| Under the development of science and technology and the application of science and technology achievement, the networks of the enterprises are getting larger and larger, the number of computers in the networks is also getting larger. The workload of computer maintaining grows more. Therefore, the demand of monitoring and maintaining the computers from remote increased a lot.Using network to Monitor and maintain the computers from remote can save us manpower. We can clearly know the state of the workstations on the network and discover the fault of the workstations in time without checking the state of computers in the real place. The enterprise always has a lot of computers, if we check the state of computers manually; we can not make sure of the real-time of monitoring, can not discover the exception of computers. In some circumstance it will be very inconvenient. Therefore the predominance of monitoring the workstations from remote is evident, especially when many computes disperse on wide range.This system is a remote workstation monitoring system based on network technology and according to the requirement of the user. The requirement of the user is to monitor the on/off states of the workstations that dispersed around the park which is 300,000 square meters, and can set whether to monitor someone computer of not according to the setup of the attending system, the setting should be setting once using always. When the system detected the fault of workstations, it should send the alarm signal to the manager; tell the manager the place where the fault occurred. If the alarm message was not be confirmed in time, it should be passed to the superior manage continuously, until it had been confirmed. In the mean while, the system should record the time , place and the handle action of the fault in the system log.We use ICMP protocol to monitor the states of computers. ICMP is often considered as component of IP layer. It delivers error control datagram and other notice messages. The ICMP packet is often utilized by upper layer protocols like TCP and UDP. Some ICMP packet pass the error datagram back to the user processes. The ICMP packet is passed by encapsulated in the IP datagram. There 15 kinds of ICMP packet, each has different function.The system set the type value of the ICMP packet to 8, which mean ECHO_REQUEST. The monitor workstation sends it to the workstations which are being monitored. If the monitored workstation is working normally, it would a ICMP ECHO_REPLY datagram to the monitor workstation. On opposition, if something wrong with the monitored workstation or the line that connected to the network broke down, there would be no response. Thus, we can monitor the state of the workstations.The ICMP packet is encapsulated in the IP datagram. Like the datagram of other protocol, It has header and data parts. The header of it can be expressed as a structure:typedef struct tagIcmpHead /* icmp header */?{? BYTE icmp_type; /* icmp service type */? BYTE icmp_code; /* icmp header code,8 echo require, 0 echo reply */? USHORT icmp_chksum; /* icmp header chksum */? USHORT icmp_id; /* icmp packet identification */? USHORT icmp_seq; /* icmp packet sequent */? ULONG timestamp;?} IcmpHeader;To monitor the state of the workstations based on ICMP protocol makes the monitoring action separated from the applications of the monitored workstation. We can only install the monitor software on the monitor workstation and need not to install it on the monitored workstation, thus can decrease the cost of maintaining, and elevate the maintainability of the system.In the practice we use multi-thread technology to optimize the performance of the system. We can get efficient applications by using multi-thread technology, it makes the computer can process more then one task concurrently, thus it will improve the utilizing rate of the resources, and reduce the response time of the system. This system has more usability by using multi-thread technology to monitor the state of t...
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