0. Goals

  • manage network on Ubuntu without GUI.
  • which kind of network type
    • ethernet
    • wifi

The topic is useful for developer who want develop a linux application, for example snap application in ubuntu.

1. Network Manager On Ubuntu

Use the NetworkManager to manage the network device and connections. NetworkManager can manage network types:

  • ethenet
  • wifi
  • mobile boardband(WWAN)
  • PPPoE device for VPN

2. Usage Of NetworkManager

2.1 Install NetworkManager

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# a. find the application
snap find network-manager
# b. install
snap install network-manager
# c. view the plugs
snap interfaces network-manager
# d. check the service status
systemctl status network-manager

when execute the command c the output looks like:

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name:    network-manager
summary: allows operating as the NetworkManager service
plugs:
  - network-manager:nmcli
slots:
  - core
  - network-manager:service

we can find that the network manager command-line interface(nmcli) will be installed. the nmcli is key command what is used to manage network. If you wan to learn more about nmcli, you can use nmcli help command.

2.2 Manage WIFI

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# check whether the wifi is open
nmcli radio wifi
# if return `disabled`, please enable the wifi radio
nmcli radio wifi on
# list available wifi
nmcli device wifi list
# connect to wifi
nmcli d wifi connect my_wifi password <password>
# check the connection
nmcli connection show

Other wifi configuration:

  • powersave option(0: default, 1: ignore, 2: disable, 3: enable)
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    nmcli c modify <name> 802-11-wireless.powersave 2

2.3 Manage Ethernet

before modify the Ethernet, backup the contents of /etc/netplan is a best practice.

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# check whether support enthernet by network manager
sudo snap get network-manager ethernet.enable
# if return `false`, please enable ethernet support
snap set network-manager ethernet.enable=true
sudo reboot

after the reboot, you can edit the ethernet with nmcli. There two way to midfy the ethernet:

  • interactive console: print/set/save
  • connection modify command

We choose the second way because it can be warpped as shell script or api.

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# list all connection
nmcli connection show
# show detail a connection
nmcli connection show <myconnection name or uuid>
# change the connection name
nmcli connection modify myconnection connection.id myconn

You can get usage detail by executing nmcli connection modify help, looks like below:

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Usage: nmcli connection modify { ARGUMENTS | help }

ARGUMENTS := [id | uuid | path] <ID> ([+|-]<setting>.<property> <value>)+

Modify one or more properties of the connection profile.
The profile is identified by its name, UUID or D-Bus path. For multi-valued
properties you can use optional '+' or '-' prefix to the property name.
The '+' sign allows appending items instead of overwriting the whole value.
The '-' sign allows removing selected items instead of the whole value.

Examples:
nmcli con mod home-wifi wifi.ssid rakosnicek
nmcli con mod em1-1 ipv4.method manual ipv4.addr "192.168.1.2/24, 10.10.1.5/8"
nmcli con mod em1-1 +ipv4.dns 8.8.4.4
nmcli con mod em1-1 -ipv4.dns 1
nmcli con mod em1-1 -ipv6.addr "abbe::cafe/56"
nmcli con mod bond0 +bond.options mii=500
nmcli con mod bond0 -bond.options downdelay

3. Program