Abstract: Techniques are disclosed for improving multi-level security (“MLS”) in computing systems. Communication between MLS systems in the prior art requires explicitly tagging each packet with its security classification. The packet tags comprise variable-length bit patterns inserted into packet headers. This results in a number of drawbacks, including increased path length and code complexity, as well as reduced interoperability. An MLS system according to the present invention simulates a cluster or collection of single-level security systems, and thereby avoids packet tagging. For each security classification used by an MLS system, a distinct source address is defined. This source address is used for outbound packets having that security classification, such that the packet's source address implicitly identifies the packet's security classification.

Abstract: Techniques are disclosed for multi-level security (“MLS”) in computing systems. Communication between MLS systems in the prior art requires explicitly tagging each packet with its security classification. The packet tags comprise variable-length bit patterns inserted into packet headers. This results in a number of drawbacks, including increased path length and code complexity, as well as reduced interoperability. An MLS system according to the present invention simulates a cluster or collection of single-level security systems, and thereby avoids packet tagging. For each security classification used by an MLS system, a distinct source address is defined. This source address is used for outbound packets having that security classification, such that the packet's source address implicitly identifies the packet's security classification.

Abstract: The invention detects a denial of service attack at a node by monitoring the number of discarded packets in relationship to the number of inbound packets. When an attack is detected, relevant inbound packet information is collected during the attack to help characterize the attack and at least to pinpoint the source of the last hop to the attacked node.