This section only applies if a network card is to be configured.
If a network card will not be used, there is likely no need to create
any configuration files relating to network cards. If that is the
case, you will need to remove the
network symlinks from all run-level directories
/etc/rc.d/rc*.d) after the bootscripts
are installed in Section 7.2,
Which interfaces are brought up and down by the network script
usually depends on the files in
/etc/sysconfig/. This directory should contain a
file for each interface to be configured, such as
ifconfig.xyz, where “xyz” is
required to be a Network Card Interface name (e.g. eth0). Inside
this file are attributes to this interface, such as its IP
address(es), subnet masks, and so forth. It is necessary that the
stem of the filename be ifconfig.
If the procedure in the previous section was not used, Udev will assign network card interface names based on system physical characteristics such as enp2s1. If you are not sure what your interface name is, you can always run ip link 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 your network interface will not be initialized during the boot process.
The following command creates a sample file for the eth0 device with a static IP address:
cd /etc/sysconfig/ cat > ifconfig.eth0 << "EOF"
ONBOOT=yes IFACE=eth0 SERVICE=ipv4-static IP=192.168.1.2 GATEWAY=192.168.1.1 PREFIX=24 BROADCAST=192.168.1.255EOF
The values of these variables must be changed in every file to match the proper setup.
ONBOOT variable is set to
“yes” the System V network script will
bring up the Network Interface Card (NIC) during booting of the
system. If set to anything but “yes” the NIC
will be ignored by the network script and not be automatically
brought up. The interface can be manually started or stopped with
the ifup and
IFACE variable defines the interface
name, for example, eth0. It is required for all network device
SERVICE variable defines the method
used for obtaining the IP address. The LFS-Bootscripts package has
a modular IP assignment format, and creating additional files in
/lib/services/ directory allows
other IP assignment methods. This is commonly used for Dynamic Host
Configuration Protocol (DHCP), which is addressed in the BLFS book.
GATEWAY variable should contain the
default gateway IP address, if one is present. If not, then comment
out the variable entirely.
PREFIX variable contains 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.
If omitted, the PREFIX defaults to 24.
For more information see the ifup man page.
Enabling of the network interface card configuration in systemd is done per interface. To enable network interface card configuration at boot, run:
systemctl enable ifupdown@eth0
To disable a previously enabled network interface card configuration at boot, run:
systemctl disable ifupdown@eth0
To manually start the network interface card configuration, run:
systemctl start ifupdown@eth0
Replace eth0 with the correct network interface card name as described on the beginning of this page.
These procedures require the configuration files as specified in the previous section.
The network card can also be started or stopped with the traditional ifup <device> or ifdown <device> commands.
An alternative way to configure a NIC when booting with with systemd is to create a configuration file recognized by the systemd-networkd daemon. To configure the device create a file similar to this:
cat > /etc/systemd/network/10-static-eth0.network << "EOF" [Match] Name=eth0 [Network] Address=192.168.0.2/24 Gateway=192.168.0.1 EOF
You can use multiple .network files if desired. You can also specify DHCP=yes instead of the Address and Gateway settings. See the man page for systemd.network for more details,
If this method is used, be sure to disable ifupdown@eth0 as described in the previous section (if it was enabled).
If the system is going to be connected to the Internet, it will
need some means of Domain Name Service (DNS) name resolution to
resolve Internet domain names to IP addresses, and vice versa. This
is best achieved by placing the IP address of the DNS server,
available from the ISP or network administrator, into
/etc/resolv.conf. Create the file by running the
cat > /etc/resolv.conf << "EOF"
# Begin /etc/resolv.conf domainEOF
<Your Domain Name>nameserver
<IP address of your primary nameserver>nameserver
<IP address of your secondary nameserver># End /etc/resolv.conf
domain statement can be omitted or
replaced with a
search statement. See
the man page for resolv.conf for more details.
<IP address of the
nameserver> with the IP address of the DNS most
appropriate for the setup. There will often be more than one entry
(requirements demand secondary servers for fallback capability). If
you only need or want one DNS server, remove the second
nameserver line from the
file. The IP address may also be a router on the local network.
The Google Public IPv4 DNS addresses are 18.104.22.168 and 22.214.171.124.
During the boot process, both Systemd and System V use the same
file for establishing the system's hostname. This needs to be
configured by creating
/etc/hostname file and
enter a hostname by running:
<lfs>" > /etc/hostname
<lfs> needs to be
replaced with the name given to the computer. Do not enter the
Fully Qualified Domain Name (FQDN) here. That information is put in
Decide on the IP address, fully-qualified domain name (FQDN), and
possible aliases for use in the
/etc/hosts file. The syntax is:
IP_address myhost.example.org aliases
Unless the computer is to be visible to the Internet (i.e., there is a registered domain and a valid block of assigned IP addresses—most users do not have this), make sure that the IP address is in the private network IP address range. Valid ranges are:
Private Network Address Range Normal Prefix 10.0.0.1 - 10.255.255.254 8 172.x.0.1 - 172.x.255.254 16 192.168.y.1 - 192.168.y.254 24
x can be any number in the range 16-31. y can be any number in the range 0-255.
A valid private IP address could be 192.168.1.1. A valid FQDN for this IP could be lfs.example.org.
Even if not using a network card, a valid FQDN is still required. This is necessary for certain programs to operate correctly.
/etc/hosts file by
cat > /etc/hosts << "EOF"
# Begin /etc/hosts (network card version) 127.0.0.1 localhostEOF
[alias1] [alias2 ...]# End /etc/hosts (network card version)
need to be changed for specific uses or requirements (if assigned
an IP address by a network/system administrator and the machine
will be connected to an existing network). The optional alias
name(s) can be omitted.
If a network card is not going to be configured, create the
/etc/hosts file by running:
cat > /etc/hosts << "EOF"
# Begin /etc/hosts (no network card version) 127.0.0.1EOF
<HOSTNAME>localhost # End /etc/hosts (no network card version)