After starting the WebLogic, you cannot enter the console and apply the problem

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Yesterday, the implementation of the site staff feedback: Start WebLogic, can not enter the console, ie display blank page, even the login interface is not!

Personally telnet to the server access, indeed, to see WebLogic related documents are Ah, depressed, not to complain about the most difficult to solve. The service cannot be restarted because the system is running. Baffled after the solution feel that only the Internet to find relevant information. Later found the following article:

After starting the WebLogic, you cannot enter the console and apply the problem

This is a very strange problem, is also the strangest I encountered the most difficult to solve the problem, our system in the pilot phase, occasionally the application system can not log the phenomenon, at the same time, WebLogic's console can not log in. However, to view the processes in the operating system, the WebLogic process is still in progress, the application's backend output and the WebLogic log file output have no error messages.

At first, there was a problem with the system, and we were able to reboot the system and always solve the problem. There are occasional restarts of two times to resolve the problem. I also contacted Bea's engineers, who provided a variety of options, such as using Telnet IP port to see if they were able to connect to the application when there was a problem, such as printing dump information in a kill-3 way, sending them to see why, etc. In the end, they still failed to solve the problem. The longest time caused our application downtime for 2 hours.

Then there was a time when the system did not appear to have this problem. But one day there was a sudden recurrence of the problem, and this time the menacing, and then basically the whole day of the system was inaccessible. We use the reconstruction WebLogic domain and the server method, modifies the landing port the method, each time is insists for a while again to appear the problem. More seriously, after restarting WebLogic, the system is almost immediately inaccessible. I even thought about the problem with WebLogic software, and I almost wanted to replace it with WebSphere.

Later, we used VPN, let BEA engineer login system to see the reason, but their 800 engineers also did not find the reason, depressed to death me. It happened that Bea's Guangzhou pre-sales engineer, looking at the system, found that there were about 70 connections in the system with SYN_RCVD status. This is linked to a malicious Dos attack. (http://www-900.ibm.com/developerWorks/cn/security/se-ddos/index.shtml)

After testing, this is where the cause is. Netstat-an|grep syn|wc-l the number of times each display is greater than 70, the system is basically inaccessible. Then we solved the problem with two firewall filters (one to control access outside the intranet, one to control access inside the intranet).

This problem has plagued me for a long time and tested various methods. The main thing to write here is to illustrate two aspects of the problem. First: When troubleshooting the system, the first thing to take into account is the network and the virus. Second: When we troubleshoot system problems, and do not use all network connections disconnected from the server, the local access to the system, if this approach, it may be found earlier problems. Third: This problem without any error is the hardest to find, we should be careful.

Above bold text excerpt from Java Free people

After reading this, the heart is a lot of collapse, if so, restart the system should be all right. But in the future to strengthen the server security settings Oh.

Sure enough, after the night to restart the system, all OK, just do not know if it will happen again.