Chapter 11. Configuring ip networking with ifcfg files
Interface configuration (ifcfg) files control the software interfaces for individual network devices. As the system boots, it uses these files to determine what interfaces to bring up and how to configure them. These files are named ifcfg-name_pass, where the suffix name refers to the name of the device that the configuration file controls. By convention, the ifcfg file’s suffix is the same as the string given by the DEVICE directive in the configuration file itself.
NetworkManager supports profiles stored in the keyfile format. However, by default, NetworkManager uses the ifcfg format when you use the NetworkManager API to create or update profiles.
In a future major RHEL release, the keyfile format will be default. Consider using the keyfile format if you want to manually create and manage configuration files. For details, see NetworkManager connection profiles in keyfile format.
11.1. Configuring an interface with static network settings using ifcfg files
If you do not use the NetworkManager utilities and applications, you can manually configure a network interface by creating ifcfg files.
Procedure
To configure an interface with static network settings using
ifcfgfiles, for an interface with the nameenp1s0, create a file with the nameifcfg-enp1s0in the/etc/sysconfig/network-scripts/directory that contains:For
IPv4configuration:DEVICE=enp1s0 BOOTPROTO=none ONBOOT=yes PREFIX=24 IPADDR=192.0.2.1 GATEWAY=192.0.2.254
For
IPv6configuration:DEVICE=enp1s0 BOOTPROTO=none ONBOOT=yes IPV6INIT=yes IPV6ADDR=2001:db8:1::2/64
Additional resources
-
nm-settings-ifcfg-rh(5)man page on your system
11.2. Configuring an interface with dynamic network settings using ifcfg files
If you do not use the NetworkManager utilities and applications, you can manually configure a network interface by creating ifcfg files.
Procedure
To configure an interface named em1 with dynamic network settings using
ifcfgfiles, create a file with the nameifcfg-em1in the/etc/sysconfig/network-scripts/directory that contains:DEVICE=em1 BOOTPROTO=dhcp ONBOOT=yes
To configure an interface to send:
A different host name to the
DHCPserver, add the following line to theifcfgfile:DHCP_HOSTNAME=hostnameA different fully qualified domain name (FQDN) to the
DHCPserver, add the following line to theifcfgfile:DHCP_FQDN=fully.qualified.domain.name
NoteYou can use only one of these settings. If you specify both
DHCP_HOSTNAMEandDHCP_FQDN, onlyDHCP_FQDNis used.To configure an interface to use particular
DNSservers, add the following lines to theifcfgfile:PEERDNS=no DNS1=ip-address DNS2=ip-address
where ip-address is the address of a
DNSserver. This will cause the network service to update/etc/resolv.confwith the specifiedDNSservers specified. Only oneDNSserver address is necessary, the other is optional.
11.3. Managing system-wide and private connection profiles with ifcfg files
By default, all users on a host can use the connections defined in ifcfg files. You can limit this behavior to specific users by adding the USERS parameter to the ifcfg file.
Prerequisite
-
The
ifcfgfile already exists.
Procedure
Edit the
ifcfgfile in the/etc/sysconfig/network-scripts/directory that you want to limit to certain users, and add:USERS="username1 username2 ..."
Reactive the connection:
# nmcli connection up connection_name
