# Patent

## Title
Secure implementation of network-based sensors

## Abstract

Sensing apparatus includes a network camera, which is configured to capture images of a scene and to output a sequence of data packets containing digitized video data responsively to the images. A one-way link is coupled to the network camera so as to transmit the data packets from the network camera to a packet communication network.

## Background
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation of U.S. patent application Ser. No. 11/977,391, filed Oct. 24, 2007 now U.S. Pat. No. 8,223,205.


FIELD OF THE INVENTION
The present invention relates generally to computerized monitoring systems, and specifically to prevention of unauthorized access to such systems.
BACKGROUND OF THE INVENTION
Network cameras (also known as IP cameras) are becoming increasingly popular in surveillance applications. The term “network camera” is used in the context of the present patent application and in the claims to refer to a self-contained video device that outputs a sequence of data packets containing digitized image data. Such cameras contain not only a video sensor and associated video electronics, but also digital processing circuitry and a packet network interface with the necessary hardware and software to plug in directly to a packet communication network, such as an Ethernet local area network (LAN). Network cameras are particularly convenient for security applications, because they can be deployed freely in and around a facility using the existing LAN infrastructure, rather than requiring dedicated cabling to be run to each camera as in traditional video security systems.
A growing number of manufacturers supply network cameras. Axis Communications (Lund, Sweden), for example, sells a line of network cameras that may be used in embodiments of the present invention that are described hereinbelow.
In a computer network handling sensitive data, such as data in military or financial environments, portions of the network may be connected by one-way links. The term “one-way link” is used in the context of the present patent application and in the claims to refer to a communication link that is physically configured to carry signals in one direction and to be incapable of carrying signals in the opposite direction. For example, confidential data that must not be accessed from external sites may be stored on a computer that is configured to receive data over a one-way link and has no physical outgoing link over which data might be transmitted to the external site.
One-way links may be implemented, for example, using WaterfallTM systems, which are manufactured by Gita Technologies, Ltd. (Rosh HaAyin, Israel). The Waterfall system provides a physical one-way connection based on fiberoptic communication, using an underlying proprietary transfer protocol. When a transmitting computer is connected by a Waterfall system (or other one-way link) to a receiving computer, the receiving computer can receive data from the transmitting computer but has no physical means of sending any return communications to the transmitting computer.
SUMMARY OF THE INVENTION
Despite the convenience of network cameras (and other sorts of network sensors) for security applications, deployment of such cameras on a LAN creates a new security risk: Malicious parties may attempt to gain access to the LAN via the point of connection of the camera to the LAN. This risk is particularly acute when cameras are deployed on the outside of a secured facility, such as on the outer wall of a building or a perimeter fence, or in sparsely attended locations within the premises, such as washrooms, corridors and basements.
Embodiments of the present invention that are described hereinbelow use one-way links in order to mitigate this risk. By connecting a network camera to the network only via a one-way link, for example, the opportunity for a malicious party to access resources on the network via the point of connection of the camera is curtailed or eliminated entirely. This use of a one-way link thus protects both the surveillance network and components on the surveillance network, including other cameras, as well as protecting any other networks that are linked to the surveillance network. In some embodiments, when it is necessary to convey commands to the camera, a separate one-way link may be provided for this purpose.
Although the embodiments described herein refer mainly to network cameras, the principles of the present invention may be used in preventing malicious access via substantially any sort of network-enabled sensor.
There is therefore provided, in accordance with an embodiment of the present invention, sensing apparatus, including:
a network camera, which is configured to capture images of a scene and to output a sequence of data packets containing digitized video data responsively to the images; and
a one-way link, which is coupled to the network camera so as to transmit the data packets from the network camera to a packet communication network.
In a disclosed embodiment, the network camera is deployed outside a facility, and the packet communication network is a local area network (LAN) that is deployed inside the facility.
In some embodiments, the one-way link includes a first one-way link, and the apparatus includes a second one-way link coupled to convey commands to the network camera. The apparatus may include a switch, which is configured to be actuated in response to a predetermined condition for transmission of the commands to the network camera and to prevent transmission over the second one-way link when the predetermined condition is not satisfied. In one embodiment, the switch is configured to permit the transmission of a message to the network camera only at one or more specified times of day. Alternatively or additionally, the switch is configured to permit the transmission of a message to the network camera only upon ascertaining that the message is valid. Further alternatively or additionally, the switch is configured to permit the transmission of a message to the network camera only when the first one-way link is inactive.
In another embodiment, the one-way link includes a controller, which is coupled to submit instructions to the network camera on a predetermined schedule and to receive and convey the data packets from the network camera over the one-way link to the packet communication network.
There is also provided, in accordance with an embodiment of the present invention, sensing apparatus, including:
a network sensor, which is configured to sense a characteristic of an environment outside a facility and to output a sequence of data packets containing digitized sensor data responsively to the sensed characteristic; and
a one-way link, which is coupled to the network sensor so as to transmit the data packets from the network sensor to a packet communication network inside the facility.
The network sensor may include a network camera.
There is additionally provided, in accordance with an embodiment of the present invention, a method for sensing, including:
deploying a network sensor to sense a characteristic of an environment outside a facility and to output a sequence of data packets containing digitized sensor data responsively to the sensed characteristic; and
coupling a one-way link to the network sensor so as to transmit the data packets from the network sensor to a packet communication network inside the facility.
The present invention will be more fully understood from the following detailed description of the embodiments thereof, taken together with the drawings in which:



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic, pictorial illustration of a secured facility, which is protected in accordance with an embodiment of the present invention;
FIG. 2 is schematic, pictorial illustration of a network-based security system, in accordance with an embodiment of the present invention; and
FIG. 3 is a flow chart that schematically illustrates a method for controlling a network camera, in accordance with an embodiment of the present invention.



DETAILED DESCRIPTION OF EMBODIMENTS
FIG. 1 is a schematic, pictorial illustration of a secured facility 20, which is protected by a network camera 22 in accordance with an embodiment of the present invention. The camera is connected to a LAN inside the facility by a link 24. Camera 22 is configured to capture images of a scene outside facility 20 and to generate and output packets containing digitized video data via a built-in network interface to link 24. The network interface operates in accordance with a predetermined protocol (such as Ethernet), which is compatible with the protocol used on the LAN in facility 20. The camera may output the packets in a continuous sequence as long as the camera is powered on and enabled. Alternatively, the camera may transmit packets only intermittently, such as when motion is detected in the picture captured by the camera, or on a certain time schedule. In any case, however, the camera is typically capable of transmitting video packets autonomously, without requiring a specific prompt or request from the LAN. Alternatively, a special-purpose circuit may be connected to the camera to prompt the camera to transmit packets on a desired schedule.
Camera 22 is mounted outside facility 20, as shown in FIG. 1, and is therefore relatively accessible to malicious parties. Thus, for example, a hacker may attempt to connect a computer 26 to link 24 in order to gain access to the LAN and to other computing and storage resources on the LAN. If successful, the hacker might be able to extract sensitive information, or reprogram computers within the facility, or tamper with or destroy stored surveillance data.
In the present embodiment, however, link 24 is a one-way link, which conveys packets containing video data from camera 22 to the LAN in facility 20, but is physically incapable of supporting outward communication from the facility. Link 24 may comprise a unidirectional fiberoptic link, for example, as in the Waterfall device mentioned above. Alternatively, link 24 may comprise any other suitable sort of one-way link, such as the types of links that are described in PCT Patent Application PCT/IL2006/001499, filed Dec. 28, 2006, which is assigned to the assignee of the present patent application and whose disclosure is incorporated herein by reference.
As a result of using the one-way link, computer 26 will not receive any return messages or data from within facility 20. Consequently, the hacker will not be able to gain access to data that are stored in the facility, and the hacker's ability to access and reprogram computers in the facility will be very limited in the absence of any sort of feedback.
Although the present embodiment relates to the use of one-way links in protecting connection points of network cameras, the principles of the present invention may similarly be applied to other sorts of network sensors. A “network sensor” in this case means a self-contained sensing device that senses a characteristic of an environment and outputs a sequence of data packets containing digitized sensor data. In the case of the network camera, the characteristic of the environment is an image of a scene in the environment. Other than cameras, a network sensor may comprise any suitable type of sensor, such as an audio sensor, an infrared or ultrasonic motion sensor, a smoke detector or a pressure sensor.
FIG. 2 is schematic, pictorial illustration of a network-based security system 30, in accordance with an embodiment of the present invention. It will be assumed, for the sake of simplicity, that system 30 is installed in facility 20, with a perimeter 32 corresponding to the outer limit of the facility (such as the walls of the building shown in FIG. 1). Thus, camera 22 is deployed outside perimeter 32 and is connected by one-way link 24 to a LAN 40 inside the facility. Other network cameras 34 are deployed within perimeter 32 and are connected to LAN 40 by respective links 36. Depending on security requirements, links 36 inside perimeter 32 may also be one-way links. The use of one-way links inside the facility can be important particularly in preventing tampering with network cameras in hidden and less-trafficked locations. A console 42 receives the packets transmitted by the cameras over the LAN and displays the video images for monitoring by an operator 44, for example.
In some cases, it may be desirable to control one or more of the cameras in system 30 so as to cause the camera to change its image capture parameters. For example, operator 44 may wish to pan, tilt or zoom a camera in order to get a better view of a point of interest, or may wish to toggle the operational mode of a camera, such as switching between day and night modes, or to request that the camera provide log or status information. Alternatively or additionally, console 42 may automatically change certain image capture parameters based on scene conditions or pre-programmed rules. Such changes may be invoked from console 42 by sending suitable commands to cameras 34, for example, via LAN 40 and links 36. Camera 22, however, cannot be controlled in this manner, since there is no outgoing link from LAN 40 to the camera.
Alternatively, a second, outgoing one-way link may be used to control network cameras that are deployed outside perimeter 32, as well as any other cameras that are vulnerable to tampering. For example, as shown in FIG. 2, a network camera 38 is connected to transmit video data packets to LAN 40 via one-way link 24, while another one-way link 46 carries outgoing commands to the camera. A switch 48 on outgoing link 46 limits the availability of the outgoing link and may prevent the simultaneous use of link 46 with link 24. Therefore, even if a hacker is successful in connecting to both of links 24 and 46 at camera 38, he still will not have the necessary interactive access for extracting data or reprogramming computers via LAN 40.
Switch 48 may be actuated in a number of possible ways, in response to certain predetermined conditions:

    
    
        The switch may mechanically or electrically cut off link 46, so that no outgoing signals may be transmitted. For example, operator 44 may manually turn the switch on when he wishes to send an outgoing command to camera 38. The switch may shut off automatically thereafter. Alternatively or additionally, the switch may be actuated by a suitable message from console 42.
        The switch may operate on a timer (which cannot be controlled via LAN 40), so that outgoing commands may be sent over link 46 only at certain specific times of day.
        The switch may contain or be linked to a validation circuit, which checks outgoing messages for validity before transmitting them to camera 38. For example, the validation circuit may check the outgoing messages for a known digital signature. For added security, the digital signature may be stored on a smart card 52 or other medium, which the operator must insert into a suitable reader 50, as shown in FIG. 2. Alternatively or additionally, the switch may use other methods of validation, such as biometric authentication of the operator.
        The switch may also check the content and structure of outgoing messages, and discard messages that are not proper camera control commands.

The above list is not meant to be exhaustive, and other methods of validation may also be used, in addition to or instead of the steps listed above. Optionally, link 24 may also be switched, so that the incoming link is inactive whenever the outgoing link is active.

    
    


Although one-way links 24 and 46 are shown in FIG. 2 as each serving a single camera, a given link may alternatively be multiplexed among a number of cameras.
Other alternative configurations may also be used to control the operation of cameras that output data via one-way links. For example, as shown in FIG. 2, a one-way link 54 may be connected directly from a standalone computer 55 or other controller to camera 38 (or to multiple cameras), rather than via network 40. One-way link 54 may be switched for enhanced security in the manner described above.
As another example, a dedicated, automatic controller 56 may be coupled between a camera, such as camera 22 in FIG. 2, and the one-way link 24 that transmits data from the camera. Controller 56 may be set to submit certain instructions (commands and/or queries) to camera 22 on a predetermined schedule, such as a request to the camera to capture and transmit an image every 5 sec, or a request to transmit a status report every 5 min, or a command to pan over a certain angular range. The controller then passes the response from the camera to network 40 over link 24 and thus obviates the need for a return link to the camera.
FIG. 3 is a flow chart that schematically illustrates a method for operating switch 48 in order to control transmission of messages to camera 38, in accordance with an embodiment of the present invention. For the purposes of this method, switch 48 is assumed to comprise or to be linked to a suitable processor (not shown) for performing the validation functions that are described above. The method as shown in FIG. 3 assumes a high level of security, in which a number of different validation steps are layered in order to ensure that only valid commands are allowed to be carried over link 46. Alternatively, only a subset of these layers may actually be used.
The method of FIG. 3 is initiated when switch 48 receives a camera control message from LAN 40, at a message input step 60. Switch 48 checks the current time against a predetermined transmission timetable, at a time checking step 62. The switch will pass the message only if transmission is permitted at this time. Otherwise, the switch discards the message, at a discard step 64. Typically, when a message is discarded for any reason, the switch sends an alert to operator 44 as an indication of a possible unauthorized attempt to transmit data over link 46.
Switch 48 checks the electronic signature of the message, at a signature validation step 66. If the signature does not match a preconfigured, authorized value, the message is discarded at step 64. The switch may also check whether the message is well-formed, at a form checking step 68. For example, the switch may check the structure and data values in the message to ensure that the message has the form of a proper command to camera 38. Again, ill-formed messages are discarded at step 64.
Assuming the message passed the tests of steps 62, and 68, switch 48 may optionally shut off downlink communications over link 24, at a link shutoff step 70. Switch 48 then transmits the message over link 46 to camera 38. Once the message has been sent, switch 48 opens, preventing further outgoing transmission, and incoming transmission of video data packets resumes. Alternatively, switch 48 may be configured to allow simultaneous communication over both of links 24 and 48, at least during certain limited time periods.
It will be appreciated that the embodiments described above are cited by way of example, and that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not disclosed in the prior art.

## Claims

1. A processor communication system, comprising:
a first processor configured to transmit data packets;
a second processor configured to receive data packets;
a first one-way link, physically configured to carry signals in one direction and to be incapable of carrying signals in the opposite direction, which is coupled to the first and second processors so as to carry data packets from the first processor to the second processor and to be incapable of carrying signals from the second processor to the first processor;
a second one-way link, physically configured to carry signals in one direction and to be incapable of carrying signals in the opposite direction, which is coupled to the first and second processors so as to carry commands from the second processor to the first processor and to be incapable of carrying signals from the first processor to the second processor; and
a switch on the second one-way link, which has a first state in which the switch allows transmission of commands to the first processor over the second one-way link and a second state in which the switch prevents transmission over the second one-way link,
wherein the switch is configured to allow transmission of commands to the first processor in response to a predetermined condition and to prevent transmission over the second one-way link when the predetermined condition is not satisfied.

2. The system of claim 1, wherein the switch is configured to mechanically cut off the second one-way link in the second state.

3. The system of claim 1, wherein the switch is configured to electronically cut off the second one-way link in the second state.

4. The system of claim 1, wherein the switch is configured to automatically move from the first state to the second state.

5. The system according to claim 3, wherein the switch is configured to permit transmission to the first processor only at one or more specified times of day.

6. The system according to claim 3, wherein the switch is configured to permit the transmission of a message to the first processor only upon ascertaining that the message is valid.

7. A processor communication system, comprising:
a first processor configured to transmit data packets;
a second processor configured to receive data packets;
a first one-way link, physically configured to carry signals in one direction and to be incapable of carrying signals in the opposite direction, which is coupled to the first and second processors so as to carry data packets from the first processor to the second processor and to be incapable of carrying signals from the second processor to the first processor;
a second one-way link, physically configured to carry signals in one direction and to be incapable of carrying signals in the opposite direction, which is coupled to the first and second processors so as to carry commands from the second processor to the first processor and to be incapable of carrying signals from the first processor to the second processor; and
a switch on the second one-way link, which has a first state in which the switch allows transmission of commands to the first processor over the second one-way link and a second state in which the switch prevents transmission over the second one-way link,
wherein the switch is configured to permit transmission to the first processor only when the first one-way link is inactive.

8. The system of claim 1, wherein the first processor comprises a sensor and is configured to transmit a sequence of data packets containing digitized sensed data over the first one-way link.