Limit ssh attempts to your ubuntu computer/server to 3 attempts every 5 minutes (4th dropped)

limitSSH.sh

# Source/Reference https://serverfault.com/questions/275669/ssh-sshd-how-do-i-set-max-login-attempts#275672

# Before enabling, be sure you 
# a) Know you're public ip address
# b) Know that your public ip address won't change (fixed ip)
# c) Have a backup method to get in just in case (Digital Ocean's "console" for example)

# sudp apt-get install ufw
# sudo ufw allow to any port 22 from your.ip.address.here proto tcp
# sudo ufw enable

# You can then fine-tune any ports to allow for public access or specific ip access

# An example for mongo administration from work
sudo ufw allow to any port 12017 from my.work.ip.address proto tcp

# I can now use the -h commands in mongo to directly access it from my work computer

# Check out UFW rules, theres rate limiting and a firewall is a good thing!
# https://help.ubuntu.com/community/UFW


# Below is what I previously had written until I learned UFW does rate limiting by default
# Keeping incase people would like it (I cannot confirm 100% the accuracy of it, as I personally no longer use it.)

# Forget iptables, just enable UFW above

iptables -A INPUT -p tcp --dport 22 -m state --state NEW -m recent --set --name SSH -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -m state --state NEW -m recent --update --seconds 300 --hitcount 4 --rttl  --name SSH -j DROP

# OR

iptables -I INPUT -p tcp --dport 22 -i eth0 -m state --state NEW -m recent --set
iptables -I INPUT -p tcp --dport 22 -i eth0 -m state --state NEW -m recent --update --seconds 60 --hitcount 4 -j DROP