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, remove the network symlinks from all run-level directories (/etc/rc.d/rc*.d).
Which interfaces are brought up and down by the network script depends on the files in the /etc/sysconfig/network-devices directory. This directory should contain files in the form of ifconfig.xyz, where “xyz” is a network interface name (such as eth0 or eth0:1).
If the /etc/sysconfig/network-devices directory is to be renamed or moved, make sure to edit the /etc/sysconfig/rc file and update the “network_devices” option by providing it with the new path.
New files are created in this directory. The following command creates a sample ipv4 file for the eth0 device:
cd /etc/sysconfig/network-devices && mkdir ifconfig.eth0 && cat > ifconfig.eth0/ipv4 << "EOF" ONBOOT=yes 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. If the ONBOOT variable is set to “yes” the 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 brought up.
The SERVICE variable defines the method of obtaining the IP address. The LFS bootscripts have a modular IP assignment format, and creating additional files in the /etc/sysconfig/network-devices/services directory allows other IP assignment methods. This is commonly used for Dynamic Host Configuration Protocol (DHCP), which is addressed in the BLFS book.
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 according to the specific subnet.
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 following:
cat > /etc/resolv.conf << "EOF"
# Begin /etc/resolv.conf
domain {[Your Domain Name]}
nameserver [IP address of your primary nameserver]
nameserver [IP address of your secondary nameserver]
# End /etc/resolv.conf
EOF
Replace [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.