27 nmcli command examples (cheatsheet), compare nm-settings with if-cfg file

nmcli examples. nmcli cheatsheet in CentOS/RHEL 7/8. nmcli command exmaples. nmcli con reload. nmcli help. add ethernet connection using nmcli. nmclic command examples cheatsheet in linux. add bond connection using nmcli in linux. add and configure network teaming using nmcli. nmcli command cheatsheet. configure networkmanager using nmcli. nmcli examples. nmclic command examples cheatsheet. exit an existing connection with nmcli. nmcli command examples. nmcli enable dhcp. man nmcli examples. nmcli rename connection. nmcli remove static ipv4 address. nmcle cheat sheet. nmcli remove dns.

nmcli command examples cheatsheet

 

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 modifcfg-* fileEffect
ipv4.method manualBOOTPROTO=noneIPv4 address configured statically
ipv4.method autoBOOTPROTO=dhcpWill look for configuration settings from a DHCPv4 server
ipv4.address "192.168.0.10/24"IPADDR=192.168.0.10
PREFIX=24
Set static IPv4 address, network prefix
ipv4.gateway 192.168.0.1GATEWAY=192.168.0.1Set IPv4 Gateway
ipv4.dns 8.8.8.8DNS1=8.8.8.8Modify /etc/resolv.conf to use this nameserver
ipv4.dns-search example.comDOMAIN=example.comModify /etc/resolv.conf to use this domain in the search directive
ipv4.ignore-auto-dns truePEERDNS=noIgnore DNS Server information from the DHCP Server
connection.autoconnect yesONBOOT=yesAutomatically activate this connection on boot
connection.id eth0NAME=eth0The name of this connection
connection.interface-name eth0DEVICE=eth0The connection is bound to the network interface with this name
802-3-ethernet.mac-address 08:00:27:4b:7a:80HWADDR=08:00:27:4b:7a:80The connection is bound to the network interface with this MAC Address
ipv4.never-default noDEFROUTE=yesNever use provided interface's gateway as default gateway

 

Compare nm-settings with ifcfg-* directives (IPv6)

nmcli con modifcfg-* fileEffect
ipv6.method manualIPV6_AUTOCONF=noIPv6 is configured statically
ipv6.method autoIPV6_AUTOCONF=yesWill configure network settings using SLAAC from router advertisements.
ipv6.method dhcpIPV6_AUTOCONF=no
DHCPV6C=yes
Will configure network settings by using DHCPv6, but not SLAAC
ipv6 . addresses
"2001:db8::a/64 2001:db8::1"
IPV6ADDR=2001:db8::a/64
IPV6_DEFAULTGW=2001:db8::1
Sets static IPv6 Address and Gateway
ipv6.dns . . .DNS0=. . .Modify /etc/resolv.conf to use this nameserver
ipv6.dns-search example.comDOMAIN=example.comModify /etc/resolv.conf to use to use this domain in the search directive
ipv6.ignore-auto-dns trueIPV6_PEERDNS=noIgnore DNS server information from the DHCP server
connection.autoconnect yesONBOOT=YESAutomatically activates the connection at boot
connection.id eth0NAME=eth0The name of this connection
connection.interface-name eth0DEVICE=eth0The connection is bound to this network interface with this name
802-3-ethernet.mac-address . . .HWADDR=. . .The connection is bound to the network interface with this MAC Address

 

Brief list of nmcli commands syntax

CommandPurpose
nmcli dev statusShow the Network Manager status of all network interfaces
nmcli con showList all connections
nmcli con show nameList the current settings for the connection name
nmcli con add con-name name ..Add a new connection named name
nmcli con mod name ..Modify the connection name
nmcli con reloadTell networkManager to reread the configuration files (useful after they have been edited by hand)
nmcli con up nameActivate the connection name
nmcli dev dis devDeactivate and disconnect the current connection on the network interface dev
nmcli con del nameDelete 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
NOTE:

To use DHCP IP, use 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

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
NOTE:

If you are connected to your server using this interface then your connection would close once the connection is de-activated

 

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

 

1 thought on “27 nmcli command examples (cheatsheet), compare nm-settings with if-cfg file”

  1. Just want to say thank you for you hard work! It has/will be instrumental in my RHCSA/RHCE journey.

    Stay Safe
    .....and great hopes for your journey!

    Reply

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