wget -q -O - http://www.whatismyipaddress.com   | \
grep "Your IP address is"                       | \
sed 's@.*address is \([^<]\+\).*@\1@'

 traceroute google.be

#!/bin/bash

# ======================================================================
# /home/user/cvsroot/src/utilities/external_ip/external_ip.bash,v
# ======================================================================
# Description:
#   This script sends an email to an external email service to notify
# users when this machine's external IP address changes. The IP address
# is read from the local router connected to the ISP. The router's
# administrator status page lists the external IP address.
#
# The general flow of the script is:
#   1. Retrieve the last known IP address (stored in a file)
#   2. Use wget to read the router's status page
#   3. Grep the router's status page for the IP address
#   4. Send an email to an external email address if the last IP
#      address differs from the current one.
#
# The script should run regularly--through cron or an equivalent.
# ======================================================================


# ======================================================================
# Variables to customize the script's operation
#
# Perhaps some of these should be supported by command line arguments
# ======================================================================

WGET=/usr/bin/wget
EGREP=/bin/egrep
ECHO=/bin/echo
RM=/bin/rm
MKDIR=/bin/mkdir
MUTT=/pkgs/inst/mutt/bin/mutt
MAC2UNIX=/pkgs/inst/mac2unix/bin/mac2unix
DATE=/bin/date
CAT=/bin/cat
DIRNAME=/usr/bin/dirname

# Customize these variables
ROUTER_IP_ADDRESS=???.???.???.???
PAGE_NAME=???
TEMP_DIR=???
USERNAME=???
PASSWORD=???
DATA_FILE=???
EMAIL_ADDRESS=???

# ======================================================================
# Start of the script.
#   1. Retrieve the last known IP address (stored in a file)
#
# If the data file does not exist, use a default value to guarantee a 
# mismatch with the new IP address
# ======================================================================
if [ -e ${DATA_FILE} ] ; then
  LAST_IP_ADDRESS=$( ${CAT} ${DATA_FILE} )
else
  LAST_IP_ADDRESS=xxx.xxx.xxx.xxx
fi


# ======================================================================
# Create a temporary directory to put files as they're created.
#
# Use a self-contained directory for easy cleanup at the end of the
# script.
#
# Assume this script is the only thing using the temp directory. Delete
# any prior copy of the temp directory and make a new one.
# -- The directory might exist if a previous run were interrupted or
#    killed during execution.
# ======================================================================
if [ -d "${TEMP_DIR}" ] ; then
  ${RM} -rf "${TEMP_DIR}"
fi

${MKDIR} -p "${TEMP_DIR}"

# ======================================================================
# Next major section of the script
#   2. Use wget to read the router's status page
#
# This is unique for my setup. To get the router's status page, my
# router requires an administrator login. The router denies access on
# the first attempt--don't know why. An immediate, subsequent attempt
# with the same credentials succeeds.
#
# To accomodate the router, the script uses a loop. It repeatedly
# requests the same page with the same credentials until the script
# reaches a maximum number of retries, or succeeds.
#
# Also, the router's statuts page is returned with Mac line endings.
# The line endings must be converted to Unix line endings or grep will
# not give good results.
# ======================================================================
wget_counter=0
wget_success=0
while [ \( ${wget_counter} -lt 10 \) -a \( ${wget_success} -ne 1 \) ] ; do
  ${WGET} --quiet                          \
          --http-user=${USERNAME}          \
          --http-passwd=${PASSWORD}        \
          --directory-prefix="${TEMP_DIR}" \
          "http://${ROUTER_IP_ADDRESS}/${PAGE_NAME}"
  wget_result=$?
  if [ ${wget_result} -ne 0 ] ; then
    let wget_counter=wget_counter+1
  else
    wget_success=1
  fi
done

# If wget_counter is equal to the maximum number of retries, then
# quit; we don't have a page to grep against.
if [ ${wget_counter} -eq 10 ] ; then
  exit 1
fi

${MAC2UNIX} "${TEMP_DIR}/${PAGE_NAME}"

# ======================================================================
# Next major section of the script
#   3. Grep the router's status page for the IP address
#
# At this point, the status page is available. Extract the new IP
# address from the page.
#
# My router returns a page with the external IP address is on a line
# of its own. In addition, the line with the external IP address is the
# only line that starts with a numeric digit.
# ======================================================================
new_ip_address=$( ${EGREP} "^[0-9]" "${TEMP_DIR}/${PAGE_NAME}" )

# ======================================================================
# Next major section of the script
#   4. Send an email to an external email address if the last IP
#      address differs from the current one.
#
# At this point, the current IP address is available. Compare it
# against the old IP address. If the IP addresses are different, send a
# notification email with the current IP address. If the IP addresses
# are the same, do nothing.
#
# Do not update the IP address stored in the data file if the command
# to email user(s) fails. This guarantees the stored IP address will
# differ from the current IP address the next time the script is run--
# causing another email attempt to notify the user(s).
# ======================================================================
if [ ${new_ip_address} != ${LAST_IP_ADDRESS} ] ; then
  ${ECHO} "New IP address detected at $( ${DATE} )" | \
  ${MUTT} -s "New Router IP address: ${new_ip_address}" ${EMAIL_ADDRESS}

  mail_success=$?
  if [ ${mail_success} -eq 0 ] ; then
    if [ -e ${DATA_FILE} ] ; then
      ${ECHO} "${new_ip_address}" > ${DATA_FILE}
    else
      ${ECHO} "Error: No data file to store new IP address in!" >&2
    fi
  fi
fi

# Cleanup the temporary workspace
${RM} -rf "${TEMP_DIR}"

exit 0

<?PHP
$ip = $_SERVER['REMOTE_ADDR'];
echo "Current IP Address: ", $ip;
?>

$ alias miip="wget http://checkip.dyndns.org/ -O - -o /dev/null | cut -d: -f 2 | cut -d\< -f 1"
$ miip