System and method for controlling access to a network resource

A system for controlling access to a network resource by a user, the system comprising:

• means for reviewing at least one incoming electronic connection and/or message from a remote source or network address directed to the network resource;
• means for extracting a network address from the incoming electronic connection and/or message;
• means for performing a lookup of the extracted network address against a locally stored list of network addresses, the locally stored list of network address having a data structure for efficient lookup, and being generated by converting one or more obtained lists of network addresses to said data structure;
• and
• means for performing one or more operations on said incoming address based on whether said incoming address is contained in said locally stored list.

A computer program product in a computer-readable medium for use in a data processing system for storing a plurality of IP addresses, the computer program product comprising:

• first instructions for receiving a plurality of IP addresses;
• second instructions for merging the IP addresses into a master list;
• and
• third instructions for storing the master list on a computer-readable medium.

A system for enabling access to a network resource by a user, the system comprising:

• a mastering server for receiving a plurality of lists of IP addresses, the lists providing an indication of the status of the IP addresses listed thereon;
• a data structure held in a computer readable medium for storing the status of the IP addresses;
• and
• a master list server configured to receive and store a copy of the data structure, the master list server further configured to provide access to the data structure by the network resource in order to determine whether the user should be allowed access to the network resource.