Bashscripts.org

The script, lsnet, can be found here:
www20.brinkster.com/warranty/lsnet.txt

#!/bin/bash

# :: READ THE DESCRIPTION A FEW ROWS DOWN ::

# Copyright (c)2006 Johan Sjöberg
# kernelcfg@gmail.com
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# http://www.gnu.org/licenses/gpl.txt
#
# A copy of the GNU GPL may be obtained on the web at:
#
#   http://www.gnu.org/licenses/gpl.txt
#
# or by writing to:
#
#   Free Software Foundation, Inc.
#   59 Temple Place - Suite 330
#   Boston, MA 02111-1307, USA
#


#
# ===// DESCRIPTION //=========================================================
#
# Utility for displaying and selecting wireless networks.
# Written for archlinux but may be used by others. Users of other dhcp clients than
# dhcpcd might need to revisit and edit the dhcp function of this script.
# This script does not write or read any config files, so no backups necessary.
#
# Depends on 'wireless_tools','wpa_supplicant' and whatever network driver you are using.
#
# It assumes that your wireless networking is fully functional prior to executing this script.
# Any encrypted network must be configuered manually in i.e. wpa_supplicant.conf.
#
# If a network is encrypted, wpa_supplicant will automatically be run with $IWOPTS as
# argument. No other encryption program is nor will be supported.
#


# Your wlan interface
WLAN="eth1"

# Operating mode of the wireless device
MODE="managed"

# Path to your wpa_supplicant configuration file
WPA_CFG="/etc/wpa_supplicant.conf"

# Options to pass to wpa_supplicant
IWOPTS="-D wext"

# Name of the DHCP client. Leave blank to skip dhcp.
# Don't include a search path for the DHCP option
DHCP="dhcpcd"

# Set to no if you don't want to warn if wpa_supplicant is missing
WPA_WARN="yes"

# ===// End configurables //===================================================

# Color variables
BLUE="\e[1m\e[34m"
GREEN="\e[0;32m"
GREY="\e[0m\e[37m"
BRED="\e[1m\e[31m"
RED="\e[0;31m"
DEFAULT="\e[0m"
BS="\033[1m" #bold start
BE="\033[0m" #bold end


# Some checks to see if dependencies are a match
if [ "$(which ifconfig 2>/dev/null)" == "" ]; then
   echo "Depends on net-tools ( in archlinux: pacman -Sy net-tools )"
   exit;
fi

if [ "$(which iwconfig 2>/dev/null)" == "" ]; then
   echo "Depends on wireless_tools ( in archlinux: pacman -Sy wireless_tools )"
   exit
fi

if [ "$WPA_WARN" == "yes" ] && [ "$(which wpa_supplicant 2>/dev/null)" == "" ]; then
   echo -e "  \nYou need an encryption program to connect to encrypted networks. "
   echo -e "  The most common is wpa_supplicant which allows WPA encryption as explained below:\n"
   echo -e "  ${BS}WPA :: Wi-fi Protected Access :: ${BE}"
   echo -e "  \tA secure protocol enforcing up to 256 bits of encryption."
   echo -e "  ${BS}WEP :: Wired Equivalent Privacy ::${BE}"
   echo -e "  \tA less secure protocol with several security exploits\n"
   echo -e "  You may still connect to unencrypted networks. Set WPA_WARN=\"no\""
   echo -e "  in this file to disable this warning message\n\n"
fi

if [ "$DHCP" != "" ] && [ "$(which $DHCP 2>/dev/null)" == "" ]; then
   echo "  DHCP client: $DHCP not found"
   echo "  Please configure the DHCP option in this file to match your DHCP client. "
   echo "  If you prefer to set your IP settings manually, please set DHCP=\"\" and"
   echo "  make sure your /etc/rc.conf looks somehting like this: (for archlinux users)"
   echo
   echo "      lo=\"lo 127.0.0.1\""
   echo "      eth1=\"eth0 321.321.321.3 netmask 255.255.255.0 broadcast 321.321.321..255\""
   echo "      INTERFACES=(lo eth1)"
   echo "      gateway=\"default gw 123.123.123.1\""
   echo "      ROUTES=(gateway)"
   echo
   echo "  In this example eth1 is your wireless interface. "; echo
   exit
fi

function getData(){
   list=`/usr/sbin/iwlist ${WLAN} scan | grep -e '\(Quality\|ESSID\|Chan\|Encryption\)'`

   # Insert all essential network values into categorized arrays
   IFS=$'\n'
   ESSID=(`awk -F ':' '/ESSID/ {print $2}' <<< "$list"`)
   IFS=$' \t\n' #Back to default
   CHAN=(`awk -F ':' '/ Channel:/ {print $2}' <<< "$list"`)
   ENCRYPTION=(`awk -F ':' '/Encryption/ {print $2}' <<< "$list"`)
   QUALITY=(`awk -F '=' '/Quality/ {print $2}' <<< "$list" | awk '{print $1}'`)


   # Display all available networks
   if [ "$1" != "suspend_output" ]; then
      echo -e "\n\n $BS Available networks: $BE"
      echo -e " ${BRED} --------------------------------------------- ${DEFAULT}"
      echo -e "${GREY}   note: \"-\" means unencrypted, \"x\" mean encrypted ${DEFAULT}\n"
   fi

   # Check if any networks were returned at all
   if [ "${CHAN[0]}" == "" ]; then
      echo -e "  \n${BS}No nearby accesspoints, try again later.${BE}\n"
      exit
   fi

   i=0
   for c in ${CHAN[@]}; do

      # A variant to display encryption
      if [ "${ENCRYPTION[$i]}" == "on" ]; then
         CRYPT[i]="x"
      else
         CRYPT[i]="-"
      fi   

      # List all networks
      if [ "$1" != "suspend_output" ]; then
         echo -e "${DEFAULT}    $BS ${i}. $BE Quality:\
         ${QUALITY[i]}  ${CRYPT[$i]}  Essid:${BLUE} ${ESSID[i]}"
      fi
      i=$[$i+1]
   done

   if [ "$1" != "suspend_output" ]; then
      echo -e "\n${DEFAULT}"
      echo " Run this script with root access for changes to take effect."
      echo -e "${RED} Select network: [0-9] or [q] to exit, [d] to disassociate ${DEFAULT}"
   fi
}

function dhcp(){
   # Check if dhcp is running
   pid=`pidof $DHCP`
   if [ "$pid" != "" ]; then
      kill $pid
      sleep 1
   fi

   # If dhcpcd is used, and pid is left over
   if [ -f /etc/dhcpcd/dhcpcd-$WLAN.pid ]; then
      rm -f /etc/dhcpc/dhcpcd-${WLAN}.{pid,cache} >/dev/null 2>&1
   fi

   printf "  $ Retrieving settings from dhcp ... "
   `/usr/sbin/$DHCP $WLAN`
   sleep 1
   IP="`ifconfig eth1 | grep "inet addr" | awk '{print $2}' | sed -e 's/addr://'`"
   if [ "$IP" != "" ]; then
      printf "${GREEN}done${DEFAULT}\n    IP-address: $IP\n"
   else
      printf "${RED}FAIL${DEFAULT}\n"
   fi
}


function wpa(){
   printf "  $ Network is encrypted, running wpa_supplicant ... "
   
   # If wpa_supplicant is already running, kill it
   pid=`pidof wpa_supplicant`
   if [ "$pid" != "" ]; then
      kill $pid
   fi

   /usr/sbin/wpa_supplicant -wB -i $WLAN -c ${WPA_CFG} ${IWOPTS} 2>/dev/null
   [ "$?" == "0" ] && printf "${GREEN}done${DEFAULT}\n"
   [ "$?" != "0" ] && printf "${RED}FAIL${DEFAULT}\n"
}


function usage(){
   echo "  Usage: lsnet [-h,-wpa,-a [u]]"
   echo "  Example usage: "
   echo "    lsnet -a    | associates with the strongest AP"
   echo "    lsnet -au   | associates with the strongest unencrypted AP"
   echo "    lsnet -wpa  | generate data for wpa_supplicant.conf"
}


# Associate with the AP
# Parameter: Index for array ESSID for the ESSID to set
function associate(){
   # Apply network settings
   printf "  $ Associating with ${BLUE}${ESSID[$1]}${DEFAULT} ... "
   essid=`sed -e 's/\"//g' <<< ${ESSID[$1]}`
   if [ "`id -u`" != "0" ]; then
      printf "FAIL\n"
      echo -e "  You must be ${RED}root${DEFAULT} for changes to take effect."
      exit
   fi

   /usr/sbin/iwconfig $WLAN essid "$essid" mode "$MODE" channel ${CHAN[$1]} 2>/dev/null
   tmp=$?
   sleep 1
   [ "$tmp" == "0" ] && printf "${GREEN}done${DEFAULT}\n"
   [ "$tmp" != "0" ] && printf "${RED}FAIL${DEFAULT}\n"

   printf "  $ Bringing interface $WLAN up ... "
   /sbin/ifconfig $WLAN up 2>/dev/null
   tmp=$?
   sleep 1
   [ "$tmp" == "0" ] && printf "${GREEN}done${DEFAULT}\n"
   [ "$tmp" != "0" ] && printf "${RED}FAIL${DEFAULT}\n"

      
   # If encrypted, run wpa_config
   if [ "${CRYPT[$1]}" == "x"  ]; then
      wpa
   fi


   # Get ip address from dhcp
   if [ "${DHCP}" != "" ]; then
      dhcp
   fi

   echo "  Network is now configuered"
   exit
}


# Connect to the strongest access point
# If script arguments are -au, associate with the strongest unencrypted AP.
# Otherwise associate with the strongest AP, encrypted or not.
function autoCon(){
   getData "suspend_output"
   strongest=-1
   strongest_i=-1

   # If param u is set, find the strongest unencrypted AP
   if [ "$1" == "-au" ]; then
      for ((i=0; i<=$(( ${#CRYPT[@]} - 1 )) ; i++)); do
         if [ "${CRYPT[$i]}" == "-" ]; then
            curr=`sed -e 's/\/.*//' <<< ${QUALITY[$i]}`
            if [ "$curr" -gt "$strongest"  ] ; then
               strongest=$curr
               strongest_i=$i
            fi
         fi
      done
      echo -e "\n  ${BS}Mode:${BE} Associate with the strongest un-encrypted Access Point (AP)"

      #Check if any unencrypted networks was found at all
      if [ "$strongest_i" = "-1" ]; then
         echo -e "  No unencrypted networks found. Please try again later.\n"
         exit
      fi

   # Else find the strongest AP, encrypted or not
   # getData already made sure there will be at least one network
   else
      for ((i=0; i<=$(( ${#QUALITY[@]} - 1 )) ; i++)); do
         curr=`sed -e 's/\/.*//' <<< ${QUALITY[$i]}`

         if [ "$curr" -gt "$strongest" ]; then
            strongest=$curr
            strongest_i=$i
         fi
      done
       echo -e "\n  Mode: Associate with the strongest Access Point (AP)"
   fi

   echo -e "  Selected Access Point:${BLUE} ${ESSID[$strongest_i]}  ${DEFAULT}\n"
   associate $strongest_i
}



function configWPA(){
   echo "  This will help you generate a configuration file for wpa_supplicant. "
   if [ "which wpa_supplicant 2>/dev/null" == "" ]; then
      echo "  wpa_supplicant not found on your system, exiting ..."
      exit
   fi
   echo
   echo "  Imagine the case where you will make a WPA connection to your own Access Point(AP) / router."
   echo -e "  Please supply the WPA passphrase that the AP uses (8..63 characters)\n"
   printf "  pass:\$ "
   read passphrase
   echo -e "  Type in the SSID that the AP is using\n"
   printf "  essid:\$ "
   read ssid
   entry=`wpa_passphrase $ssid $passphrase`
   echo -e "  Add this to your /etc/wpa_supplicant.conf file\n"
   echo "$entry"
   exit
}


# Code reminder to self: [[ "$1" != -[ha] ]]
# Check script parameters
case $1 in
   -h | --help )
      usage
      exit
      ;;
   -a | -au | --auto )
      autoCon $1
      exit
      ;;
   -wpa )
      configWPA
      ;;
      
   "" )
      getData
      ;;
   * )
      usage
      exit
      ;;
esac


# Select network and associate with that AP
while [ /bin/true ]; do
  read cmd
  case $cmd in
   [[:digit:]] )
      if [ "${CHAN[$cmd]}" != "" ]; then   
         associate $cmd
      fi
      echo "Number doesn't match any available network"
      break
      ;;
     d )
        echo "Disassociating with any accesspoints"
      iwconfig "$WLAN" essid "none"
      echo "Done"
      exit
      ;;
     q )
        echo "Exiting ..."
      exit 0
      ;;
     * )
        echo "Please input a number";;
  esac
done