11.13. Configuring the network Script

#### Cross-Compiled Linux From Scratch - Version 1.0.0rc1-PowerPC64-Multilib

### Chapter 11. Setting Up System Bootscripts

- Prev

  Customizing the /etc/hosts File

- Next

  Making the CLFS System Bootable

- Up.
- Home

# 11.13. Configuring the network Script

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`).

## 11.13.1. Creating 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/network-devices` 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.

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

    cd /etc/sysconfig/network-devices &&
    mkdir -v 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 used for obtaining the IP address. The CLFS-Bootscripts package has 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 the `PREFIX` variable according to your specific subnet.

## 11.13.2. Creating the /etc/resolv.conf File

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.

- Prev

  Customizing the /etc/hosts File

- Next

  Making the CLFS System Bootable

- Up.
- Home.