About Network Interfaces
Each physical and virtual network device on an Oracle Linux system has an associated configuration file named ifcfg-
in the interface
/etc/sysconfig/network-scripts
directory, where interface
is the name of the interface. For example:
# cd /etc/sysconfig/network-scripts # ls ifcfg-* ifcfg-eth0 ifcfg-eth1 ifcfg-lo
In this example, there are two configuration files for Ethernet interfaces, ifcfg-eth0
and ifcfg-eth1
, and one for the loopback interface, ifcfg-lo
. The system reads the configuration files at boot time to configure the network interfaces.
The following are sample entries from an ifcfg-eth0
file for a network interface that obtains its IP address using the Dynamic Host Configuration Protocol (DHCP):
DEVICE="eth0" NM_CONTROLLED="yes" ONBOOT=yes USERCTL=no TYPE=Ethernet BOOTPROTO=dhcp DEFROUTE=yes IPV4_FAILURE_FATAL=yes IPV6INIT=no NAME="System eth0" UUID=5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03 HWADDR=08:00:27:16:C3:33 PEERDNS=yes PEERROUTES=yes
If the interface is configured with a static IP address, the file contains entries such as the following:
DEVICE="eth0" NM_CONTROLLED="yes" ONBOOT=yes USERCTL=no TYPE=Ethernet BOOTPROTO=none DEFROUTE=yes IPV4_FAILURE_FATAL=yes IPV6INIT=no NAME="System eth0" UUID=5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03 HWADDR=08:00:27:16:C3:33 IPADDR=192.168.1.101 NETMASK=255.255.255.0 BROADCAST=192.168.1.255 PEERDNS=yes PEERROUTES=yes
The following configuration parameters are typically used in interface configuration files:
-
How the interface obtains its IP address:
-
Bootstrap Protocol (BOOTP).
-
Dynamic Host Configuration Protocol (DHCP).
-
Statically configured IP address.
bootp
dhcp
none
-
-
IPv4 broadcast address.
-
Whether this interface is the default route.
-
Name of the physical network interface device (or a PPP logical device).
-
Media access control (MAC) address of an Ethernet device.
-
IPv4 address of the interface.
-
Whether the device is disabled if IPv4 configuration fails.
-
Whether the device is disabled if IPv6 configuration fails.
-
IPv6 address of the interface in CIDR notation. For example:
IPV6ADDR="2001:db8:1e11:115b::1/32"
-
Whether to enable IPv6 for the interface.
-
Specifies the name of the master bonded interface, of which this interface is slave.
-
Name of the interface as displayed in the Network Connections GUI.
-
IPv4 network mask of the interface.
-
IPV4 address of the network.
-
Whether the network interface device is controlled by the network management daemon,
NetworkManager
. -
Whether the interface is activated at boot time.
-
Whether the
/etc/resolv.conf
file used for DNS resolution contains information obtained from the DHCP server. -
Whether the information for the routing table entry that defines the default gateway for the interface is obtained from the DHCP server.
-
Specifies that this interface is a component of a bonded interface.
-
Interface type.
-
Whether users other than
root
can control the state of this interface. -
Universally unique identifier for the network interface device.
BOOTPROTO
BROADCAST
DEFROUTE
DEVICE
HWADDR
IPADDR
IPV4_FAILURE_FATAL
IPV6_FAILURE_FATAL
IPV6ADDR
IPV6INIT
MASTER
NAME
NETMASK
NETWORK
NM_CONTROLLED
ONBOOT
PEERDNS
PEERROUTES
SLAVE
TYPE
USERCTL
UUID