Notify WAN IP change

pschonmann · December 20, 2022, 10:29am

Hi, ive tried to script notification when IP change.
Im using it on my connection, 1 Public IP on WAN, nothing complicated like dualwan. Works fine for me.

Its necessary to add script into crontab
More info GitHub - pschonmann/turris-utils: Bunch of utils thats can be usefull for turris users.

Script itself

github.com

pschonmann/turris-utils/blob/main/notify_change_ip.sh

#!/bin/bash

NOW=$(date +%F_%T)

WORKING_DIR=/var/tmp/$(basename $0 .sh)

if [ ! -d $WORKING_DIR ];then
  mkdir -p $WORKING_DIR
fi

OLDIP_FILE=$WORKING_DIR/old.ip

if [ ! -f $OLDIP_FILE ];then
  NOWIP="CREATED_FILE_${OLDIP_FILE}_${NOW}"
  echo "$NOWIP" > $OLDIP_FILE
fi

OLDIP=$(cat $OLDIP_FILE)

NOWIP=$(dig +short myip.opendns.com @resolver1.opendns.com)

This file has been truncated. show original

Feel free to fork or improve the script.

freshdax · December 20, 2022, 5:13pm

Sounds interesting, great work!
Have implemented it, hope that is correct so far.

Copied the script as bash into the newly created folder:
/srv/custom_scripts/notify_change_ip.sh

and set the query in the crontab:
*/15 * * * /srv/custom_scripts/notify_change_ip.sh

Mail notification is turned on, but get the following message in the log:

Dec 20 16:45:01 turris crond[4948]: (root) CMD (/srv/custom_scripts/notify_change_ip.sh)
Dec 20 16:45:01 turris crond[4946]: (root) CMDOUT (/bin/sh: /srv/custom_scripts/notify_change_ip.sh: permission denied)
Dec 20 16:45:01 turris crond[4946]: (root) CMDEND (/srv/custom_scripts/notify_change_ip.sh)

Does the folder or script still need special permissions?

Many thanks already!
Best regards

hagrid · December 20, 2022, 5:27pm

Did you set the executable permission on that script?

freshdax · December 20, 2022, 5:31pm

currently Octal 0644 is set, so no execute.
Which owners should I give the right?

hagrid · December 20, 2022, 6:39pm

Up to your choice.
I would just mark it as being executable.

vcunat · December 20, 2022, 8:59pm

I don’t think you need to use cron for such things. There are hooks called on various network events: [OpenWrt Wiki] Hotplug

okias · December 26, 2022, 8:30pm

What about using mktemp for the working dir?