Block all traffic to 27017

gistfile1.txt

iptables -I INPUT -p tcp -s 0.0.0.0/0 --dport 27017 -j DROP
iptables -I INPUT -p tcp -s 127.0.0.1 --dport 27017 -j ACCEPT
iptables -I INPUT -p tcp -s <IP GOES HERE> --dport 27017 -j ACCEPT

iptables-save > /etc/iptables.conf # Save this changes to file
touch /etc/network/if-up.d/iptables # Create file to call conf from
echo "iptables-restore < /etc/iptables.conf" >> /etc/network/if-up.d/iptables # Add this line to this file
chmod +x /etc/network/if-up.d/iptables  # Make the script executable