Package Installation

sudo apt install ufw

Configure Rules

Allow Rules

sudo ufw allow <target-parameters>

e.g.

sudo ufw allow from <ip-address>

Deny Rules

sudo ufw deny <target-parameters>

e.g.

sudo ufw deny from <ip-address>

Add target specifications to rules

1. Allow/Block an IP address

    <allow/deny> from <ip-address>
   

2. Allow/Block a Subnet

    <allow/deny> from <subnet>/<subnet-mask>
   

   Note: <subnet-mask> based on the netmask. (subnet mask cheat sheet)

3. Allow/Block on a specific network interface (e.g. eth0)

    <allow/deny> in on <interface>
   

4. Allow/Block an Applicaton Profile
   • Check list of available application profiles:

       sudo ufw app list
     

   • Add a rule:

       <allow/deny> “<app>”
     

Delete a Rule

1. Delete a Rule by giving the whole rule

    sudo ufw delete <rule>
   

   e.g.

    sudo ufw delete allow from 203.0.113.101
   

2. Delete a Rule by Number

    sudo ufw status numbered
   

   e.g.

    labclub@bard:~ $ sudo ufw status numbered
    Status: active
   
        To                         Action      From
        --                         ------      ----
    [ 1] OpenSSH                    ALLOW IN    Anywhere                  
    [ 2] OpenSSH (v6)               ALLOW IN    Anywhere (v6)
   

   Make note of the number of the rule you are looking to delete, and:

    sudo ufw delete <#>
   

UFW Service

Enable

sudo ufw enable

Disable

sudo ufw disable

Check Status

sudo ufw status

Common Examples

SSH

sudo ufw allow OpenSSH

NGINX

sudo ufw allow "Nginx Full"

DNS Server

sudo ufw allow from 192.168.0.0/24 to any port 53 proto udp

sudo ufw allow from 192.168.0.0/24 to any port 53 proto tcp

DHCP Server

sudo ufw allow bootps comment 'DHCP Allow 67/UDP'

sudo ufw allow bootpc comment 'DHCP Allow 68/UDP'

Resources

• Digital Ocean