%general-entities; ]> network configuring 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). With Udev and modular network drivers, the network interface numbering is not persistent across reboots by default, because the drivers are loaded in parallel and, thus, in random order. For example, on a computer having two network cards made by Intel and Realtek, the network card manufactured by Intel may become eth0 and the Realtek card becomes eth1. In some cases, after a reboot the cards get renumbered the other way around. To avoid this, Udev comes with a script and some rules to assign stable names to network cards based on their MAC address. Pre-generate the rules to ensure the same names get assigned to the same devices at every boot, including the first: /lib/udev/write_net_rules all_interfaces Now, inspect the /etc/udev/rules.d/70-persistent-net.rules file, to find out which name was assigned to which network device: cat /etc/udev/rules.d/70-persistent-net.rules Each NIC takes up two lines in the file. The first line is a description of the NIC itself, showing its hardware IDs (e.g. its PCI vendor and device IDs, if it's a PCI card), along with its driver in parentheses, if the driver can be found. This line is a comment; neither the hardware ID nor the driver is used to determine which name to give an interface. The second line is the Udev rule that matches this NIC and actually assigns it a name. All Udev rules are made up of several keys, separated by commas and optional whitespace. This rule's keys and an explanations of each of them are as follows: SUBSYSTEM=="net" - This tells Udev to ignore devices that are not network cards. DRIVERS=="?*" - This exists so that Udev will ignore VLAN or bridge sub-interfaces (because these sub-interfaces do not have drivers). These sub-interfaces are skipped because the name that would be assigned would collide with their parent devices. ATTRS{type}=="1" - Optional. This key will only be added if this NIC is a wireless NIC whose driver creates multiple virtual interfaces; it ensures the rule only matches the primary interface. The secondary interfaces are not matched for the same reason that VLAN and bridge sub-interfaces are not matched: there would be a name collision. ATTRS{address} - The value of this key is the NIC's MAC address. NAME - The value of this key is the name that Udev will assign to this interface. The value of NAME is the important part. Make sure you know which name has been assigned to each of your network cards before proceeding, and be sure to use that NAME value when creating your configuration files below. 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 be brought up. The 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 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. /etc/resolv.conf 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.