#!/bin/sh # check_ip.sh # # Script designed to be run as a cron job. Each time this script runs, it: # # - Checks to see if the IP address of the host (as seen by the # Internet) has changed. # # - Updates the ip_history.tsv table if a change is detected. # # - Posts a HTML version back to the Internet (if a ${LDIR}/.ncftpput # config file is found). # # To make this script work: # # - Create a ${LDIR}/.ncftpput config file (if you want results posted # back to a web server). Don't forget to set the permissions to # 600. Contents of file will have three lines in the form: # # host MYFTPSERVER # user MYID # pass MYPASS # # - Optionally update the post_ip() function to construct the HTML # page the way you want. # # - Update the following environment variables to your liking: # # LDIR - Where to create local files after each check # FTP_DIR - Directory to FTP results to # TAG - Name to identify this system by (no spaces) # POST_ON_CHANGE - Set to true if you only want to post updates, set to false # to always post results (allows you to see time changes) LDIR="${PWD}" FTP_DIR=/web/info/ip NAME=home POST_ON_CHANGE=false # # You should NOT need to adjust these # CUR_IP_FILE="${LDIR}/current_ip.txt" LAST_IP_FILE="${LDIR}/last_ip.txt" IP_HISTORY_FILE="${LDIR}/ip_history.tsv" HTML_FILE="${LDIR}/${NAME}.html" NEED_POST=false # # Sets the environment variable TIME_STAMP to: # # yyyy-MM-dd HH:mm:ss # # Only does this one time (subsequent invocations are ignored) set_time_stamp() { if [ "$TIME_STAMP" = "" ]; then TIME_STAMP="$(date +'%Y-%m-%d %H:%M:%S')" fi } # # Get current IP of home LAN # # Returns 0 and updates ${CUR_IP_FILE} on success, returns 1 on failure get_ip() { if ( wget -O "${CUR_IP_FILE}" http://nst.sourceforge.net/nst/tools/ip.php > /dev/null 2>&1 ); then if ( grep '^[0-9]*.[0-9]*.[0-9]*.[0-9]*$' "${CUR_IP_FILE}" 2>&1 > /dev/null); then return 0 fi fi return 1 } # check_ip # # check for change in IP address (returns 0 if check was successful) check_ip() { set_time_stamp if ! ( get_ip ); then return 1; fi if [ -f "$LAST_IP_FILE" ]; then if ( diff "${LAST_IP_FILE}" "${CUR_IP_FILE}" > /dev/null 2>&1 ); then return 0; fi fi NEED_POST=true; cp "${CUR_IP_FILE}" "${LAST_IP_FILE}" if [ ! -f "${IP_HISTORY_FILE}" ]; then printf "IP\tDATE\n" > "${IP_HISTORY_FILE}" fi REMOTE_ADDR="$(cat "${CUR_IP_FILE}")" printf "${REMOTE_ADDR}\t${TIME_STAMP}\n" >> "${IP_HISTORY_FILE}" } # # Post information on-line # post_ip() { set_time_stamp cat > ${HTML_FILE} <Remote Access To: ${NAME}

Remote Access To: ${NAME}

As of ${TIME_STAMP} remote access can be found at ${REMOTE_ADDR}. Current services available include:

IP	Port	Description
${REMOTE_ADDR}	20022	Secure shell access to ${NAME}.

IP History

The following shows the history of IP address changes since we started running this script.

$(awk '-F\t' -- '{ if ( FNR == 1 ) printf("",$1,$2); else printf("",$1,$2); }' < ${IP_HISTORY_FILE})

%s	%s
%s	%s

EOF if [ -f "${LDIR}/.ncftpput" ]; then ncftpput -f ${LDIR}/.ncftpput ${FTP_DIR} ${HTML_FILE} >/dev/null 2>&1 fi } check_ip if [ "${POST_ON_CHANGE}" != "true" -o "${NEED_POST}" = "true" ]; then REMOTE_ADDR="$(cat "${CUR_IP_FILE}")" post_ip fi