Gentoo Linux ia64 手册：网络配置/zh-cn

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This page is a translated version of the page Handbook:IA64/Full/Networking and the translation is 100% 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.

开始

This networking guide presumes that the user has correctly configured the system and has determined the hardware's network interface name(s). The network interface name is produced based on the bus location of the network card(s) in the system. Because of this there is potential for interface name variants including: eno0, ens1, wlan0, enp1s0, etc. Each system may have a slightly different interface name. The following content presumes the name of the interface to configured is eth0, although any of the aforementioned names will work.

To get started configuring the network card, tell the Gentoo RC system about it. This is done by creating a symbolic link from net.lo to net.eth0 (or whatever the network interface name is on the system) in /etc/init.d.

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

Gentoo's RC system now knows about that interface. It also needs to know how to configure the new interface. All the network interfaces are configured in /etc/conf.d/net file. Below is a sample configuration for DHCP and static addresses.

文件 /etc/conf.d/net网络配置示例
# For DHCP
config_eth0="dhcp"
  
# For static IP using CIDR notation
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"
  
# For static IP using netmask notation
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"
附注
If no configuration is mentioned for an interface then DHCP is assumed.
附注
CIDR stands for Classless InterDomain Routing. Originally, IPv4 addresses were classified as A, B, or C. The early classification system did not envision the massive popularity of the Internet, and is in danger of running out of new unique addresses. CIDR is an addressing scheme that allows one IP address to designate many IP addresses. A CIDR IP address looks like a normal IP address except that it ends with a slash followed by a number; for example, 192.168.0.0/16. CIDR is described in RFC 1519.

Now that the interface is configured, we can start and stop it using the following commands:

root #/etc/init.d/net.eth0 start
root #/etc/init.d/net.eth0 stop
重要
When troubleshooting networking, take a look at /var/log/rc.log. Unless the rc_logger variable is set to NO in /etc/rc.conf, information on the boot activity will be stored in that log file.

Now that the network interface has been successfully stopped and started, the next step is to have it started when Gentoo boots. Here is how to do this.:

root #rc-update add net.eth0 default
root #rc
附注
The last rc command instructs Gentoo to start any scripts in the current runlevel that have not yet been started.




高级配置

config_eth0 变量是接口配置的核心。它是用于配置接口（在本例中为 eth0）的高级指令列表。指令列表中的每个命令都是按顺序执行的。如果至少有一个命令起作用，则认为该接口正常。

以下是内置指令列表：

值 描述
null 不做任何事。
noop 如果接口已启动并且有地址，则成功中止配置。
An IPv4 or IPv6 address 将地址添加到接口。
dhcp, adsl, or apipa （或来自 3rd 方模块的自定义值） 运行提供命令的模块。例如，dhcp 将运行一个提供 DHCP 的模块，该模块可以由 dhcpcd、dhclient 或 pump 提供服务。

如果命令失败，请指定回退值。回退必须与配置结构完全匹配。

可以将这些值链接在一起。以下是一些真实例子：

文件 /etc/conf.d/net配置示例
# Adding three IPv4 addresses
config_eth0="192.168.0.2/24
192.168.0.3/24
192.168.0.4/24"
  
# Adding an IPv4 address and two IPv6 addresses
config_eth0="192.168.0.2/24
4321:0:1:2:3:4:567:89ab
4321:0:1:2:3:4:567:89ac"
  
# Keep our kernel assigned address, unless the interface goes
# down so assign another via DHCP. If DHCP fails then add a
# static address determined by APIPA
config_eth0="noop
dhcp"
fallback_eth0="null
apipa"
附注
When using the ifconfig module and adding more than one address, interface aliases are created for each extra address. So with the above two examples users will get interfaces eth0, eth0:1 and eth0:2. It is not possible to do anything special with these interfaces as the kernel and other programs will just treat eth0:1 and eth0:2 as eth0.
重要
回退顺序很重要！如果未指定 null 选项，则 apipa 只会在 noop 失败时运行。
附注
APIPA 和 DHCP 稍后讨论。

网络依赖

Init scripts in /etc/init.d/ can depend on a specific network interface or just "net". All network interfaces in Gentoo's init system provide what is called "net".

If, in /etc/rc.conf, the rc_depend_strict variable is set to YES, then all network interfaces that provide "net" must be active before a dependency on "net" is assumed to be met. In other words, if a system has a net.eth0 and net.eth1 and an init script depends on "net", then both must be enabled.

On the other hand, if rc_depend_strict="NO" is set, then the "net" dependency is marked as resolved the moment at least one network interface is brought up.

But what about net.br0 depending on net.eth0 and net.eth1? net.eth1 may be a wireless or PPP device that needs configuration before it can be added to the bridge. This cannot be done in /etc/init.d/net.br0 as that's a symbolic link to net.lo.

The answer is to define a rc_net_{interface}_need setting in /etc/conf.d/net:

文件 /etc/conf.d/net添加 net.br0 依赖项
rc_net_br0_need="net.eth0 net.eth1"

That alone, however, is not sufficient. Gentoo's networking init scripts use a virtual dependency called "net" to inform the system when networking is available. Clearly, in the above case, networking should only be marked as available when net.br0 is up, not when the others are. So we need to tell that in /etc/conf.d/net as well:

文件 /etc/conf.d/netUpdating virtual dependencies and provisions for networking
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.

变量名和值

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:

文件 /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.

网络接口命名

它是如何工作的

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.)

使用旧式内核命名

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.

使用自定义名称

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).




网络模块

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.

附注
All settings discussed here are stored in /etc/conf.d/net unless otherwise specified.
文件 /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.

As iproute2 and ifconfig do very similar things, we allow their basic configuration to work with each other. For example, the below configuration works regardless of the module used.

文件 /etc/conf.d/netExample configuration
config_eth0="192.168.0.2/24"
config_eth0="192.168.0.2 netmask 255.255.255.0"

DHCP

DHCP 是一种从 DHCP 服务器获取网络信息（IP地址、DNS 服务器、网关等）的手段。这意味着，如果网络上有一台 DHCP 服务器在运行，用户只需告诉每个客户使用 DHCP，它就会自行设置网络。当然，在使用 DHCP 之前，如果需要的话，用户还必须对其他东西进行配置，如无线、PPP 或其他东西。

DHCP 可以由 dhclient 或 dhcpcd 提供。每个 DHCP 模块都有其有缺点——这里是一个快速概述：

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, it is possible to specify which client to use by setting the "modules" variable, e.g. modules="dhcpcd". Otherwise, if dhcpcd is installed, it's used by default.

To send specific options to the DHCP module, use module_eth0="...", where module is the name of the DHCP module being used - for example, "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
文件 /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
附注
dhcpcd sends the current hostname to the DHCP server by default so this no longer needs to be specified.
文件 /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 with 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.

文件 /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.

文件 /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.

重要
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 using arping to ping a random address in that range on the interface. If no reply is received, that address is assigned to the interface.

This is only useful for LANs where:

  • there is no DHCP server;
  • 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.

文件 /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 the face of hardware failures. If a system has two network cards going to the same network, they can be bonded: applications will see just one interface, but both network cards will be used.

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:

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

Next, define the bonding between the interfaces:

文件 /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 relevant runlevel, create a net.bond0 service, and add that service to the appropriate runlevel.

Bridging (802.1d support)

Bridging is used to join networks together. For example, a network may have a server that connects to the Internet via an ADSL modem, and also has a wireless adapter to allow other devices on the network to access the Internet via that modem. It is possible to create a bridge to join the two interfaces together.

文件 /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"
重要
For using some bridge setups, consult the variable name documentation.
重要
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.

文件 /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.

文件 /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 the configuration module (rather than ifconfig).

A VLAN, 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. Members of a VLAN can only see other members of the same VLAN, even when they share the same physical network.

To configure VLANs, first specify the VLAN numbers in /etc/conf.d/net like so:

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

Next, configure the interface for each VLAN:

文件 /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:

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



介绍

Linux 上的无线网络通常非常简单。有三种方式来配置 WiFi ：图形客户端、文本模式和命令行。

最简单的方法是在安装桌面环境后使用图形客户端。大多数图形客户端，例如NetworkManager 都无需多说。他们都提供了很方便地让用户点击的界面，只需几秒钟即可使用户连接网络。

附注
除图形界面以外，NetworkManager 还包含了命令行工具及文字界面。使用 ncurses USE 标记安装 net-misc/networkmanager 即可。对于不使用 X 或者 Wayland，但仍需要一个简单易用的网络管理工具的人而言，nmtui 会相当有用。

也可以通过编辑一些配置文件从命令行配置无线网络。这需要更多的时间来设置，但它仅需下载和安装少量的包。由于图形客户端的使用方法大多是不言自明的（在其主页上有有用的屏幕截图），因此我们将重点介绍命令行替代方案。

共有三种支持命令行驱动无线网络配置的工具：net-wireless/iw、net-wireless/wireless-tools 和 {{Package|net-wireless/wpa_supplicant} }。在这三个中，net-wireless/wpa_supplicant 是首选。要记住的重要一点是，无线网络是在全局基础上配置的，而不是在接口基础上进行配置的。

net-wireless/iw 软件，net-wireless/wireless-tools 的继承者，支持几乎所有的网卡和驱动程序，但它不能连接到 WPA-only 接入点。如果网络仅提供 WEP 加密或完全开放，那么 net-wireless/iw 在简单性方面优于其他软件包。

默认情况下，某些无线网卡处于停用状态。要激活它们，请查阅硬件文档。其中一些网卡可以使用 rfkill 应用程序解锁。如果是这种情况，请使用 rfkill list 查看可用网卡并使用 rfkill unblock INDEX 激活无线功能。如果没有，则可能需要通过笔记本电脑上的按钮、开关或特殊组合键来解锁无线网卡。

WPA supplicant

WPA supplicant project 提供了一个软件包允许用户连接到 WPA 认证的接入点。

root #emerge --ask net-wireless/wpa_supplicant
重要
必须在内核中启用 CONFIG_PACKET 才能使 wpa_supplicant 工作。要查看它是否在当前内核上启用，请尝试：
root #zgrep CONFIG_PACKET /proc/config.gz
root #grep CONFIG_PACKET /usr/src/linux/.config
附注
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.

接下来，配置 /etc/conf.d/net 以便 wpa_supplicant 模块优先于 wireless-tools（如果两者都安装，则 wireless-tools 是默认值）。

文件 /etc/conf.d/net强制使用 wpa_supplicant
# 优先使用 wpa_supplicant 而非 wireless-tools
modules="wpa_supplicant"
附注
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.

接下来配置 wpa_supplicant 本身（考虑到接入点的安全性，这有点棘手）。以下示例取自 wpa_supplicant 附带的 /usr/share/doc/wpa_supplicant-<version>/wpa_supplicant.conf.gz。

文件 /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"
}

无线工具

初始设置和管理模式

无线网络工具项目提供了一种将基本无线网络接口配置到 WEP 安全级别的通用方法。虽然 WEP 是一种较弱的安全方法，但它仍然在世界范围内流行。

无线网络工具配置由几个主要变量控制。下面的配置文件示例应该描述了所有需要的内容。要记住的一件事是，没有配置意味着“连接到信号最强的未加密接入点”——无线网络工具总是会尝试将系统连接到某些热点。

root #emerge --ask net-wireless/wireless-tools
附注
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.
文件 /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.

文件 /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 和主模式

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:

文件 /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.

文件 /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"
重要
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.

无线网络工具故障排除

由于驱动程序或环境问题，还有一些变量可以帮助启动和运行无线网络。这是可以尝试的其他方法的表格。

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.

定义每个 ESSID 的网络配置

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.

附注
This works with both wpa_supplicant as well as wireless-tools
重要
请查阅变量名文档。
文件 /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

Four functions can be defined in /etc/conf.d/net:

  • preup(), called before an interface is brought up;
  • predown(), called before an interface is brought down;
  • postup(), called after an interface is brought up; and
  • postdown(), called after an interface is brought down.

Each of these these functions is called with the interface name, available within each function via the IFACE variable, so that one function can control multiple interfaces.

The return values for the preup() and predown() functions should be:

  • 0 to indicate success, and that configuration or de-configuration of the interface can continue.
  • A non-zero value otherwise.

If preup() returns a non-zero value, interface configuration will be aborted. If predown() returns a non-zero value, the interface will not be allowed to continue de-configuration.

Return values for the postup() and postdown() functions are ignored since there's nothing to do if they indicate failure.

${IFACE} is set to the interface being brought up/down. ${IFVAR} is ${IFACE} converted to variable name bash allows.

文件 /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
}
附注
For more information on writing functions, please read /usr/share/doc/netifrc-*/net.example.bz2.

Wireless function hooks

附注
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:

  • preassociate(), called before association.
  • postassociate(), called after association.

Each of these these functions is called with the interface name, available within each function via the IFACE variable, so that one function can control multiple interfaces.

The return values for the preassociate() function should be:

  • 0 to indicate success, and to continue configuration.
  • A non-zero value otherwise.

If preassociate() returns a non-zero value, interface configuration will be aborted.

The return value for the postassociate() function is ignored since there's nothing to do if it indicates failure.

Within each function, the exact ESSID of the AP the system is connecting to is available via the ESSID variable. ${ESSIDVAR} is ${ESSID} converted to a variable name bash allows.

文件 /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
}
附注
${ESSID} and ${ESSIDVAR} are unavailable in predown() and postdown() functions.
附注
For more information on writing custom functions, please read /usr/share/doc/netifrc-*/net.example.bz2.




网络管理

With laptops, systems can be always on the move. As a result, the system may not always have an Ethernet cable or plugged in or an access point available. Also, the user may want networking to automatically work when an Ethernet cable is plugged in or an access point is found.

在本章中，我们将介绍如何做到这一点。

附注
This document only talks about ifplugd, but there are alternatives such as netplug. netplug is a lightweight alternative to ifplugd, but it relies on the kernel network drivers working correctly, and many drivers do not.

ifplugd

ifplugd is a daemon that starts and stops interfaces when an Ethernet cable is inserted or removed. It can also manage detecting association to Access Points or when new ones come in range.

root #emerge --ask sys-apps/ifplugd

Configuration for ifplugd is fairly straightforward too. The configuration is held in /etc/conf.d/net. Run man ifplugd for details on the available variables. Also, see /usr/share/doc/netifrc-*/net.example.bz2 for more examples.

文件 /etc/conf.d/netSample ifplug configuration
# Replace eth0 with the interface to be monitored
ifplugd_eth0="..."
  
# To monitor a wireless interface
ifplugd_eth0="--api-mode=wlan"

In addition to managing multiple network connections, users may want to add a tool that makes it easy to work with multiple DNS servers and configurations. This is very handy when the system receives its IP address via DHCP.

root #emerge --ask net-dns/openresolv

参考 man resolvconf 以了解更多关于它的功能。



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