$ ping -c 1 -s $((1500-28)) -M do www.debian.org
PING www.debian.org (140.112.8.139) 1472(1500) bytes of data.
1480 bytes from linux3.cc.ntu.edu.tw (140.112.8.139): icmp_seq=1 ttl=47 time=52.7 ms

--- www.debian.org ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 52.778/52.778/52.778/0.000 ms
		

Try 1454 instead of 1500