Electrical computers and digital processing systems: support – Multiple computer communication using cryptography – Protection at a particular protocol layer
Reexamination Certificate
1999-05-07
2003-11-04
Hua, Ly V. (Department: 2131)
Electrical computers and digital processing systems: support
Multiple computer communication using cryptography
Protection at a particular protocol layer
C713S152000
Reexamination Certificate
active
06643780
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of communications in general and more particularly to cable modems and methods.
BACKGROUND OF THE INVENTION
With the rise in popularity of the Internet, many users are accessing the Internet through the Public Switched Telephone Network (PSTN) over a modem connected to a telephone line in the user's home. Unfortunately, the bandwidth provided by home telephone lines may prove to be inadequate for some applications on the Internet. For example, some data sets provided by the Internet may be so large that it is difficult to transfer the data set over the telephone line in a given time so that the application operates in a real-time manner. In particular, current residential telephone modem technology may be limited to data rates on the order of 56 kilobaud (kb).
In an attempt to reduce the bandwidth problem associated with the telephone lines described above, there have been efforts to provide Internet service over coaxial cables used to provide cable TV. Accordingly, the user may access the Internet over the cable system using a cable modem to provide data rates of 42 megabaud or higher. Accessing the Internet via a cable system may involve initializing the cable modem each time the cable modem is turned on, during which the cable modem may register with the cable system. For example, when the user wishes to access the Internet, the user may turn on the cable modem which then registers with the cable system.
As the number of cable modems handled by the cable system increases, the time needed to register each cable modem may also increase thereby lengthening the registration time. For example, if hundreds of cable modems are used in a cable system, the registration time for a selected cable modem may be several minutes. Consequently, the user may wish to avoid turning the cable modem off in an effort to avoid the delay incurred by a lengthy registration process. For example, if the user turns the cable modem on just prior to accessing the Internet, the user may need to wait for the registration process to complete before gaining access to the Internet. Moreover, cable systems may also provide television and telephone service to a user's home such as by routing these services through the cable modem to the television and telephone. Accordingly, the user may desire that the cable modem be left on so as not to interrupt telephone or television service.
Unfortunately, leaving the cable modem turned on may decrease the security of the computer to which the cable modem is attached. In particular, the computer may be more susceptible to attack via the cable. For example, an unauthorized user may attempt to gain access to the computer via the cable. Moreover, because the cable provides relatively high bandwidth, relatively simple attacks, such as trying a large number of password combinations, may require only a short time to be successful. In view of the above, there exists a need to improve the security of cable modems used to access the Internet via cable systems.
Accordingly, the present invention may allow improvement in the security of cable modems by blocking access to the cable modem from the cable system while the cable modem is in safe mode. Blocking data transfers may allow the subscriber to leave the host system connected to the cable modem, thereby possibly avoiding the delay associated with the registration process while reducing the security threats posed by maintaining a physical connection to the cable modem.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to allow improvement in cable modems and methods.
It is another object of the present invention to allow improvement in the security of able modems and methods.
These and other objects are provided by blocking data transfers from a cable system to a cable modem addressed to a host system coupled to the cable modem during a safe mode of operation and providing the data transferred from the cable system to the addressed host system during a normal mode of operation. Blocking the data transfers addressed to a host system during the safe mode of operation may improve the security of the cable modem. In particular, while the cable modem operates in the safe mode of operation, unauthorized users will not be able to gain access to the host system via the cable system. Moreover, other services provided via the cable modem can be available while the cable modem operates in the safe mode. For example, telephone or television services may be unaffected by the safe mode of operation. Subscribers may, therefore, leave the cable modem and host turned on to avoid a lengthy registration process while reducing the likelihood of unauthorized access to the host system.
In another aspect of the present invention, multiple host systems can be coupled to the cable modem. Accordingly, the cable modem can provide a safe mode of operation for each host system coupled to the cable modem. In particular, the data transfer can include an address portion, and each of the host systems can be identified by a respective host address. Data transfers can be addressed to a selected host system using the respective host address. Therefore, data transfers addressed to a first host system can be blocked when the cable modem operates in a first safe mode of operation for the first host system, and data transfers addressed to a second host system can be blocked when the cable modem operates in a second safe mode of operation for the second host system.
In a further aspect of the present invention, the cable modem can include a safe mode button wherein the safe mode of operation is invoked upon pushing the safe mode button. In another embodiment, the safe mode of operation can be invoked after the expiration of a timer that times an interval of inactivity at the host system. In a further embodiment, the cable modem can switch from the safe mode of operation to the normal mode of operation after activity is detected at the host system. In still another embodiment, the mode of operation is invoked on receipt of a command from the host system.
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International Search Report, PCT/US00/10473, Sep. 13, 2000.
Ericsson Inc.
Hua Ly V.
Myers Bigel Sibley & Sajovec P.A.
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