subject: Firewall secretly block, caused failure of network access [print this page] Firewall secretly block, caused failure of network access
Unable to access Network Failure often occurs, resulting in this failure is also a variety of reasons; in accordance with general train of thought in turn to troubleshoot network faults, but also quickly to get rid of the fault phenomena. However, I once encountered a very strange network unreasonable failure, such failure is due to address the conflict situation even after the Firewall Secretly block caused, taking into account the special nature of the fault, and now the process of this investigation will be its contribution in the hope that everyone will be enlightened!
Failure phenomenon The author's local area network unit size is not large, only about 20 sets of ordinary computers, all computers are connected through 100M network cable to the LAN Switch On, switch it with a TP-LINK branded broadband Router Directly connected, and finally through the hiring of local telecommunications 10M fiber broadband lines to connect to the provincial network of centers and network access through the Internet network of provincial centers. LAN performance with a good paper Server , Usually units of various types of information as well as other administrative information to inform all published in the Server , The unit staff can direct a computer in their own way through the Web easy access to the contents of the above; To ensure the security of server access, the author deliberately installed in the file server Fair firewall and the firewall's operating mode set server model.
However, recently a staff writer calls to reflect that his computer can not access the file server unit; as the other staff did not reflect the failure situation, I subconsciously think the issue is likely to staff their own computer problems, in particular, He may be no contact with reliable network connection cables, so the proposed fault repair staff who look to re-plug the network cable, it does not work, then try to restart about computer systems. However, there is no more time, employees who call back again, said, according to the author's proposed operation, the computer still can not get their normal access to the file server unit.
Fault tracing Given the other employees are reflected in the file server to access all normal, I without thinking, immediately rushed to the scene a network failure; after re-plug the network cable and restart the computer system and a series of routine operations, the author found that a network failure really has not been resolved, is it physical connection there was an accident? In order to determine the computer's network cable connection failure is normal connectivity, a computer system failure author Click "Start" / "Run" command, the system is running in the pop-up dialog box, do the ping command to test the target file server's IP address, destination address was found to be normal ping really can not pass, could fault the computer and the network connection between the file server is really unreasonable? I worry about their possible physical cable there is the phenomenon of short circuit or broken, this deliberately get a professional cable Tester To this root network cable for connectivity testing, and found that the root of the connectivity of the network cable is normal, why can not fault the normal ping the computer through a file server? Then I look at random ping the other LAN Internet address of the computer, the results obtained so I was very surprised, you can pass the normal ping the other computer's internet address, and also pass the My Network Places window to access other computers in the sharing of resources, indicating that the computer is not a problem employee.
As from the employee's computer system can not find obvious errors, I had to try to shift attention to the file server system; rushed to the scene file server, I first look at the file server system restart; when the system restarts successfully After I accidentally found the system even on the desktop there is a error, saying that the computer's IP address and file server IP address conflict situation, is it the fault address conflict can not properly access the computer file server for? In order to determine their own analysis is correct, I immediately went to the computer field failure, click "Start" / "Settings" / "network connection" command, the list of network connections in the pop-up window, use Mouse Right-click the target local connection icon and perform the shortcut menu "Properties" command, open the target property of the local connection Settings dialog box, select one of the TCP / IP protocol option, click the "Properties" button, enter TCP / IP protocol in the property dialog box, where I really find fault with the computer using the Internet address of the file server's Internet address is the same, it seems unreasonable that the problem is the computer network failure is due to address conflict factors.
