Lai The Hung creator Phan, Minh Dung Chairperson Vatcharaporn Esichaikul Examination Committee Ho Dinh Duan Examinaiton committee Electricity of Vietnam Scholarship donor text series technical report th Pathum Thani, Thailand Asian Institute of Technology 2003 continuing eng 51 p. Computer network security is very important issues in building and managing computer networks today. There are many good Internet services offered to users, but besides that advantage there are many threatening risks that can damage the system or a computer at any time. That threats can comes from any outside network or even from a local computer. So that, for any safe system, it is need to consider about a good security system goes along in order to protect the local network or private computers from any outside attack. Building a tool in order to monitor the connections between a computer and another, obtaining the information about an IP address and provide a typical packet filter is the purpose of this research. In this document we will examine and analysis the literature that relate to our implementation works and besides that we will present the method how to implement a monitoring tool. A research study submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Advanced Technologies Computer networks Security measures Computer network protocols Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B08457 http://203.159.5.9/ait-thesis/detail.php?q=B08457 040730 20260818084550.0