How to resolve conflicts between vswitch IP addresses and Server IP addresses

Fault symptom

All clients in the company's lan use the Windows 98 operating system. However, one day after the client starts up, the system successfully passes verification when logging on to the NT domain. However, in the address bar of the browser, enter "http: // 192.168.0.1 ", when trying to view the Web server page of the local area network, you must enter the user name and password (the Web service we set allows anonymous access), and the verification domain has changed, no matter whether you enter a valid user password, Superuser password, or Webmaster administrator password, the verification fails. However, the command "ping 192.168.0.1" successfully received a response.

Diagnosis Process

First, we initially estimated that the user access permission of the Web server has been changed, but after inspection, no matter whether anonymous access is set or basic verification, the fault still exists, thus eliminating this possibility.

Then, we checked the server Event Log and found that an information system detected a conflict between the IP address 192.168.0.1 and the network hardware address 00: 90: 04: E2: 28: 78, the Local interface has been disabled, and network operations may be interrupted at any time ". This information indicates that the IP address of a client on the network conflicts with the IP address of the server. It is suspected that someone has modified the IP address of a client.

Then, disconnect the server from the vswitch and run the "ping 192.168.0.1" command on a client with the IP address 192.168.0.2 in the LAN to receive a response, it indicates that there is a device with the same IP address as the server on the Internet.

Run the "nbtstat-a 192.168.O.1" command, but the result of "hostnotfound" is displayed. Pinq indicates that the two devices can communicate through the TCP/IP protocol, because the computer name and the working group name must be entered in the network ID during Nic installation in Windows98, if the device that conflicts with the server IP address is a Windows 98 client, use the nbtstat command to return the computer name and the working group name. Based on this, the device that conflicts with the server IP address is not a Windows 98 client.

As a result, the vswitch can also set IP addresses. However, since the networking, the default settings of the vswitch have been working normally. Has someone changed the IP address of the vswitch?

To prove this idea, we disconnected the redundant network cable on the switch, leaving only the server and the Windows98 client with the IP address 192.168.0.2. The fault still exists. Disconnect the server and only connect the Windows 98 client with the IP address 192.168.0.2 to the vswitch. Run the command: ping 192.168.0.1 and get a response. Finally, the fault source is determined on the vswitch.

Originally, for the convenience of management and configuration parameters, a Web service runs on the switch and provides a Web interface. We can set the parameters of the switch through the browser, however, this Weh server cannot be accessed anonymously. Each device in the network must have a unique IP Address: When the IP address of the switch is set to 192.168.0.1, the LAN Web Server suspends the service due to IP address conflict. When "http: // 192.168.0.1" is entered, the Web service on the vswitch is accessed.

To eliminate this fault, you only need to avoid repeated IP addresses of the LAN Web server and the switch. There are two ways to change the IP address of the switch: one is to use the WebInterface provided by the switch, enter "http: // 192.168.0.1" in the address bar of the browser of the Windows 98 client, and enter the Default User Name "admin". The password is not entered, after entering the system, you can change the IP address, sub-stuffy mask, and default route of the switch in IPsetup.

Alternatively, you can log on to the vswitch using the Super Terminal Program attached to Windows 98. There are two methods:

(1) Use the signal cable to directly connect the serial port of the Windows98 client to the console port of the switch. When creating a new connection, choose to directly connect to the serial port (9600 is recommended for the baud rate;

(2) The use of twisted pair wire (RJ-45 connector) Windows98 client and switch connected, new connection selected through TCP/IP (WINSOCK) mode, enter the IP address of the switch, the default port number is 23.

After establishing a connection using the above two methods, you can use the system default password to log on to the system and modify the IP address configuration according to the system menu.

Tips　

Due to the lack of weekly consideration for the security of the company's internal LAN, the default configuration of the switch is not modified during networking, this makes it easy for people who know about our network device models to modify the IP address of the switch using the default password of the switch, resulting in a one-stop LAN Web service.

Improvement Measures: Set a unique IP address for the switch in the network, and modify all the default logon passwords of the switch to prevent the occurrence of such incidents.

1. Solution to the conflict between the LAN and the lan ip Address