7.a Configure IPv4 and IPv6 addresses...
📌 EXAM TIPs
- Check if
bash-completionis installed. If it's not, install it - Use
man nmcli-examplesto get usage examples
Nmcli - NetworkManager Command Line Interface...
nmcli is a command-line tool for controlling NetworkManager and reporting network status. Connections are added under the default location '/etc/sysconfig/network-scripts'.
Nmcli allows you to use shorthand for the commands:
Notes About Making changes...
Connection Changes...
After making changes to a connection (adding IP, removing IP, adding DNS, etc.), you will need to restart the connection (or NetworkManager) for the changes to take effect. There are a few ways you can do that.
Restart the connectio with ifup and ifdown
# ifdown [conn-name] ; ifup [conn-name]
Restart the connection with nmcli
# nmcli connection down [conn-name] ; nmcli connection up [conn-name]
You can also restart NetworkManager, however this will restart all connections
# systemctl restart NetworkManager
Adding Removing Connections...
Adding removing connections will apply the changes in real-time.
When removing a connection, if another connection is configured with autoconnect yes for the same interface, it will come up as soon as the connection is deleted.
ip4 vs ipv4...
when creating a new connection it's ok to use ip4. However, when modifying existing connections you might want to use ipv4.addresses (depending on your goal).
Table 25. IPv4 options
┌──────┬────────────────┬────────────────────────┐
│Alias │ Property │ Note │
├──────┼────────────────┼────────────────────────┤
│ip4 │ ipv4.addresses │ The alias is │
│ │ ipv4.method │ equivalent to the │
│ │ │ +ipv4.addresses syntax │
│ │ │ and also sets │
│ │ │ ipv4.method to manual. │
│ │ │ It can be specified │
│ │ │ multiple times. │
├──────┼────────────────┼────────────────────────┤
Viewing Connections...
Showing a detailed summary for all connections
# nmcli
enp0s3: connected to enp0s3
"Intel 82540EM"
ethernet (e1000), 08:00:27:88:D9:41, hw, mtu 1500
ip4 default
inet4 10.0.2.15/24
route4 0.0.0.0/0
route4 10.0.2.0/24
inet6 fe80::8ae2:af6:2a08:da9f/64
route6 fe80::/64
route6 ff00::/8
virbr0: connected (externally) to virbr0
"virbr0"
bridge, 52:54:00:23:91:BD, sw, mtu 1500
inet4 192.168.122.1/24
route4 192.168.122.0/24
enp0s8: disconnected
"Intel 82540EM"
1 connection available
ethernet (e1000), 08:00:27:13:B0:B4, hw, mtu 1500
lo: unmanaged
"lo"
loopback (unknown), 00:00:00:00:00:00, sw, mtu 65536
virbr0-nic: unmanaged
"virbr0-nic"
tun, 52:54:00:23:91:BD, sw, mtu 1500
DNS configuration:
servers: 10.13.15.1
domains: localdomain
interface: enp0s3
Use "nmcli device show" to get complete information about known devices and
"nmcli connection show" to get an overview on active connection profiles.
Consult nmcli(1) and nmcli-examples(7) manual pages for complete usage details.
Show connections
# nmcli connection show
NAME UUID TYPE DEVICE
enp0s3 705f36b0-b830-41bd-9c6e-f6fa9172f5b4 ethernet enp0s3
Wired connection 1 573da91e-f3a4-3022-8d8a-f50724cba81b ethernet enp0s8
virbr0 67335241-6637-4453-8bd1-14b5513c5178 bridge virbr0
Show only active
# nmcli con show --active
NAME UUID TYPE DEVICE
System eth0 5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03 ethernet eth0
Show device status
# nmcli device status
DEVICE TYPE STATE CONNECTION
enp0s3 ethernet connected enp0s3
enp0s8 ethernet connected Wired connection 1
virbr0 bridge connected (externally) virbr0
lo loopback unmanaged --
virbr0-nic tun unmanaged --
Show information for device
# nmcli device show enp0s8
GENERAL.DEVICE: enp0s8
GENERAL.TYPE: ethernet
GENERAL.HWADDR: 08:00:27:13:B0:B4
GENERAL.MTU: 1500
GENERAL.STATE: 100 (connected)
GENERAL.CONNECTION: eth1
GENERAL.CON-PATH: /org/freedesktop/NetworkManager/ActiveConnection/7
WIRED-PROPERTIES.CARRIER: on
IP4.ADDRESS[1]: 10.0.2.3/24
IP4.ADDRESS[2]: 10.0.3.15/24
IP4.GATEWAY: --
IP4.ROUTE[1]: dst = 10.0.2.0/24, nh = 0.0.0.0, mt = 101
IP4.ROUTE[2]: dst = 10.0.3.0/24, nh = 0.0.0.0, mt = 101
IP4.DNS[1]: 10.13.15.1
IP4.DNS[2]: 8.8.8.8
IP4.DOMAIN[1]: localdomain
IP6.ADDRESS[1]: fe80::c67a:fc98:efeb:4501/64
IP6.GATEWAY: --
IP6.ROUTE[1]: dst = fe80::/64, nh = ::, mt = 101
IP6.ROUTE[2]: dst = ff00::/8, nh = ::, mt = 256, table=255
Adding New Connections...
A connection is "active" when a device uses that connection's configuration to create or connect to a network. There may be multiple connections that apply to a device, but only one of them can be active on that device at any given time. The additional connections can be used to allow quick switching between different networks and configurations.
DHCP
# nmcli con add con-name [connection name] method auto type ethernet ifname eth1
Static IP
# nmcli con add con-name [connection name] type ethernet ifname eth1 ip4 10.0.0.2 gw4 10.0.0.1
Static IP with DNS
# nmcli connection add con-name [connection name] type ethernet ifname eth1 ip4 10.0.2.3/24 gw4 10.0.2.2 ipv4.dns 8.8.8.8
Common options:
-
autoconnect - Connection comes up automatically at boot
-
method
- auto - DHCP asigned
- manual - static IP
- disabled - connection is disabled
- shared - connection sharing
-
type - ethernet, wifi, bluetooth, vlan, tun, dummy, etc...
-
ifname - Interface that will be used for activation
# cat /etc/sysconfig/network-scripts/ifcfg-eth1 TYPE=Ethernet PROXY_METHOD=none BROWSER_ONLY=no BOOTPROTO=dhcp IPADDR=10.0.2.3 PREFIX=24 DNS1=8.8.8.8 DEFROUTE=no IPV4_FAILURE_FATAL=yes IPV6INIT=yes IPV6_AUTOCONF=yes IPV6_DEFROUTE=yes IPV6_FAILURE_FATAL=no IPV6_ADDR_GEN_MODE=stable-privacy NAME=eth1 UUID=42995f47-e0b1-4c81-aa22-7662cba404c7 DEVICE=enp0s8 ONBOOT=yes
Modify Connection...
Change the default IP
# nmcli connection modify eth1 ipv4.addresses 10.0.2.5/24
Add a secondary IP
# nmcli connection modify eth1 +ipv4.addresses 10.0.2.4/24
Delete secondary IP for connection
# nmcli connection modify eth1 -ipv4.addresses 10.0.2.4
Restart the interface
# nmcli connection down eth1 && nmcli connection up eth1
Connection 'eth1' successfully deactivated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/2)
Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/4)
Enable/Disable Connections...
To bring up connections
# nmcli con up [connection name]
To take down connection
# nmcli connection down eth1
Connection 'eth1' successfully deactivated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/7)
Deleting Connections...
Delete "Wired connection 1"
# nmcli connection delete "Wired connection 1"
Connection 'Wired connection 1' (573da91e-f3a4-3022-8d8a-f50724cba81b) successfully deleted.
Adding IPv6 Connections...
You can use an IPv4 address as part of an IPv6 address to make it easier to understand things
# nmcli connection modify enp0s8 ip6 ::fff:10.0.2.3/64 ipv6.gateway ::fff:10.0.2.2
nmcli interactive connection editor...
With the 'edit' option, nmcli presents you with a iteractive editor. The interactive editor will guide you through the connection editing and allow you to change connection parameters according to your needs by means of a simple menu-driven interface.
# nmcli connection 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 [<setting>.<prop>]' 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>
Configure the IP
nmcli> set ipv4.addresses
Enter 'addresses' value: 10.0.2.4/24
Configure default route
nmcli> set ipv4.gateway 10.0.2.2
Configure DNS
nmcli> set ipv4.dns 8.8.8.8
Check that it's working, save and quit
nmcli> verify
Verify connection: OK
nmcli> save
Connection 'eth1' (42995f47-e0b1-4c81-aa22-7662cba404c7) successfully updated.
nmcli> quit
Nmtui - NetworkManager Text Based User Interface...
nmtui is a curses‐based TUI application for interacting with NetworkManager.
Adding a connection...
IP Command...
The 'ip' command will also accept shorthand
Changes are not persistent
Common used commands:
- ip addr - Shows addresses assigned to all network interfaces.
- ip neigh - Shows the current neighbour table in kernel (ARP table).
- ip link set x up - Bring up interface x.
- ip link set x down - Bring down interface x.
- ip route - Show table routes.
Adding a new IP
# ip addr add 10.0.0.2 dev eth0
Deleting the IP
# ip addr del 10.0.0.2/32 dev eth0