Creating ipip tunnels in RedHat 8 that is compatible with LVS/TUN.

Every few seasons I built a virtual LVS (Linux Virtual Server) mock up just to keep in shape.  LVS-TUN (lvs/tunnel mode) ipip configuration for RH8 had me stumped for a while.  

There was a change from RH7 to RH8 in that network scripts are being deprecated.  So, /etc/sysconfig/ network scripts behave just a bit different.  For one thing I could not build a reliable ipip tunnel interface in RH8 even after installing and using traditional RH-style network scripts.  

After a lot of difficult tests I am posting the solution for keeping up an ipip tunnel interface for RH8.  Here it is:

# In this example 192.168.131.239 is the RIP (Real Server IP) IP address, 

# 192.168.131.235 is the VIP address.

nmcli con add type ip-tunnel ip-tunnel.mode ipip con-name tun0

          ifname tun0 remote 0.0.0.0 local 192.168.131.239

nmcli con mod tun0 ipv4.addresses 192.168.131.235

nmcli con mod tun0 ipv4.method manual

nmcli con up tun0

The key thing to remember is that the remote ip should be 0.0.0.0.    In RH7 you could use an ipip for LVS-TUN without specifying remote and local IP's.  

If this helps somebody out there with a similar problem, please let me know by replying to this blog.

Raspberry pi simple fan control script

Here is a simple fan control script that I made to turn on and off a raspberry pi fan.  It turns on a fan when the temp reaches a threshold (in this case, 60 degrees).  

#!/bin/bash

#

# Wed Feb 17 19:14:54 EST 2021 JondZ very simple fan controller

GPIO_PIN=4

GPIO_NAME=gpio${GPIO_PIN}

GPIO_PATH=/sys/class/gpio/$GPIO_NAME/value

TEMP_THRESHOLD=60000

TEMP_SOURCE_FILE=/sys/class/thermal/thermal_zone0/temp

# 600: 10 minutes

# 900: 15 minutes

# 1800: 30 minutes

SLEEP_TIME=600

SLEEP_POLL=10

function get_temp {

         if [[ -e $TEMP_SOURCE_FILE ]] ; then

            cat $TEMP_SOURCE_FILE

         fi

         }

function init_ports {

         if [[ ! -e /sys/class/gpio/$GPIO_NAME ]]; then

            echo $GPIO_PIN > /sys/class/gpio/export && \

            sleep 5 && \

            echo out > /sys/class/gpio/$GPIO_NAME/direction

         fi

         }

init_ports

function turn_on_fan {

         temp=$(get_temp)

         if [[ -e $GPIO_PATH ]]; then

            echo "$(date) fan on ($temp)"

            v=$(< $GPIO_PATH )

            if [[ $v == 0 ]]; then

               echo 1 > $GPIO_PATH

            fi

         fi

         }

function turn_off_fan {

         temp=$(get_temp)

         if [[ -e $GPIO_PATH ]]; then

            v=$(< $GPIO_PATH )

            if [[ $v == 1 ]]; then

               echo "$(date) fan off ($temp)"

               echo 0 > $GPIO_PATH

            fi

         fi

         }

while :

   do

   CT=$(get_temp)

   if [[ $TEMP_THRESHOLD -lt $CT ]]; then

      turn_on_fan

      sleep $SLEEP_TIME

   else

      turn_off_fan

   fi

   sleep $SLEEP_POLL

   done

 

Here is the systemd script:

[Unit]
Description=Simple Fan Controller
DefaultDependencies=no
After=sysinit.target

[Service]
Type=simple
ExecStart=/root/scriptsd/system-fan-control.sh

[Install]
WantedBy=graphical.target multi-user.target

As far as I can see it is working fine.

Here is a picture of the circuit that i soldered.  I copied the circuit from some other site on the web.   This comprises of a resistor, a transistor, and a diode.

Here is what the fan circuit looks like on my setup.  The case is already crowded with an OLED display and an RTC clock:

There may be minor bugs.  I was tired from soldering so I only did the coding in a few minutes' rush so comments are welcome...

EP 20210217