Computer system which is disabled when it is disconnected from a network

• US 6,105,136 A
• Filed: 02/13/1998
• Issued: 08/15/2000
• Est. Priority Date: 02/13/1998
• Status: Expired due to Term

• Current Assignee: Lenovo PC International Limited (Lenovo Group Ltd.)
• Original Assignee: International Business Machines Corporation
• Inventors: Locker, Howard J., Ellison, Brandon J., Steinmetz, Michael J., Springfield, Randall S., Cromer, Daryl C., Ward, James P.
• Primary Examiner(s): Palys, Joseph E.
• Assistant Examiner(s): Mai, RiJue
• Application Number:
  US09/023,606
• Time in Patent Office: 914 Days
• Field of Search: 713/200, 713/201, 713/202, 714/43, 714/4, 395/700, 380/25, 380/4, 340/571, 709/201, 709/220, 709/221, 709/222, 709/223, 709/217, 709/218, 709/227, 709/228, 709/249, 709/305, 709/304, 710/10, 710/100, 710/104
• US Class Current: 726/34
• CPC Class Codes: G06F 21/78 to assure secure storage of data address-based protection against unauthorised use of memory G06F12/14; record carriers for use with machines and with at least a part designed to carry digital markings G06K19/00
• CPC Class Codes: G06F 21/86 Secure or tamper-resistant housings

Abstract

Described is a computer system which is coupled to a remote computer via a data communication link. The computer system has a normally closed enclosure and is capable of securing data retained within the system against unauthorized access. The computer system includes an erasable memory element mounted within the enclosure for selective activation to active and inactive states and for receiving and storing a security password when in the active state. A manually operable option switch is mounted within the enclosure. The option switch is operatively connected with the erasable memory element and manually settable by a user of the computer system for setting the erasable memory element to the active and inactive states. A communication line detector is operatively connected with the erasable memory element for detecting a disconnection of the data communication link and for clearing any stored security password from the erasable memory element in response to a change of the communication link detector between a first state and a second state.

Claims

1. A computer system for receiving and retaining data and capable of securing data retained within the system against unauthorized access, said system being coupled to a remote computer via a data communication link, said system comprising:

a normally closed enclosure,

an erasable memory element mounted within said enclosure for selective activation to active and inactive states and for receiving and storing a security password when in the active state,

a manually operable option switch mounted within said enclosure, said option switch being operatively connected with said erasable memory element and manually settable by a user of the computer system for setting said erasable memory element to the active and inactive states,

communication link detector operatively connected with said erasable memory element for detecting a disconnection of said data communication link and for clearing any stored security password from said erasable memory element in response to a change of said communication link detector between a first state and a second state, and

a central processing unit mounted within said enclosure and operatively connected with said erasable memory element for controlling access to at least certain levels of data stored within the system by distinguishing between the active and inactive states of said memory element and between entry and non-entry of any stored security password.

2. The computer system of claim 1, wherein said detector is a network connector in circuit communication with said CPU, said network connector being operative to generate a link signal in a first state as long as a valid communication link is maintained with said remote computer and wherein said detector is operative to change said link signal from said first state to a second state when said data communication link is disconnected and further wherein said link signal status is detected by said computer system.

3. The computer system of claim 2, wherein on a power on after said communication line has been disconnected, said system is unable to boot its operating system until a valid link is reestablished with said remote computer system.

4. The computer system of claim 2, wherein after said system is reconnected to said remote computer system with a valid link, said network connector sends an information packet over said communication link to said remote computer, said information packet containing information which allows a system administrator to specifically identify whether said computer system was disconnected inadvertently or a system level break-in has occurred.

5. The computer system of claim 4, wherein if said system was inadvertently disconnected from said remote computer, said remote computer sends an approval to boot packet to said computer system which in response thereto clears said LANLeash tamper signal and continues a boot process to boot the operating system.

6. The computer system of claim 1, wherein said detector is a network connector in circuit communication with said CPU, said network connector being operative to generate a link signal which changes from a first state to a second state when said data communication link is disconnected.

7. The computer system of claim 1, further including a tamper detection switch mounted within said enclosure and operatively connected with said erasable memory element for detecting opening of said enclosure and for clearing any stored security password from said erasable memory element in response to any switching of said tamper switch.

8. The computer system of claim 1, wherein said security password is a privileged access password.

9. The computer system of claim 5, wherein said security password is a privileged access password.

10. The computer system of claim 1, further including a logic circuit coupled to said communication link detector and said logic circuit is settable by a user between an enabled state and a disabled state,

wherein when said logic circuit is in the enabled state, said changing of said link signal from said first state to said second state clears said security password and activates a LANLeash tamper signal and wherein when said logic circuit is in said disabled state said changing of said states of said link signal does not clear said security password and said LANLeash tamper signal is not activated.

11. The computer system of claim 8, wherein said computer system is operative to monitor said LANLeash tamper signal such that on a power on cycle, said system checks the status of said LANLeash tamper signal and (1) if said tamper signal is active, said system is unable to boot its operating system until a valid link is reestablished with said remote computer system, or (2) if said tamper signal is not active, said system is able to boot its operating system.

12. A computer system for receiving and retaining data and capable of securing data retained within the system against unauthorized access, said system being coupled to a remote computer via a data communication link, said system comprising:

a normally closed enclosure,

a first erasable memory element mounted within said enclosure for selective activation to active and inactive states and for receiving and storing a privileged access password when in the active state,

a manually operable option switch mounted within said enclosure and operatively connected with said first erasable memory element for setting said first erasable memory element to the active and inactive states,

a second erasable memory element mounted within said enclosure for receiving and storing data indicative of the state of said first erasable memory element and of correct entry of any stored privileged access password,

communication link detector operatively connected with said second erasable memory element for detecting unauthorized disconnection from said data communication link and for invalidating any privileged access password stored in said first erasable memory element in response to any change of said communication link detector between a first state and a second state,

a tamper detection switch mounted within said enclosure and operatively connected with said second erasable memory element for detecting unauthorized opening of said enclosure and for invalidating any privileged access password stored in said first erasable memory element in response to any switching of said tamper switch, and

a central processing unit mounted within said enclosure and operatively connected with said erasable memory elements for controlling access to at least certain levels of data stored within the system by distinguishing between the active and inactive states of said first memory element and between entry and non-entry of any valid stored privileged access password.

13. The computer system of claim 12, wherein said detector is a network connector in circuit communication with said CPU, said network connector being operative to generate a link signal in a first state as long as a valid communication link is maintained with said remote computer and wherein said detector is operative to change said link signal from said first state to a second state when said data communication link is disconnected.

14. The computer system of claim 13, wherein on a power on after said communication line has been disconnected, said system is unable to boot its operating system until a valid link is reestablished with said remote computer system.

15. The computer system of clam 13, further including a logic circuit coupled to said communication link detector and said logic circuit is settable by a user between an enabled state and a disabled state,

wherein when said logic circuit is in the enabled state, said changing of said link signal from said first state to said second state clears said security password and activates a LANLeash tamper signal and wherein when said logic circuit is in said disabled state said changing of said states of said link signal does not clear said security password and said LANLeash tamper signal is not activated.

16. The computer system of claim 15, wherein said computer system is operative to monitor said LANLeash tamper signal such that on a power on cycle, said system checks the status of said LANLeash tamper signal and (1) if said tamper signal is active, said system is unable to boot its operating system until a valid link is reestablished with said remote computer system, or (2) if said tamper signal is not active, said system is able to boot its operating system.

17. A computer system for receiving and retaining data and capable of securing data retained within the system against unauthorized access, said system being coupled to a remote computer via a data communication link, said system comprising:

a network connector for communicating data with said computer system, said network connector being supplied with auxiliary power and being operative to communicate with said computer system regardless of whether said computer system is in a normal operating state,

said network connector being in circuit communication with a CPU, said network connector being operative to generate a link signal in a first state as long as a valid communication link is maintained with said remote computer and wherein said connector is operative to change said link signal from said first state to a second state when said data communication link is disconnected, and

wherein on a power on after said communication link has been disconnected, said system is unable to boot its operating system until a valid link is reestablished with said remote computer system.

18. The computer system of claim 17, wherein if said communication link is valid said link signal is active and if said communication link is not valid said link signal is inactive and further wherein said link signal status is detected by said computer system.

19. The computer system of claim 17, wherein said computer system further includes a normally closed enclosure and an erasable memory element mounted within said enclosure for selective activation to active and inactive states for receiving and storing a security password when in the active state.

22. The computer system of claim 17, wherein after said system is reconnected to said remote computer system with a valid link, said network connector sends an information packet over said communication link to said remote computer, said information packet containing information which allows a system administrator to specifically identify whether said computer system was disconnected inadvertently or a system level break-in has occurred.

23. The computer system of claim 22, wherein if said system was inadvertently disconnected from said remote computer, said remote computer sends an approval to boot packet to said computer system which in response thereto clears said LANLeash tamper signal and continues a boot process to boot the operating system.

20. The computer system of clam 19, further including a logic circuit coupled to said network connector, said logic circuit being settable by a user between an enabled state and a disabled state,

wherein when said logic circuit is in the enabled state, said changing of said link signal from said first state to said second state clears said security password and activates a LANLeash tamper signal and wherein when said logic circuit is in said disabled state said changing of said states of said link signal does not clear said security password and said LANLeash tamper signal is not activated.

21. The computer system of claim 20, wherein said computer system is operative to monitor said LANLeash tamper signal such that on a power on cycle, said system checks the status of said LANLeash tamper signal and (1) if said tamper signal is active, said system is unable to boot its operating system until a valid link is reestablished with said remote computer system, or (2) if said tamper signal is not active, said system is able to boot its operating system.