Here are some quick tips on the UFW firewall
apt install ufw
enable or disable
ufw enable ufw disable
allow ssh
ufw app list ufw allow openSSH ufw limit openSSH
block all outgoing traffic and allow all
ufw default deny outgoing ufw default allow outgoing
allow access to only one ip in LAN
ufw allow out to 192.168.0.10 ufw allow in from 192.168.0.10
check settings
ufw status ufw status verbose
check settings with numbered & delete the particular number
ufw status numbered
ufw delete 2
allow traffic in and out on certain port
ufw allow 5900
allow traffic from 192.168.0.1 to 255
ufw allow from 192.168.0.0/24
ufw reset
open ssh