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http://kixhelp.com/udfs/

EnumIPInfoAll() - Enables enumeration of TCP/IP information of all network adapters
http://www.kixtart.org/board/ultimatebb.php?ubb=get_topic;f=12;t=000146

CheckNICs() - Checks/Updates a NICs TCP/IP settings
http://www.kixtart.org/board/ultimatebb.php?ubb=get_topic;f=12;t=000148

IsInSubnet() - Checks if a given IP address is in a specified subnet
http://www.kixtart.org/board/ultimatebb.php?ubb=get_topic;f=12;t=000053