Funtoo Linux Networking
This document explains how to configure your network settings by explaining the network configuration functionality available in Funtoo Linux. Also covered is dhcpcd 5.x, Wi-Fi (IEEE 802.11) configuration, and the OpenResolv framework.
- 1 Introduction
- 2 A Gentle Introduction to Funtoo Network Configuration
- 2.1 The Easy (Dynamic) Way
- 2.2 Server Network Configuration
- 2.3 Configuration Variables
- 2.4 General Variables
- 2.5 OpenResolv and resolv.conf
- 2.6 Network-Dependent Services
- 2.7 Multiple Network Configurations
- 2.8 Alternate Configs
- 2.9 Interface Renaming
- 2.10 Basic VLAN Configuration
- 2.11 Custom VLAN Names
- 2.12 Bonding Configuration
- 2.13 Bridge Configuration
- 2.14 More Complex Network Configuration
- 3 Wireless Configuration
- 4 Other Network Configurations
- 5 License
In this document, I will explain the unique additions and changes to the Funtoo network configuration and show you how to use this system to configure your network.
I'll also explain how to use dhcpcd 5.x for managing network interfaces on DHCP-based networks, and will also cover OpenRC stacked runlevel configuration, Wi-Fi (IEEE 802.11) configuration, and the OpenResolv framework, which is enabled in Funtoo Linux by default.
A Gentle Introduction to Funtoo Network Configuration
Before I get into the technical details of configuring your network, it's important to understand that Funtoo Linux has a number of different options available to you for network configuration, with more likely to be added in the future. Each approach is different and has its own strengths and weaknesses, and this is, in my opinion, a good thing.
The Easy (Dynamic) Way
When configuring your network, one option is to skip traditional network configuration and simply rely on DHCP. This is by far the simplest method of configuring your network. If you are on a wired network, no other steps are typically required beyond enabling a DHCP client, and Funtoo Linux includes dhcpcd 5.x by default.
Network Manager, Wicd
If you are going to use a third party package such as Network Manager or Wicd to manage your network then you do not need to configure DHCP at all. These packages configure DHCP for you. Simply emerge the package you want to use and start using it.
If you are not planning to use a third-party package to manage your network interfaces, it is still extremely easy to set up DHCP networking, especially if you always use DHCP to connect to networks, which is common for desktops or laptops. In this scenario, we can simply enable dhcpcd to run at system startup. It will run in the background and automatically look for DHCP servers on all your network interfaces, and will attempt to lease an IP address from any DHCP servers found.
If this sounds like what you want to do, then add dhcpcd to your default runlevel as follows:
# rc-update add dhcpcd default
To enable DHCP immediately, you would follow the previous command with an rc command, which would start the dhcpcd client you just added:
If you're on a wired network and have the necessary drivers in your kernel, then this should get you going. For wireless networks, more steps are required to utilize your wireless hardware to associate with an access point, which will be covered later in this document.
For now, it's important to note that dhcpcd 5.x will manage all available network interfaces by default. If you want to run a DHCP client on all but one interface, or some other subset of interfaces, you can add the appropriate denyinterfaces or allowinterfaces glob pattern to /etc/dhcpcd.conf:
# manage all interfaces but eth0 with dhcpcd denyinterfaces eth0
This can also be accomplished by modifying /etc/init.d/dhcpcd directly and adding -Z ifglob or -z ifglob (the equivalent command-line parameters) to command_args.
Using Funtoo Scripts for DHCP
You can also use the Funtoo Linux networking scripts to start a DHCP client just on a specific interface. This approach is best if you are planning to also do some advanced bridging, bonding or VLAN configuration on your machine along with DHCP, since you will be using the Funtoo Linux networking scripts for that too.
To use this variant approach, don't enable /etc/init.d/dhcpcd directly. Instead, use the Funtoo Linux dhcpcd template which will start dhcpcd on only one interface. Below, you will see the steps to do this. This is very similar to how we set up advanced network interfaces, which will be covered later in this documentation:
# cd /etc/init.d # ln -s netif.tmpl netif.eth0 # rc-update add netif.eth0 default # echo template=dhcpcd > /etc/conf.d/netif.eth0 # rc
The last command, rc, causes netif.eth0 to be started.
Server Network Configuration
For servers and advanced networking scenarios, Funtoo Linux offers its own modular, template-based network configuration system. This system offers a lot of flexibility for configuring network interfaces, essentially serving as a "network interface construction kit." This system can be used by itself, or even combined with dhcpcd, as shown in the previous section.
Here are the key components of the template-based network configuration system:
- An init script that configures the localhost interface. This script is always enabled and is part of the boot process.
- This is a directory that contains various network configuration templates. Each of these templates is focused on configuring a particular type of network interface, such as a general static IP-based interface, a bridge interface, a bond interface, etc.
- This is the master init script for the template-based network configuration system. New interfaces are added to your system by creating symbolic links to this file in /etc/init.d.
So, if you wanted to use this system to configure eth0 with a static IP address, you would create a netif.eth0 symlink to netif.tmpl as follows:
# cd /etc/init.d # ln -s netif.tmpl netif.eth0
Then, you would create an /etc/conf.d/netif.eth0 configuration file that would specify which template to use from the /etc/netif.d directory:
template="interface" ipaddr="10.0.1.200/24" gateway="10.0.1.1" nameservers="10.0.1.1 10.0.1.2" domain="funtoo.org"
To complete our static IP network configuration we would need to:
# rc-update add netif.eth0 default
When configuring your own static network interface, one of ipaddr or ipaddrs is required and should specify the IP address(es) to configure for this interface, in "a.b.c.d/netmask" format. Optional parameters include gateway, which defines a default gateway for your entire network, and if set should specify the gateway's IP address. In addition, domain and nameservers (space-separated if more than one) can be used to specify DNS information for this interface.
The ipaddr and ipaddrs variables are supported by the interface and bridge templates, and are used to specify a single or multiple IPv4 or IPv6 address(es) for the interface. IP addresses should be specified in 'IP/netmask' format, such as 10.0.0.1/24. Multiple IP addresses can be specified delimited by whitespace:
By default, a broadcast address will be calculated based on the IP address and network mask. If you need to manually specify a broadcast address, use the following format for your IP address:
Not Specifying An Address
Note that in some cases, you may choose to not specify ipaddr or ipaddrs for a bridge template. That is allowed. If you don't want to specify an IP address for a regular interface, you can choose to use the interface template without an IP address specified in the config, or use the interface-noip template instead, for the sake of clarity.
Viewing All Configured IP Addresses
Also note that if you specify multiple IPv4 addresses, ifconfig will only show the first IP address. To view all IP addresses associated with the interface, use the ip addr show command.
The following variables are enabled by default for all network scripts, and if specified will trigger a corresponding configuration action:
- Set DNS nameservers using OpenResolv. Specify multiple IPv4 or IPv6 nameservers like this: "220.127.116.11 18.104.22.168 22.214.171.124". Please note that OpenResolv treats 127.0.0.1 specially, and it indicates that you are running a local name resolver like dnsmasq or bind. OpenResolv will ignore all other name servers specified alongside 127.0.0.1. See man resolvconf and man resolvconf.conf for additional setup information.
- Set DNS search information using OpenResolv.
- Set DNS domain using OpenResolv.
- Define a default IPv4 gateway on this interface.
- Define a default IPv6 gateway on this interface.
- Specify a semi-colon delimited list of IPv4 routes to apply when this interface is brought up. Will be appended to ip -4 route add.
- Specify a semi-colon delimited list of IPv6 routes to apply when this interface is brought up. Will be appended to ip -6 route add.
- Set Maximum Transmit Unit for the interface
VLAN support is enabled by default for all network configuration scripts. If a network script has a name in the format netif.ethX.Y, then it is assumed to be a VLAN interface referencing trunk ethX and VLAN ID Y. If you desire a custom name for your VLAN interface, you can name your interface whatever you'd like and specify the following variables in your interface config:
- VLAN trunk interface, e.g. "eth0"
- VLAN id, e.g. "32"
Bridge / Tap Variables
The following variables for configuring a functional bridge interface with optional tap interfaces:
- Set slave interfaces of this interface (for bridges, etc.) All slaves will automatically be depended upon, and will also automatically have their mtu set to that of the current interface, if an mtu is specified for the current interface. This setting is required for the bond template and optional for the bridge template.
- Enables Spanning Tree Protocol on a bridge interface like this "stp=on"
- Enables forwarding on a bridge interface by calling sysctl; as this interface does not exist when sysctl is called by init, we do it here. If this is disabled, your bridge will not forward traffic back out onto the network. useage: "forwarding=1"
- Sets a MAC address on a tap interface. This is usefull for avoiding layer2 address collisions when using large numbers of TUN interfaces (KVM, openVPN, ect)
OpenResolv and resolv.conf
OpenResolv will be used to set DNS information provided by the nameservers, domain and search variables when an interface is brought up. The OpenResolv framework will add entries to /etc/resolv.conf, and will also handle removing these entries when the interface is brought down. This way, /etc/resolv.conf should always contain current information and should not need to be manually edited by the system administrator. dhcpcd will use OpenResolv for updating system DNS information as well.
One important difference between Gentoo Linux and Funtoo Linux is that, in Funtoo Linux, network-dependent services only strictly depend on netif.lo. This means that if another network service requires an interface to be up, such as samba requiring eth0, then the system administrator must specify this relationship by adding the following line to /etc/conf.d/samba:
This will have the effect of ensuring that netif.eth0 is started prior to samba and that samba is stopped prior to stopping netif.eth0.
Many network services, especially those that listen on all network intefaces, don't need an rc_need line in order to function properly. Avoiding the use of rc_need when required will optimize boot times and allow more network services to remain available when network interfaces are brought up and down by the system administrator.
Multiple Network Configurations
For information on how to have multiple, independent network configurations, please see Stacked Runlevels.
If you need to run the same service with different configuration parameters depending upon runlevel, then you'll be happy to know that you can specify runlevel-specific conf.d files by appending a . <runlevel> suffix. In this particular example, we could imagine a situation where we had two child runlevels named home and work:
/etc/conf.d/netif.eth0.home /etc/conf.d/netif.eth0.workNote that this feature works for all init scripts, not just network configuration scripts.
Funtoo network scripts now support interface renaming, so you can create an interface called lan if you would like. To do this, simply specify the MAC address of the interface you would like to rename using the macaddr variable:
macaddr="00:15:17:19:b6:a3"If this MAC address is part of the netif.lan configuration file, then when this interface starts, whatever interface currently has the MAC address of 00:15:17:19:b6:a3 (i.e. eth5) will be renamed to lan prior to the interface being brought up, and will show up in ifconfig and ip commands as being an interface named lan.
Basic VLAN Configuration
The standard interface template supports VLANs. To use VLAN support, first ensure that your kernel was compiled with VLAN support (the module name is 8021q) :
# grep CONFIG_VLAN /usr/src/linux/.config CONFIG_VLAN_8021Q=m CONFIG_VLAN_8021Q_GVRP=y
Then, configure the trunk interface using the interface-noip template. Assuming eth1 is trunked, you would create the file /etc/conf.d/netif.eth1 with the following contents:
Then, create a network interface symlink for the trunk and add it to your default runlevel:
# cd /etc/init.d # ln -s netif.tmpl netif.eth1 # rc-update add netif.eth1 default
Now, assuming you wanted to configure a VLAN of 32, you would create a config file named /etc/conf.d/netif.eth1.32 that looks something like this:
template="interface" ipaddr="126.96.36.199/24" gateway="188.8.131.52"# etc...
Then, create a VLAN network interface symlink and add it to your default runlevel:
# cd /etc/init.d # ln -s netif.tmpl netif.eth1.32 # rc-update add netif.eth1.32 default
The Funtoo network configuration scripts will automatically recognize the filename netif.eth1.32 as being VLAN 32 of trunk interface netif.eth1.
When the VLAN interface is brought up, it will be named eth1.32.
Custom VLAN Names
However, sometimes you may want to turn off automatic file-based VLAN naming and give your VLAN interface a custom name, such as mgmt. To do this, you would set up the trunk interface in the exact same way as described above, but instead of creating a netif.eth1.32 interface, you would create a netif.mgmt interface, and specify vlan and trunk in the /etc/conf.d/netif.mgmt config file, as follows:
template="interface" vlan="32" trunk="eth1" ipaddr="184.108.40.206/24" gateway="220.127.116.11" # etc...
When you specify trunk and vlan in the interface config file, filename-based auto-detecting of VLAN ID and trunk is disabled. Both trunk and vlan must be specified -- you can't specify just one.
Then you would simply create a VLAN network interface symlink for netif.mgmt:
# cd /etc/init.d # ln -s netif.tmpl netif.mgmt # rc-update add netif.mgmt default
When the VLAN interface is brought up, it will be named mgmt.
Bonding allows you to aggregate multiple network interfaces into a single logical network interface, allowing for benefits in throughput as well as resiliency in the case that an individual interface may go down. This example shows how you would create a bonding interface (mybond) with a simple static ip setup, containing two slave devices (eth0 and eth1).
First, ensure that your kernel is configured to support bonding (the module name is bonding) :
$ grep CONFIG_BONDING /usr/src/linux/.config CONFIG_BONDING=m
You'l want to ensure that CONFIG_BONDING is set to "m" or "y". You can find this kernel configuration option tucked under "Device Drivers" -> "Network Device Support" -> "Bonding driver support". Be sure that ifenslave is emerged:
Once bonding is enabled in the kernel, you will need to choose at least two devices to bond together. These will be set up as "slave" interfaces with no IP address.
# cd /etc/init.d/ # ln -s netif.tmpl netif.eth0 # ln -s netif.tmpl netif.eth1
Then, configure the slave interfaces by creating /etc/conf.d/netif.eth0 and /etc/conf.d/netif.eth1 with the following contents:
Now, we will create the bond interface and make netif.eth0 and netif.eth1 slaves of this interface. Note that our bond interface can have any name. To demonstrate this, we will give it the name of "mybond" below:
# ln -s netif.tmpl netif.mybond # rc-update add netif.mybond default
Now we can configure "mybond" using its configuration file /etc/conf.d/netif.mybond, just as we would a regular interface, except that we specify slaves:
template="bond" ipaddr="10.0.1.200/24" gateway="10.0.1.1" nameservers="10.0.1.1 10.0.1.2" domain="funtoo.org" slaves="netif.eth0 netif.eth1"
In a bonded configuration, it is common to set the MTU to the maximum possible value supported by hardware to maximize throughput. In order to do this, simply set the MTU option in /etc/conf.d/netif.mybond to the maximum value supported by your hardware. The network scripts will ensure that this MTU setting is applied to all slave interfaces:
When hosting virtual machines, it can be convenient to use a bridge setup. This example shows how you would create a bridge (br0) with a simple static ip setup, containing two slave devices (eth0, tap0).
First, ensure that your kernel is configured to support bridging (the module name is bridge) :
$ grep CONFIG_BRIDGE /usr/src/linux/.config CONFIG_BRIDGE=m CONFIG_BRIDGE_IGMP_SNOOPING=y
Second, make sure you have the required software installed:
# emerge -av bridge-utils usermode-utilities
Then, create the necessary symlinks for the interfaces and add them to your default runlevel :
# cd /etc/init.d/ # ln -s netif.tmpl netif.eth0 # ln -s netif.tmpl netif.br0 # ln -s netif.tmpl netif.tap0 # rc-update add netif.br0 default # rc-update add netif.tap0 default
Then, configure the slave interface /etc/conf.d/netif.eth0 :
Then, configure the slave interface /etc/conf.d/netif.tap0 - note you only require group OR user, not both :
template="tap" group="kvm" user="kvm" mac_addr="10:20:30:40:50:66"
... and the bridge interface /etc/conf.d/netif.br0 :
template="bridge" ipaddr="10.0.1.200/24" gateway="10.0.1.1" nameservers="10.0.1.1 10.0.1.2" domain="funtoo.org" slaves="netif.eth0 netif.tap0" stp="on" forwarding=1
If you are using dhcpcd, you should ensure that it does not attempt to configure eth0 or br0 by adding the following to /etc/dhcpcd.conf :
# don't attempt to pull an ip address for br0 or its slave device denyinterfaces eth0 br0
More Complex Network Configuration
If the standard templates don't work for your needs, simply create a new template -- I recommend starting from the interface template for most things:
# cd /etc/netif.d # cp interface custom
You can now call whatever commands you need to /etc/netif.d/custom. The following shell functions can be defined in a network script:
In netif_create, you should call any commands to create the interface if it does not yet exist.
In netif_depend, you can define dependencies, using the functions need and use.
In netif_pre_up, you can define network configuration actions to perform prior to bringing the interface up. You can also ensure certain variables are specified by calling require var1 [var2...] here.
In netif_post_up, you can define network configuration actions to perform after bringing the interface up.
In netif_pre_down, you can define network configuration actions to perform prior to bringing the interface down.
In netif_post_down, you can define network configuration actions to perform after bringing the interface down.
In netif_destroy, you can call any commands necessary to destroy/delete the interface if it is dynamic in nature (tun/tap, etc.)
How It Works
You do not specify a function for actually bringing up the interface, because the template-based system does this for you. The template-based system also performs all normal actions required to bring an interface down, so you only need to specify atypical actions that must be performed - such as removing child interfaces or destroying a bridge using brctl.
When you create your own network configuration template, the following capabilities are available for use automatically, as long as the appropriate variables are set in the /etc/conf.d/netif.<ifname> file, without requiring any explicit steps on your part:
- DNS configuration using domain and nameservers config settings. OpenResolv is used automatically.
- VLAN configuration using auto-naming (netif.ethX.Y) or via custom naming with trunk and vlan config settings.
- Default IPv4 gateway and route configuration using the gateway and route settings.
- Default IPv6 gateway and route configuration using the gateway6 and route6 settings.
- MTU configuration using the mtu setting.
- Auto-depend (and auto-MTU configuration) of slave interfaces specified using slaves setting.
- Renaming of existing network interface (specify MAC address using macaddr setting).
To take advantage of this functionality, simply enable the appropriate variables.
All other necessary network configuration and dependency behavior should be defined using the netif_-prefix functions described above.
The recommended approach for setting up Wi-Fi under Funtoo Linux is to use NetworkManager. Steps are provided in the Wi-Fi section of the Funtoo Linux Installation Guide.
Other Network Configurations
If you have a network configuration template that might be useful to others, please post it to the funtoo-dev mailing list so we can review it and possibly incorporate it into Funtoo.
Funtoo Linux networking scripts are released under the following license:
| BSD 2-Clause Funtoo License
This work is free software. Source code is available.
Copyright 2009-2011 Funtoo Technologies. You can redistribute and/or modify it under the terms of the 2-clause BSD license. Alternatively you may (at your option) use any other license that has been publicly approved for use with this program by Funtoo Technologies (or its successors, if any.)