connect.sh

#!/bin/bash

#
# 01/06/2013
# This script attempts to semi-automate the wifi connection process from the command line.
# It is intended to be used on a headless machine without the requirement of typing several commands for a connection.
# The script stores previous connection credentials in PLAINTEXT as *.wpa files in the executed directory and in /etc/wpasupplicant.conf.  These .wpa files are used to connect to several different ap using  previously stored info.
# Probably a good idea to stop and other network managing software while running this script, also in testing wpa_supplicant does a pretty good job of re-connecting a disassociated link automatically.
#
# Mainly created from a combination of scripts taken from theses two sources:
# http://www.backtrack-linux.org/forums/archive/index.php/t-3367.html
# AND
# http://www.linuxquestions.org/questions/linux-general-1/wifi-connect-script-tested-in-ubuntu-772646/
#
# Copy, Distribute and Modify Freely.
#


INT=$1

if [ -z "$1" ]; then
    printf "Usage: $0 [interface]\n"
    exit
fi

if [ "$(id -u)" != "0" ]; then
    printf "This script must be run as root\n" 1>&2
    exit
fi

#
# Search for previous saved config files
#
function read_saved {
    #
    # Search for previous wpa configuration files.
    #

    #
    # Save and change IFS so spaces in file names are not interpreted as separate lines in the array
    #
    OLDIFS=$IFS
    IFS=$'\n'

    #
    # Read all file names into an array ref:http://www.cyberciti.biz/tips/handling-filenames-with-spaces-in-bash.html
    # " -printf '%f\n' " removes path info from outputs ref:http://serverfault.com/questions/354403/remove-path-from-find-command-output
    #
    SAVED_LIST=($(find . -type f -name "*.wpa" -printf '%f\n'))

    #
    # restore ifs
    #
    IFS=$OLDIFS


    #
    # Tests for number of saved wifi connections, if none exit
    #
    if [ -z "${SAVED_LIST[0]}" ]; then
        printf "There are no previous saved wifi connections\n\n"
        #
        # Create new connection
        #
        conf_create
    fi

    #
    #PS3 Sets the prompt for the select statement below
    #
    PS3="Choose a previously saved wifi connection or 's' to skip: "

#
#Select one of the previous saved configurations to connect with or quit
#
select ITEM in "${SAVED_LIST[@]}"; do
    #
    # Quit if selected number does not exist or alpha in entered
    #
    if [ -z "$ITEM" ] ; then
            printf "Skipping\n"
            conf_create
    fi

    printf "$ITEM is selected\n"
    cat "$ITEM">/etc/wpa_supplicant.conf | xargs
    connect "$ITEM"
done
}

function conf_create (){
    #
    # Scans for wifi connections & isolates wifi AP name
    #
    eval LIST=( $(sudo iwlist $INT scan 2>/dev/null | awk -F":" '/ESSID/{print $2}') )

    #
    #PS3 Sets the prompt for the select statement below
    #
    PS3="Choose wifi connection or 'q' to quit: "

    #
    # Tests for number of wifi connections, exits if none
    #
        if [ -z "${LIST[0]}" ]; then
            printf "No available wifi connection using $INT\n"
            exit
        fi

    #
    # Select from a LIST of scanned connections
    #
    select ITEM in "${LIST[@]}"; do
    ifconfig $INT | grep inet

        #
        # Quit if selected number does not exist or alpha in entered
        #
        if [ -z "$ITEM" ] ; then
                printf "Exiting\n"
                exit
        fi

        #
        # Get user input for passphrase no need to escape spaces
        #
        printf "Enter the passphrase for $ITEM?\n"
        read "PASSPHRASE"

        #
        # Append the ITEM variable (ESSID) to .wpa to make a filename for saved configs
        #
        FILENAME=$ITEM".wpa"

        #
        # Run wpa_passphrase to generate a file for wpa_supplicant to use, store it locally and in etc/wpa_supplicant.conf
        #
        printf "Running wpa_passphrase\n"
        wpa_passphrase "$ITEM" "$PASSPHRASE" > "$FILENAME" | xargs
        cat "$FILENAME">/etc/wpa_supplicant.conf | xargs
        printf "Creating new configuration using $ITEM\n"

        #
        # Jump to connect function, pass on the ESSID variable for connection
        #
        connect $ITEM
    done
}

function connect (){
    printf "Connecting using file $*\n"

    #
    # Capture incoming argument
    #
    ESSID=$*

    #
    # Kill previous instances of wpa_supplicant to stop other instances wpa_supplicant fighting several different AP's
    # Kill based on ref: http://thegeekstuff.com/2011/10/grep-or-and-not-operators/ and  http://stackoverflow.com/questions/3510673/find-and-kill-a-process-in-one-line-using-bash-and-regex
    # Release dhcp ip's and bring down the interface
    #
    kill $(ps aux | grep -E '[w]pa_supplicant.*\'$INT'' |  awk '{print $2}') | xargs
    dhclient $INT -r
    ifconfig $INT down

    #
    # Assign new credentials to interface
    #
    iwconfig $INT mode managed essid "$ESSID"
    printf "Configured interface $INT; ESSID is $ESSID\n"
    ifconfig $INT up
    printf "Interface $INT is up\n"
    wpa_supplicant -B -Dwext -i$INT -c/etc/wpa_supplicant.conf 2>/dev/null | xargs
    printf "wpa_supplicant running, sleeping for 15...\n"

    #
    # Wait to connect before asking for a ip address
    #
    sleep 15
    printf "Running dhclient\n"
    dhclient $INT

    #
    # Show current ip for interface
    #
    ifconfig $INT | grep inet
exit
}

#
# Start here
#
read_saved

exit