setup reverse ssh tunnel with cron

autossh.sh

#!/bin/bash
#
# add the following job into crontab
# */5 * * * * /usr/local/bin/autossh.sh

IP="1.1.1.1"
/bin/ping -c 3 $IP > /dev/null

if [ $? != 0 ]
then
  exit 1
fi

#SSH_COMMAND="ssh -f -N -R 12322:localhost:22 -p 2222 [email protected]"
SSH_COMMAND="ssh -f -N -R 12322:localhost:22 -i $HOME/.ssh/id_rsa [email protected]"

cnt=$(ps -aux | grep -v "grep" | grep -c "$SSH_COMMAND")
if [[ $cnt < 1 ]]
then exec $SSH_COMMAND
fi

config

cat << EOF >> ~/.ssh/config
Host *
  ServerAliveInterval 30
  ServerAliveCountMax 5
EOF