Cross-Compiled Linux From Scratch - Version GIT-20170803-MIPS

Chapter 12. Networking Configuration

12.7. Static Networking Configuration

12.7.1. Creating the Static Network Interface Configuration Files

Which interfaces are brought up and down by the network script depends on the files and directories in the /etc/sysconfig hierarchy. This directory should contain a sub-directory for each interface to be configured, such as ifconfig.xyz, where “xyz” is a network interface name. Inside this directory would be files defining the attributes to this interface, such as its IP address(es), subnet masks, and so forth.

[Note]

Note

Udev may assign random Network Card Interface names for some network cards such as enp2s1. If you are not sure what your Network Card Interface name is, you can always run ip l after you have booted your system. Again, it is important that ifconfig.xyz is named after correct Network Card Interface name (e.g. ifconfig.enp2s1 or ifconfig.eth0) or systemd will fail to bring up your network interface.

The following command creates a sample ipv4 file for the eth0 device: 

mkdir -pv /etc/sysconfig &&
cd /etc/sysconfig &&
cat > ifconfig.eth0 << "EOF"
IFACE="eth0"
SERVICE="ipv4-static"
IP="192.168.1.1"
GATEWAY="192.168.1.2"
PREFIX="24"
BROADCAST="192.168.1.255"
EOF

The values of these variables must be changed in every file to match the proper setup.

The IFACE variable defines the interface name, for example, eth0. It is required for all network device configuration files.

The SERVICE variable defines the method used for obtaining the IP address. The CLFS-Network-Scripts package has a modular IP assignment format, and creating additional files in the /lib/services directory allows other IP assignment methods.

The GATEWAY variable should contain the default gateway IP address, if one is present. If not, then comment out the variable entirely.

The PREFIX variable needs to contain the number of bits used in the subnet. Each octet in an IP address is 8 bits. If the subnet's netmask is 255.255.255.0, then it is using the first three octets (24 bits) to specify the network number. If the netmask is 255.255.255.240, it would be using the first 28 bits. Prefixes longer than 24 bits are commonly used by DSL and cable-based Internet Service Providers (ISPs). In this example (PREFIX=24), the netmask is 255.255.255.0. Adjust the PREFIX variable according to your specific subnet.

For more information see the ifup man page.

To configure another DHCP Interface, Follow Section 12.8, “DHCPCD-6.11.5”.

12.7.2. Configuring the Network Interface at boot

Enabling of the Network Interface configuration is done per interface. To enable Network Interface configuration at boot, run: 

systemctl enable ifupdown@eth0

To disable previously enabled Network Interface configuration at boot, run: 

systemctl disable ifupdown@eth0

To manually start the Network Interface configuration, run: 

systemctl start ifupdown@eth0

Replace eth0 with the correct Network Interface name as described on the beginning of this page.