Master CentOS 7 Network Configuration: nmcli, nmtui, and Custom Interface Names

1 Network Configuration

CentOS 7 network interface names follow these patterns: Ethernet interfaces start with en, WLAN with wl, WWAN with ww. The next character indicates adapter type (o = on‑board, s = hot‑plug slot, p = PCI). An optional x can merge MAC addresses, and a trailing number serves as the index or port. If the naming scheme is unclear, the traditional ethN format may be used.

NetworkManager

NetworkManager is a dynamic network controller that keeps devices and connections active when hardware is available. Multiple connections can be attached to a device, but only one can be active at a time. It is installed and enabled by default on CentOS/RHEL 7.

Key commands:

# systemctl status NetworkManager   # check NetworkManager status
# systemctl status network          # check legacy network service status

nmcli basics

List all devices:

# nmcli device
DEVICE      TYPE      STATE   CONNECTION
virbr0      bridge    unmanaged  --
ens33       ethernet  unmanaged  --
lo          loopback  unmanaged  --
virbr0-nic  tun       unmanaged  --

Show detailed device information: # nmcli device show List all connections:

# nmcli connection
NAME   UUID                                  TYPE      DEVICE
ens33  5ae89fd0-897c-40cc-bdfa-fd716dd6fcc5  ethernet  --

Add a new connection (replace parameters as needed):

# nmcli connection add con-name ens33-siso autoconnect yes ifname ens33 type ethernet

Activate a connection: # nmcli connection up ens33-siso Delete a connection:

# nmcli connection delete ens33-siso

Editing configuration files

Modify the interface file directly (example for ens33):

# vi /etc/sysconfig/network-scripts/ifcfg-ens33
TYPE="Ethernet"
PROXY_METHOD="none"
BROWSER_ONLY="no"
BOOTPROTO="dhcp"
DEFROUTE="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_FAILURE_FATAL="no"
IPV6_ADDR_GEN_MODE="stable-privacy"
NAME="ens33"
UUID="5ae89fd0-897c-40cc-bdfa-fd716dd6fcc5"
DEVICE="ens33"
ONBOOT="yes"
# (static example) IPADDR="192.168.30.101"
# NETMASK="255.255.255.0"
# GATEWAY="192.168.30.2"
# DNS1="114.144.144.144"

Reload connections and restart the network service to apply changes:

# nmcli connection reload
# nmcli connection down ens33
# systemctl restart network

Text and graphical tools

Use the text UI: # nmtui Or the graphical editor:

# nm-connection-editor

Hostname configuration

# vi /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=master
# hostname master   # apply new hostname

9.2 Rename Interface to eth0

Rename the interface configuration file:

# cd /etc/sysconfig/network-scripts
# mv ifcfg-ens33 ifcfg-eth0
# vi ifcfg-eth0
TYPE="Ethernet"
... (same parameters as above) ...
NAME="eth0"
DEVICE="eth0"

Add kernel parameter for predictable naming

# vi /etc/sysconfig/grub
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="crashkernel=auto rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet"
net.ifname="0"   # add this line
GRUB_DISABLE_RECOVERY="true"

Rebuild the GRUB configuration and reboot for the changes to take effect.

9.3 Chapter Summary

This chapter covered Linux network configuration on CentOS, showing the location of key interface files, how to view and modify network settings with both command‑line and GUI tools, and how to rename network interfaces.