HOWTO Wireless Configuration and Startup

From Gentoo Linux Wiki

[edit] Configuration by hand

If you are having issues, it may help to see the full output of the Gentoo network init script to troubleshoot the connection. Set RC_VERBOSE=yes in /etc/conf.d/rc.

It's possible to run completely different network settings per ESSID connected to - check the /etc/conf.d/wireless.example file for details on how to achieve this. Note: /etc/conf.d/wireless is deprecated. Please put all settings in /etc/conf.d/net. Also for more details look at the

• Gentoo Linux Networking Handbook

A sample configuration file would look like this:

essid_ath1="YOUR_ACCESS_POINT"
config_ath1=( "dhcp" )
dhcpcd_ath1="-t 30" # Timeout after 30 seconds

Now you should be able to scan the area for router ESSIDS.

wlanconfig DEVICE list scan

or

iwlist DEVICE scanning

If iwlist is not available as a command, you need to emerge net-wireless/wireless-tools:

# emerge wireless-tools

Connect using the Gentoo networking init script.

Create a link that corresponds to your network interface/device in /etc/init.d and then start it:

cd /etc/init.d
ln -s net.lo net.DEVICE
/etc/init.d/net.DEVICE start

To start the Gentoo networking init script at boot.

rc-update add net.DEVICE default

Connect Manually

Sometimes the Gentoo networking init script won't work for you, or you would just prefer to do it quicker. You'll likely have to add more details than just the WEP key, like channel, essid... See the MadWifi document listed above.

ifconfig DEVICE up
iwconfig DEVICE key WEPKEY...
dhcpcd DEVICE

If you're roaming and don't require a WEPKEY,

iwconfig DEVICE essid any

This command will connect to the strongest station.

Some people may have to bring the network and the card down before being able to bring the device up:

ifconfig DEVICE down
rmmod MODULENAME
modprobe MODULENAME

Of course, one can also create a script to connect to your wireless connection, for example:

#!/bin/bash
ifconfig DEVICE up
iwconfig DEVICE key E7D6CA05773D038378F5E26748
dhcpcd DEVICE

Then make it executable:

chmod +x wireless-connect

Many people put this in local.start to have it initiated at boot.

# My init script to start the network
/home/user/myscripts/wireless-connect

[edit] Configuration using wpa_supplicant

The second way of configuring wireless, and in my opinion the best way, is by using wpa_supplicant. To install, simply emerge wpa_supplicant. Once installed, you can edit the /etc/wpa_supplicant/wpa_supplicant.conf file by checking out the examples in /etc/wpa_supplicant/wpa_supplicant.conf.example (or if not there, check in /usr/share/doc/wpa_supplicant-?.?.?/, filling in your version number) This file contains many options, is well documented and is a little easier to setup for multiple APs than by using /etc/conf.d/wireless. A sample configuration file would look like this:

# This is a network block that connects to a specific unsecured access point.
# We give it a higher priority.
network={
	ssid="YOUR_ACCESS_POINT_NAME"
	key_mgmt=NONE
	priority=5
}

# This is a network block that connects to any unsecured access point.
# We give it a low priority so any defined blocks are preferred.
network={
	key_mgmt=NONE
	priority=-9999999
}

You may also want to be able to configure wireless networks comfortable using wpa_gui which is very powerful and convenient. In order to use it as a user and, more important, to make it save the configs, you have to add followings to wpa_supplicant.conf:

ctrl_interface=/var/run/wpa_supplicant
ctrl_interface_group=users
update_config=1

The bonus in configuring your wireless setup using wpa_supplicant is that it supports all types of encryption currently used: WEP, WPA and even non-encrypted. Do not forget to compile the kernel modules necessary for encryption. These may be Networking -> IEEE 802.11i TKIP Encryption and similar ones.

To use wpa_supplicant over iwconfig for wireless configuration, put the following in /etc/conf.d/net:

modules=( "wpa_supplicant" )
# Users of madwifi add this:
wpa_supplicant_ath0="-Dmadwifi"
# Users of Intel ipw2100/2200 (Centrino) chips with older kernels add this:
wpa_supplicant_ath0="-Dipw"
wpa_timeout_ath0=60

# As of kernel 2.6.15 (and probably earlier), centrino users have to use
wpa_supplicant_ath0="-Dwext -c /etc/wpa_supplicant/wpa_supplicant.conf"
# wpa_supplicant.conf by default now is located in /etc/wpa_supplicant
# but yours could be in /etc.
wpa_timeout_ath0=60

Note: Replace ath0 as required with wlan0, eth1 etc. and madwifi with ndiswrapper or the correct drivers for your wireless card (see wpa_supplicant --help for a list of drivers).

Note: With ndiswrapper version 1.13 and newer, use -Dwext instead of -Dndiswrapper (ndiswrapper.sourceforge.net). Also make sure that you add "ap_scan=2" to your wpa_supplicant.conf if you want to connect to hidden networks.

Note: You will need to comment out any config_ESSID settings, as they do not work in conjunction with wpa_supplicant. If not, you will receive the following hard-to-read error:

Nov 13 06:14:20 yourhost wpa_cli: interface ath0 CONNECTED
Nov 13 06:14:21 yourhost wpa_cli: executing '/etc/init.d/net.ath0 --quiet start' failed

[edit] Madwifi and Wpa_supplicant

Madwifi support depends on the version of wpa_supplicant (see bug 110791). Check whether the package has a madwifi useflag (and don't forget to add it to your /etc/make.conf). As of writing, all versions in Portage have this useflag.

[edit] Links

• If your laptop needs different configurations depending on the network, this article on arping will be very helpful.