2-14 System and Communications Protection System and communications protection guidelines are as follows: Monitor, control, and protect communications (i.e., information transmitted or received by organizational systems) at the external boundaries and key internal boundaries of organizational systems. Employ architectural designs, software development techniques, and systems engineering principles that promote effective information security within organizational systems. Separate user functionality from system management functionality. Prevent unauthorized and unintended information transfer via shared system resources. Implement subnetworks for publicly accessible system components that are physically or logically separated from internal networks. Deny network communications traffic by default and allow network communications traffic by exception (i.e., deny all, permit by exception). Prevent remote devices from simultaneously establishing non-remote connections with organizational systems and communicating via some other connection to resources in external networks (i.e., split tunneling). Implement cryptographic mechanisms to prevent unauthorized disclosure of Postal Service information during transmission unless otherwise protected by alternative physical safeguards. Terminate network connections associated with communications sessions at the end of the sessions or after a defined period of inactivity. Establish and manage cryptographic keys for cryptography employed in organizational systems. Employ FIPS-validated cryptography when used to protect the confidentiality of Postal Service information. Prohibit remote activation of collaborative computing devices and provide indication of devices in use to users present at the device. Control and monitor the use of mobile code. Control and monitor the use of Voice over Internet Protocol (VoIP) technologies. Protect the authenticity of communications sessions. Protect the confidentiality of Postal Service information at rest.