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====== Backup Script ======

==== Goals ====

 \\

  - You want to schedule a backup done via a cron job. 
  - You want the script initiated from, and stored in a safe location  \\ on a server on the network, (not on the router).
  - You do not wish to install SFTP just for these backups.

 \\

The script at the bottom of this page will create and download the backup without needing to have SFTP enabled on the router.

We could, of course, create the backup as a cron job on the router itself, and then use the mechanism applied in the script below to download the backup file. However, let's assume you want everything done in just one run of the script. To achieve this, the script covers creation of the backup in an individual file with timestamp and download.

In this way, just one run of the script on the backup server will create the backup and download it to to a safe location.

Action is based on using a here doc to execute commands on the router.

 \\ \\ The backup is created using the "//nvram save//" command. This is how backups are done "under the hood" in the web interface.

You may cross-check that the backups are identical to the ones via the GUI using the following steps (last tested at 22.04.2025):

 \\

  - Download the backup via the graphical interface
  - Create a backup via a script
  - Copy both files to router
  - Convert both files via the command "//nvram convert// <filename1/2>  > result_file1/2.txt"
  - Perform a diff between the two resulting text files.

 \\

The script then archives the resulting data in a tar file and sends it through the netcat command, transferring it over the network.
Restore a backup file is the same procedure as resorting an archive created in the WEB-GUI (last testet 29.04.2025).

 \\


==== Prerequisites ====

 \\

  - The netcat command must be available on the backup server.
  - The router's root user must have access to the public SSH key of the user executing the script on backup server.

 \\

==== Remarks ====

 \\

  - Date covers from 1970 - in case Tomato Router has no time.
  - Sometimes tar fails - cover this error by just cleaning, next cron run may do it
  - All ealier backup from the same day are abandoned
  - A configurable number of backups in total is kept. Older ones are deleted.

 \\
   #!/bin/bash
   
   USER=root
   LOCAL_ID_FILE=/home/${LOGNAME}/.ssh/id_tomato_ecdsa
   PORT=5555
   BACKUP_DIR=/home/${LOGNAME}/Router_Backups
   SCRIPT_FILE=nvram_save_cfg.sh
   PREFIX=FreshTomato
   EXT=.cfg
   TRANSFER_FILENAME=config.tar
   
   # DATE_REGEX covers back to 1970 and further, in case Tomato Router has no date or date 1970-01-101
   # Total coverage: 1900-01-01 until 2999-12-31 :-)
   DATE_REGEX=[12][09][0-9][0-9][01][0-9][0123][0-9]_[012][0-9][0-5][0-9]
   
   NO_OF_DIFF_FILES_TO_BE_KEPT=10
      
   ROUTER=`ip r | grep default | head -1 | cut -d " " -f 3`
   BACKUPHOST=`ip r | grep default | head -1 | cut -d " " -f 9`
   
   pushd ${BACKUP_DIR}
   rm ${TRANSFER_FILENAME}
   
   (netcat -l -p ${PORT} > ${TRANSFER_FILENAME}) &
   #
   # Thinks like
   # VAR=`nvram get os_version`
   # seem not to work in bash via here doc, so write results into script file and source it
   # Further, the individual filename is generally not known, so tar it into temp file
   #
   ssh ${USER}@${ROUTER} -i ${LOCAL_ID_FILE}<<ENDSSH
           rm -f ${SCRIPT_FILE} ${TRANSFER_FILENAME} ${PREFIX}_*_${DATE_REGEX}${EXT}
           echo "nvram save ${PREFIX}" >> ${SCRIPT_FILE}
           nvram get os_version | sed -e "s/ .*$//" >> ${SCRIPT_FILE}
           echo "on" >> ${SCRIPT_FILE}
           nvram get t_model_name | tr " " "_" >> ${SCRIPT_FILE}
           nvram get router_name >> ${SCRIPT_FILE}
           date +%Y%m%d_%H%M >> ${SCRIPT_FILE}
           sed -e "N;N;N;N;N;s/\n/_/g;s/$/${EXT}/" -i ${SCRIPT_FILE}
           cat ${SCRIPT_FILE}
           source ${SCRIPT_FILE}
           tar -cvf ${TRANSFER_FILENAME} ${PREFIX}_*_${DATE_REGEX}${EXT}
           cat ${TRANSFER_FILENAME} | nc ${BACKUPHOST} ${PORT}
           sleep 5 # just wait a little bit before de
           leting the files not needed here any more
           rm -f ${SCRIPT_FILE} ${TRANSFER_FILENAME} ${PREFIX}_*_${DATE_REGEX}${EXT}
   ENDSSH
   
   THIS_BACKUP_FILE=`tar -tvf ${TRANSFER_FILENAME} | sed -e "s/^.*${PREFIX}/${PREFIX}/"`
   if [ "${THIS_BACKUP_FILE}" ]; then
        TODAYS_BACKUP_FILE=${THIS_BACKUP_FILE%_*}
        OLD_BACKUPS_OF_TODAY=`ls ${TTODAYS_BACKUP_FILEE}_[012][0-9][0-5][0-9]${EXT} 2> /dev/null`
        if [ "${OLD_BACKUPS_OF_TODAY}" ]; then
                echo "deleting today's earlier bakups (to keep just one per day):"
                rm -v ${OLD_BACKUPS_OF_TODAY}
        fi
        tar -xvf ${TRANSFER_FILENAME}
        DELETE_OLDER=`ls -t ${TODAYS_BACKUP_FILE%_*}_${DATE_REGEX}${EXT} | sed -e 1,${NO_OF_DIFF_FILES_TO_BE_KEPT}d`
        if [ "${DELETE_OLDER}" ]; then
                echo "keep only ${NO_OF_DIFF_FILES_TO_BE_KEPT} in total delete:"
                rm -fv ${DELETE_OLDER}
        fi
   else
        echo "unknown error while untaring"
   fi
   rm ${TRANSFER_FILENAME}
   popd

 \\

 \\
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