In this tutorial we will cover different examples to configure network using ncmli command such as nmcli con reload, add ethernet connection using nmcli, add bond connection using nmcli in linux, add and configure network teaming using nmcli, configure networkmanager using nmcli, exit an existing connection with nmcli, nmcli enable dhcp, nmcli rename connection. nmcli remove static ipv4 address and much more.
Understanding nmcli
- nmcli is a command-line tool for controlling NetworkManager and reporting network status.
- It can be utilised as a replacement for nm-applet or other graphical clients. nmcli is used to create, display, edit, delete, activate, and deactivate network connections, as well as control and display network device status.
- Connections are stored in configuration files
- The NetworkManager service must be running to manage these files
Compare nm-settings with ifcfg-* directives (IPv4)
| nmcli con mod | ifcfg-* file | Effect |
|---|---|---|
<strong>ipv4.method</strong>manual |
<strong>BOOTPROTO</strong>=none |
IPv4 address configured statically |
<strong>ipv4.method</strong>auto |
<strong>BOOTPROTO</strong>=dhcp |
Will look for configuration settings from a DHCPv4 server |
<strong>ipv4.address</strong>"192.168.0.10/24" |
<strong>IPADDR</strong>=192.168.0.10<strong>PREFIX</strong>=24 |
Set static IPv4 address, network prefix |
<strong>ipv4.gateway</strong>192.168.0.1 |
<strong>GATEWAY</strong>=192.168.0.1 |
Set IPv4 Gateway |
<strong>ipv4.dns</strong>8.8.8.8 |
<strong>DNS1</strong>=8.8.8.8 |
Modify/etc/resolv.confto use thisnameserver |
<strong>ipv4.dns-search</strong>example.com |
<strong>DOMAIN</strong>=example.com |
Modify /etc/resolv.conf to use this domain in the search directive |
<strong>ipv4.ignore-auto-dns</strong>true |
<strong>PEERDNS</strong>=no |
Ignore DNS Server information from the DHCP Server |
<strong>connection.autoconnect</strong>yes |
<strong>ONBOOT</strong>=yes |
Automatically activate this connection on boot |
<strong>connection.id</strong>eth0 |
<strong>NAME</strong>=eth0 |
The name of this connection |
<strong>connection.interface-name</strong>eth0 |
<strong>DEVICE</strong>=eth0 |
The connection is bound to the network interface with this name |
<strong>802-3-ethernet.mac-address</strong>08:00:27:4b:7a:80 |
<strong>HWADDR</strong>=08:00:27:4b:7a:80 |
The connection is bound to the network interface with this MAC Address |
<strong>ipv4.never-default</strong>no |
<strong>DEFROUTE</strong>=yes |
Never use provided interface's gateway as default gateway |
Compare nm-settings with ifcfg-* directives (IPv6)
| nmcli con mod | ifcfg-* file | Effect |
|---|---|---|
<strong>ipv6.method</strong>manual |
<strong>IPV6_AUTOCONF</strong>=no |
IPv6 is configured statically |
<strong>ipv6.method</strong>auto |
<strong>IPV6_AUTOCONF</strong>=yes |
Will configure network settings using SLAAC from router advertisements. |
<strong>ipv6.method</strong>dhcp |
<strong>IPV6_AUTOCONF</strong>=no<strong>DHCPV6C</strong>=yes |
Will configure network settings by using DHCPv6, but not SLAAC |
<strong>ipv6 . addresses</strong><br> "2001:db8::a/64 2001:db8::1" |
<strong>IPV6ADDR</strong>=2001:db8::a/64<br> <strong>IPV6_DEFAULTGW</strong>=2001:db8::1 |
Sets static IPv6 Address and Gateway |
<strong>ipv6.dns . . .</strong> |
<strong>DNS0=. . .</strong> |
Modify/etc/resolv.confto use thisnameserver |
<strong>ipv6.dns-search</strong>example.com |
<strong>DOMAIN</strong>=example.com |
Modify/etc/resolv.confto use to use this domain in thesearchdirective |
<strong>ipv6.ignore-auto-dns</strong>true |
<strong>IPV6_PEERDNS</strong>=no |
Ignore DNS server information from the DHCP server |
<strong>connection.autoconnect</strong>yes |
<strong>ONBOOT</strong>=YES |
Automatically activates the connection at boot |
<strong>connection.id</strong>eth0 |
<strong>NAME</strong>=eth0 |
The name of this connection |
<strong>connection.interface-name</strong>eth0 |
<strong>DEVICE</strong>=eth0 |
The connection is bound to this network interface with this name |
<strong>802-3-ethernet.mac-address . . .</strong> |
<strong>HWADDR=. . .</strong> |
The connection is bound to the network interface with this MAC Address |
Brief list of nmcli commands syntax
| Command | Purpose |
|---|---|
<b>nmcli dev status</b> |
Show the Network Manager status of all network interfaces |
<b>nmcli con show</b> |
List all connections |
<b>nmcli con show<em>name</em></b> |
List the current settings for the connection name |
<b>nmcli con add con-name<em>name</em>..</b> |
Add a new connection named name |
<b>nmcli con mod<em>name</em>..</b> |
Modify the connection name |
<b>nmcli con reload</b> |
Tell networkManager to reread the configuration files (useful after they have been edited by hand) |
<b>nmcli con up<em>name</em></b> |
Activate the connection name |
<b>nmcli dev dis<em>dev</em></b> |
Deactivate and disconnect the current connection on the network interface dev |
<b>nmcli con del<em>name</em></b> |
Delete the connection name and its configuration file |
nmcli command examples (cheatsheet)
Below are some of the chosen nmcli command examples
1. Check if NetworkManager is running
You can use below command to check if NetworkManager is running or not
# nmcli -t -f RUNNING general
running
To get a general status
# nmcli general
STATE CONNECTIVITY WIFI-HW WIFI WWAN-HW WWAN
connected full enabled enabled enabled enabled
2. List all the available device
To view and list all the available devices on your Linux system
# nmcli dev status
DEVICE TYPE STATE CONNECTION
eth0 ethernet connected eth0
virbr0 bridge disconnected --
eth1 ethernet disconnected --
eth2 ethernet disconnected --
lo loopback unmanaged --
virbr0-nic tun unmanaged --
3. List all the available connections
To list all the available connections
# nmcli con show
NAME UUID TYPE DEVICE
eth1 01fa0bf4-b6bd-484f-a9a3-2b10ff701dcd ethernet eth1
eth0 2e9f0cdd-ea2f-4b63-b146-3b9a897c9e45 ethernet eth0
eth2 186053d4-9369-4a4e-87b8-d1f9a419f985 ethernet eth2
4. List all the configuration of interface
To view all the configured values (default and custom) of an interface
# nmcli con show eth2
connection.id: eth2
connection.uuid: 186053d4-9369-4a4e-87b8-d1f9a419f985
connection.stable-id: --
connection.type: 802-3-ethernet
connection.interface-name: eth2
connection.autoconnect: yes
<Output trimmed>
5. Check physical network device status
Now the status of all the connection network devices
# nmcli dev status
DEVICE TYPE STATE CONNECTION
eth1 ethernet connected eth1
eth0 ethernet connected eth0
eth2 ethernet disconnected --
lo loopback unmanaged --
6. Change hostname using nmcli
You can ideally change hostname using hostnamectl command, but you can
also update hostname using nmcli
To get the current hostname
# nmcli general hostname
centos-8.example.com
Next to update the hostname
# nmcli general hostname centos-8.golinuxcloud.com
Verify the same
# nmcli general hostname
centos-8.golinuxcloud.com
# hostname
centos-8.golinuxcloud.com
7. Create a new ethernet connection and assign static IP Address
In this example nmcli configures the eth2 interface statically, using
the IPv4 address and network prefix 10.10.10.4/24 and default gateway
10.10.10.1, but still auto connects at
startup and saves its configuration into
/etc/sysconfig/network-scripts/ifcfg-eth2 file.
# nmcli con add con-name eth2 type ethernet ifname eth2 ipv4.method manual ipv4.address 10.10.10.4/24 ipv4.gateway 10.10.10.1
Connection 'eth2' (460b16aa-e755-403e-b0ec-5e1560dcc441) successfully added.
8. Create a new ethernet connection and assign DHCP IP Address
The following command will add a new connection for the interface eth2,
which will get IPv4 networking information using DHCP and will
autoconnect on startup. The configuration will be
saved in /etc/sysconfig/network-scripts/ifcfg-eth2 because the
con-name is eth2
# nmcli con add con-name eth2 type ethernet ifname eth2 ipv4.method auto
Connection 'eth2' (d75cb87f-cd15-40a2-9c33-138e69a06a1f) successfully added.
We can verify the same in the mapped interface configuration file
# egrep BOOTPROTO /etc/sysconfig/network-scripts/ifcfg-eth2
BOOTPROTO=dhcp
9. Create and configure bond connection (active-backup) with two slave interface
You can create bond connection with multiple slave interface using nmcli.
Delete any configuration file which exists for slave interface
# nmcli con del "eth1"
# nmcli con del "Wired connection 1"
Add bond interface using nmcli. This command adds a master bond
connection, naming the bonding interface mybond0 and using
active-backup mode. I have given some dummy values for MII,
UPDELAY and DOWNDELAY. If you wish to add primary interface
using “primary=<ifname>”
# nmcli con add type bond ifname mybond0 bond.options "mode=active-backup,downdelay=5,miimon=100,updelay=10"
Connection 'bond-mybond0' (a5c76dbe-550b-4abf-8dc0-88184ade369e) successfully added.
Similarly for round-robin bonding you can use bond.options as
“downdelay=5,miimon=100,mode=balance-rr,updelay=10”
Next add the slaves for mybond0 using nmcli. This command binds first
slave to eth1 interface
# nmcli con add type ethernet ifname eth1 master mybond0
Connection 'bond-slave-eth1' (54dc4282-b90b-4469-9cbf-82bce042de85) successfully added.
This command binds slave 2 to eth2 interface
# nmcli con add type ethernet ifname eth2 master mybond0
Connection 'bond-slave-eth2' (41a5b4a6-8e6b-4df9-bff2-b67c5328311a) successfully added.
List the active connections. So we have our bond and slave interface with us.
# nmcli con show
NAME UUID TYPE DEVICE
bond-mybond0 25ce17b2-fffb-4bf1-a5a3-e7593299f303 bond mybond0
bond-slave-eth1 54dc4282-b90b-4469-9cbf-82bce042de85 ethernet eth1
bond-slave-eth2 41a5b4a6-8e6b-4df9-bff2-b67c5328311a ethernet eth2
eth0 d05aee6a-a069-4e55-9fe4-771ca3336db6 ethernet eth0
Here I am setting static IP Address, NetMask, Gateway, DNS and DNS Search to mybond0 using nmcli
# nmcli con mod bond-mybond0 ipv4.method manual ipv4.address 10.10.10.8/24 ipv4.gateway 10.10.10.1 ipv4.dns 8.8.8.8 ipv4.dns-search example.com
ipv4.method auto and do not provide any IP Address
related details in the above command
Verify your mybond0 configuration file
# egrep 'BOOTPROTO|IPADDR|PREFIX|GATEWAY|DNS' /etc/sysconfig/network-scripts/ifcfg-bond-mybond0
BOOTPROTO=none
IPADDR=10.10.10.8
PREFIX=24
GATEWAY=10.10.10.1
DNS1=8.8.8.8
refresh/reload the network configuration change for mybond0
# nmcli con up bond-mybond0
Connection successfully activated (master waiting for slaves) (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/11)
Verify the bond IP Address
# ip addr show mybond0
7: mybond0: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether 08:00:27:0d:ca:0c brd ff:ff:ff:ff:ff:ff
inet 10.10.10.8/24 brd 10.10.10.255 scope global noprefixroute mybond0
valid_lft forever preferred_lft forever
Verify the list of available connection
# nmcli con show --active
NAME UUID TYPE DEVICE
eth1 01fa0bf4-b6bd-484f-a9a3-2b10ff701dcd ethernet eth1
eth0 2e9f0cdd-ea2f-4b63-b146-3b9a897c9e45 ethernet eth0
10. Create and configure Network Bridge
I have written another article with detailed steps to create and configure network bridge using nmcli and nmtui separately on RHEL/CentOS 7 and 8 Linux.
11. Create and configure Network Teaming
I have written another article with detailed steps to create and configure NIC teaming with two slaves using nmcli validated on RHEL/CentOS 7/8 Linux
12. Reload connection using nmcli (restart)
Reload all connection files from disk. NetworkManager does not monitor changes to connection files by default. So you need to use this command in order to tell NetworkManager to re-read the connection profiles from disk when a change was made to them.
# nmcli con reload
13. Interactively add/edit a connection
You can use nmcli con edit to Edit an existing connection or add a new
one, using an interactive editor. In the below example we will edit
eth1’s IP Address
# nmcli con edit eth1
===| nmcli interactive connection editor |===
Editing existing '802-3-ethernet' connection: 'eth1'
Type 'help' or '?' for available commands.
Type 'print' to show all the connection properties.
Type 'describe [.]' for detailed property description.
You may edit the following settings: connection, 802-3-ethernet (ethernet), 802-1x, dcb, sriov, ethtool, match, ipv4, ipv6, tc, proxy
nmcli> help
------------------------------------------------------------------------------
---[ Main menu ]---
goto [ | ] :: go to a setting or property
remove [.] | :: remove setting or reset property value
set [. ] :: set property value
describe [.] :: describe property
print [all | [.]] :: print the connection
verify [all | fix] :: verify the connection
save [persistent|temporary] :: save the connection
activate [] [/|] :: activate the connection
back :: go one level up (back)
help/? [] :: print this help
nmcli :: nmcli configuration
quit :: exit nmcli
------------------------------------------------------------------------------
nmcli> print ipv4.address
ipv4.addresses: 10.10.10.4/24
nmcli> remove ipv4.address "10.10.10.4/24"
nmcli> print ipv4.address
ipv4.addresses:
nmcli> set ipv4.address 10.10.10.5/24
Do you also want to set 'ipv4.method' to 'manual'? [yes]: yes
nmcli> print ipv4.address
ipv4.addresses: 10.10.10.5/24
nmcli> verify
Verify connection: OK
nmcli> save
Connection 'eth1' (7e3a1246-1743-4bb8-9eab-09664ab996b8) successfully updated.
nmcli> quit
Now verify your changes in eth1’s configuration file
# egrep IPADDR /etc/sysconfig/network-scripts/ifcfg-eth1
IPADDR=10.10.10.5
14. Change ethernet connection BOOTPROTO from DHCP to Static
Now to change ethernet connection BOOTPROTO from DHCP to static using
nmcli, we must modify ipv4.method directive to use manual
# nmcli con mod eth2 ipv4.method manual ipv4.address 10.10.10.4/24 ipv4.gateway 10.10.10.1
Now verify the network configuration file for eth2
# egrep 'BOOTPROTO|IPADDR|PREFIX|GATEWAY' /etc/sysconfig/network-scripts/ifcfg-eth2
BOOTPROTO=none
IPADDR=10.10.10.4
PREFIX=24
GATEWAY=10.10.10.1
15. Change ethernet connection BOOTPROTO from Static to DHCP
Similarly to change ethernet connection BOOTPROTO from static to DHCP
using nmcli, we must modify ipv4.method directive to use auto
# nmcli con mod eth2 ipv4.method auto
Now verify the eth2 network configuration file
# egrep 'BOOTPROTO|IPADDR|PREFIX|GATEWAY' /etc/sysconfig/network-scripts/ifcfg-eth2
BOOTPROTO=dhcp
IPADDR=10.10.10.4
PREFIX=24
GATEWAY=10.10.10.1
As you see we still have IPADDR and other variables from previous
command but they are considered null, because you can see my DHCP has
assigned 10.10.10.5 to eth2
# ip addr show dev eth2
4: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 08:00:27:a8:19:0a brd ff:ff:ff:ff:ff:ff
inet 10.10.10.5/24 brd 10.10.10.255 scope global noprefixroute dynamic eth2
valid_lft 1068sec preferred_lft 1068sec
inet6 fe80::b81f:a58b:43f1:b8d3/64 scope link noprefixroute
valid_lft forever preferred_lft forever
16. Change ONBOOT directive using nmcli
By default ONBOOT is yes in the interface configuration file. So to
disable ONBOOT we must modify connection.autoconnect directive using
nmcli
Verify the ONBOOT value before changing this directive
# egrep 'ONBOOT' /etc/sysconfig/network-scripts/ifcfg-eth2
ONBOOT=yes
Change ONBOOT directive, disable ONBOOT using nmcli
# nmcli con mod eth2 connection.autoconnect no
Re-verify the ONBOOT directive for eth2
# egrep 'ONBOOT' /etc/sysconfig/network-scripts/ifcfg-eth2
ONBOOT=no
17. Change DEFROUTE directive (Never use this network for default route)
By default any gateway we add for any ethernet connection will also be
considered as default gateway, to turn off this directive use
ipv4.never-default with nmcli
Before we make any change verify DEFROUTE directive in the eth2
configuration file
# egrep '^DEFROUTE' /etc/sysconfig/network-scripts/ifcfg-eth2
DEFROUTE=yes
So by default this directive is ON, we will disable the default gateway
option for eth2. To turn off this directive we must select
ipv4.never-default as “yes”
# nmcli con mod eth2 ipv4.never-default yes
Next verify the DEFROUTE directive for eth2
# egrep '^DEFROUTE' /etc/sysconfig/network-scripts/ifcfg-eth2
DEFROUTE=no
18. Disable IPv6 Address for ethernet connection (IPV6INIT)
By default both IPv4 and IPv6 connection type (IPV6INIT) is enabled
for any ethernet connection type. To only use IPv4 and disable IPv6
using nmcli
Verify the existing status of IPv6 connection type for eth2
# egrep 'IPV6INIT' /etc/sysconfig/network-scripts/ifcfg-eth2
IPV6INIT=yes
So this is enabled, we will disable IPv6 connection type using
ipv6.method directive with nmcli
# nmcli con mod eth2 ipv6.method ignore
ipv6.method are ignore, auto, dhcp,
link-local, manual, shared. You can use the same options to
enable/disable IPv4 using ipv4.method
Now re-verify the IPV6INIT directive from eth2 config file
# egrep 'IPV6INIT' /etc/sysconfig/network-scripts/ifcfg-eth2
IPV6INIT=no
19. Change “Automatically Connect” Directive
By default any ethernet connection will be allowed to automatically connect, you can modify this using
# nmcli con mod eth2 connection.autoconnect no
20. Add or Modify DNS to existing connection
You can use ipv4.dns to add DNS server to an new connection or modify
any existing connection using nmcli.
Currently there are no DNS server IP provided for eth1
# egrep DNS /etc/sysconfig/network-scripts/ifcfg-eth1
Next modify connection to add DNS Server IP Address
# nmcli con mod eth1 ipv4.dns 8.8.8.8
Verify the eth1 config file
[root@rhel-8 ~]# egrep DNS /etc/sysconfig/network-scripts/ifcfg-eth1
DNS1=8.8.8.8
21. Append single/multiple DNS Server to connection
Use + prefix with ipv4.dns to append new DNS IP Addresses to an
existing connection using nmcli. In the previous example we added
8.8.8.8 as my DNS server for eth1. Now we will append 8.2.2.2 to the
same connection
# nmcli con mod eth1 +ipv4.dns 8.2.2.2
Verify the eth1 configuration file
# egrep DNS /etc/sysconfig/network-scripts/ifcfg-eth1
DNS1=8.8.8.8
DNS2=8.2.2.2
22. Remove single/multiple DNS Server from connection
As it is understood, with + we append so with - we remove
single/multiple entries of DNS Server from the interface connection
using nmcli.
# nmcli con mod eth1 -ipv4.dns 8.2.2.2,8.8.8.8
Verify the eth1 configuration file
# egrep DNS /etc/sysconfig/network-scripts/ifcfg-eth1
23. Display selected fields with values of connection
You can list all the configured values of a connection using
“nmcli con show <ifname>” but that gives you a long list of details,
you can actually also get selected value of the provided directive of an
individual connection
To get the IPv4 Address of eth1
# nmcli -g ip4.address connection show eth1
10.10.10.4/24
You can use -g to print values from specific fields using nmcli
# nmcli -g ip4.address,ipv4.dns connection show eth1
8.8.8.8,8.2.2.2
10.10.10.4/24
But here as you see we do not get a field to value mapping. You can use
-f to specify what fields (column names) should be printed using
nmcli. Valid field names differ for specific commands. List available
fields by providing an invalid value to the --fields option.
# nmcli -f ipv4.dns,ipv4.addresses,ipv4.gateway con show eth1
ipv4.dns: 8.8.8.8,8.2.2.2
ipv4.addresses: 10.10.10.4/24
ipv4.gateway: 10.10.10.1
24. Monitor connection and device activity
Using nmcli monitor you can observe NetworkManager activity. Watches for
changes in connectivity state, devices or connection profiles. Here in
this example we will execute nmcli monitor for eth1 in one terminal,
and on the other terminal we will make some modification to eth1
connection
# nmcli con mod eth1 ipv4.method manual ipv4.address 10.10.10.4/24
As you see, after the modification, the monitor command gives below output
# nmcli con monitor eth1
eth1: connection profile changed
25. Activate a connection
Just opposite to what we used above, we will use nmcli con up
# nmcli con up eth2
Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/23)
Verify the list of available connection
# nmcli con show --active
NAME UUID TYPE DEVICE
eth1 01fa0bf4-b6bd-484f-a9a3-2b10ff701dcd ethernet eth1
eth0 2e9f0cdd-ea2f-4b63-b146-3b9a897c9e45 ethernet eth0
eth2 186053d4-9369-4a4e-87b8-d1f9a419f985 ethernet eth2
26. De-activate a connection
Deactivate a connection from a device without preventing the device from
further auto-activation using nmcli con down <ifname>. Multiple
connections can be passed to the command.
# nmcli con down eth1
Connection 'eth1' successfully deactivated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/32)
Verify the list of active connections
# nmcli con show --active
NAME UUID TYPE DEVICE
eth0 d05aee6a-a069-4e55-9fe4-771ca3336db6 ethernet eth0
27. Delete connection
Lastly in nmcli command examples, you can delete all type of available
connection using “nmcli con del <ifname>”
# nmcli con del bond-mybond0 bond-slave-eth1 bond-slave-eth2
Connection 'bond-mybond0' (25ce17b2-fffb-4bf1-a5a3-e7593299f303) successfully deleted.
Connection 'bond-slave-eth1' (54dc4282-b90b-4469-9cbf-82bce042de85) successfully deleted.
Connection 'bond-slave-eth2' (41a5b4a6-8e6b-4df9-bff2-b67c5328311a) successfully deleted.
Lastly I hope the steps from the article with nmcli command examples (cheatsheet) on Linux was helpful. So, let me know your suggestions and feedback using the comment section.
References:
man page nmcli
man page nmcli-examples
