sSmtp send email with dynamic ip renew script

tojestzart · July 30, 2018, 12:37am

orginal author:

#!/bin/bash

check and send ip address to email

MYIP=ifconfig pppoe-wan | grep 'inet addr'| awk '{print $2}' | cut -d ':' -f 2;
TIME=date;

LASTIPFILE='/tmp/last_ip_addr';
LASTIP=cat ${LASTIPFILE};

if [[ ${MYIP} != ${LASTIP} ]]
then
echo "New IP = ${MYIP}"
echo "sending email.."
echo -e "Hello\n\nTimestamp = ${TIME}\nIP = ${MYIP}\n\nBye" |
/usr/bin/mail -s "[INFO] New IP" nick@some.somewhere;
echo ${MYIP} > ${LASTIPFILE};
else
echo "no IP change!"
fi

root@OpenWrt:~#

there are few problems with this script

file last_ip_addr must exist,
will be erased after reboot
cant be empy at 1st run of script
something else?

does anyone have more developed script, or any other easy way ?

stangri · July 30, 2018, 1:20am

Change LASTIPFILE='/tmp/last_ip_addr'; to LASTIPFILE='/etc/last_ip_addr';.

1 & 3 -- if you don't want to get notifications when LASIPFILE does not exist, change: if [[ ${MYIP} != ${LASTIP} ]] to if [[ -e "$LASTIPFILE" && ${MYIP} != ${LASTIP} ]].

PS. If it's crucial for you to know immediately when IP has changed, for Android there're apps like Join and NotifyMyAndroid which provide (shell one-liner) API for push notifications.

tojestzart · July 30, 2018, 1:50am

i just want to make this script working.

1 & 3 -- if you don't want to get notifications when LASIPFILE does not exist, change: if [[ ${MYIP} != ${LASTIP} ]] to if [[ -e "$LASTIPFILE" && ${MYIP} != ${LASTIP} ]].

i want to have notifications all the time, so if file doesnt exist, must be created .

actually i have some error:

sh: !=: argument expected
no IP change!

storage under /etc/ doesnt damage in long time flash?

stangri · July 30, 2018, 3:17am

If you want to have notifications "all the time", might as well keep the file in /tmp/. Also, then do if [[ "${MYIP}" != "${LASTIP}" ]]

tojestzart · July 30, 2018, 10:40pm

root@OpenWrt:~# cat /overlay/ip\ check.sh


#!/bin/bash
# check and send ip address to email

MYIP=`ifconfig pppoe-wan | grep 'inet addr'| awk '{print $2}' | cut -d ':' -f 2`;
TIME=`date`;

LASTIPFILE='/tmp/last_ip_addr';
LASTIP=`cat ${LASTIPFILE}`;

if [[ "${MYIP}" != "${LASTIP}" ]]
then
        echo "New IP = ${MYIP}"
        echo "sending email.."

        echo -e "Hello\n\nTimestamp = ${TIME}\nIP = ${MYIP}\n\nBye" | ssmtp -v name@o2.pl | \

        echo ${MYIP} > ${LASTIPFILE};

> else
        echo "no IP change!"
fi
root@OpenWrt:~#

and

*/50 * * * * sh /overlay/ip\ check.sh

i m almost happy with that, works but, sender is hidden and recipient is hidden

im total noob with coding can anyone code/syntax it properly? please

jeff · July 30, 2018, 11:31pm

You may need to incorporate them in the message -- ssmtp is not a full-featured mail-sending client.

There are a couple options on that man page that may help, such as:

-Ffullname
Set the full name of the sender.

-fname
Sets the name of the ''from'' person. This option is valid only if no From: line is specified within the header of the email.

but it's "easier" (the way I think about things) to include them in the message.

https://www.ietf.org/rfc/rfc2822.txt -- for the format of the message itself

It probably needs to be something like:

Subject: Your subject goes here
To: Destination <destination@example.com>
From: Sender <sender@example.com>

Body text goes here after a "blank" line
...

ralpho · July 31, 2018, 10:27am

Haven't tested it, but something like this should work with ssmtp:

#!/bin/sh
TO=recipient@gmail.com
FROM=sender@openwrt
HOSTNAME=$(cat /proc/sys/kernel/hostname)
MSG="$HOSTNAME IP change, please review"

MYIP=$(ifconfig pppoe-wan | grep 'inet addr'| awk '{print $2}' | cut -d ':' -f 2)
LASTIPFILE='/tmp/last_ip_addr'
LASTIP=cat ${LASTIPFILE}

mailto ()
{
 {
  echo To: "$TO"
  echo From: "$FROM"
  echo Subject: "$MSG"
  echo
  echo "New IP = $MYIP"
 } | ssmtp "$TO"
}

if [[ "${MYIP}" != "${LASTIP}" ]]; then
  mailto
fi

jeff · July 31, 2018, 2:01pm

@tojestzart "Welcome to the Dark Side"

Shell scripts can be written as many ways as there are authors, it seems. There is no one "right" (though a lot of ways that things don't work).

A couple things I've found helpful over the years:

sh isn't bash and many postings use "Bash-isms" that aren't supported with POSIX sh
quoting of strings can drive you nuts
Using variables with curly braces can makes things clearer ${LABEL}
"here documents" are one way to manage "long" variables or pipe input (one tutorial)
echo is fine for a single line of output, but printf is a lot more reliable and portable, especially if you need to do it without a newline; printf %s "${SOMESTRING}"

tojestzart · August 1, 2018, 11:14pm

@jeff [edited] @ralpho your beauty works perfectly but:

root@OpenWrt:~# /overlay/ip\ check
-ash: /overlay/ip check: Permission denied
root@OpenWrt:~# sh /overlay/ip\ check
/overlay/ip check: line 11: /tmp/last_ip_addr: not found
root@OpenWrt:~# touch /tmp/last_ip_addr
root@OpenWrt:~# sh /overlay/ip\ check
/overlay/ip check: line 11: /tmp/last_ip_addr: Permission denied
root@OpenWrt:~# sh /overlay/ip\ check
/overlay/ip check: line 11: /tmp/last_ip_addr: Permission denied
root@OpenWrt:~# chmod 777 /tmp/last_ip_addr
root@OpenWrt:~# sh /overlay/ip\ check
root@OpenWrt:~#

after reboot:
there last_ip_addr doesnt exist,
secondly if doesNT (how?), has no privleges.

thanks for you script btw, i need to move my mind personally

mbo2o · August 1, 2018, 11:53pm

# ls -l ip\ check 
-rw-r--r--    1 root     root           557 Aug  2 11:08 ip check
# chmod u+x ip\ check 
# ls -l ip\ check 
-rwxr--r--    1 root     root           557 Aug  2 11:08 ip check

Fixed issue with missing file and spamming

#!/bin/sh
TO=recipient@gmail.com
FROM=sender@openwrt
HOSTNAME=$(cat /proc/sys/kernel/hostname)
MSG="$HOSTNAME IP change, please review"

MYIP=$(ifconfig wlan0 | grep 'inet addr'| awk '{print $2}' | cut -d ':' -f 2)
LASTIPFILE='/tmp/last_ip_addr'
if [ ! -f "$LASTIPFILE" ]
then
    LASTIP="0.0.0.0"
else
    LASTIP=$(cat ${LASTIPFILE})
fi

mailto ()
{
 {
  echo To: "$TO"
  echo From: "$FROM"
  echo Subject: "$MSG"
  echo
  echo "New IP = $MYIP"
 } | ssmtp  "$TO"
}

if [[ "${MYIP}" != "${LASTIP}" ]]; then
  mailto
  echo -n "${MYIP}" > "${LASTIPFILE}"
fi

tojestzart · August 2, 2018, 1:49am

actually i created spambomb for myself which wasnt wanted

cron:

*/3 * * * * sh /overlay/ip\ check

send ip only if changes?

mbo2o · August 2, 2018, 2:04am

check my previous post for improved script

slh · August 2, 2018, 2:17am

Despite the danger of stating the obvious, you are aware of DDNS?

Both in terms of free-as-in-beer services and free-as-in-freedom example code?

tojestzart · August 2, 2018, 2:49am

@slh

seems to work? need more testing

slh hmm i dont honestly, i need to have access to router when ip changes,
i know what has been told before is sensitive and even might be/should be hidden,

i need to read more / communicate under our local forums, regards

system · August 9, 2018, 2:49am

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