4. Wireless Networking

Code Listing 2.1: Install wpa_supplicant

# emerge net-wireless/wpa_supplicant

Code Listing 2.2: configure /etc/conf.d/net for wpa_supplicant

# Prefer wpa_supplicant over wireless-tools
modules="wpa_supplicant"

# It's important that we tell wpa_supplicant which driver we should
# be using as it's not very good at guessing yet
wpa_supplicant_eth0="-Dmadwifi"

Code Listing 2.3: An example /etc/wpa_supplicant/wpa_supplicant.conf

# The below line not be changed otherwise we refuse 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"
}

Code Listing 3.1: Install wireless-tools

# emerge net-wireless/wireless-tools

Code Listing 3.2: sample iwconfig setup in /etc/conf.d/net

# 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'"

Code Listing 3.3: blacklist_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"

Code Listing 3.4: fallback to ad-hoc mode

adhoc_essid_eth0="This Adhoc Node"

Code Listing 3.5: sample 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"

Code Listing 4.1: override 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"