Debian static IP configuration: Wifi adapter

Following steps illustrate configuration of static IP to Wi-Fi connection on Debian Wheezy

Static configuration for the wifi interface is added into /etc/network/interfaces

First you need to generate 256 bit Pre-Shared Key (PSK) from passphrase for your WIFI connection as below

$ sudo wpa_passphrase MY_SSID
# reading passphrase from stdin
xxxxxx123   <= type in the passphrase
network={
    ssid="MY_SSID"
    #psk="xxxxxx123"
    psk=c2ddfd959c6febdc4aac1f3575ded17278a0749d9997d08c07d03a241a812e1c
}

in above example MY_SSID is wireless SSID and 'psk' is the 256-bit pre-shared key calculated from provided 'passphrase'

Now you can add this information into 'interfaces' file as below

$ tail /etc/network/interfaces
# for wifi connection
auto wlan0
iface wlan0 inet static
    address 192.168.0.200
    netmask 255.255.255.0
    gateway 192.168.0.1
    dns-nameservers 192.168.0.1
    wpa-ssid MY_SSID
    wpa-scan-ssid 1
    wpa-psk c2ddfd959c6febdc4aac1f3575ded17278a0749d9997d08c07d03a241a812e1c

If your SSID is configured to be hidden, then you need 'wpa-scan-ssid' to be set 1

Once interfaces file is properly configured, you can bring up interface using "ifup wlan0"

Check interface details with 'iw' (or) iwconfig as below

$ sudo iw wlan0 link
Connected to xx:xx:xx:xx:xx:xx (on wlan0)
    SSID: MY_SSID
    freq: 2427
    RX: 73561328 bytes (398315 packets)
    TX: 8602925 bytes (32204 packets)
    signal: -39 dBm
    tx bitrate: 39.0 MBit/s MCS 10

    bss flags:    short-slot-time
    dtim period:    0
    beacon int:    100

$ sudo iwconfig wlan0
wlan0     IEEE 802.11bgn  ESSID:"MY_SSID" 
          Mode:Managed  Frequency:2.427 GHz  Access Point: xx:xx:xx:xx:xx:xx  
          Bit Rate=39 Mb/s   Tx-Power=20 dBm  
          Retry  long limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality=70/70  Signal level=-38 dBm 
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:6  Invalid misc:877   Missed beacon:0


Note: Disable avahi-daemon and also change hosts line in nsswitch.conf as below

$ grep hosts: /etc/nsswitch.conf
#hosts:          files mdns4_minimal [NOTFOUND=return] dns mdns4
hosts:          files dns