Set up Linux network card independently and fully control the network environment

With the rapid development of Internet technology, the role of the Internet in our daily lives is becoming more and more important. When building a network environment, the network interface card (NIC) is an important link between the computer and the external network. This article will provide an in-depth introduction to the method of modifying the network card configuration in Linux systems, allowing users to fully control the network environment by independently setting network parameters.

1. Environment

VirtualBox CentOS6.5

**2. Question

**

Sometimes you will encounter such a situation when configuring the network after cloning the server, or when maintaining the server built by others. As shown below:

That is: in the interface configuration file ifcfg-eth0, the information of the network card eth1 is configured.

This kind of inconsistency may cause some trouble for obsessive-compulsive disorder. Sometimes what we want more is: in the ifcfg-eth0 file, the information of the network card eth0 should be configured, and the network card eth1 should be configured in ifcfg -Configure in eth1.

3. Solution

To solve the above problem, there are roughly two methods:

1) Change the file name of the interface configuration file from ifcfg-eth0 to ifcfg-eth1;

2) Change the name of the network card eth1 to eth0.

method one:

This method is feasible in actual testing, as shown in the figure below. After modification, just restart the network.

Method Two:

The intuitive feeling of this method is to directly change the network card name from eth1 to eth0 in the ifcfg-eth0 configuration file. However, if you change it like this, Device eth0 does not seem to be present when you restart the network. That is, Device eth0 does not exist. error, as shown in the figure below. To solve this problem, please refer to "L08-Linux solves the problem of Device eth0 does not seem to be present, delaying initialization".

So it cannot be changed simply and crudely, because, as shown in the figure below by the ifconfig -a command, the network card recognized by the server is still eth1, not eth0.

Note: Remember the mac address here 08:00:27:74:39:02, which can be used as a basis for modification in subsequent implementation steps, because the IP of a server can be changed at will, but the mac address is unique of.

In order to solve this problem, we first modify the configuration in the /etc/udev/rules.d/70-persistent-net.rules file so that the server’s network card name changes from eth1 to eth0, and then, we Change the network card name in ifcfg-eth0 and finally restart the network.

1) Modify the configuration file /etc/udev/rules.d/70-persistent-net.rules.

The contents of the original /etc/udev/rules.d/70-persistent-net.rules file are as follows:

# This file was automatically generated by the /lib/udev/write_net_rules

# program, run by the persistent-net-generator.rules rules file.

#

# You can modify it, as long as you keep each rule on a single

# line, and change only the value of the NAME= key.

# PCI device 0x8086:0x100e (e1000)

SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="08:00:27:9b:bb:3c", ATTR{type}=="1

", KERNEL=="eth*", NAME="eth0"

 
# PCI device 0x8086:0x100e (e1000)

SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="08:00:27:74:39:02", ATTR{type}=="1

", KERNEL=="eth*", NAME="eth1"

The modified content is as follows:

# This file was automatically generated by the /lib/udev/write_net_rules

# program, run by the persistent-net-generator.rules rules file.

#

# You can modify it, as long as you keep each rule on a single

# line, and change only the value of the NAME= key.

  
# PCI device 0x8086:0x100e (e1000)

SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="08:00:27:74:39:02", ATTR{type}=="1

", KERNEL=="eth*", NAME="eth0"

As shown above

a) Delete the eth0 configuration in the original file (because it is useless. This configuration is the configuration of the source machine when I cloned this server during this test. The corresponding mac address in the configuration is also the source server. The mac address is useless for our current server);

b) Change the eth1 network card name to eth0 (you can notice that its mac address is 08:00:27:74:39:02, which is exactly the entry we want to modify.)

2) Modify the interface configuration file ifcfg-eth0 and change the network card from eth1 to eth0

3) Restart the machine and let the server reconfigure the network card information according to the /etc/udev/rules.d/70-persistent-net.rules file

It can be found that after restarting the machine and entering the server, the network has been configured to be consistent, as shown below:

At this point, the modification is completed.

In today's information age, the network has become an indispensable part of our work and life, and the network card is the key device to achieve network communication. This article explains in detail how to modify the network card configuration in Linux systems and provides some practical cases. By learning this knowledge, we can manage and configure network cards more flexibly, and fully control our own devices in the network environment.

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