Patent Publication Number: US-2010115624-A1

Title: Method and system for securing data from a point of sale device over a lan

Description:
FIELD OF THE INVENTION 
     The present invention relates to local area networks and, more particularly, to a local area network with point of sale devices. 
     BACKGROUND OF THE INVENTION 
     One way of providing such a point of sale system is by utilizing a local area network (LAN) with wireless capability. Such a LAN can be implemented with a wireless router that communicates with one or more wireless devices within a reasonably short range and also connects to an external network. The wireless router can thus allow a number of wireless point of sale terminals in a shop or singularly located business to communicate with the appropriate payment host over the internet, thus allowing for payment transactions to be processed. 
     As payment transactions involve sensitive cardholder data, it is essential that this data is inaccessible to parties and processes that are not an intended part of the transaction. This inaccessibility may be compromised if point of sale devices are allowed to communicate with non-point of sale devices. This is because point of sale devices are normally designed to prevent unauthorized access or non-payment related uses, whereas non-point of sale devices cannot be assumed to have such restrictions. For this reason, current best practices dictate that point of sale devices should not be allowed to share the same immediate local network with non-point of sale devices. This practice is also mandated by the Payment Card Industry Data Security Standard (PCI-DSS) which has been developed to secure payment card data. Compliance with this standard is very important as it is typically required of merchants by acquirers associated with popular payment cards such as VISA and MasterCard. 
     Implementing a point of sale system on a LAN as described above therefore introduces security concerns that are not present in conventional systems designed exclusively for point of sale devices. This is because the router that implements the LAN will also have the capability of communication with other devices on the LAN, which may include non-point of sale devices. Although this problem might be solved by the merchant adopting a practice that only point of sale devices can be members of the LAN, there is no simple means of ensuring continual compliance with such a practice. Furthermore, especially in the case of smaller merchants, it may be unreasonable to expect separate physical networks to be maintained for both point of sale devices and other kinds of devices that the merchant may need or wish to operate. 
     An additional concern is that a router as described above may allow for devices to be connected both wirelessly and by wire. Although this provides a potentially advantageous capability, as a practical matter one form of connection may be less secure than the other, and thus combining both wired and wireless connections on a same LAN may potentially weaken the security of devices connected by the more secure method. It is therefore desirable to provide a means for securing data on a local area network with point of sale devices as well as non-point of sale devices. It is also desirable to provide a means for securing data when such a local area network has both wired and wireless devices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described in terms of the preferred embodiments set out below and with reference to the following drawings in which like reference numerals are used to refer to like elements throughout. 
         FIG. 1  is a block diagram illustrating a system in which an embodiment of the invention is provided. 
         FIG. 2  is a flow diagram illustrating configuration of a point of sale LAN in accordance with an embodiment of the invention. 
         FIG. 3  is a flow diagram illustrating the data control performed by a data control system in various aspects of the invention. 
         FIG. 4  is a flow diagram illustrating a process performed by the data control system for data from a point of sale LAN that is destined for a location on the system LAN. 
         FIG. 5  is a flow diagram illustrating a process performed by the data control system for data from a point of sale LAN that is destined for a location on the external network. 
         FIG. 6  is a flow diagram illustrating the process performed by the data control system for data from a non-point of sale device that is destined for a location on the system LAN. 
         FIG. 7  is a flow diagram illustrating the process performed by the data control system for data from a non-point of sale device that is destined for a location on the external network. 
         FIG. 8  is a flow diagram illustrating the process performed by the data control system for data from the external network that is destined for a point of sale device on the system LAN. 
         FIG. 9  is a flow diagram illustrating the process performed by the data control system for data from the external network that is destined for a non-point of sale device on the system LAN. 
         FIG. 10  is a flow diagram illustrating the process of managing a white list of approved point of sale devices in accordance with an embodiment of the invention. 
     
    
    
     It should be understood that the flow diagrams provided herein represent logical relationships among functions in order to generally illustrate functional elements that are provided in various embodiments of the invention. One of ordinary skill in the art will recognize that the elements described in these flow diagrams may be arranged differently while still, where consistent with the description herein, remaining within the spirit and scope of the invention. 
     DETAILED DESCRIPTION 
     A method and system are described for securing data on a local area network (LAN) that includes point of sale devices as well as non-point of sale devices. A point of sale device can be defined as a device which is dedicated to processing point of sale transactions and which stores, processes or transmits cardholder data or other sensitive information related to processing a payment made by a payment card, and is thus designed to prevent unauthorized access or uses unrelated to payment transactions. A non-point of sale device can be defined as a computing device which is capable of sending data to and/or receiving data from other devices but which is not a point of sale device as defined above. 
     In one aspect of the invention, a point of sale network is defined within the LAN which includes point of sale devices but excludes non-point of sale devices. In a second aspect of the invention, point of sale devices are prevented from sending data to non-point of sale devices on the LAN. In a third aspect of the invention, point of sale devices are prevented from sending data to an external network other than via a secure connection. In a fourth aspect of the invention, non-point of sale devices are prevented from sending data to point of sale devices on the LAN. In a fifth aspect of the invention, non-point of sale devices are prevented from sending data to the external network via a secure connection reserved for point of sale devices. In a sixth aspect of the invention, point of sale devices are prevented from receiving data from the external network other than via a secure connection. In a seventh aspect of the invention, non-point of sale devices are allowed to receive data from the external network when established conditions are met. By controlling the data in this fashion, cardholder data and other sensitive information related to point of sale transactions are protected even though the point of sale devices share the LAN with non-point of sale devices. 
     In the above described aspects, the LAN may include wired point of sale or non-point of sale devices as well as wireless point of sale or non-point of sale devices. In correspondingly appropriate variations of the above described aspects, wireless devices may be prevented from sending data to wired devices and wired devices may be prevented from sending data to wireless devices. Other aspects, additions and variations will be apparent to one of ordinary skill in the art based on the description herein. 
     Configuration 
       FIG. 1  is a block diagram illustrating a system in which an embodiment of the invention is provided. The system has a system LAN  100  which includes and is implemented by a wireless router  110 . The system LAN  100  includes a wireless point of sale LAN  120 , wireless non-point of sale LAN  130 , wired point of sale LAN  140  and wired non-point of sale LAN  150 . The system LAN  100  is also connected to an external network  160  which is, for example, a wide area network (WAN) such as the internet. A payment host  170  is connected to the external network  160 . The payment host  170  processes payment transactions initiated by point of sale devices on the system LAN  100 . A secure host  180  is also provided on the external network  160 . The secure host  180  secures data that is transmitted between the system LAN  100  and the payment host  170 , and may also provide additional functions related to payment processing and configuration and security of the system LAN  100 . 
     The wireless router  110  is a conventional wireless router that is capable of being configured to provide the functions described herein. In a preferred embodiment, the wireless router  110  is an ASUS WL-500 g Premium running OpenWrt, a version of the Linux operating system for embedded devices. The wireless router  110  includes one or more Wi-Fi antennas which transmit and receive to and from devices on the wireless point of sale LAN  120  and wireless non-point of sale LAN  130 . The wireless router  110  may also include Ethernet ports which connect to devices on the wired point of sale LAN  140  and wired non-point of sale LAN  150 . The wireless router  110  also includes a WAN port which connects to the external network  160 . 
     The wireless router  110  defines the wireless point of sale LAN  120 , wireless non-point of sale LAN  130 , wired point of sale LAN  140  and wired non-point of sale LAN  150  each as a separate virtual LAN (VLAN.) Only point of sale devices can be members of the wireless point of sale LAN  120  or wired point of sale LAN  140 , and only non-point of sale devices can be members of the wireless non-point of sale LAN  130  or wired non-point of sale LAN  150 . Additionally, only wireless devices can be members of the wireless point of sale LAN  120  or wireless non-point of sale LAN  130 , and only wired devices can be members of the wired point of sale LAN  140  or wired non-point of sale LAN  150 . One of ordinary skill in the art will readily implement appropriate VLANs to accomplish such rules consistent with the objectives and environment at hand in accordance with the general description provided herein. 
     The wireless point of sale LAN  120  includes one or more wireless point of sale devices  125  which communicate wirelessly with the wireless router  110 . The wired point of sale LAN  140  includes one or more wired point of sale devices  145  connected by wire to the wireless router  110 . A wireless point of sale device  125  or wired point of sale device  145  may be, for example, a point of sale terminal which accepts payment information in order to process a sales transaction. A wireless point of sale device  125  or wired point of sale device  145  could also be a dedicated computer which processes payment transactions or administers point of sale devices and related configuration information. 
     The wireless non-point of sale LAN  130  includes one or more wireless non-point of sale devices  135  which communicate wirelessly with the wireless router  110 . The wired non-point of sale LAN  150  includes one or more wired non-point of sale devices  155  connected by wire to the wireless router  110 . A wireless non-point of sale device  135  or wired non-point of sale device  155  may be, for example, a personal computer used by one or more individuals affiliated with the merchant who maintains the system LAN  100 . Such individuals may use the personal computer for web browsing, email or numerous other purposes that warrant at least partially unrestricted access by the personal computer to hosts or devices on the external network  160  or system LAN  100 , as well as access to the personal computer by such hosts or devices. 
     Configuration of the Point of Sale LAN 
     In one aspect of the invention, a data control system defines within a local area network a point of sale network which includes point of sale devices but excludes non-point of sale devices. The data control system is implemented by a router working in combination with a secure host on an external network to which the router is connected. The point of sale devices may include wireless devices which communicate wirelessly with the router such as via a Wi-Fi connection, and may also include wired devices connected by wire to the router such as via an Ethernet connection. Similarly, the non-point of sale devices may be wireless or wired devices. The data control system may additionally define a non-point of sale network which includes the non-point of sale devices. The point of sale network and the non-point of sale network may each be defined as a virtual local area network. 
       FIG. 2  is a flow diagram illustrating configuration of a wireless point of sale LAN in accordance with an embodiment of the invention. The process shown in  FIG. 2  defines a wireless point of sale LAN which includes point of sale devices and excludes non-point of sale devices. This process is performed by the wireless router  110  at an initial configuration of the system LAN  100  and may also be performed at any later time as necessary to update the configuration, such as when a new device is added to the system LAN  100 . 
     In step  210 , the wireless router  110  determines whether a device that is being introduced to the configuration is a point of sale device. The wireless router  110  may determine this in any number of ways, such as with reference to information provided by the secure host  180 . If the wireless router  110  determines that the device being introduced to the configuration is a point of sale device, it assigns the device to a point of sale LAN in step  220 . 
     Where the device is a wireless device, one possible implementation of step  220  can be described as follows. The wireless router  110  will have previously assigned a unique service set identifier (SSID) to the wireless point of sale LAN  120 . The wireless router  110  assigns the wireless device to the wireless point of sale LAN  120  as a wireless point of sale device  125  by associating a unique device identifier of the wireless point of sale device  125  with the SSID of the wireless point of sale LAN  120 . The device identifier may be, for example, a media access control (MAC) address of the wireless point of sale device  125 . 
     Where the device is a wired device, one possible implementation of step  220  can be described as follows. The wireless router  110  will have previously assigned one or more ports (such as Ethernet ports) to the wired point of sale LAN  140 . The wireless router  110  assigns the wired device to the wired point of sale LAN  140  as a wired point of sale device  145  by, for example, associating a device identifier of the wired point of sale device  145  with one of the ports assigned to the wired point of sale LAN  140 . As described above, the device identifier may be, for example, a media access control (MAC) address of the wired point of sale device  145 . 
     Returning to step  210 , if the wireless router  110  instead determines that the device is not a point of sale device, it assigns the device to a non-point of sale LAN in step  230 . Where the device is a wireless device, a possible implementation of step  230  can be described as follows. The wireless router  110  will have previously assigned a second unique service set identifier (SSID) to the wireless non-point of sale LAN  130  that is different from the SSID of the wireless point of sale LAN  120 . The wireless router  110  assigns the wireless device to the wireless non-point of sale LAN  130  as a wireless non-point of sale device  135  by, for example, associating a device identifier of the wireless non-point of sale device  135  with the SSID of the wireless non-point of sale LAN  130 . The device identifier may be, for example, a media access control (MAC) address of the wireless point of sale device  125 . 
     Where the device is a wired device, a possible implementation of step  230  can be described as follows. The wireless router  110  will have previously assigned to the wired non-point of sale LAN  150  a second group of one or more ports (such as Ethernet ports) all or which are different from the ports assigned to the wired point of sale LAN  140 . The wireless router  110  assigns the device to the wired non-point of sale LAN  150  as a wired non-point of sale device  155  by associating a device identifier of the wired non-point of sale device  155  with one of the second group of ports assigned to the wired non-point of sale LAN  150 . As above, the device identifier may be, for example, a media access control (MAC) address of the wired non-point of sale device  155 . 
     If the wireless router  110  determines in step  240  that there are still more devices that have been introduced to the system LAN  100 , the wireless router  110  repeats the above-defined process until all devices have been assigned. 
     Data Control 
       FIGS. 3-9  are flow diagrams illustrating the data control that is performed in various aspects of the invention.  FIGS. 3-9  are performed by a data control system which comprises the wireless router  110  and, depending on the implementation, may also include the secure host  180  in the case of some functional elements. The flow diagrams provided herein represent logical relationships among functions in order to generally illustrate functional elements that are provided in various embodiments of the invention. The processes shown in  FIGS. 3-9  are broken out and arranged for the purpose of logically describing the functional concepts in various aspects of the invention. One of ordinary skill in the art will recognize that the elements described in these flow diagrams may be arranged differently while still, where consistent with the description herein, remaining within the spirit and scope of the invention. For example, the steps described may be performed in different sequential or event-driven orders in alternative versions of the aspects represented. 
       FIG. 3  is a flow diagram which shows the different data control processes performed depending on the source and destination of data processed by the data control system. 
     The data control system performs the process shown in  FIG. 3  upon receipt by the wireless router  110  of a data packet from any source on the system LAN  100  or from the external network  160 . In step  305 , the data control system determines whether the data is from a point of sale LAN. For example, the wireless router  110  determines whether the data is associated with an SSID corresponding to the wireless point of sale LAN  120  or a port assigned to the wired point of sale LAN  140 . 
     Where is it determined in step  305  that the data is from a point of sale LAN, the data control system determines in step  310  whether the data is destined for a device on the system LAN  100 . For example, the wireless router  110  examines the data packet to determine whether the destination IP address contained therein corresponds to a wireless point of sale device  125  on the wireless point of sale LAN  120 , a wired point of sale device  145  on the wired point of sale LAN  140 , a wireless non-point of sale device  135  on the wireless non-point of sale LAN  130 , or a wired non-point of sale device  155  on the wired non-point of sale LAN  150 . 
     If the data from the point of sale LAN is destined for a device on the system LAN  100 , the data control system performs the “POS LAN for System LAN” process in step  315 . This process will be described with reference to  FIG. 4  below. If the data from the point of sale LAN is not destined for a device on the system LAN  100 , the data control system determines in step  320  whether the data is destined for the external network  160 . For example, the wireless router  110  examines the data packet to determine whether the destination IP address contained therein corresponds to an external internet address. If so, the data control system performs the “Point of Sale LAN for External Network” process in step  325 . This process will be described with reference to  FIG. 5  below. 
     In step  330 , the data control system determines whether the data is from a non-point of sale LAN. For example, the wireless router  110  determines whether the data is associated with an SSID corresponding to the wireless non-point of sale LAN  130  or from a port assigned to the wired non-point of sale LAN  150 . Where it is determined in step  330  that the data is from a non-point of sale LAN, the data control system determines in step  335  whether the data is destined for a device on the system LAN  100 . For example, the wireless router  110  examines the data packet to determine whether the destination IP address contained therein corresponds to an internal IP address of the wireless point of sale device  125  on the wireless point of sale LAN  120 , a wired point of sale device  145  on the wired point of sale LAN  140 , a wireless non-point of sale device  135  on the wireless non-point of sale LAN  130  or a wired non-point of sale device  155  on the wired non-point of sale LAN  150 . 
     If the data from the non-point of sale LAN is destined for a device on the system LAN  100 , the data control system performs the “Non-POS LAN for System LAN” process in step  340 . This process will be described with reference to  FIG. 6  below. If the data from the non-point of sale LAN is not destined for a device on the system LAN  100 , the data control system determines in step  345  whether the data is destined for the external network  160 . For example, the wireless router  110  examines the data packet to determine whether the destination IP address contained therein corresponds to an external internet address. If so, the wireless router  110  performs the “Non-POS LAN for External Network” process in step  350 . This process will be described with reference to  FIG. 7  below. 
     In step  355 , the data control system determines whether the data is from the external network  160 . For example, the wireless router  110  determines whether the data is received from a wide area network (WAN) port through which the router  110  is connected to the external network  160 . If so, the data control system determines whether the data is destined for a point of sale LAN. For example, the wireless router  110  examines the data packet to determine whether the destination IP address contained therein corresponds to a wireless point of sale device  125  on the wireless point of sale LAN  120  or a wired point of sale device  145  on the wired point of sale LAN  140 . 
     If the data from the external network is destined for a point of sale device, the data control system performs the “External Network for POS LAN” process in step  365 . This process will be described with reference to  FIG. 8  below. If the data from the external network is not destined for a point of sale LAN, the data control system determines in step  370  whether the data is destined for a non-point of sale LAN. For example, the wireless router  110  examines the data packet to determine whether the destination IP address contained therein corresponds to a wireless non-point of sale device  135  on the wireless non-point of sale LAN  130  or a wired non-point of sale device  155  on the wired non-point of sale LAN  150 . If the data is destined for a non-point of sale LAN, the wireless router  110  performs the “External Network for Non-POS LAN” process in step  375 . This process will be described with reference to  FIG. 9  below. 
     Data From the Point of Sale LAN Over the System LAN 
     In another aspect of the invention, a data control system for a local area network prevents point of sale devices from sending data to non-point of sale devices but allows point of sale devices to send data to other point of sale devices on the local area network. The data control system may define a point of sale network within the local area network and determine the data is from the point of sale network if the data is associated with a service set identifier corresponding to a wireless point of sale network or a port corresponding to a wired point of sale network. The data control system may also allow data to be sent to a point of sale device only if it is represented on a white list of approved point of sale devices. The data control system may also prevent wireless point of sale devices from sending data to wired point of sale devices and prevent wired point of sale devices from sending data to wireless point of sale devices. 
       FIG. 4  is a flow diagram illustrating the “POS LAN for System LAN” process performed by the data control system for data from a point of sale LAN that is destined for a location on the system LAN. The data is received, for example, from the wireless point of sale LAN  120  or the wired point of sale LAN  140 . In step  400 , the data control system determines whether the device from which the data is received is on a white list of approved point of sale devices. In one possible embodiment, the white list is maintained by the wireless router  110  based on information received from the secure host  180 . The white list contains, for example, a media access control (MAC) address of each wireless point of sale device  125  or wired point of sale device  145  that has been approved as a point of sale device on the system LAN. Management of the white list is described later in the specification with reference to  FIG. 10 . 
     If the data is from a device that is not on the white list, the data control system blocks the data from being sent in step  405 . This could occur, for example, where a point of sale device has been introduced to the system LAN  100  but has not been approved for membership in a point of sale network within the system LAN  100 . If the device from which the data is received is on the white list, the data control system determines in step  410  whether the data from the point of sale LAN is destined for a non-point of sale device. For example, the wireless router  110  examines the data packet to determine whether the destination IP address contained therein corresponds to a wireless non-point of sale device  135  on the wireless non-point of sale LAN  130  or a wired non-point of sale device  155  on the wired non-point of sale LAN  150 . If the data is destined for a non-point of sale device, the wireless router  110  blocks the data from being sent to the non-point of sale device in step  415 . 
     In step  420 , the data control system determines whether the data is from a wireless point of sale device and destined for a wired point of sale device. For example, the wireless router  110  determines whether the data is associated with an SSID assigned to the wireless point of sale LAN  120  and examines the data packet to determine whether the destination IP address contained therein corresponds to a wired point of sale device  145  on the wired point of sale LAN  140 . If so, the wireless router  110  blocks the data from being sent to the wired point of sale LAN  140  in step  425 . 
     In step  430 , the data control system determines whether the data is from a wired point of sale device and destined for a wireless point of sale device. For example, the wireless router  110  determines whether the data is from a port assigned to a wired point of sale device  145  on the wired point of sale LAN  140  and examines the data packet to determine whether the destination IP address contained therein corresponds to a wireless point of sale device  125  on the wireless point of sale LAN  120 . If so, the wireless router  110  blocks the data from being sent to the wireless point of sale LAN  120  in step  435 . 
     In step  440 , the data control system allows the point of sale device to send data over the system LAN  100  having confirmed that the data is not destined for a non-point of sale device and is not from a wireless to a wired device or from a wired to a wireless device. In a preferred embodiment, a form of encryption is employed to protect the data sent over the system LAN  100 . For example, the wireless point of sale device  125  and wireless router  110  utilize Wi-Fi Protected Access (WPA) encryption to encrypt the data. A WPA passphrase will have been created by the secure host  180  and provided to the merchant to enter into the wireless point of sale device  125  at the time of configuration. 
     Data From the Point of Sale LAN Over the External Network 
     In another aspect of the invention, the data control system allows point of sale devices to send data to the external network via a secure connection but prevents the point of sale devices from sending data to the external network other than via the secure connection. The secure connection is, for example, a virtual private network connection. The data control system may allow only devices on a white list of approved point of sale devices to send data to the external network. The data control system may also allow the point of sale devices to send data only to an authorized destination on the external network. 
       FIG. 5  is a flow diagram illustrating the “POS LAN for External Network” process performed by the data control system for data from a device on a point of sale LAN that is destined for a location on the external network. The device may be on the wireless point of sale LAN  120  or on the wired point of sale LAN  140 . The process illustrated in  FIG. 5  allows the device to send data over the external network  160  under certain circumstances, but only via a secure connection. The secure connection is, for example, a virtual private network (VPN) connection which provides a secure pathway over the external network  160  from the router  110  to a particular destination such as the payment host  170  or the secure host  180 . The VPN is created, for example, by an OpenVPN software program on the wireless router  110 . An OpenVPN server on the secure host  180  interacts with the OpenVPN program on the wireless router  110  to establish an encrypted VPN tunnel between the wireless router  110  and the secure host  180  using a VPN session key that is periodically renegotiated, preferably at least once every 24 hours. 
     In step  510 , the data control system determines whether the device attempting to send data to the external network  160  is on a white list of approved POS devices. In one possible embodiment, as explained with reference to  FIG. 4 , the white list is maintained by the wireless router  110  based on information received from the secure host  180  and contains, for example, the MAC address of each wireless point of sale device  125  or wired point of sale device  145  that has been approved as a point of sale device on the system LAN. If the data is from a device that is not on the white list, the data control system prevents the data from being sent over the VPN in step  520 . As noted above, this could occur where a point of sale device has been introduced to the system LAN  100  but has not been approved for membership in a point of sale network within the system LAN  100 . 
     In one embodiment, the data control system may block the data altogether when it is not from a POS device on the white list. In an alternative embodiment, the data control system may allow the data to be sent to a location on the external network  160  via an unsecure connection, either without restriction or limited to specified locations. 
     In addition determining in step  510  that the data is from a point of sale device on the white list, the data control system determines in step  530  whether the point of sale device is attempting to send data to an authorized destination on the external network  160 . In one possible implementation, the wireless router  110  examines the data packet to determine whether the destination IP address contained therein corresponds to the IP address of the secure host  180  or payment host  170 , and if not, prevents the data from being sent over the VPN in step  520 . In another possible implementation, the wireless router  110  may allow all data from a point of sale device on the white list to be sent via the VPN to the secure host  180 , and the secure host  180  may determine whether the data can be sent further depending on whether it is destined for an authorized destination. 
     Upon determining that the data is from a point of sale device on the white list and determining that the data is destined for an authorized destination, the data control system allows the point of sale device in step  540  to send the data to the external network  160  via the VPN. The secure connection of the VPN protects the data when sent from the wireless router  110  over the external network  160 . In a preferred embodiment, a form of encryption is also employed to protect the data exchanged between the point of sale device and the wireless router  110 . For example, the wireless point of sale device  125  and wireless router  110  utilize Wi-Fi Protected Access (WPA) encryption to encrypt the data. A WPA passphrase will have been created by the secure host  180  and provided to the merchant to enter into the wireless point of sale device  125  at the time of configuration. 
     Data From the Non-Point of Sale LAN Over the System LAN 
     In another aspect of the invention, a data control system for a local area network prevents non-point of sale devices from sending data to point of sale devices on the local area network but allows non-point of sale devices to send data to other non-point of sale devices on the local area network. The data control system may define a non-point of sale network within the local area network and determine the data is from the non-point of sale network if the data is associated with a service set identifier corresponding to a wireless non-point of sale network or a port corresponding to a wired non-point of sale network. The data control system may also prevent wireless non-point of sale devices from sending data to wired non-point of sale devices and prevent wired non-point of sale devices from sending data to wireless non-point of sale devices. 
       FIG. 6  is a flow diagram illustrating the “Non-POS LAN for System LAN” process performed by the data control system for data from a non-point of sale LAN that is destined for a location on the system LAN. The non-point of sale LAN may be the wireless non-point of sale LAN  130  or the wired non-point of sale LAN  150 . In step  610 , the wireless router  110  determines whether the data from the non-point of sale LAN is destined for a point of sale device. For example, the wireless router  110  examines the data packet to determine whether the destination IP address contained therein corresponds to a wireless point of sale device  125  on the wireless point of sale LAN  120  or a wired point of sale device  145  on the wired point of sale LAN  140 . If the data is destined for a point of sale device, the data control system blocks the data from being sent to the non-point of sale device in step  615 . 
     In one embodiment, upon determining in step  610  that the data from the non-point of sale LAN is destined for a point of sale device, the data control system in step  640  allows the non-point of sale device to send the data over the system LAN  100  without regard to whether communication between wired and wireless devices is involved. 
     In another embodiment, additional steps  620  and  630  may be taken to separate wired and wireless non-point of sale devices similar to the separation of wired and wireless point of sale devices described above. 
     In step  620 , the data control system determines whether the data is from a wireless non-point of sale device and destined for a wired non-point of sale device. For example, the wireless router  110  determines whether the data is associated with an SSID assigned to the wireless non-point of sale LAN  130  and examines the data packet to determine whether the destination IP address contained therein corresponds to a wired non-point of sale device  155  on the wired point of sale LAN  150 . If so, the wireless router  110  blocks the data from being sent to the wired non-point of sale device  155  in step  625 . 
     In step  630 , the data control system determines whether the data is from a wired non-point of sale device to a wireless non-point of sale device. For example, the wireless router  110  determines whether the data is from a port assigned to a wired non-point of sale device  155  on the wired non-point of sale LAN  150  and examines the data packet to determine whether the destination IP address contained therein corresponds to a wireless non-point of sale device  135  on the wireless non-point of sale LAN  130 . If so, the wireless router  110  blocks the data from being sent to the wireless non-point of sale device  135  in step  635 . 
     In step  640 , having confirmed that the data is not destined for a point of sale device or from a wireless to wired or wired to wireless device, the data control system allows the non-point of sale device to send the data over the system LAN  100 . In order to protect the data sent over the system LAN  100 , some form of encryption may be employed. For example, the wireless non-point of sale device  135  and wireless router  110  may utilize Wi-Fi Protected Access (WPA) encryption to encrypt the data. A WPA passphrase will have been created by the secure host  180  and provided to the merchant to enter into the wireless point of sale device  125  at the time of configuration. 
     Data From the Non-Point of Sale LAN Over the External  Network 
     In another aspect of the invention, the data control system prevents non-point of sale devices from sending data over the external network via a secure connection reserved for point of sale devices, but allows non-point of sale devices to send data over the external network other than via the secure connection. The secure connection is, for example, a virtual private network connection. The data control system may allow the data from non-point of sale devices to be sent only if it is not destined for a restricted destination. The restricted destination may be, for example, the secure host or the payment host. 
       FIG. 7  is a flow diagram illustrating the “Non-POS LAN for External Network” process performed by the data control system for data from a non-point of sale device that is destined for a location on the external network. The non-point of sale device may be a wireless non-point of sale device  135  on the wireless non-point of sale LAN  130  or a wired non-point of sale device  155  on the wired non-point of sale LAN  150 . In step  710 , the data control system determines whether the data from the non-point of sale device is destined for a restricted destination on the external network  160 . For example, the data control system examines the data packet to determine whether the destination IP address contained therein corresponds to the IP address of the payment host  170  or the secure host  180 . If the data control system determines in step  710  that the data is destined for a restricted destination on the external network  160 , the data control system logs the attempt to connect to the external network  160  in step  715  and then blocks the data from being sent over the external network  160  in step  720 . The log may be provided from the wireless router  110  to the secure host  160  and utilized, for example, to monitor the system LAN  100 . 
     Upon determining that the data is not destined for a restricted destination on the external network  160 , the data control system sends the data over the external network  160  in step  730 . In a preferred embodiment, a form of encryption may be employed to protect the data exchanged between the point of sale device and the wireless router  110 . For example, the wireless non-point of sale device  135  and wireless router  110  may utilize Wi-Fi Protected Access (WPA) encryption to encrypt the data. A WPA passphrase will have been created by the secure host  180  and provided to the merchant to enter into the wireless point of sale device  125  at the time of configuration. 
     Data From the External Network Over the Point of Sale LAN 
     In another aspect of the invention, the data control system allows point of sale devices on the local area network to receive data from the external network if received from the external network via a secure connection, but prevents point of sale devices from receiving data from the external network if not received via a secure connection. The secure connection is, for example, a virtual private network connection. The data control system may allow the data to be sent to the point of sale device only if it is associated with a communication session initiated by the point of sale device. The data control system may also allow the data to be sent to the point of sale device only if it is received from an authorized source on the external network. 
       FIG. 8  is a flow diagram illustrating the “External Network for POS LAN” process performed by the data control system for data from the external network that is destined for a point of sale device on the system LAN. The point of sale device may be a wireless point of sale device  125  on the wireless point of sale LAN  120  or a wired point of sale device  145  on the wired point of sale LAN  140 . In step  810 , the data control system determines whether the data is received from the external network  160  via a secure connection. The secure connection is, for example, a virtual private network (VPN) connection established by an OpenVPN software program on the wireless router  110  as described above with reference to  FIG. 5 . If in step  810  it is determined that the data is received from the external network  160  other than via the VPN connection, the wireless router  110  blocks the data from being sent to the point of sale device in step  820 . 
     If the data is received from the external network  160  via the VPN connection, then the data control system determines in step  830  whether the data is associated with a data communication session that was initiated by the point of sale device for which the data is now destined. If the data communication was not initiated by the point of sale device, the data control system blocks the data from being sent to the point of sale device in step  820 . 
     If the data communication was initiated by the point of sale device, then the data control system determines in step  840  whether the data from the external network  160  is from an authorized source. For example, the wireless router  110  examines the data packet to determine whether the source internet protocol (IP) address contained therein corresponds to the IP address of the payment host  170  or secure host  180 . If the data was not from an authorized source, the wireless router  110  blocks the data from being sent to the point of sale device in step  820 . 
     In step  850 , upon confirming that the data communication was initiated by the point of sale device for which the data is destined and received via a secure connection from an authorized source, the data control system allows the data from the external network  160  to be sent to the point of sale device. In a preferred embodiment, an intrusion detection system is employed to protect the wireless point of sale LAN  120  and wired point of sale LAN  140  from external attacks. For example, the wireless router  110  runs the “Snort” open source software program, provided by Sourcefire, Inc. In one embodiment, the intrusion detection system provides an alarm signal to the secure host  180  upon detecting data traffic indicative of a possible external attack based on predetermined criteria. The secure host  180  may then communicate with the wireless router  110  to take preventative or corrective action including, if necessary, shutting down some or all data traffic on the system LAN  100  until resolution or clearance from the secure host  180 . Alternatively, the wireless router  110  may initiate its own preventative or corrective action. 
     Data From the External Network Over the Non-Point of Sale LAN 
     In another aspect of the invention, the data control system allows non-point of sale devices on the LAN to receive data from the external network when established conditions are met. The data control system may allow the data to be sent to the non-point of sale devices only, for example, when the data is associated with a communication session initiated by the non-point of sale device. The data control system may also allow the data to be sent to the non-point of sale device only if it is not received from a restricted source. The restricted source may be, for example, the secure host, the payment host, or any unidentified source. Additionally, the data control system may allow the data to be sent to the non-point of sale device only if the data has not been received via a secure connection reserved for point of sale devices. The secure connection is, for example, a virtual private network connection. 
       FIG. 9  is a flow diagram illustrating the “External Network for Non-POS LAN” process performed by the data control system for data from the external network that is destined for a non-point of sale device on the system LAN. The non-point of sale device may be a wireless non-point of sale device  135  on the wireless non-point of sale LAN  130  or a wired non-point of sale device  155  on the wired non-point of sale LAN  150 . 
     In step  910 , the data control system determines whether the data received from the external network  160  is from a restricted source that has been designated as a source that the non-point of sale devices are not allowed to received data from. For example, the wireless router  110  examines the data packet to determine whether the source internet protocol (IP) address contained therein corresponds to the IP address of the payment host  170  or secure host  180 . A restricted source could also include any unidentified sources or sources not previously designated as sources the non-point of sale devices are authorized to receive data from based on information maintained by the wireless router  110  and/or the secure host  180 . A restricted source may also be any source from which data is received via the VPN connection. If the data is from a restricted source, the data control system blocks the data from being sent to the non-point of sale device in step  920 . 
     If the data is not from a restricted source, the data control system determines in step  930  whether the data communication session was initiated by the non-point of sale device for which the data is now destined. If data communication was not initiated by the non-point of sale device, the wireless router  110  blocks the data from being sent to the non-point of sale device in step  920 . In step  950 , upon confirming that the data communication was initiated by the non-point of sale device for which the data is destined and not received from a restricted source, the wireless router  110  allows the data from the external network  160  to be sent to the point of sale device. 
     In a preferred embodiment, an intrusion detection system is employed to protect the wireless non-point of sale LAN  130  and wired non-point of sale LAN  150  from external attacks. For example, the wireless router  110  runs the “Snort” open source software program, provided by Sourcefire, Inc. In one embodiment, the intrusion detection system provides an alarm signal to the secure host  180  upon detecting data traffic indicative of a possible external attack based on predetermined criteria. The secure host  180  may then communicate with the wireless router  110  to take preventative or corrective action including, if necessary, shutting down some or all data traffic on the system LAN  100  until resolution or clearance from the secure host  180 . Alternatively, the wireless router  110  may initiate its own preventative or corrective action. 
     White List Management 
       FIG. 10  is a flow diagram illustrating the process of managing the white list of approved POS devices. As discussed above, the wireless router  110  utilizes the white list to determine which devices are allowed to access authorized destinations on the external network  160 . The process shown in  FIG. 10  is performed by the secure host  180  at an initial configuration of the system LAN  100  and at any later time as necessary to modify the definition of approved point of sale devices, such as when adding new devices to the system LAN  100  at a later time. 
     In step  1010 , the secure host  180  determines whether a device has been identified as an authorized point of sale device. Such a device may be identified by a human operator or by an automated process which determines the device to be a legitimate point of sale device dedicated to processing point of sale transactions. Approval of the device may also require authentication and/or corroboration with information identifying the device in possession of the merchant. 
     If the secure host  180  determines in step  1010  that the device is an approved point of sale device, it adds a device identifier such as a media access control (MAC) address of the device to a white list in step  1020 . If the secure host  180  determines in step  1030  that more devices remain to be considered, the secure host  180  repeats the above steps until all point of sale devices have been considered. Thereafter, the secure host  180  sends the white list to the wireless router  110  in step  1040 . 
     The invention has been described above with reference to one or more illustrative embodiments. Based on this description, further modifications and improvements may occur to those skilled in the art. The claims are intended to cover all such modifications and changes as fall within the scope and spirit of the invention