Maximum MTU check script - Call with target address as first argument

mtu_check.sh

#!/bin/bash
# Check your maximum MTU size with the help of ping

if [ -z "$1" ]
  then
    echo "Using 1.1.1.1 as default target, provide your own as argument"
    HOSTNAME="1.1.1.1"
  else
    HOSTNAME=$1
fi
 

PKT_SIZE=1500
 
ping -M do -c 1 -W 1 -s $PKT_SIZE $HOSTNAME > /dev/null
r=$?
#echo $r

while [ $r -eq 1 ]; do
 PKT_SIZE=$(($PKT_SIZE - 10))
 echo "Testing MTU:" $PKT_SIZE
 ping -M do -c 1 -W 1 -s $PKT_SIZE $HOSTNAME > /dev/null
 r=$?
 #echo $r
done

printf "Your Maximum MTU is [ $((PKT_SIZE + 28)) ] \n"