connect.sh

#!/bin/bash

# 12/06/2013
# 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/
#
# old version1  http://pastebin.com/Pa90HBiU  01/06/2013
#   very simple first version
# old version2  http://pastebin.com/FzJnv5Nk  02/06/2013
#   minor additions
# old version3  http://pastebin.com/3mu1XT5Y  08/06/2013
#   included ability to call up previous saved files from
#   command line.  Some checking of command line parameters and
#   checking for empty saved files
# current version
#   Added exit retrurn values
#
# Copy, Distribute and Modify Freely.
#


if [ -z "$1" ]; then
    printf "Usage: $0 -i [interface] OR AND -f [SAVED_FILE.wpa]\n"
    exit 1
fi

while getopts  "i:f:" opt
    do
        case $opt in
        i ) INT=${OPTARG};;
        f ) ITEM=${OPTARG};;
        \?) printf "Usage: $0 -i [interface] OR AND -f [SAVED_FILE.wpa]\n"
            exit 1;;
        * ) printf "Usage: $0 -i [interface] OR AND -f [SAVED_FILE.wpa]\n"
            exit 1;;
        esac
    done

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

#
# check if interface is entered as command line argument
#
if [ -z "$INT" ]; then
printf "Usage: $0 -i [interface] OR AND -f [SAVED_FILE.wpa]\n"
exit 1
fi


#
# Search for previous saved config files
#
function read_saved (){
    #
    # Search or uses for previous wpa configuration files
    # Checks if command line argument -f [SAVED_FILE.wpa] is greater than zero length and exists
    # before writing the configiuration to wpa_supplicant.conf.  Otherwise create a new
    # configuration.
    #
    if [ -n "$ITEM" ]; then
        if [ -s "$ITEM" ]; then
            printf "File $ITEM exists, proceeding to connect\n"
            write_conf $ITEM
        else    printf "File $ITEM is invalid or does not exist, proceeding to create a new configuration\n"
            conf_create
        fi
    fi
    #
    # Save and change IFS so spaces in file names are not interpreted as
    # separate lines in the array
    #
    OLDIFS=$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"
        #
        # 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\n"
            conf_create
    fi
    #
    # Quick check if file is greater than zero length and exists
    #
    if [ -s "$ITEM" ]; then
                        printf "File $ITEM exists, proceeding to connect\n"
                        write_conf "$ITEM"
                else    printf "File $ITEM is invalid or does not exist, proceeding to create a new configuration\n"
            conf_create
    fi
    done
}


function conf_create (){
    #
    # Scans for wifi connections & isolates wifi AP name
    #
    eval LIST=( $(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 1
        fi

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

        #
        # Quit if selected number does not exist or alpha in entered
        #
        if [ -z "$ITEM" ] ; then
                printf "Exiting\n"
                exit 0
        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" > "$FILENAME" | xargs
        #
        # Jump to write_conf function, append configuration filename
        # to ITEM varibale
        #
        ITEM="$FILENAME"
        write_conf
    done
}

function write_conf (){
    #
    # Copy local wpa_supplicant file to etc/wpa_supplicant.conf
    #
    printf "Writing new configuration file using $ITEM\n"
    cat "$ITEM">/etc/wpa_supplicant.conf | xargs
    #
    # Jump to connect function, pass on the ESSID variable for connection
    #
    connect "$ITEM"
}

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}') 2>/dev/null | xargs
    dhclient $INT -r
    ifconfig $INT down

    #
    # Assign new credentials to interface
    #
    iwconfig $INT mode managed essid "$ESSID"
    printf "Configured interface $INT; Credential file 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 0
}

function clean_slate (){
    #
    # Optional Clean Slate commands, it is recommended that you perform
    # a "airmon-ng check kill" to ensure that any other network managers
    # do not interfere with the connection process
    #

    printf "It is recommended that you perform a \"airmon-ng check kill\" once to ensure that any other network managers do not interfere with the connection process\n\n"

    #
    # Untested, airmon-ng check kill works better here
    #
    #   service network-manager stop 2>/dev/null >/dev/null
    #   service avahi-daemon stop 2>/dev/null >/dev/null
    #   sleep 10
    #   killall wpa_supplicant 2>/dev/null
    #   ifconfig $INT up
}

#
# Start here
#
clean_slate
read_saved

exit 0