The nmcli utility is a very useful for managing and configuring NetworkManager. It is what I recommend people use to configure networking interfaces during the RHSCA7 and RHCE7 exams rather than using nmtui, nm-applet, or directly editing an interface configuration file.
From the nmcli(1) manpage:
nmcli is a command-line tool for controlling NetworkManager and getting its status. It is not meant as a replacement of nm-applet or other similar clients. Rather it’s a complementary utility to these programs. The main nmcli’s usage is on servers, headless machines or just for power users who prefer the command line.
This post shows you how to use the nmcli utility to rename and assign static IPv4 addresses to a networking interface in a newly created CentOS 7.0 VM running on VMware Workstation 14.
To view the status of networking interfaces:
# nmcli dev status DEVICE TYPE STATE CONNECTION eno16777736 ethernet connected eno16777736 lo loopback unmanaged -- # # nmcli connection show NAME UUID TYPE DEVICE eno16777736 570099b5-a252-4adc-ade7-83c6f440cc93 802-3-ethernet eno16777736 # nmcli connection show eno16777736 connection.id: eno16777736 connection.uuid: 570099b5-a252-4adc-ade7-83c6f440cc93 connection.interface-name: -- connection.type: 802-3-ethernet connection.autoconnect: yes connection.timestamp: 1571045800 connection.read-only: no connection.permissions: connection.zone: -- connection.master: -- connection.slave-type: -- connection.secondaries: connection.gateway-ping-timeout: 0 802-3-ethernet.port: -- 802-3-ethernet.speed: 0 802-3-ethernet.duplex: -- 802-3-ethernet.auto-negotiate: yes 802-3-ethernet.mac-address: 00:0C:29:BA:1A:27 802-3-ethernet.cloned-mac-address: -- 802-3-ethernet.mac-address-blacklist: 802-3-ethernet.mtu: auto 802-3-ethernet.s390-subchannels: 802-3-ethernet.s390-nettype: -- 802-3-ethernet.s390-options: ipv4.method: auto ipv4.dns: ipv4.dns-search: ipv4.addresses: ipv4.routes: ipv4.ignore-auto-routes: no ipv4.ignore-auto-dns: no ipv4.dhcp-client-id: -- ipv4.dhcp-send-hostname: yes ipv4.dhcp-hostname: -- ipv4.never-default: no ipv4.may-fail: yes ipv6.method: auto ipv6.dns: ipv6.dns-search: ipv6.addresses: ipv6.routes: ipv6.ignore-auto-routes: no ipv6.ignore-auto-dns: no ipv6.never-default: no ipv6.may-fail: yes ipv6.ip6-privacy: -1 (unknown) ipv6.dhcp-hostname: -- GENERAL.NAME: eno16777736 GENERAL.UUID: 570099b5-a252-4adc-ade7-83c6f440cc93 GENERAL.DEVICES: eno16777736 GENERAL.STATE: activated GENERAL.DEFAULT: yes GENERAL.DEFAULT6: no GENERAL.VPN: no GENERAL.ZONE: -- GENERAL.DBUS-PATH: /org/freedesktop/NetworkManager/ActiveConnection/0 GENERAL.CON-PATH: /org/freedesktop/NetworkManager/Settings/0 GENERAL.SPEC-OBJECT: -- GENERAL.MASTER-PATH: -- IP4.ADDRESS[1]: ip = 10.10.10.146/24, gw = 10.10.10.5 IP4.DNS[1]: 10.10.10.5 IP4.DOMAIN[1]: localdomain DHCP4.OPTION[1]: requested_domain_search = 1 DHCP4.OPTION[2]: requested_nis_domain = 1 DHCP4.OPTION[3]: requested_time_offset = 1 DHCP4.OPTION[4]: requested_broadcast_address = 1 DHCP4.OPTION[5]: requested_rfc3442_classless_static_routes = 1 DHCP4.OPTION[6]: requested_classless_static_routes = 1 DHCP4.OPTION[7]: requested_domain_name = 1 DHCP4.OPTION[8]: expiry = 1571047308 DHCP4.OPTION[9]: domain_name = localdomain DHCP4.OPTION[10]: next_server = 10.10.10.254 DHCP4.OPTION[11]: broadcast_address = 10.10.10.255 DHCP4.OPTION[12]: dhcp_message_type = 5 DHCP4.OPTION[13]: requested_subnet_mask = 1 DHCP4.OPTION[14]: dhcp_lease_time = 1800 DHCP4.OPTION[15]: routers = 10.10.10.5 DHCP4.OPTION[16]: ip_address = 10.10.10.146 DHCP4.OPTION[17]: requested_static_routes = 1 DHCP4.OPTION[18]: requested_interface_mtu = 1 DHCP4.OPTION[19]: requested_nis_servers = 1 DHCP4.OPTION[20]: requested_wpad = 1 DHCP4.OPTION[21]: requested_ntp_servers = 1 DHCP4.OPTION[22]: requested_domain_name_servers = 1 DHCP4.OPTION[23]: domain_name_servers = 10.10.10.5 DHCP4.OPTION[24]: requested_ms_classless_static_routes = 1 DHCP4.OPTION[25]: requested_routers = 1 DHCP4.OPTION[26]: subnet_mask = 255.255.255.0 DHCP4.OPTION[27]: network_number = 10.10.10.0 DHCP4.OPTION[28]: requested_host_name = 1 DHCP4.OPTION[29]: dhcp_server_identifier = 10.10.10.254 IP6.ADDRESS[1]: ip = fe80::20c:29ff:feba:1a27/64, gw = :: #
Bring down and up an interface:
# nmcli connection show NAME UUID TYPE DEVICE eno16777736 570099b5-a252-4adc-ade7-83c6f440cc93 802-3-ethernet eno16777736 # nmcli connection down eno16777736 # nmcli connection show NAME UUID TYPE DEVICE eno16777736 570099b5-a252-4adc-ade7-83c6f440cc93 802-3-ethernet -- # nmcli connection up eno16777736 Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/1) # nmcli connection show NAME UUID TYPE DEVICE eno16777736 570099b5-a252-4adc-ade7-83c6f440cc93 802-3-ethernet eno16777736 #
Rename an interface to eth0:
# nmcli connection delete eno16777736 # nmcli connection show NAME UUID TYPE DEVICE # nmcli connection add type ethernet con-name eth0 ifname eno16777736 Connection 'eth0' (ed802511-2a71-4069-bc4b-9a9e2918ef31) successfully added. # nmcli connection show NAME UUID TYPE DEVICE eth0 ed802511-2a71-4069-bc4b-9a9e2918ef31 802-3-ethernet eno16777736 #
Assign static IPv4 addresses to interface instead of using DHCP-supplied addresses:
# nmcli connection modify eth0 ipv4.addresses "10.10.10.146/24 10.10.10.5" ipv4.dns 10.10.10.146
# nmcli con show eth0 | grep ipv4\.addresses
ipv4.addresses: { ip = 10.10.10.146/24, gw = 10.10.10.5 }
#
Note that RHEL 7.0 and CentOS 7.0 do not support the ipv4.gateway option; thus you need to use this syntax ipv4.addresses “<ip addr and mask> <gateway>” as shown above.
Set the connection to not use DHCP:
# nmcli connection modify eth0 ipv4.method manual # nmcli connection down eth0 # nmcli connection up eth0 Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/1) # nmcli connection show NAME UUID TYPE DEVICE eth0 ed802511-2a71-4069-bc4b-9a9e2918ef31 802-3-ethernet eno16777736 #
Here is the contents the eth0 interface configuration file after the previous
# cat /etc/sysconfig/network-scripts/ifcfg-eth0 TYPE=Ethernet BOOTPROTO=none DEFROUTE=yes IPV4_FAILURE_FATAL=no IPV6INIT=yes IPV6_AUTOCONF=yes IPV6_DEFROUTE=yes IPV6_FAILURE_FATAL=no NAME=eth0 UUID=ed802511-2a71-4069-bc4b-9a9e2918ef31 DEVICE=eno16777736 ONBOOT=yes DNS1=10.10.10.146 IPADDR=10.10.10.146 PREFIX=24 GATEWAY=10.10.10.5 IPV6_PEERDNS=yes IPV6_PEERROUTES=yes #
Assuming the OS is RHEL 7.0 or CentOS 7.0, the device is eno16777736, the current connection name is “Wired connection 1”, and you want to rename it to “eth0” with a static address of 10.10.10.148, subnet mask 255.255.255.0, gateway 10.10.10.5 and DNS 10.10.10.146, here is the minimum list of nmcli commands you need to run:
# nmcli con delete "Wired connection 1" # nmcli connection add type ethernet con-name eth0 ifname eno16777736 # nmcli connection modify eth0 ipv4.addresses "10.10.10.148/24 10.10.10.5" ipv4.dns 10.10.10.146 # nmcli connection modify eth0 ipv4.method manual # nmcli connection down eth0; nmcli connection up eth0
Here is a bash shell script which automates the necessary modifications to an interface:
#!/bin/bash
# customize as necessary
OLD="Wired connection 1"
NEW="eth1"
DEVICE="eno16777736"
GATEWAY="10.10.10.5"
ADDRESS="10.10.10.146/24 ${GATEWAY}"
nmcli con delete "$OLD"
nmcli connection add type ethernet con-name "$NEW" ifname "$DEVICE"
nmcli connection modify "$NEW" ipv4.addresses "$ADDRESS"
nmcli connection modify "$NEW" ipv4.method manual
nmcli connection down "$NEW"; nmcli connection up "$NEW"
exit 0
Obviously, there many more things you can do with nmcli but this port should be sufficient for you to be able to quickly configure a static network interface in RHEL7 or CentOS7.
Enjoy!
