Gentoo Linux ppc64 Manual: Configuração de rede

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This page is a translated version of the page Handbook:PPC64/Full/Networking and the translation is 50% complete.


The following networking portion of the handbook describes 'advanced' network configuration for systems running the OpenRC init system utilizing netifrc as the network management system.

For systems running systemd, readers should review see the networking portion of the systemd article.

Iniciando

Este guia de rede presume que o usuário já configurou corretamente o sistema e determinou o nome da interface de rede. O nome da interface é criado baseado na localização no bus da interface de rede no sistema. Por isso existe o potencial de variação de nomes como: eno0, ens1, wlan0, enp1s0 etc. Cada sistema pode ter nomes ligeiramente diferentes de interface de rede. O conteúdo a seguir presume o nome da interface de rede configurado é eth0, embora qualquer dos nomes anteriormente mencionados pode ser o correto.

Para iniciar a configuração da placa de rede, informe ao Gentoo sobre ela. Isso é feito criando um link simbólico de net.lo para net.eth0 (ou qualquer que seja o nome da interface de rede no sistema) em /etc/init.d.

root #cd /etc/init.d
root #ln -s net.lo net.eth0

O sistema RC do Gentoo agora reconhece essa interface. Ele precisa saber também como configurar a nova interface. Todas as interfaces de rede são configuradas no arquivo /etc/conf.d/net. Abaixo encontra-se um exemplo de configuração de endereços DHCP e estático.

FILE /etc/conf.d/netExamplo de configuração de rede
# Usando DHCP
config_eth0="dhcp"
  
# Usando IP estático com notação CIDR
config_eth0="192.168.0.7/24"
routes_eth0="default via 192.168.0.1"
dns_servers_eth0="192.168.0.1 8.8.8.8"
  
# Usando IP estático com notação de máscara de rede
config_eth0="192.168.0.7 netmask 255.255.255.0"
routes_eth0="default via 192.168.0.1"
dns_servers_eth0="192.168.0.1 8.8.8.8"
Nota
Se nenhuma configuração for feita para uma interface, então é assumido DHCP.
Nota
CIDR significa "Classless InterDomain Routing" (Roteamento Entre Domínios sem uso de Classes). Originalmente, endereços IPv4 eram classificados como de classe A, B ou C. Esse sistema de classificação não previu a maciça popularidade da Internet e o perigo de se acabar o estoque de novos endereços IP únicos. O CIDR é um esquema de endereçamento que permite a alocação mais flexível de endereços. Um endereço IP em CIDR se parece com um endereço IP normal exceto que termina com uma barra seguida de um número; por exemplo, 192.168.0.0/16. O CIDR é descrito na RFC 1519.

Estando a interface configurada, podemos ativá-la ou desativá-la com os seguintes comandos:

root #/etc/init.d/net.eth0 start
root #/etc/init.d/net.eth0 stop
Importante
Quando estiver diagnosticando problemas de rede, cheque o arquivo /var/log/rc.log. A menos que a variável rc_logger estiver como NO em /etc/rc.conf, informações sobre as atividades de boot ficarão armazenadas nesse arquivo de log.

Agora que a interface de rede foi parada e inicializada com sucesso, o próximo passo e fazer com que ela seja inicializada durante o boot. Aqui está como fazer isso:

root #rc-update add net.eth0 default
root #rc
Nota
O comando rc acima diz ao Gentoo para executar todos os scripts no nível de execução (runlevel) atual que ainda não foram executados.




Configuração avançada

A variável config_eth0 é o coração da configuração de uma interface. É uma lista de instruções de alto nível para configuração da interface (eth0 neste caso). Cada comando na lista é executado sequencialmente. A interface é considerada OK se ao menos um dos comandos funcionar.

Aqui está uma lista de instruções embutidas:

Valor Descrição
null Nenhuma ação.
noop Se a interface está ativa e possui um endereço, então aborte a configuração reportando sucesso.
Um endereço IPv4 ou IPv6 Adicione o endereço à interface.
dhcp, adsl, ou apipa (ou algum valor de algum módulo de terceiros) Execute o módulo que define o comando. Por exemplo, dhcp executa o módulo que provê DHCP, que pode ser servido pelo dhcpcd, dhclient, ou pump.

Se um comando falhar, execute um valor de "fallback". O fallback deve casar a estrutura de configuração exatamente.

É possível encadear esses valores em conjunto. Alguns exemplos reais:

FILE /etc/conf.d/netExemplos de configuração
# Adicionar três endereços IPv4
config_eth0="192.168.0.2/24
192.168.0.3/24
192.168.0.4/24"
  
# Adicionar um endereço IPv4 e dois endereços IPv6
config_eth0="192.168.0.2/24
4321:0:1:2:3:4:567:89ab
4321:0:1:2:3:4:567:89ac"
  
# Manter o endereço fornecido pelo kernel, a menos que a
# interface seja desconfigurada, então atribua outro
# via DHCP. Se o DHCP falhar, atribua um endereço
# estático determinado por APIPA
config_eth0="noop
dhcp"
fallback_eth0="null
apipa"
Nota
Quando usar o módulo ifconfig e adicionar mais de um endereço, são criados aliases para as interfaces para cada endereço extra. Então, com os dois exemplos acima, o usuário terá as interfaces eth0, eth0:1 e eth0:2. Não é possível fazer nada especial com essas interfaces pois o kernel e outros programas simplesmente tratarão eth0:1 e eth0:2 como eth0.
Importante
A ordem de "fallback" é importante! Se a opção "null" não for especificada o apipa apenas seria executado se o noop falhasse.
Nota
APIPA e DHCP são discutidos mais adiante.

Dependências de rede

Scripts de inicialização em /etc/init.d/ podem depender de uma interface específica ou apenas "net". Todas as interfaces de rede no sistema de inicialização do Gentoo fornecem o que é chamado "net".

Se, em /etc/rc.conf, a variável rc_depend_strict for YES, então as interfaces de rede que provêm "net" devem estar ativas antes que a dependência de "net" seja assumida como satisfeita. Em outras palavras, se um sistema possui as interfaces net.eth0 e net.eth1 e um script de inicialização depende de "net", então ambas devem estar habilitadas.

Por outro lado, usando rc_depend_strict="NO" a dependência "net" é marcada como resolvida no momento em que pelo menos uma das interfaces de rede for ativada.

Mas e se net.br0 depender de net.eth0 e net.eth1? net.eth1 pode ser um dispositivo sem fio ou PPP que precisa de configuração antes de poder ser adiciona à bridge. Isso não pode ser feito em /etc/init.d/net.br0 já que é um link simbólico para net.lo.

A solução é definir uma configuração rc_net_{interface}_need em /etc/conf.d/net:

FILE /etc/conf.d/netAdicionando uma dependência a net.br0
rc_net_br0_need="net.eth0 net.eth1"

Isso, porém, não é suficiente. Os scripts de inicialização de rede do Gentoo usam uma dependência virtual chamada "net" para informar ao sistema quando a rede está disponível. Obviamente, no caso acima, a rede só deve ser marcada como disponível quando net.br0 está configurada, não quando as outras estão. Assim, precisamos dizer isso também em /etc/conf.d/net:

FILE /etc/conf.d/netAtualizando as dependências virtuais para a rede
rc_net_eth0_provide="!net"
rc_net_eth1_provide="!net"

For a more detailed discussion about dependency, consult the section on writing initscripts in the Gentoo Handbook. More information about /etc/rc.conf is available as comments within that file.

Variable names and values

Variable names are dynamic. They normally follow the structure of variable_${interface|mac|essid|apmac}. For example, the variable dhcpcd_eth0 holds the value for dhcpcd options for eth0 and dhcpcd_essid holds the value for dhcpcd options when any interface connects to the ESSID "essid".

However, there is no hard and fast rule that states interface names must be ethx. In fact, many wireless interfaces have names like wlanx, rax as well as ethx. Also, some user defined interfaces such as bridges can be given any name. To make life more interesting, wireless Access Points can have names with non alpha-numeric characters in them - this is important because users can configure networking parameters per ESSID.

The downside of all this is that Gentoo uses bash variables for networking - and bash cannot use anything outside of English alpha-numerics. To get around this limitation we change every character that is not an English alpha-numeric into an _ (underscore) character.

Another downside of bash is the content of variables - some characters need to be escaped. This can be achieved by placing the \ (backslash) character in front of the character that needs to be escaped. The following list of characters needs to be escaped in this way: ", ' and \.

In this example we use wireless ESSID as they can contain the widest scope of characters. We shall use the ESSID My "\ NET:

FILE /etc/conf.d/netVariable names
# This does work, but the domain is invalid
dns_domain_My____NET="My \"\\ NET"

The above sets the DNS domain to My "\ NET when a wireless card connects to an AP whose ESSID is My "\ NET.

Network interface naming

Como funciona

Network interface names are not chosen arbitrarily: the Linux kernel and the device manager (most systems have udev as their device manager although others are available as well) choose the interface name through a fixed set of rules.

When an interface card is detected on a system, the Linux kernel gathers the necessary data about this card. This includes:

  • The onboard (on the interface itself) registered name of the network card, which is later seen through the ID_NET_NAME_ONBOARD value.
  • The slot in which the network card is plugged in, which is later seen through the ID_NET_NAME_SLOT value.
  • The path through which the network card device can be accessed, which is later seen through the ID_NET_NAME_PATH value.
  • The (vendor-provided) MAC address of the card, which is later seen through the ID_NET_NAME_MAC value.

Based on this information, the device manager decides how to name the interface on the system. By default, it uses the first hit of the first three variables above (ID_NET_NAME_ONBOARD, _SLOT or _PATH). For instance, if ID_NET_NAME_ONBOARD is found and set to eno1, then the interface will be called eno1.

Given an active interface name, the values of the provided variables can be shown using udevadm:

root #udevadm test-builtin net_id /sys/class/net/enp3s0 2>/dev/null
ID_NET_NAME_MAC=enxc80aa9429d76
ID_OUI_FROM_DATABASE=Quanta Computer Inc.
ID_NET_NAME_PATH=enp3s0

As the first (and actually only) hit of the top three variables is ID_NET_NAME_PATH, its value is used as the interface name. If none of the variables contain values, then the system reverts back to the kernel-provided naming (eth0, eth1, etc.)

Using the old-style kernel naming

Before this change, network interface cards were named by the Linux kernel itself, depending on the order that drivers are loaded (amongst other, possibly more obscure reasons). This behavior can still be enabled by setting the net.ifnames=0 boot parameter in the boot loader.

Using custom names

The entire idea behind the change in naming is not to confuse people, but to make changing the names easier. Suppose a system has two interfaces that are otherwise called eth0 and eth1. One is meant to access the network through a wire, the other one is for wireless access. With the support for interface naming, users can have these called lan0 (wired) and wifi0 (wireless - it is best to avoid using the previously well-known names like eth* and wlan* as those can still collide with the suggested names).

Find out what the parameters are for the cards and then use this information to set up a custom own naming rule:

root #udevadm test-builtin net_id /sys/class/net/eth0 2>/dev/null
ID_NET_NAME_MAC=enxc80aa9429d76
ID_OUI_FROM_DATABASE=Quanta Computer Inc.
root #vim /etc/udev/rules.d/70-net-name-use-custom.rules
# First one uses MAC information, and 70- number to be before other net rules
SUBSYSTEM=="net", ACTION=="add", ATTR{address}=="c8:0a:a9:42:9d:76", NAME="lan0"
root #vim /etc/udev/rules.d/76-net-name-use-custom.rules
# Second one uses ID_NET_NAME_PATH information, and 76- number to be between
# 75-net-*.rules and 80-net-*.rules
SUBSYSTEM=="net", ACTION=="add", ENV{ID_NET_NAME_PATH}=="enp3s0", NAME="wifi0"

Because the rules are triggered before the default one (rules are triggered in alphanumerical order, so 70 comes before 80) the names provided in the rule file will be used instead of the default ones. The number granted to the file should be between 76 and 79 (the environment variables are defined by a rule start starts with 75 and the fallback naming is done in a rule numbered 80).




Módulos de rede

Netifrc supports modular networking scripts, which means support for new interface types and configuration modules can easily be added 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.

Nota
All settings discussed here are stored in /etc/conf.d/net unless otherwise specified.
FILE /etc/conf.d/netModule definitions
# Prefer ifconfig over iproute2
# modules="ifconfig"
  
# You can also specify other modules for an interface
# In this case we prefer dhclient over dhcpcd
modules_eth0="dhclient"
  
# You can also specify which modules not to use - for example you may be
# using a supplicant or linux-wlan-ng to control wireless configuration but
# you still want to configure network settings per ESSID associated with.
modules="!iwconfig"

Interface handlers

We provide two interface handlers: ifconfig and iproute2. You need one of these to do any kind of network configuration.

Both are installed by default as part of the system profile. iproute2 is the more powerful and flexible package. ifconfig and net-tools should not be used anymore for networking configuration setups.

iproute2 and ifconfig 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.

FILE /etc/conf.d/netExample different approaches for configuration
config_eth0="192.168.0.2/24"
config_eth0="192.168.0.2 netmask 255.255.255.0"

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 may have to configure a connection to a wireless AP, PPPoE, or other aspects before the DHCP service can be used.

DHCP can be provided by dhclient or dhcpcd. Each DHCP module has its pros and cons - here is a quick run down:

DHCP module Package Pros Cons
dhclient net-misc/dhcp Made by ISC, the same people who make the BIND DNS software. Very configurable. Can be used to provide DHCPv4 or DHCPv6. Configuration is overly complex, software is quite bloated, cannot get NTP servers from DHCP, does not send hostname by default. No longer maintained upstream.
dhcpcd net-misc/dhcpcd Long time Gentoo default, no reliance on outside tools, actively developed by Gentoo. Provides DHCPv4 and DHCPv6 at the same time. Can be slow at times, does not yet daemonize when lease is infinite.

If more than one DHCP client is installed, specify which one to use - otherwise dhcpcd is used by default (if it is installed).

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 to 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 /etc/resolv.conf
nontp
Don't overwrite /etc/ntp.conf
nonis
Don't overwrite /etc/yp.conf
FILE /etc/conf.d/netSample DHCP (v4) configuration
# Only needed if more than one DHCP module is installed
modules="dhcpcd"
  
config_eth0="dhcp"
dhcpcd_eth0="-t 10" # Timeout after 10 seconds
dhcp_eth0="release nodns nontp nonis" # Only get an address
Nota
dhcpcd sends the current hostname to the DHCP server by default so this no longer needs to be specified.
FILE /etc/conf.d/netSample DHCPv6 configuration
# Only needed if more than one DHCP module is installed
modules="dhclient"
  
config_eth0="dhcpv6"
# To use both DHCPv4 and DHCPv6 on a dual-stack network, remove the above line and uncomment the following lines
#config_eth0="dhcp
#dhcpv6"
</div>

<div lang="en" dir="ltr" class="mw-content-ltr">
# To pass runtime arguments to dhclient for DHCPv6
dhclientv6_eth0="-t 10" # Timeout after 10 seconds
</div>

<div lang="en" dir="ltr" class="mw-content-ltr">
# Set generic DHCPv6 options
dhcpv6_eth0="release nodns nontp nonis nogateway nosendhost"

ADSL com PPPoE/PPPoA

First install the ADSL software:

root #emerge --ask net-dialup/ppp

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

root #ln -s /etc/init.d/net.lo /etc/init.d/net.ppp0
root #ln -s /etc/init.d/net.lo /etc/init.d/net.eth0

Be sure to set rc_depend_strict to YES in /etc/rc.conf.

Now we need to configure /etc/conf.d/net.

FILE /etc/conf.d/netA basic PPPoE setup
config_eth0=null (Specify the ethernet interface)
config_ppp0="ppp"
link_ppp0="eth0" (Specify the ethernet interface)
plugins_ppp0="pppoe"
username_ppp0='user'
password_ppp0='password'
pppd_ppp0="
noauth
defaultroute
usepeerdns
holdoff 3
child-timeout 60
lcp-echo-interval 15
lcp-echo-failure 3
noaccomp noccp nobsdcomp nodeflate nopcomp novj novjccomp"
  
rc_net_ppp0_need="net.eth0"

It is also possible to set the password in /etc/ppp/pap-secrets.

FILE /etc/ppp/pap-secretsSample pap-secrets
# The * is important
"username"  *  "password"

If PPPoE is used with a USB modem then make sure to emerge br2684ctl. Please read /var/db/repos/gentoo/net-dialup/speedtouch-usb/files/README for information on how to properly configure it.

Importante
Please carefully read the section on ADSL and PPP in /usr/share/doc/netifrc-*/net.example.bz2. It contains many more detailed explanations of all the settings any particular PPP setup will likely need.

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 net-misc/iputils with the arping USE flag or net-analyzer/arping.

FILE /etc/conf.d/netAPIPA configuration
# Try DHCP first - if that fails then fallback to APIPA
config_eth0="dhcp"
fallback_eth0="apipa"
  
# Just use APIPA
config_eth0="apipa"

Bonding

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 /usr/src/linux/Documentation/networking/bonding.txt.

First, clear the configuration of the participating interfaces:

FILE /etc/conf.d/netClearing interface configuration
config_eth0="null"
config_eth1="null"
config_eth2="null"

Next, define the bonding between the interfaces:

FILE /etc/conf.d/netDefine the bonding
slaves_bond0="eth0 eth1 eth2"
config_bond0="192.168.100.4/24"
# Pick a correct mode and additional configuration options which suit your needs
mode_bond0="balance-alb"

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)

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.

FILE /etc/conf.d/netBridge configuration
# Configure the bridge - "man brctl" for more details
bridge_forward_delay_br0=0
bridge_hello_time_br0=200
bridge_stp_state_br0=1
  
# To add ports to bridge br0
bridge_br0="eth0 eth1"
  
# You need to configure the ports to null values so dhcp does not get started
config_eth0="null"
config_eth1="null"
  
# Finally give the bridge an address - you could use DHCP as well
config_br0="192.168.0.1/24"
  
# Depend on eth0 and eth1 as they may require extra configuration
rc_net_br0_need="net.eth0 net.eth1"
Importante
For using some bridge setups, consult the variable name documentation.
Importante
When bridging using IPv6, SLAAC requires STP to be set to 1 as seen in the example above.

MAC address

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

FILE /etc/conf.d/netMAC Address change example
# To set the MAC address of the interface
mac_eth0="00:11:22:33:44:55"
  
# To randomize the last 3 bytes only
mac_eth0="random-ending"
  
# To randomize between the same physical type of connection (e.g. fibre,
# copper, wireless) , all vendors
mac_eth0="random-samekind"
  
# To randomize between any physical type of connection (e.g. fibre, copper,
# wireless) , all vendors
mac_eth0="random-anykind"
  
# Full randomization - WARNING: some MAC addresses generated by this may
# NOT act as expected
mac_eth0="random-full"

Tunneling

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

FILE /etc/conf.d/netTunneling configuration
# For GRE tunnels
iptunnel_vpn0="mode gre remote 207.170.82.1 key 0xffffffff ttl 255"
  
# For IPIP tunnels
iptunnel_vpn0="mode ipip remote 207.170.82.2 ttl 255"
  
# To configure the interface
config_vpn0="192.168.0.2 peer 192.168.1.1"

VLAN (802.1q support)

For VLAN support, make sure that sys-apps/iproute2 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 /etc/conf.d/net like so:

FILE /etc/conf.d/netSpecifying VLAN numbers
vlans_eth0="1 2"

Next, configure the interface for each VLAN:

FILE /etc/conf.d/netInterface configuration for each VLAN
config_eth0_1="172.16.3.1 netmask 255.255.254.0"
routes_eth0_1="default via 172.16.3.254"
  
config_eth0_2="172.16.2.1 netmask 255.255.254.0"
routes_eth0_2="default via 172.16.2.254"

VLAN-specific configurations are handled by vconfig like so:

FILE /etc/conf.d/netConfiguring the VLANs
vlan1_name="vlan1"
vlan1_ingress="2:6 3:5"
eth0_vlan1_egress="1:2"
Importante
For using some VLAN setups, consult the variable name documentation.



Introdução

Wireless networking on Linux is usually pretty straightforward. There are three ways of configuring wifi: graphical clients, text-mode interfaces, and command-line interfaces.

The easiest way is to use a graphical client once a desktop environment is installed. Most graphical clients, such as NetworkManager, are pretty self-explanatory. They offer a handy point-and-click interface that gets users on a network in just a few seconds.

Nota
NetworkManager offers text-mode or command-line interface utilities in addition to the main graphical interface. Emerge the net-misc/networkmanager package with the tools USE flag enabled. The nmtui utility is particularly useful for folks who do not use a X or Wayland based desktop environment, but still desire an easy-to-use tool that does not require hand-editing configuration files.

Wireless can also be configured from the command line by editing a few configuration files. This takes a bit more time to setup, but it also requires the fewest packages to download and install. Since the graphical clients are mostly self-explanatory (with helpful screen shots at their home pages), we'll focus on the command line alternatives.

There are three tools that support command-line driven wireless configurations: net-wireless/iw, net-wireless/wireless-tools, and net-wireless/wpa_supplicant. Of these three, net-wireless/wpa_supplicant is the preferred one. The important thing to remember is that wireless networks are configured on a global basis and not an interface basis.

The net-wireless/iw software, the successor of net-wireless/wireless-tools, supports nearly all cards and drivers, but it cannot connect to WPA-only Access Points. If the networks only offer WEP encryption or are completely open, then net-wireless/iw beats the other package over simplicity.

Some wireless cards are deactivated by default. To activate them, please consult the hardware documentation. Some of these cards can be unblocked using the rfkill application. If that is the case, use rfkill list to see the available cards and rfkill unblock INDEX to activate the wireless functionality. If not, then the wireless card might need to be unlocked through a button, switch or special key combination on the laptop.

WPA supplicant

The WPA supplicant project provides a package that allows users to connect to WPA enabled access points.

root #emerge --ask net-wireless/wpa_supplicant
Importante
It is necessary to have CONFIG_PACKET enabled in the kernel for wpa_supplicant to work. To see if it is enabled on the current kernel, try:
root #zgrep CONFIG_PACKET /proc/config.gz
root #grep CONFIG_PACKET /usr/src/linux/.config
Nota
Depending on the USE flags, wpa_supplicant can install a graphical interface written in Qt5, which will integrate nicely with KDE. To get it, enable USE="qt5" for the net-wireless/wpa_supplicant package.

Next, configure /etc/conf.d/net so that the wpa_supplicant module is preferred over wireless-tools (if both are installed, wireless-tools is the default).

FILE /etc/conf.d/netForce the use of wpa_supplicant
# Prefer wpa_supplicant over wireless-tools
modules="wpa_supplicant"
Nota
When using the host-ap driver it is necessary to put the card in Managed mode before it can be used with wpa_supplicant correctly. This can be achieved by setting iwconfig_eth0="mode managed" in /etc/conf.d/net.

Next configure wpa_supplicant itself (which is a bit more tricky depending on how secure the Access Points are). The below example is taken and simplified from /usr/share/doc/wpa_supplicant-<version>/wpa_supplicant.conf.gz which ships with wpa_supplicant.

FILE /etc/wpa_supplicant/wpa_supplicant.confSomewhat simplified example
# The below line not be changed otherwise wpa_supplicant refuses to work
ctrl_interface=/var/run/wpa_supplicant
  
# Ensure that only root can read the WPA configuration
ctrl_interface_group=0
  
# Let wpa_supplicant take care of scanning and AP selection
ap_scan=1
  
# Simple case: WPA-PSK, PSK as an ASCII passphrase, allow all valid ciphers
network={
  ssid="simple"
  psk="very secret passphrase"
  # The higher the priority the sooner we are matched
  priority=5
}
  
# Same as previous, but request SSID-specific scanning (for APs that reject
# broadcast SSID)
network={
  ssid="second ssid"
  scan_ssid=1
  psk="very secret passphrase"
  priority=2
}
  
# Only WPA-PSK is used. Any valid cipher combination is accepted
network={
  ssid="example"
  proto=WPA
  key_mgmt=WPA-PSK
  pairwise=CCMP TKIP
  group=CCMP TKIP WEP104 WEP40
  psk=06b4be19da289f475aa46a33cb793029d4ab3db7a23ee92382eb0106c72ac7bb
  priority=2
}
  
# Plaintext connection (no WPA, no IEEE 802.1X)
network={
  ssid="plaintext-test"
  key_mgmt=NONE
}
  
# Shared WEP key connection (no WPA, no IEEE 802.1X)
network={
  ssid="static-wep-test"
  key_mgmt=NONE
  # Keys in quotes are ASCII keys
  wep_key0="abcde"
  # Keys specified without quotes are hex keys
  wep_key1=0102030405
  wep_key2="1234567890123"
  wep_tx_keyidx=0
  priority=5
}
  
# Shared WEP key connection (no WPA, no IEEE 802.1X) using Shared Key
# IEEE 802.11 authentication
network={
  ssid="static-wep-test2"
  key_mgmt=NONE
  wep_key0="abcde"
  wep_key1=0102030405
  wep_key2="1234567890123"
  wep_tx_keyidx=0
  priority=5
  auth_alg=SHARED
}
  
# IBSS/ad-hoc network with WPA-None/TKIP
network={
  ssid="test adhoc"
  mode=1
  proto=WPA
  key_mgmt=WPA-NONE
  pairwise=NONE
  group=TKIP
  psk="secret passphrase"
}

Wireless tools

Initial setup and managed mode

The wireless tools project provides a generic way to configure basic wireless interfaces up to the WEP security level. While WEP is a weak security method it's still prevalent in the world.

Wireless tools configuration is controlled by a few main variables. The sample configuration file below should describe all that is needed. One thing to bear in mind is that no configuration means "connect to the strongest unencrypted Access Point" - wireless tools will always try and connect the system to something.

root #emerge --ask net-wireless/wireless-tools
Nota
Although net-wireless/iw is the current tool for the wireless stack, net-misc/netifrc before version 0.6.0 does not work with the new commands. net-wireless/wireless-tools must be used with netifrc with earlier versions. For more information consult the variable name documentation.
FILE /etc/conf.d/netSample iwconfig setup
# Prefer iwconfig over wpa_supplicant
modules="iwconfig"
  
# Configure WEP keys for Access Points called ESSID1 and ESSID2
# You may configure up to 4 WEP keys, but only 1 can be active at
# any time so we supply a default index of [1] to set key [1] and then
# again afterwards to change the active key to [1]
# We do this incase you define other ESSID's to use WEP keys other than 1
#
# Prefixing the key with s: means it's an ASCII key, otherwise a HEX key
#
# enc open specified open security (most secure)
# enc restricted specified restricted security (least secure)
key_ESSID1="[1] s:yourkeyhere key [1] enc open"
key_ESSID2="[1] aaaa-bbbb-cccc-dd key [1] enc restricted"
  
# The below only work when we scan for available Access Points
  
# Sometimes more than one Access Point is visible so we need to
# define a preferred order to connect in
preferred_aps="'ESSID1' 'ESSID2'"

Fine-tune AP selection

It is possible to add some extra options to fine-tune the AP selection, but these are not required.

One way is to configure the system so it only connects to preferred APs. By default if everything configured has failed and wireless-tools can connect to an unencrypted Access Point then it will. This can be controlled by the associate_order variable. Here's a table of values and how they control this.

Value Description
any Default behavior.
preferredonly Only connect to visible APs in the preferred list.
forcepreferred Forceably connect to APs in the preferred order if they are not found in a scan.
forcepreferredonly Do not scan for APs - instead just try to connect to each one in order.
forceany Same as forcepreferred + connect to any other available AP.

There is also the blacklist_aps and unique_ap selection. blacklist_aps works in a similar way to preferred_aps. unique_ap is a yes or no value that says if a second wireless interface can connect to the same Access Point as the first interface.

FILE /etc/conf.d/netblacklist_aps and unique_ap example
# Sometimes you never want to connect to certain access points
blacklist_aps="'ESSID3' 'ESSID4'"
  
# If you have more than one wireless card, you can say if you want
# to allow each card to associate with the same Access Point or not
# Values are "yes" and "no"
# Default is "yes"
unique_ap="yes"

Ad-hoc and master modes

To set the system up as an ad-hoc node when it fails to connect to any Access Point in managed mode, use this as a fallback:

FILE /etc/conf.d/netFallback to ad-hoc mode
adhoc_essid_eth0="This Adhoc Node"

It is also possible to connect to ad-hoc networks, or to run the system in master mode so it becomes an access point itself.

FILE /etc/conf.d/netSample ad-hoc/master configuration
# Set the mode - can be managed (default), ad-hoc or master
# Not all drivers support all modes
mode_eth0="ad-hoc"
  
# Set the ESSID of the interface
# In managed mode, this forces the interface to try and connect to the
# specified ESSID and nothing else
essid_eth0="This Adhoc Node"
  
# We use channel 3 if you don't specify one
channel_eth0="9"
Importante
An important resource about channel selection is the BSD wavelan documentation found at the NetBSD documentation. There are 14 channels possible; We are told that channels 1-11 are legal for North America, channels 1-13 for most of Europe, channels 10-13 for France, and only channel 14 for Japan. If in doubt, please refer to the documentation that came with the card or access point. Make sure that the channel selected is the same channel the access point (or the other card in an ad-hoc network) is on. The default for cards sold in North America and most of Europe is 3; the default for cards sold in France is 11, and the default for cards sold in Japan is 14.

Troubleshooting wireless tools

There are some more variables that can help to get the wireless up and running due to driver or environment problems. Here's a table of other things that can be tried.

Variable name Default value Description
iwconfig_eth0 See the iwconfig man page for details on what to send iwconfig.
iwpriv_eth0 See the iwpriv man page for details on what to send iwpriv.
sleep_scan_eth0 0 The number of seconds to sleep before attempting to scan. This is needed when the driver/firmware needs more time to active before it can be used.
sleep_associate_eth0 5 The number of seconds to wait for the interface to associate with the Access Point before moving onto the next one.
associate_test_eth0 MAC Some drivers do not reset the MAC address associated with an invalid one when they lose or attempt association. Some drivers do not reset the quality level when they lose or attempt association. Valid settings are MAC, quality and all.
scan_mode_eth0 Some drivers have to scan in ad-hoc mode, so if scanning fails try setting ad-hoc here.
iwpriv_scan_pre_eth0 Sends some iwpriv commands to the interface before scanning. See the iwpriv man page for more details.
iwpriv_scan_post_eth0 Sends some iwpriv commands to the interface after scanning. See the iwpriv man page for more details.

Defining network configuration per ESSID

In this section, we show how to configure network settings based on the ESSID. For instance, with the wireless network with ESSID ESSID1 configure a static IP address while ESSID ESSID2 uses DHCP.

Nota
This works with both wpa_supplicant as well as wireless-tools
Importante
Please consult the variable name documentation.
FILE /etc/conf.d/netoverride network settings per ESSID
config_ESSID1="192.168.0.3/24 brd 192.168.0.255"
routes_ESSID1="default via 192.168.0.1"
  
config_ESSID2="dhcp"
fallback_ESSID2="192.168.3.4/24"
fallback_route_ESSID2="default via 192.168.3.1"
  
# We can define nameservers and other things too
# NOTE: DHCP will override these unless it's told not to
dns_servers_ESSID1="192.168.0.1 192.168.0.2"
dns_domain_ESSID1="some.domain"
dns_search_domains_ESSID1="search.this.domain search.that.domain"
  
# You override by the MAC address of the Access Point
# This handy if you goto different locations that have the same ESSID
config_001122334455="dhcp"
dhcpcd_001122334455="-t 10"
dns_servers_001122334455="192.168.0.1 192.168.0.2"




Standard function hooks

Quatro funções podem ser definidas em /etc/conf.d/net que serão chamadas em torno das operações de iniciar/parar. As funções são chamadas com o nome da interface primeiro de modo que a função pode controlar múltiplos adaptadores.

Os valores de retorno das funções preup() e predown() deve ser 0 (sucesso) para indicar que a configuração ou desconfiguração da interface pode continuar. Se preup() retornar um valor não zero, a configuração da interface será abortada. Se predown() retornar um valor não zero, a interface não será permitida a continuar a desconfiguração.

Os valores de retorno das funções postup() e postdown() são ignorados uma vez que nada resta a fazer se elas indicarem falha.

${IFACE} é a interface sendo configurada ou desconfigurada. ${IFVAR} é ${IFACE} convertida para nome de variável permitida pelo bash.

FILE /etc/conf.d/netpre/post up/down function examples
preup() {
  # Test for link on the interface prior to bringing it up.  This
  # only works on some network adapters and requires the ethtool
  # package to be installed.
  if ethtool ${IFACE} | grep -q 'Link detected: no'; then
    ewarn "No link on ${IFACE}, aborting configuration"
    return 1
  fi
  
  # Remember to return 0 on success
  return 0
}
  
predown() {
  # The default in the script is to test for NFS root and disallow
  # downing interfaces in that case.  Note that if you specify a
  # predown() function you will override that logic.  Here it is, in
  # case you still want it...
  if is_net_fs /; then
    eerror "root filesystem is network mounted -- can't stop ${IFACE}"
    return 1
  fi
  
  # Remember to return 0 on success
  return 0
}
  
postup() {
  # This function could be used, for example, to register with a
  # dynamic DNS service.  Another possibility would be to
  # send/receive mail once the interface is brought up.
       return 0
}
  
postdown() {
  # This function is mostly here for completeness... I haven't
  # thought of anything nifty to do with it yet ;-)
  return 0
}
Nota
Para mais informações sobre escrever funções, por favor veja /usr/share/doc/netifrc-*/net.example.bz2.

Wireless tools function hook

Nota
This will not work with WPA Supplicant - but the ${ESSID} and ${ESSIDVAR} variables are available in the postup() function.

Two functions can be defined in /etc/conf.d/net which will be called surrounding the associate function. The functions are called with the interface name first so that one function can control multiple adapters.

Os valores de retorno da função preassociate() deve ser 0 (sucesso) para indicar que a configuração e desconfiguração da interface pode continuar. Se preassociate() retornar um valor não zero, a configuração da interface é abortada.

O valor de retorno da função postassociate() é ignorado uma vez que não há nada a ser feito se ele indicar falha.

${ESSID} is set to the exact ESSID of the AP the system is connecting to. ${ESSIDVAR} is ${ESSID} converted to a variable name bash allows.

FILE /etc/conf.d/netpre/post association functions
preassociate() {
  # The below adds two configuration variables leap_user_ESSID
  # and leap_pass_ESSID. When they are both configured for the ESSID
  # being connected to then we run the CISCO LEAP script
  
  local user pass
  eval user=\"\$\{leap_user_${ESSIDVAR}\}\"
  eval pass=\"\$\{leap_pass_${ESSIDVAR}\}\"
  
  if [[ -n ${user} && -n ${pass} ]]; then
    if [[ ! -x /opt/cisco/bin/leapscript ]]; then
      eend "For LEAP support, please emerge net-misc/cisco-aironet-client-utils"
      return 1
    fi
    einfo "Waiting for LEAP Authentication on \"${ESSID//\\\\//}\""
    if /opt/cisco/bin/leapscript ${user} ${pass} | grep -q 'Login incorrect'; then
      ewarn "Login Failed for ${user}"
      return 1
    fi
  fi
  
  return 0
}
  
postassociate() {
  # This function is mostly here for completeness... I haven't
  # thought of anything nifty to do with it yet ;-)
  
  return 0
}
Nota
${ESSID} and ${ESSIDVAR} are unavailable in predown() and postdown() functions.
Nota
For more information on writing custom functions, please read /usr/share/doc/netifrc-*/net.example.bz2.




Gerenciamento de rede

Laptops podem estar sempre em locais diferentes. Como resultado, o sistema nem sempre tem um cabo de rede plugado ou um ponto de acesso sem fio disponível. O usuário pode também querer que a rede funcione automaticamente quanto um cabo Ethernet seja plugado ou seja encontrado um ponto de acesso sem fio.

Neste capítulo mostramos como isso pode ser feito.

Nota
Este documento discute apenas o ifplugd, mas existem alternativas, como o netplug. O netplug é uma alternativa mais leve ao ifplugd, mas ele depende dos drivers de rede do kernel funcionarem corretamente, o que não é o caso de muitos.

ifplugd

O ifplugd é um daemon que inicia e para interfaces quando um cabo de rede é inserido ou removido. Ele também pode gerenciar a associação com pontos de acesso sem fio ou quando um novo entra na faixa de alcance.

root #emerge --ask sys-apps/ifplugd

A configuração do ifplugd é bem direta. A configuração é mantida em /etc/conf.d/net. Use man ifplugd para detalhes sobre as variáveis disponíveis. Também, veja /usr/share/doc/netifrc-*/net.example.bz2 para mais exemplos.

FILE /etc/conf.d/netExemplo de configuração do ifplug
# Substitua eth0 pela interface a ser monitorada
ifplugd_eth0="..."
  
# Para monitorar uma interface sem fio
ifplugd_eth0="--api-mode=wlan"

Além de gerenciar múltiplas conexões de rede, usuários podem querer adicionar uma ferramente que facilite trabalhar com múltiplas configurações e servidores de DNS. Isso é muito prático quando o sistema recebe seu endereço IP por DHCP.

root #emerge --ask net-dns/openresolv

Veja man resolvconf para aprender mais sobre seus recursos.