#!/bin/bash
# inspired on this article
# https://www.linuxnet.ch/automatic-tunnels-with-xinetd-and-netcat/
# script is called from xinetd
# script starts and stops service using /etc/init.d scripts
SERVICE=/etc/init.d/lighttpd # script used to start/stop service
PORT=81 # port where end service should listen
PID_FILE=/var/run/lighttpd.pid # pid file generated by init script
REAPER_PID_FILE="/var/run/lighttpd_reaper.pid" # pid file generated by this script
REAPER_SLEEP=180 # The reaper sleeps in seconds and checks for idle conns
LOG=/var/log/syslog # where to log messages
# this function checks if we already have reaper
check_reaper(){
if [ -s $REAPER_PID_FILE ]
then
reaper_pid=`cat $REAPER_PID_FILE 2>/dev/null`
ps -p $reaper_pid &> /dev/null
if [ $? -ne 0 ]
then
start_reaper & # If we dontdon't have a reaper we start one
echo $! > $REAPER_PID_FILE
fi
else
start_reaper &
echo $! > $REAPER_PID_FILE
fi
}
# this function starts a reaper, which is a background process that will kill the end service if its inactive
start_reaper(){
while [ -f $PID_FILE ]
do
sleep $REAPER_SLEEP # We wait
touched=`stat --printf %W $REAPER_PID_FILE 2>/dev/null` # We check when the reaper PID was last touched
now=`date +%s 2>/dev/null`
let idle=$now-$touched
if [ $idle -gt $REAPER_SLEEP ] # If reaper pid has not been touched in more than a sleep cycle we stop the service
then
echo `date`" REAPER STOPPING SERVICE AFTER BEING $idle" >> $LOG
$SERVICE stop >> $LOG # This is the stop service instruction
rm $REAPER_PID_FILE
exit 0
fi
done
}
# This is where we start our service
start_service(){
sleep 1 # Added a delay to trouble shoot as browsers kickstart several connections, we need to allow the PID file to be created this can be improved.
if [ -s $PID_FILE ] # We check if the PID file for the end service exist to avoid calling the start script when the service has already been started
then
return
else
echo `date`" STARTING $SERVICE" >> $LOG
$SERVICE start &>> $LOG #this is the start service instruction
return
fi
}
# We probe and wait for the service to come on line
wait_for_service(){
nc -w30 -z 127.0.0.1 $PORT &>/dev/null # probe end port with a timeout of 30 seconds
if [[ $? -ne 0 ]]
then
echo `date`" XINET SERVICE START ON $PORT TIMED OUT" >> $LOG
fi
}
# This is were all the magic happens netcat passes traffic back and forth
transmit(){
nc -w30 127.0.0.1 $PORT 2>/dev/null # netcat is awesome, timeout flag of 30 seconds can be adjusted
}
# this is the main program that is called every time
main()
{
nc -z 127.0.0.1 $PORT &>/dev/null # We probe the end service
if [[ $? -ne 0 ]] # If its not responding
then
start_service # We start service
wait_for_service # We wait for service to became online
fi
check_reaper # We always check we have a reaper
touch $REAPER_PID_FILE # We log activity by touching the reaper PID file
transmit # We transmit data
exit 0
}
main
#!/bin/bash
# inspired on this article
# https://www.linuxnet.ch/automatic-tunnels-with-xinetd-and-netcat/
# script is called from xinetd
# script starts and stops service using /etc/init.d scripts
SERVICE=/etc/init.d/lighttpd # script used to start/stop service
PORT=81 # port where end service should listen
PID_FILE=/var/run/lighttpd.pid # pid file generated by init script
REAPER_PID_FILE="/var/run/lighttpd_reaper.pid" # pid file generated by this script
REAPER_SLEEP=180 # The reaper sleeps in seconds and checks for idle conns
LOG=/var/log/syslog # where to log messages
# this function checks if we already have reaper
check_reaper(){
if [ -s $REAPER_PID_FILE ]
then
reaper_pid=`cat $REAPER_PID_FILE 2>/dev/null`
ps -p $reaper_pid &> /dev/null
if [ $? -ne 0 ]
then
start_reaper & # If we dont have a reaper we start one
echo $! > $REAPER_PID_FILE
fi
else
start_reaper &
echo $! > $REAPER_PID_FILE
fi
}
# this function starts a reaper, which is a background process that will kill the end service if its inactive
start_reaper(){
while [ -f $PID_FILE ]
do
sleep $REAPER_SLEEP # We wait
touched=`stat --printf %W $REAPER_PID_FILE 2>/dev/null` # We check when the reaper PID was last touched
now=`date +%s 2>/dev/null`
let idle=$now-$touched
if [ $idle -gt $REAPER_SLEEP ] # If reaper pid has not been touched in more than a sleep cycle we stop the service
then
echo `date`" REAPER STOPPING SERVICE AFTER BEING $idle" >> $LOG
$SERVICE stop >> $LOG # This is the stop service instruction
rm $REAPER_PID_FILE
exit 0
fi
done
}
# This is where we start our service
start_service(){
sleep 1 # Added a delay to trouble shoot as browsers kickstart several connections, we need to allow the PID file to be created this can be improved.
if [ -s $PID_FILE ] # We check if the PID file for the end service exist to avoid calling the start script when the service has already been started
then
return
else
echo `date`" STARTING $SERVICE" >> $LOG
$SERVICE start &>> $LOG #this is the start service instruction
return
fi
}
# We probe and wait for the service to come on line
wait_for_service(){
nc -w30 -z 127.0.0.1 $PORT &>/dev/null # probe end port with a timeout of 30 seconds
if [[ $? -ne 0 ]]
then
echo `date`" XINET SERVICE START ON $PORT TIMED OUT" >> $LOG
fi
}
# This is were all the magic happens netcat passes traffic back and forth
transmit(){
nc -w30 127.0.0.1 $PORT 2>/dev/null # netcat is awesome, timeout flag of 30 seconds can be adjusted
}
# this is the main program that is called every time
main()
{
nc -z 127.0.0.1 $PORT &>/dev/null # We probe the end service
if [[ $? -ne 0 ]] # If its not responding
then
start_service # We start service
wait_for_service # We wait for service to became online
fi
check_reaper # We always check we have a reaper
touch $REAPER_PID_FILE # We log activity by touching the reaper PID file
transmit # We transmit data
exit 0
}
main
#!/bin/bash
# inspired on this article
# https://www.linuxnet.ch/automatic-tunnels-with-xinetd-and-netcat/
# script is called from xinetd
# script starts and stops service using /etc/init.d scripts
SERVICE=/etc/init.d/lighttpd # script used to start/stop service
PORT=81 # port where end service should listen
PID_FILE=/var/run/lighttpd.pid # pid file generated by init script
REAPER_PID_FILE="/var/run/lighttpd_reaper.pid" # pid file generated by this script
REAPER_SLEEP=180 # The reaper sleeps in seconds and checks for idle conns
LOG=/var/log/syslog # where to log messages
# this function checks if we already have reaper
check_reaper(){
if [ -s $REAPER_PID_FILE ]
then
reaper_pid=`cat $REAPER_PID_FILE 2>/dev/null`
ps -p $reaper_pid &> /dev/null
if [ $? -ne 0 ]
then
start_reaper & # If we don't have a reaper we start one
echo $! > $REAPER_PID_FILE
fi
else
start_reaper &
echo $! > $REAPER_PID_FILE
fi
}
# this function starts a reaper, which is a background process that will kill the end service if its inactive
start_reaper(){
while [ -f $PID_FILE ]
do
sleep $REAPER_SLEEP # We wait
touched=`stat --printf %W $REAPER_PID_FILE 2>/dev/null` # We check when the reaper PID was last touched
now=`date +%s 2>/dev/null`
let idle=$now-$touched
if [ $idle -gt $REAPER_SLEEP ] # If reaper pid has not been touched in more than a sleep cycle we stop the service
then
echo `date`" REAPER STOPPING SERVICE AFTER BEING $idle" >> $LOG
$SERVICE stop >> $LOG # This is the stop service instruction
rm $REAPER_PID_FILE
exit 0
fi
done
}
# This is where we start our service
start_service(){
sleep 1 # Added a delay to trouble shoot as browsers kickstart several connections, we need to allow the PID file to be created this can be improved.
if [ -s $PID_FILE ] # We check if the PID file for the end service exist to avoid calling the start script when the service has already been started
then
return
else
echo `date`" STARTING $SERVICE" >> $LOG
$SERVICE start &>> $LOG #this is the start service instruction
return
fi
}
# We probe and wait for the service to come on line
wait_for_service(){
nc -w30 -z 127.0.0.1 $PORT &>/dev/null # probe end port with a timeout of 30 seconds
if [[ $? -ne 0 ]]
then
echo `date`" XINET SERVICE START ON $PORT TIMED OUT" >> $LOG
fi
}
# This is were all the magic happens netcat passes traffic back and forth
transmit(){
nc -w30 127.0.0.1 $PORT 2>/dev/null # netcat is awesome, timeout flag of 30 seconds can be adjusted
}
# this is the main program that is called every time
main()
{
nc -z 127.0.0.1 $PORT &>/dev/null # We probe the end service
if [[ $? -ne 0 ]] # If its not responding
then
start_service # We start service
wait_for_service # We wait for service to became online
fi
check_reaper # We always check we have a reaper
touch $REAPER_PID_FILE # We log activity by touching the reaper PID file
transmit # We transmit data
exit 0
}
main
Doing it anyway
If you're absolutely sure you want to run it like this then take a look at this tutorial that shows exactly this scenario on a Raspberry Pi. The tutorial is titled: Starting mysqld and httpd on demand with xinetd.
This script was created, /etc/xinetd.init.d/lighttpd:
#!/bin/bash
# inspired on this article
# https://www.linuxnet.ch/automatic-tunnels-with-xinetd-and-netcat/
# script is called from xinetd
# script starts and stops service using /etc/init.d scripts
SERVICE=/etc/init.d/lighttpd # script used to start/stop service
PORT=81 # port where end service should listen
PID_FILE=/var/run/lighttpd.pid # pid file generated by init script
REAPER_PID_FILE="/var/run/lighttpd_reaper.pid" # pid file generated by this script
REAPER_SLEEP=180 # The reaper sleeps in seconds and checks for idle conns
LOG=/var/log/syslog # where to log messages
# this function checks if we already have reaper
check_reaper(){
if [ -s $REAPER_PID_FILE ]
then
reaper_pid=`cat $REAPER_PID_FILE 2>/dev/null`
ps -p $reaper_pid &> /dev/null
if [ $? -ne 0 ]
then
start_reaper & # If we dont have a reaper we start one
echo $! > $REAPER_PID_FILE
fi
else
start_reaper &
echo $! > $REAPER_PID_FILE
fi
}
# this function starts a reaper, which is a background process that will kill the end service if its inactive
start_reaper(){
while [ -f $PID_FILE ]
do
sleep $REAPER_SLEEP # We wait
touched=`stat --printf %W $REAPER_PID_FILE 2>/dev/null` # We check when the reaper PID was last touched
now=`date +%s 2>/dev/null`
let idle=$now-$touched
if [ $idle -gt $REAPER_SLEEP ] # If reaper pid has not been touched in more than a sleep cycle we stop the service
then
echo `date`" REAPER STOPPING SERVICE AFTER BEING $idle" >> $LOG
$SERVICE stop >> $LOG # This is the stop service instruction
rm $REAPER_PID_FILE
exit 0
fi
done
}
# This is where we start our service
start_service(){
sleep 1 # Added a delay to trouble shoot as browsers kickstart several connections, we need to allow the PID file to be created this can be improved.
if [ -s $PID_FILE ] # We check if the PID file for the end service exist to avoid calling the start script when the service has already been started
then
return
else
echo `date`" STARTING $SERVICE" >> $LOG
$SERVICE start &>> $LOG #this is the start service instruction
return
fi
}
# We probe and wait for the service to come on line
wait_for_service(){
nc -w30 -z 127.0.0.1 $PORT &>/dev/null # probe end port with a timeout of 30 seconds
if [[ $? -ne 0 ]]
then
echo `date`" XINET SERVICE START ON $PORT TIMED OUT" >> $LOG
fi
}
# This is were all the magic happens netcat passes traffic back and forth
transmit(){
nc -w30 127.0.0.1 $PORT 2>/dev/null # netcat is awesome, timeout flag of 30 seconds can be adjusted
}
# this is the main program that is called every time
main()
{
nc -z 127.0.0.1 $PORT &>/dev/null # We probe the end service
if [[ $? -ne 0 ]] # If its not responding
then
start_service # We start service
wait_for_service # We wait for service to became online
fi
check_reaper # We always check we have a reaper
touch $REAPER_PID_FILE # We log activity by touching the reaper PID file
transmit # We transmit data
exit 0
}
main
And the following xinetd service was created:
service http
{
disable = no
socket_type = stream
protocol = tcp
port = 80
server = /etc/xinetd.init.d/lighttpd
user = root
wait = no
}
Doing it anyway
If you're absolutely sure you want to run it like this then take a look at this tutorial that shows exactly this scenario on a Raspberry Pi. The tutorial is titled: Starting mysqld and httpd on demand with xinetd.
This script was created, /etc/xinetd.init.d/lighttpd:
#!/bin/bash
# inspired on this article
# https://www.linuxnet.ch/automatic-tunnels-with-xinetd-and-netcat/
# script is called from xinetd
# script starts and stops service using /etc/init.d scripts
SERVICE=/etc/init.d/lighttpd # script used to start/stop service
PORT=81 # port where end service should listen
PID_FILE=/var/run/lighttpd.pid # pid file generated by init script
REAPER_PID_FILE="/var/run/lighttpd_reaper.pid" # pid file generated by this script
REAPER_SLEEP=180 # The reaper sleeps in seconds and checks for idle conns
LOG=/var/log/syslog # where to log messages
# this function checks if we already have reaper
check_reaper(){
if [ -s $REAPER_PID_FILE ]
then
reaper_pid=`cat $REAPER_PID_FILE 2>/dev/null`
ps -p $reaper_pid &> /dev/null
if [ $? -ne 0 ]
then
start_reaper & # If we dont have a reaper we start one
echo $! > $REAPER_PID_FILE
fi
else
start_reaper &
echo $! > $REAPER_PID_FILE
fi
}
# this function starts a reaper, which is a background process that will kill the end service if its inactive
start_reaper(){
while [ -f $PID_FILE ]
do
sleep $REAPER_SLEEP # We wait
touched=`stat --printf %W $REAPER_PID_FILE 2>/dev/null` # We check when the reaper PID was last touched
now=`date +%s 2>/dev/null`
let idle=$now-$touched
if [ $idle -gt $REAPER_SLEEP ] # If reaper pid has not been touched in more than a sleep cycle we stop the service
then
echo `date`" REAPER STOPPING SERVICE AFTER BEING $idle" >> $LOG
$SERVICE stop >> $LOG # This is the stop service instruction
rm $REAPER_PID_FILE
exit 0
fi
done
}
# This is where we start our service
start_service(){
sleep 1 # Added a delay to trouble shoot as browsers kickstart several connections, we need to allow the PID file to be created this can be improved.
if [ -s $PID_FILE ] # We check if the PID file for the end service exist to avoid calling the start script when the service has already been started
then
return
else
echo `date`" STARTING $SERVICE" >> $LOG
$SERVICE start &>> $LOG #this is the start service instruction
return
fi
}
# We probe and wait for the service to come on line
wait_for_service(){
nc -w30 -z 127.0.0.1 $PORT &>/dev/null # probe end port with a timeout of 30 seconds
if [[ $? -ne 0 ]]
then
echo `date`" XINET SERVICE START ON $PORT TIMED OUT" >> $LOG
fi
}
# This is were all the magic happens netcat passes traffic back and forth
transmit(){
nc -w30 127.0.0.1 $PORT 2>/dev/null # netcat is awesome, timeout flag of 30 seconds can be adjusted
}
# this is the main program that is called every time
main()
{
nc -z 127.0.0.1 $PORT &>/dev/null # We probe the end service
if [[ $? -ne 0 ]] # If its not responding
then
start_service # We start service
wait_for_service # We wait for service to became online
fi
check_reaper # We always check we have a reaper
touch $REAPER_PID_FILE # We log activity by touching the reaper PID file
transmit # We transmit data
exit 0
}
main
And the following xinetd service was created:
service http
{
disable = no
socket_type = stream
protocol = tcp
port = 80
server = /etc/xinetd.init.d/lighttpd
user = root
wait = no
}
Do not do it this way, run lighttpd strictly as a daemon. The daemon xinetd is mean to start services that are not actually running all the time. When xinetd sees traffic it "spins up" a particular service to meet the need, but otherwise the processes are not running.
By the way, you cannot share a TCP port between 2 daemons/services. Only one service can bind to a particular TCP port, essentially owning it for the duration of the time that it's running.