Handbook:Parts/Networking/Modular

Network modules
We now support modular networking scripts, which means we can easily add support for new interface types and configuration modules while keeping compatibility with existing ones.

Modules load by default if the package they need is installed. If users specify a module here that doesn't have its package installed then they get an error stating which package they need to install. Ideally, the modules setting is only used when two or more packages are installed that supply the same service and one needs to be preferred over the other.

Interface handlers
We provide two interface handlers presently: ifconfig and iproute2. Only one of these is needed to do any kind of network configuration.

ifconfig is installed by default (the net-tools package is part of the system profile). iproute2 is a more powerful and flexible package, but it's not included by default.

As both ifconfig and iproute2 do very similar things we allow their basic configuration to work with each other. For example both the below code snippet work regardless of which module the user is using.

DHCP
DHCP is a means of obtaining network information (IP address, DNS servers, Gateway, etc) from a DHCP server. This means that if there is a DHCP server running on the network, the user just has to tell each client to use DHCP and it sets up the network all by itself. Of course, the user will have to configure for other things like wireless, PPP or other things if required before he can use DHCP.

DHCP can be provided by dhclient, dhcpcd, or pump. Each DHCP module has its pros and cons - here's a quick run down.

If more than one DHCP client is installed, specify which one to use - otherwise we default to dhcpcd if available.

To send specific options to the DHCP module, use module_eth0="..." (change module to the DHCP module being used - i.e. dhcpcd_eth0).

We try and make DHCP relatively agnostic - as such we support the following commands using the dhcp_eth0 variable. The default is not to set any of them:
 * release - releases the IP address for re-use
 * nodns - don't overwrite
 * nontp - don't overwrite
 * nonis - don't overwrite

ADSL with PPPoE/PPPoA
First we need to install the ADSL software.

Second, create the PPP net script and the net script for the Ethernet interface to be used by PPP:

Be sure to set rc_depend_strict to  in.

Now we need to configure.

It is also possible to set the password in.

If PPPoE is used with a USB modem then make sure to emerge br2684ctl. Please read for information on how to properly configure it.

APIPA (Automatic Private IP Addressing)
APIPA tries to find a free address in the range 169.254.0.0-169.254.255.255 by arping a random address in that range on the interface. If no reply is found then we assign that address to the interface.

This is only useful for LANs where there is no DHCP server and the system doesn't connect directly to the Internet and all other computers use APIPA.

For APIPA support, emerge or.

Bonding
For link bonding/trunking emerge.

Bonding is used to increase network bandwidth or to improve resiliency in face of hardware failures. If a system has two network cards going to the same network, then the administrator can bond them together so the applications see just one interface but they really use both network cards.

There are many ways to configure bonding. Some of them, such as the 802.3ad LACP mode, require support and additional configuration of the network switch. For a reference of the individual options, please refer to the local copy of.

First, clear the configuration of the participating interfaces:

Next, define the bonding between the interfaces:

Remove the net.eth* services from the runlevels, create a net.bond0 one and add that one to the correct runlevel.

Bridging (802.1d support)
For bridging support emerge.

Bridging is used to join networks together. For example, a system may have a server that connects to the Internet via an ADSL modem and a wireless access card to enable other computers to connect to the Internet via the ADSL modem. It is possible to create a bridge to join the two interfaces together.

MAC address
It is possible to change the MAC address of the interfaces through the network configuration file too.

Tunneling
Tunneling does not require any additional software to be installed as the interface handler can do it.

VLAN (802.1q support)
For VLAN support, make sure that is installed and ensure that iproute2 is used as configuration module rather than ifconfig.

Virtual LAN is a group of network devices that behave as if they were connected to a single network segment - even though they may not be. VLAN members can only see members of the same VLAN even though they may share the same physical network.

To configure VLANs, first specify the VLAN numbers in like so:

Next, configure the interface for each VLAN:

VLAN-specific configurations are handled by vconfig like so: