Nowadays, Network Management System (NMS) is a vital role and some key components of NMS include network device discovery, network device monitoring, network performance analysis and so many benefits. This paper aims to present a security management system for a own LAN based Client Server Network to control the security of a network using Java Programming Language. This system can provide the security feature for the user account setting and user management and proxy server feature. And all of the history of the security such as user account and proxy server history are kept in the java standard serializable file. So the user can view anytime the history of the security and proxy server.