JP2004272319A - Computer and method provided with device for improving security and facilitating management - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a remote access from the Internet while keeping security by cybersecurity and the multiple security of a physical security means to a computer which is access-restricted for a security measure in a data center. <P>SOLUTION: According to a connection from a computer management by telephone or the like, an operation staff turns an external storage medium connecting switch 51 ON by physical motion to connect a computer A11 to the line of an external storage medium 31. With this connection as a turning point, a setting change starting program 201 is started, whereby a setting changing program 310 is started to change a first setting file 202 and a second setting file 410. A daemon program 303 such as telnet becomes accessible from a computer B12 by the setting change to enable the remote management work of the computer A11 from the computer B12. After the remote management work is ended, a setting recovery program 304 is executed to restore the access control. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a computer system including a plurality of computers, such as an Internet data center, which is used to manage and improve the security of other computers by remote access from a management computer. To a computer and a method for realizing the simplification.
Another aspect of the present invention is a computer that controls an application-specific device connected to the Internet, such as an information home appliance, in order to improve security and facilitate management when performing maintenance by remote access from a management computer. The computer to be realized.
[0002]
[Prior art]
The prior art of the present invention is as follows. With the spread of the Internet, large-scale computer systems such as data centers have become common, and each computer in the computer system provides a Web service or the like to a user. In order to enable these computers to provide services stably, it is necessary to perform management work such as upgrading of OS and applications, application of patches such as security, and system settings. Management work may be performed by going to the location of the target computer and logging in directly.However, in data centers and the like, the computer room and the staff room where operation staff are usually resident are often separated, and the computer room However, there is a case where a monitor, a keyboard, a desk or a chair at the time of work are not placed because of space, and it is very troublesome for a computer administrator to go to a computer room and perform management work. For this reason, the management work of the computer is usually performed by remote access such as logging in to the computer in the computer room by telnet or transferring a file by ftp from the management computer in the staff room. In this case, since remote access always involves the risk of unauthorized entry by a malicious third party, sufficient security measures are required. As one of the security measures, for example, in order to prevent a malicious third party from intruding into the computer system illegally, it is necessary to restrict the remote access between computers by opening the computer system's ports only to the minimum necessary. is there. Also, even if a malicious third party illegally invades the computer system, only the minimum necessary applications are activated on the computer so that applications related to system settings such as telnet and ftp are not executed without permission. Alternatively, the executable file of the unnecessary application may be deleted. Although such security measures impair the ease of management, security vulnerabilities also cover the survival of the data center, so the operation of the security measures is covered by the operations with some inconvenience. . For example, if direct remote access is restricted between arbitrary computers, a combination of computers that allow remote access is determined in advance, and remote access is possible when remote access is performed between arbitrary computers. Access the target computer via a combination of various computers. It is recommended to use a command with enhanced security such as SSH instead of using a vulnerable command such as telnet or ftp. In addition, management work may be performed by remote control software with security measures such as "Desktop On-Call (trademark)" developed and released by IBM and "VNC" (free software developed by AT & T). . Remote control software is software that allows a desktop screen of an arbitrary computer to be displayed as it is on the management computer, and allows the management computer to perform system settings for the target computer.
[0003]
The prior art of another embodiment of the present invention is as follows. With the spread of the Internet, information home appliances such as microwave ovens and air conditioners that connect to a network and exchange information have been developed. Until now, maintenance and repairs have been carried out by maintenance staff who go to the site or bring the home appliance to the manufacturer's maintenance center, etc.In the case of information home appliances, firmware can be updated via a network . However, each company is currently developing a maintenance method.
[0004]
[Problems to be solved by the invention]
By the way, when the restriction of remote access due to security measures is covered by the operation as in the prior art of the present invention, there is a problem that the operation management process becomes complicated or complicated. When the process becomes complicated, the number of causes of problems caused by human factors increases. On the other hand, if the process is to be carried out properly, an operation staff having such a skill must be constantly allocated, which causes a rise in labor costs. Even if remote control software and commands with enhanced security measures are used to make management easier, security is not necessarily sufficiently guaranteed, such as the risk that software has security holes. . Moreover, if the administrator authority of the computer is illegally stolen by a malicious third party in some way, security measures by the system setting have little meaning. Access to the computer system from the Internet is severely restricted in order to prevent malicious third parties from intruding into the system, but this limits the location of computer administrators.
[0005]
The problem to be solved by the present invention is to simplify the management of a computer such as a data center without reducing security during management by multiple security of cyber security and physical security.
One of the major features of information home appliances that are expected to spread in the future, as in the prior art of another embodiment of the present invention, is maintenance by remote access via the Internet. There is a risk of unauthorized remote access. In particular, it is expected that there will be many consumers of information home appliances who do not have knowledge of security. A problem to be solved by the second invention is to enable maintenance by remote access while maintaining security by means that do not burden consumers.
[0006]
[Means for Solving the Problems]
A computer system according to the basic concept of the present invention is a computer system in which a first computer (host) and a second computer (client) are connected via a network, and the first computer is physically intermittent. It has an external recording device connected via a switch, and the external recording device stores software necessary for system setting of the first computer. The first computer has an internal recording device (magnetic disk or semiconductor memory), and the internal recording device stores a setting file for permitting or prohibiting system setting by remote access from the second computer.
[0007]
Since the external recording device is isolated from the first computer by the physical intermittent means, it is safe from a software attack via the network. For example, the following can be considered as software or data stored in the external recording device.
(1) A setting change program that changes a setting file so as to permit system setting from the second computer.
(2) A daemon program for system settings.
(3) A setting recovery program that recovers based on the changes made by the setting change program
(4) A line disconnection program that physically disconnects the first computer and the external recording medium in conjunction with the setting recovery program.
[0008]
The most important of these is a setting change program for permitting external system settings, which must be stored in an external recording device. The other (2) to (4) may be stored in a recording device inside the first computer or other recording means.
[0009]
Another embodiment of the present invention is a computer connected to a client computer via a network, the computer including an external recording device connected via a switch that cannot be connected by software, and the external recording device includes: Stores software required for computer system settings.
[0010]
The software of the external recording device includes a setting change program that rewrites a setting file for permitting or prohibiting system setting by remote access from a client computer. The software of the external recording device may include a line disconnection program for disconnecting the switch. In other words, this switch cannot be connected by software but can be disconnected by software.When the permitted system settings are completed, the switch is automatically disconnected and access via the network is not possible. It becomes.
[0011]
To explain the present invention in more detail, in the present invention, there is a computer having an internal recording medium constituting a computer system in which at least two or more computers are connected by a network, and any first computer is any A setting file for permitting or prohibiting the system setting by remote access from the second computer is stored in the internal recording medium, and the setting file is a computer set to prohibit the system setting. In a computer that does not store a program for performing the processing in an internal recording medium, the first computer has an external recording medium and a connecting means physically connected to a line only by a physical connecting means. A setting change program that changes a setting file to allow system setting from the two computers, and a A program, a setting recovery program that recovers based on the change performed by the setting change program, and a line disconnection program that physically disconnects the first computer and the external recording medium in conjunction with the setting recovery program. In the internal recording medium, a setting change start program for detecting that the connecting means has been executed and starting to execute the setting change program is stored, and by executing the connecting means, the first computer and the external recording medium are connected to each other. The external recording medium becomes physically accessible from the computer, and the setting change program is executed by the setting change start program which is started to be executed by executing the connecting means, and the program for system setting is logically executed from the second computer. Executing the setting program allows the program for system setting from the second computer to be logically executed. Becomes infeasible, the external recording medium from the first computer is characterized by physically be inaccessible state by line disconnection program. In addition, the identification information of the second computer may be stored in the external recording medium, and the setting change program may use the identification information to change the setting file so as to permit only remote access from the second computer. Further, the setting change program may include a step of reflecting the change of the setting file on the first computer. Further, the internal recording medium may store a dummy program having the same name as the program for system setting but having a function different from the original function. Further, the setting change program may include a step of changing the setting to permit access when the first computer has been set to prohibit access from the second computer when the computer system includes a router. The connection means may have a function of turning on the power of the external recording medium. Further, the line disconnection program may have a function of turning off the power of the external recording medium. As described above, in the first invention, a computer having an internal recording medium constituting a computer system in which at least two or more computers are connected by a network, wherein the first computer is a system by remote access from a second computer A setting file for permitting or prohibiting the setting is stored in the internal recording medium, and the setting file is a computer which is set to prohibit the system setting by remote access, and the first computer internally records a program for performing the system setting. When the system setting of the first computer is performed by remote access from the second computer in a computer not stored in the medium, remote access is permitted by physical means such as connection means, and a program for system setting is executed. Depending on how you enable system configuration by making it executable , In the management of computer such as a data center, without reducing security when administered by multiple security cyber security and physical security, and to facilitate the management.
[0012]
According to another aspect of the present invention, in an embedded computer connected to the Internet and controlling an application-specific device remotely accessed from the computer via the Internet, the computer is connected to the line only by physical connection means. An external storage medium having an external storage medium and connection means, the external storage medium storing identification information of a computer remotely accessing the computer, a program for operating the computer, and a line disconnection program for disconnecting the line, and executing the connection means to execute the computer. The external storage medium is connected to the computer so that the computer can access the computer.By permitting remote access of the computer by the identification information, the computer can execute the above program. The feature is that the computer and the external storage medium are disconnected by implementing That. Note that the computer may have a timer, and the connection unit may be executed at a designated time according to the setting of the timer. Further, the computer may have a remote controller having a built-in timer, and when the time comes according to the setting of the timer, the remote controller may issue a command to execute the connecting means, and the connecting means may be executed. Therefore, in the second invention, it is possible to perform maintenance by remote access while maintaining security by means that does not burden consumers.
[0013]
The present invention also includes a method using the above system and an example in which these systems are applied to information home appliances.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a block diagram showing an overall configuration including a data center 1 constituted by computers in this embodiment, a computer B12 used by a computer administrator, and the Internet 2 connecting them. In FIG. 1, a computer A11 is connected to the Internet 2 via a router 41. Although not shown in this embodiment, the OS of the computer A11 is assumed to be UNIX (registered trademark). However, it is obvious that the present invention is applied to an OS other than UNIX (registered trademark).
[0015]
In FIG. 1, the computer A11 has a built-in internal storage medium 21. The internal storage medium 21 stores a setting change start program 201, a first setting file 202, and a dummy daemon program 203. The computer A11 has an associated external storage medium 31, and the external storage medium 31 stores a setting change program 301, identification information 302, a daemon program 303, a setting recovery program 304, and a line disconnection program 305. In the present embodiment, the daemon program 303 is described as telnet for the sake of simplicity, but the present invention is similarly effective with any program.
[0016]
The computer A11 and the external storage medium 31 are connected by the line L2, but the line L2 is disconnected by the external storage medium connection switch 51 in the initial state of the present invention. Although FIG. 1 illustrates the computer A11 and the external storage medium 31 physically separated from each other, the computer A11 and the external storage medium 31 may be included in the same housing. Further, although a switch is described as a means for connecting the computer A11 and the external storage medium 31, any other shape may be used as long as the function is the same. Further, when the computer A11 and the external storage medium 31 are physically separated from each other, the external storage medium 31 is directly connected to or inserted into a corresponding connection or insertion portion of the computer A11, thereby also functioning as the external storage medium connection switch 51. It doesn't matter. Further, the external storage medium connection switch 51 has a function of turning on the power of the external storage medium 31. When the external storage medium connection switch 51 is executed, the power of the external storage medium 31 is turned on and the external storage medium 31 is transmitted from the computer A11. It may be accessible.
[0017]
When the line L2 is connected by the external storage medium connection switch 51, the setting change activation program 201 generates an external interrupt, and is activated by the external interrupt. The setting change start program 201 is programmed to start the setting change program 301 stored in the external storage medium 31.
In the computer A11, Xinetd, which is a known server program, is running in order to respond to a service request from another computer. In Xinetd, access control by domain name or IP address, restriction of access time, restriction of the number of connections, and the like can be performed. One example of the first setting file 202 is a setting file for setting access control by Xinetd. conf. Xinetd. The directory in which the executable file of the daemon program such as telnet exists is described in the conf. When the computer A11 receives a service request from another computer, the request source is Xinetd. conf is checked, and if the request is from a valid computer, Xinetd. A daemon program having an executable file in the location described by "conf" is executed. In the initial state of the present invention, it is assumed that the setting is such that the daemon program of the computer A11 cannot be executed from another computer.
[0018]
Access control between computers is also performed by the router 41. For example, the router 41 can permit or reject a packet entering the computer A11 based on a source address, a destination address, a requested service, and the like by using an ACL (access control list). A specific example of the second setting file 401 is an access control list. In the initial state of the present invention, the second setting file 401 is set so that the computer A11 rejects telnet from other computers.
The dummy daemon program 203 is a dummy of a daemon program such as telnet. Even if a malicious third party gets under the access control and accesses the computer A11, it is common to delete the daemon program from the internal storage medium 21 so that the third party does not execute the daemon program. is there. In the present invention, the dummy daemon program 203 is stored in the internal storage medium 21 instead of the daemon program. Thus, even if a third party attempts to start the daemon program, the dummy daemon program 203 is actually started. The dummy daemon program 203 can be programmed to have an arbitrary function. For example, the dummy daemon program 203 is programmed to record the IP or domain name of the computer to which the service is requested and to display a warning on the monitor of the computer A11. Thus, the behavior of a malicious third party can be recorded and later used as reference data for identifying the third party. The first setting file 202 is set so that the execution file of the dummy daemon program 203 is executed for the requested service.
[0019]
The setting change program 301 has two functions. In the first function, the first setting file 202 of the computer A11 and the second setting file 401 of the router 41 are changed to make a specific daemon program of the computer A11 logically accessible from a specific computer (here, the computer B12). . The information registered in advance in the identification information 302 as shown in FIG. 2 is used for changing the first setting file 202 and the second setting file 401. The information included in the identification information 302 includes at least an access-permitted computer ID 321 corresponding to the computer identifier 101 of the computer B12 to which access is permitted, an access-permitted user ID 322 of an accessible person, and execution of a daemon name permitted to the computer B12. An authorization daemon program 323. Here, for example, an IP address is used as the access permission computer ID. Note that there may be a plurality of access-permitted computer IDs, access-permitted user IDs, and execution-permitted daemon programs. In the second function, the first setting file 202 is changed so that Xinetd operating on the computer A11 starts the daemon program 303 on the external storage medium 31. Specifically, Xinetd. The directory where the executable file of the conf daemon program exists is changed from the directory where the dummy daemon program 203 exists on the internal storage medium 21 to the location where the daemon program 303 exists on the external storage medium 31. The setting change program 301 also has a function of creating backups of these setting files (the first setting backup file 204 and the second setting backup file 402, respectively) before changing the first setting file 202 and the second setting file 401. Have.
The setting recovery program 304 has a function of returning the change made by the setting change program 301 to the state before the change. Specifically, the first setting backup file 204 is changed to the first setting file 202, and the second setting backup file 402 is changed to the second setting file 401. After the change is made, the line disconnection program 305 is started. The line disconnection program 305 has a function of disconnecting the line L2 connected by the external storage medium connection switch 51.
[0020]
The procedure of the first embodiment of the present invention will be described below with reference to FIGS.
FIG. 3 shows a physical operation procedure at the start of the computer management work. When the computer administrator starts the computer management work, he or she notifies the computer operation staff resident in the data center of the intention to start the management work using a telephone or the like (A1). In this case, the location of the computer administrator is arbitrary. Since the data center staff is directly contacted by the computer administrator, the validity of the computer administrator can be confirmed (A2). Therefore, it is determined whether the contacted person is a legitimate computer administrator (A3), and if the contact is from the legitimate computer administrator, the operation staff turns on the external storage medium connection switch 51 of the computer (A4). At this time, the staff room in which the operation staff resides and the computer room may not be the same, but usually, they are close to each other, so that the external storage medium connection switch 51 can be turned on immediately after contact from the computer administrator. On the other hand, if the communication is not from a valid computer administrator, an alarm is issued to notify the communication from an unauthorized third party (A5), and the management work is terminated without turning on the external storage medium connection switch 51. The procedure shown in FIG. 3 improves security by interposing physical means.
[0021]
FIG. 4 shows the procedure until the computer A11 becomes logically accessible after the external storage medium connection switch 51 is turned on (A4). When the external storage medium connection switch 51 is turned on, the line between the computer A11 and the external storage medium 31 is connected (A7), which triggers an external interrupt (A8). The computer A11 detects this external interrupt and activates the setting change activation program 201 (A9). The setting change start program 201 starts the setting change program 301 by its function (A10). Subsequently, the setting change program 301 first creates the first setting backup file 204 using the function (A11), and thereafter changes the first setting file 202 using the access-permitted computer ID 321, the access-permitted user ID 322, and the execution-permitted daemon program 323. (A12). Subsequently, the setting change program 301 creates the second setting backup file 402 (A13), and thereafter changes the second setting file 401 using the access-permitted computer ID 321, the access-permitted user ID 322, and the execution-permitted daemon program 323 (A14). . After the change of the first setting file 202 and the second setting file 401 is completed, if necessary, a process for reflecting the changes to the computer A11 and the router 41 is performed (A15). For example, restarting Xinetd or restarting the router 41 is a process for reflecting the change. At this point, the daemon program 303 of the external storage medium 31 can be physically and logically accessed from the computer B12.
[0022]
FIG. 5 shows a procedure from when the daemon program 303 becomes accessible from the computer B12 to when the computer administrator becomes able to use the daemon program. The computer administrator executes telnet on the computer A11 because the daemon program 303 can be accessed (A16). The computer A11 determines the validity of the user according to the access-permitted user ID 322 (A17). If it is determined that the user is a valid user, a login permission is issued (A18), and a daemon program execution permission is issued (A19). On the other hand, if it is not determined that the user is a legitimate user, a warning that an unauthorized third party accesses is issued (A20), and the management work is terminated. Thereafter, the computer administrator can perform the management work of the computer A11 within the allowable range.
[0023]
FIG. 6 shows a procedure at the end of the management work. The computer administrator executes the setting recovery program 304 when a series of management operations is completed and it is no longer necessary to use the daemon program (B1). The setting recovery program 304 changes the first setting file 202 based on the first setting backup file 204 by the function. Subsequently, the second setting file 401 is changed based on the second setting backup file 402. After the change of the first setting file 202 and the second setting file 401 is completed, if necessary, a process for reflecting the changes to the computer A11 and the router 41 is performed (B4). For example, Xinetd is restarted, and the router 41 is restarted. As a result, the daemon program 303 becomes logically inaccessible from the computer B12.
[0024]
Finally, as shown in FIG. 7, the line disconnection program 305 is started following the setting recovery program 304 (B6). Thereby, the external storage medium 31 is disconnected from the computer A11.
The above is the description of the first embodiment of the present invention.
[0025]
Next, a second embodiment of the present invention will be described with reference to FIGS. 8 to 9 by taking an information home appliance connected to the Internet as an example. FIG. 8 is a block diagram showing the overall configuration including the information home appliance and the computer that manages the information home appliance in this embodiment. In FIG. 8, the information home appliance 71 is connected to the computer C61 via the Internet 2.
In FIG. 8, the information home appliance 71 has a corresponding external storage medium 91, and the external storage medium 91 stores identification information 92, a management program 93, and a line disconnection program 94. An arbitrary program can be stored as the management program 93. The information home appliance 71 and the external storage medium 91 are connected by a line L4. The line L4 is disconnected by an external storage medium connection switch 81 in an initial state of the present invention. There are several methods for mounting the external storage medium connection switch 81 and the external storage medium 91 as in the first embodiment.
[0026]
The external storage medium connection switch activation timer A72 is a timer for automatically operating the external storage medium connection switch 81. The external storage medium connection switch 81 can be operated at an arbitrary time according to the setting of the user of the information home appliance 71. The remote controller 73 incorporates an external storage medium connection switch activation timer B74 for automatically operating the external storage medium connection switch 81. By implementing the external storage medium connection switch 81 by the remote controller 73 physically separated from the information home appliance 71, the security is further improved.
[0027]
In the following, the procedure of the means for implementing the remote management of the information home appliance according to the second embodiment of the present invention will be described with reference to FIG. The user sets the remote management start time in the timer A72 for activating the external storage medium connection switch or the timer B74 for activating the external storage medium connection switch in accordance with a prior agreement with the management work executor (C1). Timer input is a common operation and is not too burdensome for many consumers. The start of management work may be directly input to the information home appliance 71 without using a timer by using a switch or the like. At the designated time, the external storage medium connection switch 81 is operated by the external storage medium connection switch activation timer A72 or the command of the external storage medium connection switch activation timer B74 (C2). At the scheduled time, the management worker attempts to access the information home appliance 71 (C3). The information home appliance 71 determines the legitimacy of the manager based on the identification information 92 (C4), and if the manager is a valid manager, gives the manager permission to access the information home appliance 71 and the external storage medium 91 ( C5) If the administrator is an unauthorized administrator, a warning is issued that the access is made by a third party, and the management work is terminated (C8). Finally, after the management of the information home appliance 71 is completed, the legitimate administrator executes the line disconnection program 94 to normally end the management work. The above is the description of the second embodiment of the present invention.
[0028]
【The invention's effect】
According to the first embodiment of the present invention, in the management of a computer such as a data center, it becomes possible to simplify the management without lowering the security at the time of management by the multiple security of cyber security and physical security. The second embodiment of the present invention enables maintenance by remote access while maintaining security by means that do not burden consumers.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration including a data center configured by a computer according to a first embodiment of the present invention, computers used by a computer administrator, and the Internet connecting them.
FIG. 2 is a diagram showing details of identification information in an external storage medium.
FIG. 3 is a flowchart showing a procedure of a physical operation at the start of a computer management operation.
FIG. 4 is a flowchart showing a procedure until an external storage medium becomes logically accessible.
FIG. 5 is a flowchart showing a procedure until a computer administrator can use a daemon program in an external storage medium.
FIG. 6 is a flowchart showing an end procedure at the end of management work.
FIG. 7 is a flowchart showing a procedure for disconnecting a line between a computer and an external storage medium.
FIG. 8 is a diagram showing an overall configuration including an information home appliance and a management computer according to a second embodiment of the present invention.
FIG. 9 is a flowchart showing a procedure of a means for performing remote management of the information home appliance.
[Explanation of symbols]
11 Computer
31 External storage media
51 External storage medium connection switch
41 router
12 Management computer
201 Setting change start program
301 Setting change program
302 Identification information
303 daemon program
304 Setting recovery program
305 Line disconnection program
71 Information appliances
72 External storage medium connection switch start timer A
73 Remote Controller
74 Timer B for activating external storage medium connection switch
91 External storage media
81 External storage medium connection switch
93 Management program
94 Line disconnection program.

Claims (18)

A system setting method of a computer system in which at least a first computer and a second computer are connected by a network,
The first computer stores a setting file for permitting or prohibiting system setting by remote access from the second computer in an internal recording medium,
The above configuration file is set to prohibit system settings by remote access.
The first computer does not store a program for performing the system setting in the internal recording medium,
The first computer has a configuration in which a line is connected only by an external recording medium and physical connection means,
The external recording medium is configured based on a setting change program that changes the setting file so as to permit the system setting from the second computer, a program for the system setting, and a change performed by the setting change program. Storing a setting recovery program for recovering, and a line disconnection program for physically disconnecting the first computer and the external recording medium in conjunction with the setting recovery program;
The internal recording medium stores a setting change start program that detects execution of the connection unit and starts executing the setting change program,
When the first computer and the external recording medium are physically connected, the external recording medium is physically accessible from the first computer,
By executing the connection means, the setting change start program started to be executed, the first setting change program is executed, and the program for the system setting can be logically executed from the second computer,
By executing the setting recovery program, the system setting program becomes logically unexecutable from the second computer,
A system setting method, wherein the external recording medium is physically inaccessible from the first computer by the line disconnection program. A computer system in which a first computer and a second computer are connected by a network,
The first computer has an external recording device connected via a physically intermittent switch,
A computer system in which the external recording device stores software necessary for system setting of the first computer. The first computer has an internal recording device,
3. The computer system according to claim 2, wherein the internal recording device stores a setting file for permitting or prohibiting a system setting by remote access from the second computer. 4. The computer system according to claim 3, wherein the software includes a setting change program that changes a first-half setting file so as to permit a system setting from the second computer. The computer system according to claim 4, wherein the software includes a daemon program for the system setting. The software includes a setting recovery program that recovers based on the change performed by the setting change program, and a line disconnection program that physically disconnects the first computer and the external recording medium in conjunction with the setting recovery program. The computer system according to claim 5, including: The external recording device stores identification information of the second computer, and the setting change program uses the identification information to change the setting file so as to permit only remote access from the second computer. 7. The computer system according to claim 6, wherein: 7. The computer system according to claim 6, wherein the setting change program includes a step of reflecting the change of the setting file on the first computer. 7. The computer according to claim 6, wherein the internal recording medium stores a dummy program having the same name as the system setting program but having a function different from an original function. The first term setting change program includes a step of changing the setting to permit access when the first computer is set to prohibit access from the second computer when a router is included in the computer system. Item 6. The computer according to Item 6. 7. The computer system according to claim 6, wherein said connection means has a function of turning on said external recording medium. 7. The computer system according to claim 6, wherein the line disconnection program has a function of turning off the power of the external recording medium. A computer connected to the client computer via a network,
The computer has an external recording device connected via a switch that cannot be connected by software,
A computer in which the external recording device stores software necessary for system setting of the computer. 14. The computer according to claim 13, wherein the software of the external recording device includes a setting change program for rewriting a setting file for permitting or prohibiting a system setting by remote access from the client computer. 14. The computer according to claim 13, wherein the software of the external recording device includes a line disconnection program for disconnecting the switch. An embedded computer that connects to the Internet and controls an application-specific device that is remotely accessed from the computer via the Internet.
The computer includes an external storage medium to which a line is connected only by physical connection means and the connection means,
The external storage medium stores identification information of a computer that remotely accesses the computer, a program for operating the computer, and a line disconnection program for disconnecting the line,
The computer is accessible from the computer by executing the connection means and connecting the computer and the external storage medium,
By allowing remote access of the computer by the identification information, the computer can execute the program,
A computer wherein the computer and the external storage medium are disconnected by executing the line disconnection program from the computer. 17. The computer according to claim 16, wherein the computer includes a timer, and the connection unit is executed at a designated time according to the setting of the timer. The computer comprises a remote controller having a built-in timer, wherein at a specified time by the setting of the timer, the remote controller issues a command to execute the connecting means, and the connecting means is executed. 16. The computer according to item 16.

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