JP2011221616A - Url filtering system, system control method, and system control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce network load caused by URL filtering.SOLUTION: The URL filtering system includes a content display terminal 30 having a cache memory 32, and a URL filtering device 40 having a proxy server unit 41. The URL filtering device 40 includes an html file conversion unit 43 converting a URL for a regulation object site found in a downloaded file into a non-regulation site. The html file conversion unit 43 scans a downloaded file received by the proxy server unit 41 to check whether any URL is written. When a URL is written, a URL evaluation unit 42 searches for a matching URL in a regulation object site URL DB51. When it is found the URL is for a regulation object site as a result of the search, the regulation object URL is converted into a URL that is defined for each file format in an error screen location DB62.

Description

  The present invention relates to a URL filtering system, a system control method, and a system control program that regulate browsing of a specific site on a network.

  A myriad of files exist on the Internet, which is a collection of computer networks, and the storage location is stored in a character called a URL (Uniform Resource Locator) for an arithmetic processing unit that is running a browsing program called a browser. Often specified in columns.

  The URL described above includes a file described in a html (hypertext markup language) format programming language called a website composed of text files, image files, and the like.

  Also, on the website, the computer is controlled so that a program called a computer virus is automatically saved (downloaded) on the user's computer, and the downloaded computer virus program is automatically executed. There are also sites that have been created to prevent the normal use of a computer by controlling the computer and erasing or modifying data stored on the user's computer.

  In addition to the Internet to which a large number of unspecified computers can be connected, a network to which only a limited number of computers can be connected is called an intranet. For example, a network of computers installed in a company is generally an intranet.

  A proxy server that manages the connection between the Internet and the intranet is installed at the boundary between the Internet and the intranet, and computers on the Internet and computers on the intranet may exchange data via this proxy server. Many.

  The proxy server described above is provided with a transmission / reception unit for the Internet, a transmission / reception unit for the intranet, and a transfer unit connecting the two transmission / reception units. The Internet transmission / reception unit and the intranet transmission / reception unit have different addresses on the network.

  For this reason, when a connection request is transmitted from a computer on the intranet to a website on the Internet, it is once connected to a transmission / reception unit for the intranet, and the transfer unit sends the transmission source address of the connection request to the computer on the intranet. To the address of the Internet transmitting / receiving unit, and the Internet transmitting / receiving unit transmits a connection request to the website.

  Here, regarding the connection location of the proxy server, in addition to being installed at the connection point between the Internet and the intranet as described above, it is also possible to connect as follows. First, a firewall that restricts the connection between the Internet and the intranet is installed at the connection point between the Internet and the intranet, and a proxy server is installed on the intranet side of the firewall. The intranet security can be improved by setting the above-described firewall so that only the connection from the intranet to the Internet is permitted through the proxy server.

  Then, the website transmits a connection permission response to the transmission / reception unit for the Internet of the proxy server that is the transmission source address of the connection request, and the transfer unit transmits the transmission destination address (connection request of the connection request) from the website. (Transmission source address) is converted into the address of the computer on the intranet, and a connection permission response is transmitted to the computer on the intranet.

For this reason, when viewed from the side of the website, it appears that the proxy server has connected to this website.
As described above, the proxy server has a function of connecting to a website as a proxy of a computer on the intranet.

  In addition, the proxy server checks all the data content that passes through this proxy server, and the above-mentioned computer virus program enters a computer connected to the intranet, or confidential data held by a computer on the intranet enters the Internet. It also has a filtering function to prevent leakage.

  This filtering function has a connection restriction target list inside the proxy server so that it does not connect to the malicious site (malicious site) as described above, and it is registered as a part of this restriction target list. Some of them have a URL filtering function for notifying the user that “it cannot be connected because it is a regulated site” when trying to connect without knowing the malicious site.

  Here, the aforementioned restriction target list includes sites that are restricted under specific circumstances and sites that are always restricted. Under certain circumstances, for example, browsing of sites that provide entertainment information not related to business (entertainment related sites) is restricted during business, but the above entertainment related sites are browsed outside of business Indicates that this is permitted. Further, the constantly restricted sites include malicious sites that control the computer to execute the above-described computer virus program or modify information stored in the user's terminal.

  In recent years, a proxy server with a URL filtering function has been set to control information, improve business efficiency, and reduce capital investment to restrict users from browsing entertainment sites that are not related to business. As a result, an increasing number of companies reduce the load on the network.

  However, in general, the user cannot confirm the above-described connection restriction target list. For this reason, it is often impossible for a user to determine in advance whether or not a site to be connected is subject to regulation. Actually, a connection request is actually transmitted from the browser arithmetic processing unit of the display terminal, Because it is often found that a connection has been made to a regulated site after receiving a notification such as “Cannot connect”, wasteful communication occurs in the intranet part to the proxy server.

  In addition, if the browser arithmetic processing unit mentioned above is instructed to connect to the regulated site (redirect function) or refer to content downloaded from a non-regulated website, the user intends Even if not, the browser calculation processing unit described above may automatically try to download from the restricted site. In such a case, it is impossible to avoid the request to the regulated site only by alerting the user.

  On the other hand, as technical contents of the above technical fields that have been specifically known, there are, for example, the following Patent Documents 1 to 3.

  In Patent Document 1, in order not to connect to the regulated site, the above-described filtering server having the URL filtering function is provided at the boundary between the user's computer and the Internet, and the browser of the user's computer is provided. Technology that newly adds a program (plug-in program) and executes the contents of the browser on the computer, technology that causes the computer to execute an agent program that constantly monitors information (packets) sent and received from the user's computer, etc. A network system is disclosed.

  This network system, for example, when a site related to violence provided on the Internet, which is not desirable for a child such as a child at home, is connected from a computer installed in a child's room, attributes such as the age of the viewer in advance. Is transmitted to the filtering server described above, and the filtering server determines whether or not browsing is possible based on the URL of the connection request destination transmitted from the computer in the child room and the attribute of the viewer. This is a network system that allows the computer that is executing the above-described plug-in program or agent program to function according to the determination result.

  Further, Patent Document 2 discloses a spam processing server that reads the content of spam mail (spam mail) that is sent without being requested by the user, and filtering that restricts connections to regulated sites. A spam mail filtering system including an engine is disclosed.

  This system first extracts the URL described in the body of the spam mail, determines whether or not this URL belongs to a regulated site, and if it is a regulated site, the extracted URL is used. Save as a list of regulated sites. Next, it is a spam mail filtering system that determines whether or not the URL that the user intends to browse matches the URL of the above-mentioned list of regulated sites, and restricts browsing because the URL is regulated. .

  Furthermore, in Patent Document 3, when a site for a personal computer with a large amount of data is accessed by a mobile phone, the program described in the html language of the site for the personal computer is decoded and displayed by converting the program for the mobile phone. A web content conversion method for converting a structure and displaying a reduced screen display is disclosed.

Japanese Patent Application No. 2006-079205 JP 2005-128922 A JP 2006-243829 A

  However, in the URL filtering server disclosed in Patent Document 1, a connection request transmitted from a user's computer in which the browser including the plug-in program described above is in execution to each display terminal. An inconvenience has arisen in that it is necessary to distribute an agent program that monitors packets whether the destination is a regulated site.

  Further, by inquiring of the server about the information on the restriction target site from the calculation unit that processes the above-mentioned program, communication between the display terminal, the distribution server, and the restriction site information providing server is newly generated. In addition, there is a disadvantage that the network load increases.

  Further, since the URL filtering server disclosed in Patent Document 1 must distribute the above-described plug-in program and agent program to the user's computer, the operation manager managing the user's computer increases. Inconvenience occurred.

  Further, even when a proxy server having the above-described URL filtering function is installed in each system disclosed in Patent Documents 2 to 3, downloading is performed via the proxy server according to a command from a calculation unit in which the browser is in an execution state. If the html format file contains a link to the regulated site, a redirect function, and an image reference, the browser function automatically or manually downloads again from the regulated site to the proxy server. Since there is a function for requesting, there is a disadvantage that unnecessary access from the browser to the proxy server occurs.

(Object of invention)
An object of the present invention is to provide a URL filtering system that improves the disadvantages of the related technology and can suppress connection to a regulated site without increasing the network load.

  In order to achieve the above object, the URL filtering system according to the present invention, when a connection request is transmitted from a content display terminal used by a user to a content server specified in advance as a regulated site on the Internet. A URL filtering system having a function of blocking the connection request by a relay proxy server, wherein a URL filtering device including the proxy server is provided in the content display terminal, and the URL filtering device is In response to an inquiry from a server, a URL evaluation unit that determines whether or not the destination of the connection request is the regulated site, and a download file downloaded from a content server other than the regulated site on the Internet Contact the regulated site An html file conversion unit that converts a destination of the connection request to a site other than the regulated site when there is a description for transmitting the request, and the html file conversion unit connects the download file to another site. A search function for searching whether or not a URL for the URL is included, and whether or not the detected URL is the restriction target site for the URL evaluation unit when the URL is detected by the search function An inquiry function for making an inquiry, and a URL that replaces the detected URL with a URL other than the restriction target site so as not to connect to the restriction target site when there is a reply from the URL evaluation unit that it is the restriction target site And a replacement function.

In addition, the URL filtering system control method according to the present invention provides a connection request when a connection request is transmitted from a content display terminal used by a user to a content server specified in advance as a regulated site on the Internet. In a URL filtering system having a function of blocking the proxy server for relay, the proxy server receives a download file downloaded from a content server other than the regulated site,
The proxy server transmits the download file received by the proxy server to an html file conversion unit provided in advance in the proxy server, and connects the download file received by the html conversion unit to another site. The html file conversion unit searches whether the URL is described, and when the URL is detected by the search, the html file conversion unit determines whether the URL belongs to the regulated site. An inquiry is made to the URL evaluation unit provided in advance in the html file conversion unit,
The URL evaluation unit that has received the inquiry determines whether or not the restriction target list provided in advance in the URL evaluation unit matches the detected URL, and the determination result is sent to the inquiry from the html file conversion unit. As a result, the URL evaluation unit returns the URL to the html file conversion unit, and when the restriction target list matches the detected URL in response to the inquiry result, the html conversion unit sets the URL other than the restriction target site. The html conversion unit returns the download file including the converted URL to the proxy server.

Furthermore, the URL filtering system control program according to the present invention is connected when a connection request is transmitted from a content display terminal used by a user to a content server specified in advance as a regulated site on the Internet. A URL filtering system having a function of blocking a request by a proxy server for relay, a download function for receiving a download file downloaded from a content server other than the regulated site, and the download file received by the proxy server Html file conversion unit transmission function for transmitting to the html file conversion unit provided in advance in the proxy server,
A search result determination function for determining whether or not a URL for connecting to another site is described in the download file received by the html conversion unit. When the URL is detected by the determination result, the URL is A detection URL inquiry function for making an inquiry to a URL evaluation unit provided in advance in the html file conversion unit as to whether or not the site is subject to restriction, and the URL evaluation unit provided in advance for receiving the inquiry URL determination function for determining whether or not the restriction target list matches the detected URL and returning the determination result to the html file conversion unit as a result of the inquiry from the html file conversion unit, and receiving the inquiry result When the detected URL is the restriction target site, this URL is used as the restriction target. Regulatory URL replacement function to replace the description of the other site,
And a replacement content return function for returning the download file including the replaced URL to the proxy server and returning the download file from the proxy server to the content display terminal. It is characterized by.

  As described above, according to the present invention, the URL information of the regulated site is replaced with the error content screen URL by the html file conversion unit, so that the html file downloaded from the non-regulated site is read by the browser calculation processing unit. It is possible to prevent the connection request from being automatically transmitted to the regulated site, and the download of the error screen content from the error content server to be displayed instead of the regulated image is fixed. By using the URL, if the data stored in the cache memory of the display terminal device is within the valid period, the content held in this cache is used, and the error content server 2 is used. No more download requests will be made after the first time. It is possible to reduce the load on the workpiece, it is possible to provide an excellent URL filtering system, system control method and system control program that can suppress the equipment cost of such connection fees.

It is a block diagram which shows one Embodiment of the URL filtering system concerning this invention. It is explanatory drawing which showed the storage location of the error screen content with respect to each file extension stored in error screen position DB of the block diagram disclosed in FIG. It is explanatory drawing which showed the content of the file downloaded from the content server of the block diagram disclosed in FIG. It is explanatory drawing which shows the content of the file which replaced the URL of the restriction | limiting site | site by URL other than a restriction | limiting site | part by the html file conversion part for the file content disclosed in FIG. FIG. 2 is a flowchart showing the operation of the present invention in the block diagram disclosed in FIG. 6 is a flowchart continued from the flowchart disclosed in FIG.

[First Embodiment]
Hereinafter, a first embodiment of a URL filtering system according to the present invention will be described with reference to FIGS. 1 and 2.

  First, in FIG. 1, the URL filtering system is provided with a content display terminal 30 for downloading content information stored in the content server 80 according to a user's command, and the content display terminal 30, and the content server 80. If there is a URL (Uniform Resource Locator) of a regulated site that is set in advance to prevent the user from browsing the content information downloaded from the URL, the URL is not connected to the URL of the regulated site. And a URL filtering device 40 that provides the content display terminal 30 after rewriting the URL to a URL other than the restriction target site.

  Furthermore, the URL filtering system includes a DB server (database server) 50 that is provided alongside the URL filtering device 40 and provides site information indicating which sites are regulated sites to the URL filtering device 40; And an error content server 60 that provides the URL filtering device 40 with a procedure for rewriting the URL to be regulated according to the content of the downloaded content.

  The above-described content display terminal 30 includes an input device 10 that receives input from the user to the content display terminal 30 and a display device 20 that displays the processing result of the content display terminal 30 on the screen. It is attached.

  Further, the content display terminal 30 is a browser having a function of processing by the arithmetic processing unit so that the user can view the content of the content described in the html (hypertext markup language) format downloaded from the content server 80 described above. The stored browser memory 31, the browser calculation processing unit 33 that executes the contents of the browser memory 31 and controls the display device 20 to display the content obtained by the contents, the URL that has been downloaded, and And a cache memory 32 for temporarily storing the acquired content.

  The browser arithmetic processing unit 33 that executes the contents of the browser stored in the browser memory 31 uses a protocol such as the http (hyper text transfer protocol) format and the ftp (file transfer protocol) format for the URL filtering device 40. It has a function of transmitting the URL of the content display terminal 30 itself to the content server 80 and downloading content such as an html file.

  Further, the browser calculation processing unit 33 temporarily stores the downloaded content in the cache memory 32 according to the content of the browser memory 31 described above, and when the connection is made again to the previously connected URL, the content is again displayed. It has a cache data acquisition function for controlling the content held in the cache memory 32 to be reused without being downloaded.

  With this cache data acquisition function, when reconnecting to a previously connected URL, the content held in the cache memory 32 is used, so the network load is reduced.

  The browser arithmetic processing unit 33 has a function of controlling the display screen to be assembled so that the user can recognize the downloaded html file according to the contents of the browser memory 31 described above.

  The URL filtering device 40 described above includes a proxy server unit 41 that downloads content to the URL on the Internet requested by the browser calculation processing unit 33 and returns the content to the browser calculation processing unit 33.

  Furthermore, the URL filtering device 40 described above includes a URL evaluation unit 42 that searches the DB server 50 to determine whether the URL requested from the browser arithmetic processing unit 33 is a restriction target, and returns the result, and a URL in the content And an html file conversion unit 43 that replaces the restriction target URL with the error screen URL.

  Here, the functions of the html conversion unit 43 will be described. The html conversion unit 43 includes a URL search function for searching whether or not a URL is described in the download file, and a URL described by the URL search function. If it is found that the URL detected by the URL search function with respect to the URL evaluation unit 42 is an URL of the restriction target site, it has an inquiry function.

  Furthermore, the html conversion unit 43 has a replacement function for replacing the URL in the download file detected based on the result of the inquiry function described above with another URL so as not to connect to the URL.

  Thereby, the URL evaluation unit 42 determines whether or not the URL requested from the browser arithmetic processing unit 33 is a regulated site. If the URL is a regulated site, the html knitting unit 43 displays the regulated URL as an error screen. It can be returned to the browser calculation processing unit 33 after being replaced with the URL.

  The above-described DB server 50 includes a restriction site URL DB (URL database) 51 in which restriction target URLs are recorded, and the URL of which site is the restriction target site with respect to the URL filtering device 40 based on the contents of the restriction site URL DB 51. Provide information.

  Thus, the URL evaluation unit 42 described above refers to the content of the restriction site URL DB 51 and determines whether or not the connection destination URL requested from the browser calculation processing unit 33 is included in the restriction site URL DB 51. Is possible.

  The error content server 60 provided in the URL filtering device 40 described above provides an error screen content DB 61 for providing an error screen to the browser calculation processing unit 33 of the content display terminal 30 and the URL filtering device 40. An error screen position DB 62 that provides a storage location of an error screen, and an error screen management unit 63 that manages input / output of information in the error screen content DB 61 and the error screen position DB 62 described above are provided.

  In addition, the error screen content DB 61 has content indicating that “I am trying to access a URL subject to restriction” in order to notify the user when accessing the restriction site.

Further, the error screen position DB 62 indicates where in the error screen content DB 61 the error screen content to be displayed is stored for the file type that is subject to restriction as shown in FIG. Has location information.
At that time, even if the file type cannot be determined, the file type is stored as a blank as the specified value.

  For this reason, when the URL evaluation unit 42 determines that the connection request destination transmitted from the browser calculation processing unit 33 is a regulated site, the error screen content is transmitted from the error screen content DB 61 via the proxy server unit 41. Can be transmitted to the browser arithmetic processing unit 33.

  In addition, the html file conversion unit 43 analyzes a file downloaded from an unregulated site, and if the URL of the regulated site is included in the file, the URL of the regulated site is stored in the error screen position DB 62. The URL of the error screen content DB 61 is replaced with the URL and transmitted to the browser arithmetic processing unit 33 via the proxy server unit 41.

  Therefore, the browser arithmetic processing unit 33 can process the returned download file, access the URL of the error screen content DB 61 converted by the html file conversion unit 43 described above, and acquire the error screen content.

Further, the error screen management unit 63 has a maintenance function for the error screen content 61 and the error screen position 62.
With this maintenance function, it is possible to add, delete, and modify the file type for the error screen position 62, and to add, delete, and modify the error screen content for the error screen content 61.

  Further, an error content management terminal 70 is provided outside the error content server 60 described above, and the administrator can control the operation of the error screen management unit 63 by transmitting a command from the error content management terminal. It can be configured.

[Overall operation]
Next, the overall operation of the URL filtering system will be described with reference to FIGS. 1 to 5B.

  First, the browser information processing unit 33 stores the browser information stored in the browser memory 31 to the browser calculation processing unit 33 using the input device 10 connected to the content display terminal 30. The content is read and the content of the browser memory 31 is executed by the browser arithmetic processing unit 33, and the content server 80 is requested to transmit the content including the html file existing on the Internet from the input device 10. (FIG. 5: Step S101 / request start process).

  Next, the browser arithmetic processing unit 33 confirms whether or not the above-described content exists on the cache memory 32 in accordance with the content of the above-described browser memory 31 (FIG. 5: step S102 / cache data determination step). At this time, if the content exists on the cache memory 32, the browser arithmetic processing unit 33 acquires the content on the cache memory 32 (FIG. 5: Step S110 / cache data acquisition step).

  Subsequently, the browser arithmetic processing unit 33 processes a tag (html) included in the acquired content and displays the processing result on the display device 20 (FIG. 5: step S208 / display process). Thus, if the content is held on the cache memory 32, the content can be displayed without being connected to the network.

  On the other hand, when the corresponding content does not exist in the cache memory 32, the browser calculation processing unit 33 transmits a content download request to the proxy server unit 41 (FIG. 5: step S103 / proxy server request process). Upon receiving the download request, the proxy server unit 41 transmits the requested URL to the URL evaluation unit 42 and inquires whether or not this URL is a URL to be regulated (FIG. 5: Step S104 / URL inquiry process). ).

  Upon receiving the inquiry, the URL evaluation unit 42 searches the restricted site URL DB 51 using the received URL as a search term, and returns the result to the proxy server unit 41 (FIG. 5: step S105 / restricted site DB search step).

  The proxy server unit 41 that has received the search result from the URL evaluation unit 42 determines whether or not the download request destination URL exists in the restricted site URL DB 51 (FIG. 5: Step S106 / URL determination step). As a result, when content is downloaded from the Internet, whether download is possible or not can be determined based on the restriction site URL DB 51.

  As a result of the determination, if the restriction site URL DB 51 exists, the content of the error screen content DB 61 defined as the specified value in the error screen position DB 62 is returned to the browser arithmetic processing unit 33 (FIG. 5: Step S107 / Error screen). Content return process). The browser calculation processing unit 33 interprets a tag included in the content and displays the screen on the display device 20 (FIG. 5: step S208 / display process).

  Specifically, referring to FIG. 2, the error screen content defined as the default value (<blank>) in the error screen content DB 61 is error.intra.co.jp/error/html. Return to the arithmetic processing unit 33.

  Here, if the content of error.intra.co.jp/error/html is, for example, “This URL cannot be displayed because it is a regulated site”, the content is displayed on the display device 20 of the user and used. Can be notified of access to regulated sites.

  Further, the browser calculation processing unit 33 instructs the cache memory 32 to hold the acquired error screen content 61 for a certain period. As a result, when the user transmits a download request to the same URL to be regulated again, the error screen content acquired from the error screen content DB 61 held on the cache memory 32 can be reused. For this reason, since the error screen content is not acquired from the error screen content DB 61 again, the network load can be reduced.

  On the other hand, when the result that the URL is not regulated is returned from the URL evaluation unit 42, the proxy server unit 41 downloads the content 80 from the Internet (FIG. 5: step S200 / download process).

  The above-described downloaded file format is analyzed by the proxy server unit 41, and if it is a MIME (Multipurpose Internet Mail Extension) type or html file that is an e-mail standard, it is transmitted to the html file conversion unit 43 (FIG. 5: Step S201 / html file converter transmission step).

  The html file conversion unit 43 that has received the downloaded file from the proxy server unit 41 searches for the URL embedded in the content (FIG. 5: step S202 / embedded URL search step). Thereby, even when the URL of the restriction target site is embedded in the downloaded html file, it can be found out.

  As a result of the search described above, the html file conversion unit 43 determines whether there is a URL embedded in the downloaded file (FIG. 5: step S203 / search result determination step).

  Furthermore, if the URL is present as a result of the above determination, the html file conversion unit 43 inquires of the URL evaluation unit 42 whether the URL is a URL to be regulated (FIG. 5: step S204 / detection URL). Inquiry process).

  Upon receiving the inquiry from the file conversion unit 43, the URL evaluation unit 42 determines whether the transmitted URL exists in the restriction site URL DB 51, and returns the determination result to the html file conversion unit 43 (FIG. 5: Step S205). / Detection URLDB determination step).

  Here, in the present embodiment, the URL of the restriction site is stored in the restriction site URL DB 51, but this does not limit the storage location. For example, the URL of the restriction site is included in the URL evaluation unit 42 described above. May be stored.

  In the above case, the URL evaluation unit 42 that has received the inquiry from the file conversion unit 43 determines whether or not the transmitted URL exists in the restriction target list provided in advance in the URL evaluation unit 42, and the html file A determination result is returned to the conversion part 43 (FIG. 5: step S205 / detection URL determination process).

  As a result of inquiring the URL evaluation unit 42, the html file conversion unit 43 returns a URL that corresponds to the file format defined in the error screen position DB 62 when the result that it is a regulated site is returned. (FIG. 5: Step S206 / error screen position conversion step).

  For example, if http://www.danger.com/images/top/logo.gif is the URL subject to regulation in the third line of FIG. 3, the extension of this URL is in the gif (image) format, so that in FIG. Replace with http://error.intra.co.jp/image/error.gif as the error screen for the gif at the error screen position. Thereby, the description of the URL to be regulated can be replaced with the description of the URL defined in the error screen position DB 62 for each file format.

  If the file is completed with / (slash) as in the fourth line and no extension exists, it is replaced with an error screen position corresponding to a blank defined as a default value in the error screen position of FIG. For this reason, even if the file format is not specified in advance in the error screen position 62, it can be replaced with http://www.error.intra.co.jp/error/html as the specified value.

  Here, in the present embodiment, the URL of the restriction target site is replaced with the URL stored in the error screen position DB 62, but this does not limit the storage location. For example, the html file conversion unit 43 The above error screen position may be stored inside.

  In the above case, the html file conversion unit 43, if the result of inquiring the URL evaluation unit 42 returns a result that it is a regulated site, the html file conversion unit 43 includes the corresponding URL portion in advance. The URL corresponding to the file format defined in the error screen position is replaced (FIG. 5: step S206 / restricted URL replacement step).

  The content replaced as described above is returned to the proxy server unit 41, and the proxy server unit 41 returns the replaced content to the browser calculation processing unit 33 (FIG. 5: Step S207 / replaced content return step). The browser calculation processing unit 33 interprets a tag included in the content and displays the screen on the display device 20 (FIG. 5: step S208 / display process).

  At this time, if there is content that needs to be downloaded again, a request is transmitted to the URL filtering device 40. Further, the browser operation processing unit 33 instructs the cache memory 32 to retain the content replaced with the acquired error screen content for a certain period (FIG. 5: Step S209 / cache memory saving step).

  For this reason, if there is an error screen content on the cache memory 32, the content on the cache memory 32 can be reused without being acquired from the error screen content 61 again, thereby reducing the load on the network. it can.

  Here, in the overall operation in the embodiment described above, a request start process, a cache data determination process, a cache data acquisition process, a proxy server request process, a URL inquiry process, a regulated site search process, a URL determination process, and an error screen Content return process, download process, html file converter transmission process, embedded URL search process, search result determination process, detection URL inquiry process, detection URL DB confirmation process, detection URL confirmation process, restriction URL replacement process, error screen position replacement process, Each execution content executed in the replaced content return process, the display process, and the cache memory storage process may be programmed and functioned by a computer.

[Effect of the embodiment]
As described above, in the present invention, the URL filtering device 40, the DB server 50, and the error content server 60 are used. By replacing the URL information of the regulated site with the URL defined in the error screen position DB 62 by the html file conversion unit 43, automatic connection to the regulated site based on the result of interpreting the html tag by the browser calculation processing unit 33 Requests can be suppressed. Also, for downloading error screen content from the error screen content DB 61 for display instead of the regulated site, a fixed URL is used so that the content on the cache memory 32 is within the valid cache period of the content. The content is reused, and the second and subsequent download requests are not made to the error content server 60. For example, when the browser arithmetic processing unit 33 tries to display the content before replacement as shown in FIG. 3 according to the contents of the browser memory 31, images for displaying the third and fifth lines are displayed on the restriction site. A request is made to the URL filtering device 40 to try to download from a certain www.danger.com, but the URL filtering device 40 replaces the URL with the error content server 60 as shown in FIG. The error screen content 61 is downloaded from the error content server 60. The browser calculation processing unit 33 downloads from the error screen content 61 in the third line, but since the fifth line has the same URL as the third line and is within the cache validity period, the browser calculation processing unit 33 No request is made to the error content server 60. For this reason, the load on the network can be reduced.

About the embodiment mentioned above, if the summary of the novel technical content is put together, it will become as the following additional remarks.
In addition, although one part or all part of the said embodiment is put together as follows as a novel technique, this invention is not necessarily limited to this.

(Supplementary note 1) A function for blocking a connection request by a relay proxy server when a connection request is transmitted from a content display terminal used by a user to a content server specified in advance as a regulated site on the Internet A URL filtering system comprising:
A URL filtering device including the proxy server is provided in the content display terminal,
The URL filtering device receives an inquiry from the proxy server and determines whether the destination of the connection request is the restriction target site; and other than the restriction target site on the Internet An html file conversion unit that replaces the destination of the connection request with a site other than the regulated site when there is a description for transmitting the connection request to the regulated site in the download file downloaded from the content server;
The html file conversion unit searches for whether the download file includes a URL for connecting to another site, and when the URL is detected by the search function, An inquiry function for inquiring whether or not the detected URL is the restriction target site, and when there is a reply from the URL evaluation unit that the detection target site is, the connection to the restriction target site is not made. As described above, a URL filtering system comprising a URL replacement function for replacing the detected URL with a URL other than the restricted site.

(Appendix 2) In the URL filtering system described in Appendix 1,
A URL database for restriction that stores a list of URLs of the restriction target sites is attached to the URL filtering device,
The URL evaluation unit searches whether the connection request transmission destination is included in the restriction target URL database,
A URL filtering system that determines whether or not the site is the restriction target site based on the search result.

(Appendix 3) In the URL filtering system described in Appendix 1,
An error content server for storing an error screen content for notifying the user that the connection destination is a regulated site as a URL other than the regulated site is provided in the URL filtering device,
The error content server includes an error screen location database that provides the html file conversion unit with a storage location of error screen content corresponding to the file format of the regulated site, the error screen content as the content display terminal, and the proxy A URL filtering system comprising: an error screen content database provided to a server unit; and an error screen management unit that adds, deletes, and corrects the contents of the error screen position database and the error screen content database by an external command .

(Appendix 4) In the URL filtering system according to any one of appendices 1 to 3,
The URL filtering system, wherein the content display terminal has a cache function for temporarily storing a downloaded file.

(Supplementary Note 5) A function for blocking a connection request by a relay proxy server when a connection request is transmitted from a content display terminal used by a user to a content server specified in advance as a regulated site on the Internet URL filtering system with
The proxy server receives a download file downloaded from a content server other than the regulated site,
The proxy server transmits the download file received by the proxy server to an html file conversion unit provided in advance in the proxy server,
The html file converter searches whether the URL for connecting to another site is described in the download file received by the html converter,
When the URL is detected by the search, the html file conversion unit inquires of the URL evaluation unit provided in advance in the html file conversion unit whether the URL belongs to the restricted site. Done
The URL evaluation unit that has received the inquiry determines whether the restriction target list provided in advance in the URL evaluation unit matches the detected URL,
The URL evaluation unit returns the determination result to the html file conversion unit as a result of an inquiry from the html file conversion unit,
In response to the inquiry result, when the restriction target list matches the detected URL, the html conversion unit replaces the URL with a description other than the restriction target site,
The URL filtering system control method, wherein the html conversion unit returns the download file including the converted URL to the proxy server.

(Supplementary note 6) In the URL filtering system control method according to supplementary note 5,
The URL evaluation unit that has received an inquiry about the URL detected by the html file conversion unit, based on the regulated site URL database provided in advance in the URL filtering device, the detected URL and the regulated site URL database To determine whether the URL matches
The URL filtering system control method, wherein the URL evaluation unit returns the determination result to the html file conversion unit as a result of an inquiry from the html file conversion unit.

(Supplementary note 7) In the URL filtering system control method according to supplementary note 5,
When the html file conversion unit that has received the inquiry result from the URL evaluation unit for the detected URL determines that the detected URL belongs to the restricted site, the URL is converted to the html file conversion unit. Replace with the error screen position in the error screen position database provided in advance in the
The URL filtering system control method, wherein the html conversion unit returns the download file including the replaced URL to the proxy server.

(Supplementary note 8) In the URL filtering system control method according to supplementary note 5,
The proxy server returns the download file returned from the html file conversion unit to the content display terminal,
A URL filtering system control method, wherein the download file is stored in a cache memory provided in advance in the content display terminal.

(Supplementary Note 9) A function of blocking a connection request by a relay proxy server when a connection request is transmitted from a content display terminal used by a user to a content server specified in advance as a regulated site on the Internet URL filtering system with
A download function for receiving a download file downloaded from a content server other than the regulated site;
An html file conversion unit transmission function for transmitting the download file received by the proxy server to an html file conversion unit provided in advance in the proxy server;
A search result determination function for determining whether or not a URL for connecting to another site is described in the download file received by the html conversion unit;
When the URL is detected as a result of the determination, a detected URL inquiry that inquires to the URL evaluation unit provided in advance in the html file conversion unit whether or not the URL belongs to the regulated site. function,
Upon receiving the inquiry, it is determined whether or not the restriction target list provided in advance in the URL evaluation unit matches the detected URL, and the determination result is used as a result of the inquiry from the html file conversion unit. URL determination function to return to the department,
A regulated URL conversion function for replacing the URL with a description other than the regulated site when the detected URL is the regulated site in response to the inquiry result;
And a replaced content return function for returning the download file including the replaced URL to the proxy server and returning the download file from the proxy server to the content display terminal;
A URL filtering system control program characterized in that a computer is realized.

(Appendix 10) In the URL filtering system control program described in appendix 9,
In response to an inquiry about the URL detected by the html file conversion unit, the detected URL and the URL in the regulated site URL database based on the regulated site URL database provided in advance in the URL filtering device, A URL database determination function in which the URL evaluation unit returns the determination result to the html file conversion unit as a result of an inquiry from the html file conversion unit.
A URL filtering system control program characterized in that the computer is realized.

(Appendix 11) In the URL filtering system control program described in Appendix 9,
In response to an inquiry result from the URL evaluation unit for the URL detected by the html conversion unit, when the detected URL is from the restricted site, the URL is preliminarily attached to the html file conversion unit. Error screen position replacement function to replace the error screen position stored in the error screen position database
A URL filtering system control program characterized in that the computer is realized.

(Supplementary note 12) In the URL filtering system control program according to supplementary note 9,
A cache memory storage function for operating the arithmetic unit of the content display terminal so as to store the download file returned from the proxy server in a cache memory provided in advance in the content display terminal;
A URL filtering system control program characterized in that the computer is realized.

  The present invention rewrites the information of the regulated site downloaded by the URL filtering device and holds it in the cache memory, so that URL filtering can be performed without imposing a load on the network when attempting to browse the regulated site for the second time or later. Can be performed.

30 Content display terminal 32 Cache memory (cache function)
40 URL filtering device 41 Proxy server part (proxy server)
42 URL evaluation unit 43 html file conversion unit 51 Restricted site URL (restricted site URL database)
60 Error content server 61 Error screen content DB (Error screen content database)
62 Error screen position DB (Error screen position database)
63 Error screen manager

Claims (10)

URL having a function of blocking a connection request by a relay proxy server when a connection request is transmitted from a content display terminal used by a user to a content server specified in advance as a regulated site on the Internet A filtering system,
A URL filtering device including the proxy server is provided in the content display terminal,
The URL filtering device receives an inquiry from the proxy server and determines whether the destination of the connection request is the restriction target site; and other than the restriction target site on the Internet An html file conversion unit that replaces the destination of the connection request with a site other than the regulated site when there is a description for transmitting the connection request to the regulated site in the download file downloaded from the content server;
The html file conversion unit searches for whether the download file includes a URL for connecting to another site, and when the URL is detected by the search function, An inquiry function for inquiring whether or not the detected URL is the restriction target site, and when there is a reply from the URL evaluation unit that the detection target site is, the connection to the restriction target site is not made. As described above, a URL filtering system comprising a URL replacement function for replacing the detected URL with a URL other than the restricted site. The URL filtering system according to claim 1,
A URL database of restriction target sites storing a list of URLs of the restriction target sites is attached to the URL filtering device,
The URL evaluation unit searches whether the connection request transmission destination is included in the restriction target URL database,
A URL filtering system that determines whether or not the site is the restriction target site based on the search result. The URL filtering system according to claim 1,
An error content server for storing an error screen content for notifying the user that the connection destination is a regulated site as a URL other than the regulated site is provided in the URL filtering device,
The error content server includes an error screen location database that provides the html file conversion unit with a storage location of error screen content corresponding to the file format of the regulated site, the error screen content as the content display terminal, and the proxy A URL filtering system comprising: an error screen content database provided to a server unit; and an error screen management unit that adds, deletes, and corrects the contents of the error screen position database and the error screen content database by an external command . The URL filtering system according to any one of claims 1 to 3,
The URL filtering system, wherein the content display terminal has a cache function for temporarily storing a downloaded file. URL having a function of blocking a connection request by a relay proxy server when a connection request is transmitted from a content display terminal used by a user to a content server specified in advance as a regulated site on the Internet In the filtering system,
The proxy server receives a download file downloaded from a content server other than the regulated site,
The proxy server transmits the download file received by the proxy server to an html file conversion unit provided in advance in the proxy server,
The html file converter searches whether the URL for connecting to another site is described in the download file received by the html converter,
When the URL is detected by the search, the html file conversion unit inquires of the URL evaluation unit provided in advance in the html file conversion unit whether the URL belongs to the restricted site. Done
The URL evaluation unit that has received the inquiry determines whether the restriction target list provided in advance in the URL evaluation unit matches the detected URL,
The URL evaluation unit returns the determination result to the html file conversion unit as a result of an inquiry from the html file conversion unit,
In response to the inquiry result, when the restriction target list matches the detected URL, the html conversion unit replaces the URL with a description other than the restriction target site,
The URL filtering system control method, wherein the html conversion unit returns the download file including the replaced URL to the proxy server. The URL filtering system control method according to claim 5,
The URL evaluation unit that has received an inquiry about the URL detected by the html file conversion unit, based on the regulated site URL database provided in advance in the URL filtering device, the detected URL and the regulated site URL database To determine whether the URL matches
The URL filtering system control method, wherein the URL evaluation unit returns the determination result to the html file conversion unit as a result of an inquiry from the html file conversion unit. The URL filtering system control method according to claim 5,
When the html file conversion unit that has received the inquiry result from the URL evaluation unit for the detected URL determines that the detected URL belongs to the restricted site, the URL is converted to the html file conversion unit. Is replaced with the error screen position in the error screen position database provided in advance,
The URL filtering system control method, wherein the html conversion unit returns the download file including the replaced URL to the proxy server. The URL filtering system control method according to claim 5,
The proxy server returns the download file returned from the html file conversion unit to the content display terminal,
A URL filtering system control method, wherein the download file is stored in a cache memory provided in advance in the content display terminal. URL having a function of blocking a connection request by a relay proxy server when a connection request is transmitted from a content display terminal used by a user to a content server specified in advance as a regulated site on the Internet In the filtering system,
A download function for receiving a download file downloaded from a content server other than the regulated site;
An html file conversion unit transmission function for transmitting the download file received by the proxy server to an html file conversion unit provided in advance in the proxy server;
A search result determination function for determining whether or not a URL for connecting to another site is described in the download file received by the html conversion unit;
When the URL is detected as a result of the determination, a detected URL inquiry that inquires to the URL evaluation unit provided in advance in the html file conversion unit whether or not the URL belongs to the regulated site. function,
Upon receiving the inquiry, it is determined whether or not the restriction target list provided in advance in the URL evaluation unit matches the detected URL, and the determination result is used as a result of the inquiry from the html file conversion unit. URL determination function to return to the department,
A regulated URL replacement function that replaces the URL with a description other than the regulated site when the detected URL is the regulated site in response to the inquiry result;
And a replaced content return function for returning the download file including the replaced URL to the proxy server and returning the download file from the proxy server to the content display terminal;
A URL filtering system control program characterized in that a computer is realized. The URL filtering system control program according to claim 9,
In response to an inquiry about the URL detected by the html file conversion unit, the detected URL matches the URL in the restricted site URL database based on the restricted site URL database provided in advance in the URL filtering device. A URL database determination function in which the URL evaluation unit returns the determination result to the html file conversion unit as a result of an inquiry from the html file conversion unit.
A URL filtering system control program characterized in that the computer is realized.

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