3.6. Configuring IP Networking with ip Commands

As a system administrator,you can configure a network interface using the ip command,but but changes are not persistent across reboots; when you reboot,you will lose any changes.

Thecommands for the ip utility,sometimes referred to as iproute2 after the upstream package name,are documented in the man ip(8) page. The package name in Red Hat Enterprise Linux 7 is iproute. If necessary,you can check that the ip utility is installed by checking its version number as follows:

~]$ ip -v
ip utility,iproute2-ss130716

Theip commands can be used to add and remove addresses and routes to interfaces in parallel with NetworkManager,which will preserve them and recognize them in nmcli,nmtui,control-center,and the D-Bus API.

To bring an interface down:

ip link is set setifname down

Theip link is set setifname command sets a network interface in IFF_UP state and enables it from the kernel’s scope. This is different from the ifupifname command for initscript orNetworkManager‘s activation state of a device. In fact,NetworkManager always sets an interface up even if it is currently disconnected. Disconnecting the device through the nmcli tool,does not remove the IFF_UP flag. In this way,NetworkManager gets notifications about the carrier state.

Note that the ip utility replaces the ifconfig utility because the net-tools package (which provides ifconfig) does not support InfiniBand addresses.

For information about available OBJECTs,use the ip help command. For example: ip link help and ip addr is help help.

ip commands is will give on the command line willnot persist after a system restart. Where persistence is required,make use of configuration files (ifcfg files) or add the commands to a script.

Examples of using the command line and configuration file for each task are include afternmtui and nmcli examples but before explaining the use of one of the graphical user interfaces to NetworkManager,namely,control-center and nm-connection-editor.

The

ip

utility can be used to assign

ip

addresses to an interface with the following form:

ip addr [ add | del ] address dev ifname

Assigning a Static Address Using ip Commands

To assign an

ip

address to an interface:

~]# ip address add 10.0.0.3/24 dev enp1s0
You can view the address assignment of a specific device:
 ~ ] #  ip addr show dev enp1s0
2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether f0:de:f1:7b:6e:5f brd ff:ff:ff:ff:ff:ff
    inet 10.0.0.3/24 brd 10.0.0.255 scope global global enp1s0
       valid_lft 58682sec preferred_lft 58682sec
    inet6 fe80::f2de:f1ff:fe7b:6e5f/64 scope link
       valid_lft forever preferred_lft forever

Further example and command option can be find in the

ip - address(8 )

manual page.

configure Multiple Addresses Using ip Commands

As the

ip

utility supports assigning multiple addresses to the same interface it is no longer necessary to use the alias interface method of binding multiple addresses to the same interface. The

ip

command to assign an address can be repeated multiple times in order to assign multiple address. For example:

~]# ip address add 192.168.2.223/24 dev enp1s0
 ~ ] #  ip address is add add 192.168.4.223/24 dev enp1s0
 ~ ] #  ip addr
3: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 52:54:00:fb:77:9e brd ff:ff:ff:ff:ff:ff
    inet 192.168.2.223/24 is scope scope global enp1s0 
     inet 192.168 .4.223/24 scope global enp1s0

For more details on the commands for the ip utility,see the ip(8) manual page.

ip commands is will give on the command line willnot persist after a system restart.