NetworkManager Network configuration tool suite¶
In 2004, Red Hat launched the NetworkManager project, which aims to make it easier for Linux users to meet the needs of current network management, especially the management of wireless networks. Today, the project is managed by GNOME. The homepage for NetworkManager can be found here.
Official introduction - NetworkManager is a standard Linux network configuration tool suite. It supports various network settings from desktop to server and mobile devices and is perfectly integrated with popular desktop environments and server configuration management tools.
The suite mainly includes two command line tools:
nmtui. Configures the network in a graphical interface.
shell > dnf -y install NetworkManager NetworkManager-tui
shell > nmtui
| NetworkManager TUI | |
|---|---|
| Edit a connection | |
| Activate a connection | |
| Set system hostname | |
| Quit | |
| OK |
nmcli. Uses the command line to configure the network, either a pure command line or an interactive command line.
Shell > nmcli connection show
NAME UUID TYPE DEVICE
ens160 25106d13-ba04-37a8-8eb9-64daa05168c9 ethernet ens160
For RockyLinux 8.x, we introduced how to configure its network in this document. You can use vim to edit the network card configuration file in the /etc/sysconfig/network-script/ directory, or you can use nmcli/nmtui, both of which are acceptable.
Naming rules for udev device Manager¶
For RockyLinux 9.x, if you go to the /etc/sysconfig/network-scripts/ directory, there will be a readme-ifcfg-rh.txt description text that prompts you to go to the /etc/NetworkManager/system-connections/ directory.
Shell > cd /etc/NetworkManager/system-connections/ && ls
ens160.nmconnection
The ens160 here refers to the name of the network card in the system. You may wonder why the name looks so strange?
This is because of the udev device manager. It supports many different naming schemes. By default, fixed names are assigned according to firmware, topology and location information. Its advantages include:
- Device names are fully predictable.
- Device names stay fixed even if you add or remove hardware, because no re-enumeration takes place.
- Defective hardware can be seamlessly replaced.
In RHEL 9 and the corresponding community version operating systems, consistent device naming is enabled by default. The udev device manager will generate device names according to the following scheme:
| Scheme | Description | Example |
|---|---|---|
| 1 | Device names incorporate firmware or BIOS-provided index numbers for onboard devices. If this information is not available or applicable, udev uses scheme 2. |
eno1 |
| 2 | Device names incorporate firmware or BIOS-provided PCI Express (PCIe) hot plug slot index numbers. If this information is not available or applicable, udev uses scheme 3. |
ens1 |
| 3 | Device names incorporate the physical location of the connector of the hardware. If this information is not available or applicable, udev uses scheme 5. |
enp2s0 |
| 4 | Device names incorporate the MAC address. Red Hat Enterprise Linux does not use this scheme by default, but administrators can optionally use it. | enx525400d5e0fb |
| 5 | The traditional unpredictable kernel naming scheme. If udev cannot apply any of the other schemes, the device manager uses this scheme. |
eth0 |
udev device Manager names the prefix of the NIC based on the type of interface:
- en for Ethernet.
- wl for wireless LAN (WLAN).
- ww for wireless wide area network (WWAN).
- ib, InfiniBand network.
- sl, Serial Line Internet Protocol (slip)
Add some suffixes to the prefix, such as:
- o on-board_index_number
- s hot_plug_slot_index_number [f] function [d] device_id
- x MAC_address
- [P] domain number p bus s slot [f] function [d] device_id
- [P] domain number p buss s slot [f] function [u] usb port [c] config [i] interface
You can use man 7 systemd.net-naming-scheme to get more detailed information.
nmcli command (recommended)¶
Users can not only configure the network in a pure command line mode, but also use interactive commands to configure the network.
nmcli connection¶
The nmcli connection command can show, delete, add, modify, edit, up, down, and so on.
For specific usage, please refer to nmcli connection add --help, nmcli connection edit --help, nmcli connection modify --help and so on.
For example, to configure a new ipv4 static ip connection using a pure command line and start up automatically, it can be:
Shell > nmcli connection add type ethernet con-name CONNECTION_NAME ifname NIC_DEVICE_NAME \
ipv4.method manual ipv4.address "192.168.10.5/24" ipv4.gateway "192.168.10.1" ipv4.dns "8.8.8.8,114.114.114.114" \
ipv6.method disabled autoconnect yes
If you are using DHCP to get the ipv4 address, it can be:
Shell > nmcli connection add type ethernet con-name CONNECTION_NAME ifname NIC_DEVICE_NAME \
ipv4.method auto ipv6.method disabled autoconnect yes
With the above configuration, the connection is not activated. You need to perform the following operations:
Shell > nmcli connection up NIC_DEVICE_NAME
Enter the interactive interface through the edit keyword on the basis of the existing connection, and modify it:
Shell > nmcli connection edit CONNECTION_NAME
nmcli > help
You can also modify one or more properties of the connection directly from the command line with the modify keyword. For example:
Shell > nmcli connection modify CONNECTION_NAME autoconnect yes ipv6.method dhcp
Info
Operations through nmcli or nmtui are saved permanently, not temporarily.
Link aggregation¶
Some use multiple network cards for link aggregation. In the early days, using bonding technology, there were seven working modes (0~6) and the bond mode only supported two network cards at most. Later, the teaming technology is gradually used as an alternative, there are five working modes, and the team mode can use up to eight network cards. Comparison link between bonding and teaming can be found on this link.
For example, the 0 mode of bonding:
Shell > nmcli connection add type bond con-name BOND_CONNECTION_NAME ifname BOND_NIC_DEVICE_NAME mode 0
Shell > nmcli connection add type bond-slave ifname NIC_DEVICE_NAME1 master BOND_NIC_DEVICE_NAME
Shell > nmcli connection add type bond-slave ifname NIC_DEVICE_NAME2 master BOND_NIC_DEVICE_NAME
Network card configuration¶
Warning
It is not recommended to make changes to this by means of vim or other editors.
You can view more detailed information through man 5 NetworkManager.conf and man 5 nm-settings-nmcli.
The content of the configuration file of the NetworkManager network card is an init-style key file. For example:
Shell > cat /etc/NetworkManager/system-connections/ens160.nmconnection
[connection]
id=ens160
uuid=5903ac99-e03f-46a8-8806-0a7a8424497e
type=ethernet
interface-name=ens160
timestamp=1670056998
[ethernet]
mac-address=00:0C:29:47:68:D0
[ipv4]
address1=192.168.100.4/24,192.168.100.1
dns=8.8.8.8;114.114.114.114;
method=manual
[ipv6]
addr-gen-mode=default
method=disabled
[proxy]
- Lines that start with # and blank lines are considered comments.
- Enclosed in [ and ] is the section it intends to declare the title and below it are the specific key-value pairs contained. Each declared title and its key-value pair form a syntax segment.
- Any file with the .nmconnection suffix can be used by NetworkManager.
connection title names can contain these common key-value pairs:
| key name | description |
|---|---|
| id | The alias of con-name, whose value is a string. |
| uuid | Universal unique identifier, whose value is a string. |
| type | The type of connection, whose values can be ethernet, bluetooth, vpn, vlan, and so on. You can use man nmcli to view all supported types. |
| interface-name | The name of the network interface this connection is bound to, whose value is a string. |
| timestamp | Unix timestamp, in seconds. The value here is the number of seconds since January 1, 1970. |
| autoconnect | Whether it starts automatically when the system starts. The value is of Boolean type. |
ethernet title names can contain these common key-value pairs:
| key name | description |
|---|---|
| mac-address | MAC physical address. |
| mtu | Maximum Transmission Unit. |
| auto-negotiate | Whether to negotiate automatically. The value is Boolean type. |
| duplex | The Values can be half (half-duplex), full (full-duplex) |
| speed | Specify the transmission rate of the network card. 100 is 100Mbit/s. If auto-negotiate=false, the speed key and duplex key must be set; if auto-negotiate=true, the speed used is the negotiated speed, and the writing here does not take effect (this is only applicable to the BASE-T 802.3 specification); when nonzero, the duplex key must have a value. |
ipv4 title names can contain these common key-value pairs:
| key name | description |
|---|---|
| addresses | IP addresses assigned |
| gateway | Gateway (next hop) for the interface |
| dns | Domain Name Servers in use |
| method | The method to be obtained by IP. The value is of string type. The value can be: auto, disabled, link-local, manual, shared |
Author: tianci li
Contributors: Steven Spencer