openmptcprouter-feeds/openmptcprouter/files/bin/omr-mtu

#!/bin/sh

PKT_SIZE=1472
INTERFACE="$1"
HOSTNAME="$2"

#count=$(ping -q -w 1 -M do -c 1 -s $PKT_SIZE -I $INTERFACE $HOSTNAME | grep -cE 'Message too long|100% packet loss')
#count=$(ping -B -w 1 -M do -c 1 -s $PKT_SIZE -I $INTERFACE $HOSTNAME 2>&1 | grep -c 'Message too long')
count=$(ping -B -w 2 -M do -c 3 -s $PKT_SIZE -I $INTERFACE $HOSTNAME 2>&1 | grep -cE 'Message too long|100% packet loss')

while [ $count -ge 1 ]; do
	PKT_SIZE=$((PKT_SIZE - 1))
	if [ "$PKT_SIZE" -lt "1252" ]; then 
		exit 0
	fi
	#count=$(ping -q -w 1 -M do -c 1 -s $PKT_SIZE -I $INTERFACE $HOSTNAME | grep -cE 'Message too long|100% packet loss')
	#count=$(ping -B -w 1 -M do -c 1 -s $PKT_SIZE -I $INTERFACE $HOSTNAME 2>&1 | grep -c 'Message too long')
	count=$(ping -B -w 2 -M do -c 3 -s $PKT_SIZE -I $INTERFACE $HOSTNAME 2>&1 | grep -cE 'Message too long|100% packet loss')
done

printf "$((PKT_SIZE + 28))"