fig1 presents a preferred embodiment of the device 10 of the present invention . the device may have an exterior enclosure that can be made of any material , preferably plastic or metal . it can be any size or shape , preferably a size or shape that is the most space efficient . the device may have a source 12 receptacle in the form of an rj45 connector and a target 14 receptacle the form of an rj45 connector . the source and the target receptacles can be located anywhere on the enclosure , preferably at locations that offer best access . the device may have at least one circuitry to enable network traffic to move from the source to the target , but no circuitry to enable traffic to move from the target to the source . this is the preferred embodiment of this invention , particularly because rj45 connectors are extremely economical and widely used in all networks . in fact , cost effectiveness is one of the primary differentiators and motivators of this invention , which is a huge contrast to conventional methods disclosed in the prior art . case in point : a complete and fully functioning prototype of this embodiment costs less than five us dollars to assemble at the time of this disclosure . fig2 shows a basic method of use to illustrate the usefulness of this invention . a source computer 22 comprises a plurality of network adapters , one 28 of which may be connected directly or indirectly to an external network , such as the internet , and one 26 of which is connected to the source 12 receptacle of the present invention . the source computer 22 may download content ( such as data and applications ) from the internet and may use a connectionless protocol ( such as udp ) to transmit the content to the device 10 of the present invention . the content enters the source 12 receptacle , exits the target 14 receptacle , and makes its way to the target computer 24 via one 27 of a plurality of network adapters attached to the target computer 24 . once the content arrives at the target computer 24 , it can then be stored on a network share on the internal network so that all devices on the internal network may make use of the content . while fig2 only shows how data may be transferred from an external network into an internal network in a controlled manner , you can use a similar approach to control the transferring of data from an internal to an external network , as illustrated in fig3 , which shows a system with two devices 10 , boa of the present invention . each device has a source 12 , 12 a and a target 14 , 14 a receptacle , wherein data may flow only from the source 12 , 12 a receptacle to the target 14 , 14 a receptacle . one device 10 can transfer data from an external network to an internal network , either directly or indirectly , and another device boa can transfer data from an internal network to an external network , either directly or indirectly . the system in fig3 also comprises a plurality of source computers 22 , 22 a . each source computer 22 , 22 a comprises a plurality of network adapters , one 28 , 28 a of which may be connected to a source network and another 26 , 26 a of which may be connect to a source 12 , 12 a receptacle of one of said devices 10 , boa of the present invention . each source computer 22 , 22 a may comprise software that may use certificates for authentication , authorization , integrity , verification , and privacy . each source computer 22 , 22 a may comprise software that may verify sender signatures , check data for malware , validate data formats , redact data contents , encode data content , and transmit data to the source 12 , 12 a receptacle . each source computer 22 , 22 a may comprise software that may transmit out - of - band acknowledgements to support guaranteed delivery . the system in fig3 also comprises plurality of target computers 24 , 24 a . each target computer 24 , 24 a comprises a plurality of network adapters , one of which 29 , 29 a may be connected to a target network and another 27 , 27 a of which may be connect to a target 14 , 14 a receptacle of one of said devices 10 , boa of the present invention . each target computer 24 , 24 a may comprise software that may use certificates for authentication , authorization , integrity , verification , and privacy . each target computer 24 , 24 a may comprise software that may receive data from the target 14 , 14 a receptacle , verify data integrity , decode data content , check data for malware , and validate data formats . each target computer 24 , 24 a may comprise software that may receive and handle out - of - band acknowledgements to support guaranteed delivery . the system in fig3 also comprises a plurality of networks , wherein each network may be a security boundary only accessible by computers belonging to said network . a plurality of these networks may comprise a plurality of source computers 22 , 22 a that may transmit data to a plurality of source 12 , 12 a receptacles of a plurality of devices 10 , boa of the present invention . a plurality of these networks may comprise a plurality of target computers 24 , 24 a that may receive data from a plurality of target 14 , 14 a receptacles of a plurality of devices 10 , boa of the present invention . the system in fig3 also comprises a plurality of firewalls , wherein each firewall may protect one network from another . a plurality of firewalls may be configured to prevent specific external network traffic from entering the internal network . a plurality of firewalls may be configured to prevent specific internal network traffic from exiting the internal network . these firewall configurations are important to prevent a complete and seamless round trip . by using certificates for authentication , authorization , integrity , verification , and privacy , and by using virus scanning software to prevent malware , only safe data may enter the internal network , and only approved and signed data may exit the internal network . summing up , with appropriate software , networking , and firewall configuration , the method illustrated in fig3 offers controlled unidirectional transfers in both directions . it can also offer guaranteed delivery with appropriate use of software that supports out - of - band acknowledgements . take advantage of certificates for authentication , authorization , integrity , verification , and privacy , and you will have a very secure controlled transfer system . of course , this setup is more appropriate for commercial or federal systems , because it requires a plurality of networks and advanced configurations that may be unrealistic for basic home use . alternatively , it is possible to daisy chain a plurality of devices of this invention , similar to the drawing in fig4 . this is a quick , simple , and inexpensive way to add layers and layers of networks and security . fig5 shows possible internal wiring and connections inside the enclosure of the device 10 of the present invention . the source 12 and target 14 receptacles may be conventional rj45 keystone jacks with all 8 pins , or unconventional ones custom made to expose only pins 1 , 2 , 3 , and 6 for the source 12 receptacle and only pins 3 and 6 for the target 14 receptacle . in either case , a conductor 52 , preferably a copper wire , can be used to connect pin 1 of the source 12 receptacle to pin 3 of the source 12 receptacle and to pin 3 of the target 14 receptacle . also , a conductor 54 can be used to connect pin 2 of the source 12 receptacle to pin 6 of the source 12 receptacle and to pin 6 of the target 14 receptacle . these conductors 52 , 54 should be twisted per standard specifications , preferably cat5 . since pins 1 and 2 are used for transmission , and pins 3 and 6 are used for reception , as shown in fig5 , both of these conductors 52 , 54 permit traffic to move from the source 12 to the target 14 . however , no conductors exist to move data from the target 14 to the source 12 , thus providing no reverse path of communication . in other words , data can move only from the source 12 to the target 14 , never from the target 14 to the source 12 . fig6 shows a different embodiment of the device 10 of the present invention shown in fig1 , this time utilizing optical fiber connectors . this embodiment may have an exterior enclosure that can be made of any material , preferably plastic or metal . it can be any size or shape , preferably a size or shape that is the most space efficient . this embodiment may have a source 12 receptacle in the form of two optical fiber connectors and a target 14 receptacle in the form of a single optical fiber connector . the advantage of this embodiment is higher bandwidth , but the disadvantage is it may require the source and target computers to have optical fiber network adapters , which are less common and more expensive than ethernet adapters . fig7 shows a possible way to connect optical cables inside the enclosure of the device 10 of the present invention . the source 12 receptacle comprises two optical connectors , one for transmission and one for reception . the target 14 receptacle comprises a single optical fiber connector , solely for reception . an optical fiber y cable 72 can be used to connect the transmission connector of the source 12 receptacle to the reception connector of the source 12 receptacle and to the reception connector of the target 14 receptacle . the optical fiber y cable 72 permits traffic to move from the source 12 to the target 14 . however , since the target 14 receptacle contains no transmission connector , no traffic can flow in the reverse direction . in other words , data can move only from the source 12 to the target 14 , never from the target 14 to the source 12 . fig8 shows a different embodiment of the device 10 of the present invention shown in fig1 , this time utilizing a form factor that may be rack mountable . this embodiment may have an exterior enclosure that can be made of any material , preferably metal . it can be any size or shape , preferably a size or shape that is rack mountable . this embodiment may have a plurality of source 12 receptacles in the form of rj45 connectors and a plurality of target 14 receptacles in the form of rj45 connectors . internally , this embodiment comprises a plurality of conductors for transferring data from said sources to said targets , but no conductors for transferring data from said targets to said sources . this embodiment may allow this device to be mounted in a server rack . it also allows for more redundancy , reliability , scalability , and availability . fig9 shows a different embodiment of the device 10 of the present invention shown in fig6 , this time utilizing a form factor that may be rack mountable . this embodiment may have an exterior enclosure that can be made of any material , preferably metal . it can be any size or shape , preferably a size or shape that is rack mountable . this embodiment may have a plurality of source 12 receptacles , each having two optical fiber connectors . it may have a plurality of target 14 receptacles , each having one optical fiber connector for the purpose of receiving data , but no optical fiber connectors for the purpose of transferring data . internally , this embodiment comprises a plurality of optical fiber y cables , each of which connects to the three optical fiber connectors associated with each source and target pair . this embodiment may allow this device to be mounted in a server rack . it also allows for more redundancy , reliability , scalability , and availability .