International Business Machines Corporation

Kira Sterling Attwood

Linwood Hugh Overby, Jr

David John Wierbowski

James Russell Godwin

Chien-En Sun

Brian Sean Perry

The invention prevents server overload and possible server crippling due to a flooding of connectionless datagrams caused by intentional attack or otherwise. In response to a datagram from a host for a specified port, the number of datagrams already queued to the port from the host is determined. If this number exceeds a first threshold, the datagram is discarded. In the preferred embodiment, the threshold is determined by multiplying a percentage P by the number of available queue slots remaining for the port.

Technique of defending against network flooding attacks using a connectionless protocol

The invention prevents server overload and possible server crippling due to a flooding of connect requests caused by intentional attack or otherwise. In response to a connection request from a host for a specified port, the number of connections to the port that are assigned to the host are determined. If this number exceeds a first threshold, the request is denied. It is possible to override this denial if a quality of service parameter pertaining to the host permits such an override. However, if the number of available connections to the port is less than a second threshold, the connection request is denied in any event.

Technique of defending against network connection flooding attacks

Ipsec rules are searched in order from rules containing the most specificity to those containing the least specificity of attributes. The static rules include placeholders for sets of dynamic rules. Dynamic rules are searched only if a placeholder is the first matching rule in the static table. Sets of dynamic rules are partitioned into separate groups. Within each group there is no rule order dependence. Each such group is searched with an enhanced search mechanism, such as a search tree. For connection oriented protocols, security rule binding information is stored in association with the connection. This allows the searching of the rules to be performed only when a connection is first established. If a static or dynamic rule is changed during a connection, a search is repeated. For selected connectionless protocols, packets are treated as if they were part of a simulated connection. A pseudo-connection memory block is allocated with the creation of each socket and Ipsec security binding information is stored in the pseudo-connection memory block on a first packet.

Security rule database searching in a network security environment

Ipsec rules are searched in order from rules containing the most specificity of attributes to those containing the least specificity of attributes. The static rules include placeholders for sets of dynamic rules. The placeholders in the static table immediately precede and point to an associated set of dynamic rules. Dynamic rules are searched only if a placeholder is found to be the first matching rule in the static table. Sets of dynamic rules are partitioned into separate groups. Within each group there is no rule order dependence. Each such group is searched with an enhanced search mechanism, such as a search tree. Searching is further improved by searching at layers higher than the IP layer.

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Chapel Hill, NC, United States of America

Kira Sterling Attwood