Address conflict caused by new Linux installation

Article title: address conflict caused by new Linux installation. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.

With the popularity of Linux in the world, more and more friends begin to use this emerging operating system. In this conversion process, new problems are inevitable.

Not long ago, I encountered a weird network fault, which made the LAN unable to access the external network. After a lot of efforts, I finally ruled out the fault, and the culprit of this fault was really disappointing. it turned out to be a new machine with a Linux system ......

On Monday, I often report to the company. Just after the cards were completed, colleagues on the general station reported that they could not access the external network. As the telecommunications company was upgrading the data room at the time, there were frequent network interruptions, so I did not care at the moment, after contacting the customer service staff of the telecommunications company and confirming that the telecom data center is being upgraded, I explained to my colleagues: "The telecom company is upgrading the data center. this is only a temporary phenomenon."

Return to my office area, the author uses the Ping command to connect to the servers of various departments, the response data shows normal, Lan should be OK. I connected the company's broadband router (see figure), and the response data also showed normal. I observed the various lights of the ADSL cat, and there was no problem. The LAN is smooth, while the ADSL cat works normally. I think: it must be a problem of a telecom company.

However, at a.m., the company still had no access to the external network, and various departments also called to inquire about the network conditions. I began to realize that something was wrong. I immediately contacted the customer service staff of the telecommunications company and got the result: "The data center has been upgraded and there should be no long-time interruptions ".

After mutual negotiation, engineers of the telecommunications company came to the company that afternoon and brought a new ADSL cat. after a single-host test on its laptop, they found that the network was accessible. What's going on? No problem with ADSL cat, and no problem with the line. the fault must be in the LAN, but the LAN is accessible, but it cannot access the external network. what is the problem?

After thinking twice, I moved my attention to the broadband router. The company's Lan accesses the external network through a broadband router. the standalone test proves that the external network is normal, and the machines on the LAN can send packets to each other to prove that the switch and HUB are also correct, the biggest challenge lies in the broadband router.

As a result, I quickly contacted the technical support staff of the router manufacturer. since the router was purchased shortly (within the package period), the technicians suggested switching one. Helpless, I had to contact the local distributor of the vro, and the company had to get off work when I changed a vro and returned to the company. After configuring the new vro to access the network, I use the Ping command to connect to the 163.com host. after receiving the relevant data, everything is normal and the page that NetEase is familiar with is successfully opened. I was overjoyed, and my sense of accomplishment after troubleshooting came to life.

Who knows it's not long? on Tuesday morning, my colleagues at work reported that the network was still disconnected. This is really confusing for me. through yesterday's troubleshooting, we can be sure that all types of devices are normal and there should be no network faults !! While I was puzzled, a colleague called to say that his machine had a problem and needed immediate help. It was this phone call that quickly solved the many doubts of the author.

After learning about this, I learned that my colleague installed a Red Hat Linux system on his debugging machine when he worked overtime last weekend. because it was the first installation, he was not very familiar with all kinds of configurations, when configuring IP addresses, some parameters are incorrectly set, resulting in IP address conflicts in the LAN, resulting in the network failure. I run the netconfig command to reset the IP address of the machine, and then everything is normal. this network fault is completely eliminated.

Coincidentally, the IP address on the debugging machine is the same as the IP address of the broadband router, which causes the bandwidth router to work abnormally. When I Ping a broadband router, the bandwidth router stops working due to IP address conflict. In fact, the new Linux machine is successfully pinged. After a vro is changed, the network returns to normal because the machine has been shut down after work, which will not cause IP conflicts. the vro works normally and the network will naturally not be faulty.

Through this experience, I have learned that as a network administrator, you must have a strict way of thinking. Use the current fashionable ad-"everything is possible !" It is very appropriate to describe the causes of numerous network faults. Sometimes our work is very much like a doctor is diagnosing a patient's cause, or a detective is handling a case. we must be diligent in thinking about new problems so that we can continue to improve at work!