Monitoring and control of communications at the external boundary of an information system to prevent and detect malicious and other unauthorized communications, through the use of boundary protection devices (e.g. gateways, routers, firewalls, guards, encrypted tunnels).
						                            Source(s):
						                            
								                            
                                                                    CNSSI 4009-2015
                                                                    from
                                                                            NIST SP 800-53 Rev. 4									                            
						                            
						                            
						                        
					                            
						                              Monitoring and control of communications at the external boundary of an information system to prevent and detect malicious and other unauthorized communications, through the use of boundary protection devices (e.g., gateways, routers, firewalls, guards, encrypted tunnels).
						                            Source(s):
						                            
								                            
                                                                    NIST SP 800-53 Rev. 4
										                             under Boundary Protection 
									                            
						                            
						                            
						                        
					                            
						                              Monitoring and control of communications at the external interface to a system to prevent and detect malicious and other unauthorized communications using boundary protection devices.
						                            Source(s):
						                            
								                            
                                                                    NIST SP 800-53 Rev. 5