Wifi & Networking Configuration

Ethernet

• With recent udevs, the ethernet card is no longer named eth0. To obtain the predictable named used, run:

udevadm test-builtin net_id /sys/class/net/eth0 2> /dev/null

• Be very careful in the order of data returned. ID_NET_NAME_ONBOARD takes precedence over ID_NET_NAME_PATH but is not always present!

NetworkManager

Setup

• For Wifi, wpa_supplicant should be running (in -u mode, and as a daemon) else nothing will work. Usually if wpa_supplicant is not running it means NetworkManager has some permissions problems. To launch manually, you can run as root:

wpa_supplicant -uB

• Then the following commands should list your wifi interface and the available Wifi networks (after restarting NetworkManager):

nmcli dev
nmcli dev wifi list

Connecting to a network at boot

• The connection file must be present in /etc/NetworkManager/system-connections. If it is, the connection is automatically made at boot time.

Obsolete Information

• Just run the following command (assuming you have policykit installed):

sudo polkit-auth --grant org.freedesktop.network-manager-settings.system.modify --user "elvanor"

• This connects at boot (no need to wait until an user has logged and nm-applet has loaded). However, due to the time required to connect, running services such as ntp-client at boot still fail.

GUI Configuration

• On KDE 4 there is a plasmoid GUI available via the package knetworkmanagement.
• Another option is wicd which is a totally different network manager. It currently seems not very stable on some wireless cards.
• The Gnome applet for NetworkManager (gnome-extra/nm-applet) also works well on KDE.

DHCP, DNS, Hosts

• If you want to be able to type ssh valinor, and have the system automatically search for valinor.elvanor.net by default, you can add the following line to /etc/resolv.conf

search elvanor.net

DHCP

• If you use DHCP, resolv.conf will be wiped, so you must edit the file /etc/dhcp/dhclient.conf and add:

supersede domain-name "elvanor.net";

Note that you could also configure the DHCP server so that it gives this information to the clients.

• To add a custom DNS server when you use DHCP (for example when using the NetworkManager), you can add the following to /etc/dhcp/dhclient.conf:

prepend domain-name-servers 127.0.0.1;

• To obtain a static IP while you are using DHCP, the best is to instruct your server (router) to associate a static IP with a given MAC address. Note that on Gentoo however, entering a static IP on /etc/conf.d/net will work:

config_wlan0=( "192.168.0.2 netmask 255.255.255.0" )

Wifi

Setting up Wifi under Gentoo involves several steps.

Get your driver working

• This depends on your wireless card. Usually it will require very recent releases of the Linux kernel, and additional drivers or programs.

• Be sure to select the following stuff:
  • Device drivers -> Network devices -> Wireless LAN
  • Generic IEEE 802.11 Networking Stack
  • Associated cryptographic support within the networking stack (WARNING: this may be available ONLY after you said "yes" to Wireless LAN)

• Once you have an interface working (eg iwconfig lists something) you can proceed to the next step.

Intel Wireless cards

• The drivers are now present in the vanilla kernel. You just need to install the microcode which is present in Portage (for example iwl3945-ucode). Be sure you build iwfwifi drivers with the RF SWITCH option.
• Update: the microcode is now available in the linux-firmware package.
• Update 2: with recent kernels (this is the case in 3.12.x and later), you need to include the microcode in the kernel image. The option is CONFIG_FIRMWARE_IN_KERNEL, in Device Drivers -> Generic Driver Options.
• You should always include the most recent release of a given firmware in the kernel blob. For instance, iwlwifi-8000C-xx.ucode, choose xx as the highest number you have installed by the linux-firmware package.
• to find the name of the firmware corresponding to your chipset (not the version), use this Intel site.

Associating with an access point and Authentication

• Emerge wpa_supplicant.

• The configuration file used by wpa_supplicant under Gentoo is in /etc/wpa_supplicant/wpa_supplicant.conf. So edit your changes there. Sample below:

network={
        ssid="Arda"
        scan_ssid=1
        proto=WPA
        pairwise=CCMP TKIP
        psk="password_goes_here_56831"
        priority=2
}

• The pairwise option specifies the cryptographic algorithms used for authentication. CCMP also means AES.

• To basically test if authentication is working, launch wpa_supplicant with the -c and -i flags, supplying both a configuration file and an interface name. Example:

wpa_supplicant -ieth1 -c/etc/wpa_supplicant/wpa_supplicant.conf

Note that if you forget the -i or -c flag, wpa_supplicant will refuse to work.

• Once it is working, create a symlink in /etc/init.d:

ln -s net.lo net.eth1

where you replace eth1 with your interface name.

• Add some configuration options to /etc/conf.d/net. See for example this Gentoo documentation.

• Finally run /etc/init.d/net.eth1 start and if everything goes smoothly, you can add it to the default run level.

WEP access

• WEP access is much easier than WPA, just don't use WPA supplicant! All you need is in the wireless-tools package. Issue the following commands:

iwconfig eth1 essid MyNetworkName
iwconfig eth1 key 0123456789
dhcpcd eth1

• Edit /etc/conf.d/net to get wifi networking automatically started at boot.

• If your ESSID name contains a single quote ('), then you are in trouble. I was unable to properly escape this character in /etc/conf.d/net. The easiest way is then to create your own script (/etc/init.d/wireless) containing the above commands.

• Note for troubleshooting: some problems can put the card in a buggy state. Issue the command:

iwlist eth1 scan

to get a list of available networks. If no results appear, then it's best to reboot your machine.

ipw3945 specific notes (pre-iwlwifi)

• These notes are obsolete now that the recommended driver to use for this card is iwlwifi.
• Be careful to add the daemon init script to the boot runlevel, not the default one. Else things won't work automatically after boot.
• Include ipw3945 in the list of modules to be autoloaded. However by default it will start the daemon as soon as it is loaded, and this does not work well on Gentoo (maybe because it should wait a little?). So modify the file /etc/modules.d/ipw3945d so that installing the module does not load the init script automatically. Then run (of course) update-modules. This way you can have a clean boot sequence without errors :)

A note on init scripts on Gentoo

In fact there is only a single init script, net.lo, for the loop back interface. Other scripts are simply added by making symbolic links to net.lo, changing the "lo" with the new interface name.

Router configuration

• If the connection is very unstable and devices keep getting disconnected, it can be because the router switches regularly to different frequencies (20Mhz / 40Mhz). There should be an option in the router configuration to manually select a frequency and keep it (no auto switch). In congested environments, it seems better to choose 20Mhz over 40Mhz.
• Note also that routers provide different networks; one at 5Ghz for modern devices and one at 2,4Ghz for backward compatibility with older devices. These two separate networks can have the same SSID (or not).