Ufw is for managing a Linux firewall and aims to provide an easy interface to iptables for the user. Install and configure ufw do this as root user or use sudo:

apt install ufw

Set default rules

ufw default deny incoming
ufw default allow outgoing

Allow connections

These commands both allow a connection on port 22 using the TCP protocol. Use one they end up in the same IPtables:

ufw allow ssh
ufw allow 22/tcp

ufw supports connection rate limiting, which is useful for protecting against brute-force login attacks:

ufw limit ssh/tcp

Allow traffic to a Webserver running on port 80 and port 443.  Ufw allows to specify a port and protocol e.g. 443/tcp or to specify a common service e.g. https:

ufw allow www
ufw allow 80/tcp
ufw allow http
ufw allow 443/tcp
ufw allow https

Allow port ranges in ufw:

ufw allow 1000:2000/tcp
ufw allow 1000:2000/udp

Allow connections from a specific IP address or address ranges:

ufw allow from
ufw allow from

By default, ufw will apply rules to all available interfaces. To limit this, specify DIRECTION on INTERFACE, where DIRECTION is one of in or out (interface aliases are not supported). For example, to allow all new incoming ssh connections on enps03, use:

ufw allow in on enps03 to port 22 proto tcp

Deny connections

Deny access to port 8080:

ufw deny 8080/tcp

Deleting rules

ufw delete allow ssh
ufw delete allow 80/tcp
ufw delete allow 1000:2000/tcp

or show a complete rule list and delete single entries:

# ufw status numbered
Status: active

     To                         Action      From
     --                         ------      ----
[ 1] 22/tcp                     ALLOW IN    Anywhere                  
[ 2] 80/tcp                     ALLOW IN    Anywhere                  
[ 3] 443/tcp                    ALLOW IN    Anywhere                  
[ 4] 22/tcp (v6)                ALLOW IN    Anywhere (v6)             
[ 5] 80/tcp (v6)                ALLOW IN    Anywhere (v6)             
[ 6] 443/tcp (v6)               ALLOW IN    Anywhere (v6)

# ufw delete [number]

Turn ufw on or off

Double check whether you created a rule for your ssh access!

ufw enable
ufw disable

Reset ufw

ufw reset

Logging in ufw

Logging levels are: off, low, medium, high, full

ufw logging LEVEL