How to configure network in centos7

The network configuration of CentOS 7 no longer uses the old ifconfig tool, but uses a more powerful systemd-networkd, which manages the network through configuration files. Configuration files ending in .network (for example, /etc/systemd/network/eth0.network) specify network settings using YAML format. Static IP configuration requires the specified address, gateway, and DNS, while dynamic IP configuration requires only one line of DHCP=yes. systemd-networkd supports a variety of complex configurations, including multiple IP addresses, VLANs, and Bonding. Need to pay attention to syntax errors

CentOS 7 Network Configuration: More than ifconfig

Many newbies will ask, how to configure the network in CentOS 7? The answer is more than just the simple ifconfig . That thing is outdated in modern Linux systems. Although it can still be used, it is just a tool and not the right way to configure the network. Only by understanding the deep principles can we deal with various strange network environments. After reading this article, you can not only configure the network, but also understand the mechanism behind it, and even write a simple network configuration tool yourself.

First, we need to figure out whether CentOS 7 uses NetworkManager or systemd-networkd to manage the network. NetworkManager is a graphical tool that is convenient for novices to get started, but it seems to be powerless for complex network scenarios; systemd-networkd is a command line tool that is more flexible and powerful, and suitable for advanced users. Generally, NetworkManager is the default, but this article mainly talks about systemd-networkd because it represents a more modern way of network management.

The core of systemd-networkd is the configuration file, located in /etc/systemd/network/ directory. Each configuration file corresponds to a network interface, and the file name usually ends with .network . The configuration file is written in YAML format and is very concise and easy to read. For example, configure a static IP address named eth0 :

<code class="yaml">[Match] Name=eth0 [Network] Address=192.168.1.100/24 Gateway=192.168.1.1 DNS=8.8.8.8</code>

This configuration is very simple. Match part specifies the matching interface name, and Network part specifies the IP address, gateway and DNS server. After saving the file, execute systemctl daemon-reload and systemctl restart network to take effect. Note that file names are important, and it determines how the system recognizes this configuration.

Of course, this is just a static IP configuration, and the dynamic IP (DHCP) configuration is also simple:

<code class="yaml">[Match] Name=eth0 [Network] DHCP=yes</code>

Just one line of DHCP=yes is done.

More advanced usage? Do you want to configure multiple IP addresses? no problem! VLAN? That's fine! Bonding? sure! systemd-networkd supports various complex network configurations. There are many options in the configuration file, so you can refer to the official documentation.

Here I want to focus on the possible pitfalls:

• Configuration file syntax error: YAML format is very sensitive to indentation, and an error in a space will cause configuration failure. Be sure to check the grammar carefully.
• Interface name: Be sure to confirm the interface name, don’t write it incorrectly. You can use ip link show command to view the interface name.
• Firewall: After configuring the network, don't forget to check whether the firewall allows access. firewall-cmd command can be used to manage firewall.
• SELinux: SELinux may also affect network configuration. If you encounter problems, you can temporarily shut down SELinux, but this is not recommended for production environments.

Performance optimization? For systemd-networkd itself, performance optimization is mainly reflected in the writing of configuration files, avoid unnecessary complex configurations, and keep the configuration files simple and easy to read. This is more effective than modifying kernel parameters.

Finally, remember that practice brings true knowledge. Only by doing more hands-on configuration and trying different configurations can you truly master the network configuration of CentOS 7. Don’t be afraid of making mistakes, making mistakes is part of learning. Network configuration is a complex topic, but as long as you master the basic principles and tools, you can easily deal with various challenges. I wish you a happy time!

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