computer:2:know

ssh "backdoor" scripts

 #use case: linux system that is behind a firewall or dsl router >>  connects to a cloud server and opens up  a tunnel, so that someone

can access the system from the cloudserver 

#(access via ssh private / public key)

#

# - improvement when hostkey is changed at target host >> use option -o UserKnownHostsFile=/dev/null otherwise the portforwarding will get disabled if it detects a new host key!



#cron jobs

*/5 * * * * /root/bin/checkSSH2Outside.sh >>/var/log/checkSSH2Outside.log

1 23 1 * * gzip -f /var/log/checkSSH2Outside.log >/dev/null

5 9,12,15,18,21,0 * * * /root/bin/killSSH.sh >/dev/null 2>/dev/null





#cat /root/bin/checkSSH2Outside.sh



#!/bin/bash



ts=`date`

num=`ps -ef |grep ssh |grep mydomain|grep 17000 |wc -l` >/dev/null

echo "$ts Number of found ssh processes = $num."



if [ $num -ge "1" ] ; then

  echo "$ts Processes to outside are already running."

else

  echo "$ts No processes found >> starting"

  ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -o ServerAliveInterval=300 -N -p 10022 -R 17000:localhost:22 user@mydomain.de

fi





#/root/bin/killSSH.sh

ps -ef |grep 17001 |grep ssh  |awk {'print $2'} |xargs -n 1 kill
Computer and IT knowledge - things to know

ssh "backdoor" scripts
