
     FIG. 5  shows a specific updating sequence of the policy. As shown in  FIG. 1 , contrary to convention, the policy that the diskless client  100  uses is included in the various file groups  231  to  233  that the server  200  retains. As needed, the server  200  starts up the updating function of the policy (S 200 ), appropriately receives the latest versions of the various file groups  231  to  233  from the management computer  300 , and concludes the updating of the policy (S 210 ). Thus, the updating of the policy, such as the file attributes, user ID, and various virus countermeasures, is conducted in the entire network to which the server  200  is connected. Thus, the latest security is secured with respect to unauthorized access and virus infiltration and attacks. 
   After updating of the policy has been concluded, the diskless client  100  starts up (S 220 ). Specifically, when the diskless client  100  is turned on, an IPL (Initial Program Loader) is started up. A basic OS is called up from the disk images  230  of the server  200  through the network by the action of the IPL, and the basic OS is deployed in the memory  120  of the diskless client  100 . The diskless client  100  begins operation as a computer by the deployed basic OS beginning operation (S 230 ). 
   Services resulting from the network connection and various pieces of software are started by the control of the started OS (S 240 ), whereby it becomes possible for the diskless client  100  to transmit and receive data through the network. When the diskless client  100  that has begun operation receives input of authentication information such as the ID (user name) and password of the user, it checks these with authentication information registered within the files groups  231  and  232  within the disk images  230  of the server  200 . When the validity of the authentication information including the group ID (group name) has been authenticated as a result of the checking, use of the client by the user is made possible. 
   Additional access control for raising security by the security software  122  will be described in a case where the application program is operated by the diskless client  100 . The security software  122  is software added to the OS in order to strengthen the access control function. The security software  122  conducts precise access control for further raising security on the basis of the access control information described in the policy file. Detailed attributes, such as users, applications, and periods of time of day, are specified in the policy file as conditions permitting access to files that the application program and the like use. 
   That is, as shown in the flow chart of  FIG. 6 , when the application program  123  requests access to a file within the disk images  230  of the server  200  under the control of the OS (S 310 ), additional file access control by the security software  122  functions (S 311 ). The policy file  232  within the disk images  230  of the server  200  is referenced by the file access control, and the policy is authenticated with regard to the file(s) whose access has been requested (S 312 ). The policy is information specifying the application, user ID permitting access, and attributes relating to each file. When file access by the application is permitted as a result of the authentication of the policy, next, the file access control by the OS functions. The file system is referenced by the file access control of the OS with regard to the file(s) whose access has been requested, and the file attributes shown in  FIG. 4  are verified (S 313 ). When access is permitted by the user ID matching or the like as a result of this verification, the network storage drive  124  accesses the file(s) within the disk images  230  of the server  200  through the network interface  130  (S 314 -&gt;S 315 -&gt;S 316 ). 
   Although an embodiment of the invention has been specifically described on the basis of that embodiment, the invention is not limited thereto and can be variously altered in a range that does not deviate from the gist thereof. 
   The following effects are provided with the embodiment of the invention. 
   The disk that the diskless client manages and uses is mounted on the server on the network. Additionally, the disk images of the client including the policy (security information) and files are stored in the disk mounted in the server. The management computer updates the policy in the disk images. 
   Thus, regardless of whether or not operation of the client is stopped, the policy (security information) can be updated as needed. Therefore, updating of the policy is already concluded at the point in time when the stopped client is started up. Thus, the client is operated according to the continually updated policy. 
   Even in a case where a plurality of clients mount disks on a single server, updating can be accomplished simply by updating the policy of the server. For example, the policy of the server is updated through the management computer. That is, there is no need to implement updating of the policy with regard to each client as has conventionally been the case, and the management burden of each client can be greatly reduced. 
   Even when operation of the client is stopped, the security information can be updated. 
   Although the preferred embodiment of the present invention has been described in detail, it should be understood that various changes, substitutions and alterations can be made therein without departing from spirit and scope of the inventions as defined by the appended claims.