Basic UFW setup

ufw.sh

# /etc/default/ufw
# ufw default deny outgoing
# ufw default deny incoming
DEFAULT_INPUT_POLICY="DROP"
DEFAULT_OUTPUT_POLICY="DROP"

# Consider /etc/ufw/before.rules etc
$ ufw allow out 22/tcp
$ ufw allow out 53/udp
$ ufw allow out 80/tcp
$ ufw allow out 443/tcp

# /etc/environment
# http_proxy="http://myproxy:1234"
# https_proxy="http://myproxy:1234"
$ ufw allow out proto tcp to 1.2.3.4 port 1234

# Attempt to block spotify connect
$ ufw deny proto tcp from any port 57621
$ ufw deny proto udp from any port 57621
$ ufw deny proto udp to any port 57621
$ ufw deny proto tcp to any port 57621
$ ufw deny proto tcp from any port 4070
$ ufw deny proto tcp to any port 4070

# verify
$ ufw reload
$ ufw status
Status: active

To                         Action      From
--                         ------      ----
57621/tcp                  DENY        Anywhere
57621/udp                  DENY        Anywhere
Anywhere                   DENY        57621/udp
Anywhere                   DENY        57621/tcp
Anywhere                   DENY        4070/tcp
4070/tcp                   DENY        Anywhere

80/tcp                     ALLOW OUT   Anywhere
22/tcp                     ALLOW OUT   Anywhere
53/udp                     ALLOW OUT   Anywhere
443/tcp                    ALLOW OUT   Anywhere
1.2.3.4 1234/tcp           ALLOW OUT   Anywhere