Run Tomcat 9.0 on port 80 or 443 with Authbind (Ubuntu 18.0)

• Install authbind like so:
  sudo apt-get install authbind
• Configure access to both ports:
  sudo touch /etc/authbind/byport/80
  sudo touch /etc/authbind/byport/443
  sudo chmod 777 /etc/authbind/byport/80
  sudo chmod 777 /etc/authbind/byport/443
• Update <tomcat home>/conf/server.xml with port number in Connector element like so:

<Connector port="443" protocol="org.apache.coyote.http11.Http11NioProtocol" maxThreads="150" SSLEnabled="true">
    <SSLHostConfig sslProtocol="TLS">
            <Certificate certificateKeystoreFile="/usr/local/tomcat9/cert-openssl.p12"
                    certificateKeystorePassword="your password" type="RSA" />
    </SSLHostConfig>
</Connector>

• Open tomcat’s startup.sh and add
  authbind --deep
  in the last line..
  exec authbind --deep "$PRGDIR"/"$EXECUTABLE" start "$@"
• Go to your tomcat service file and make sure you are calling startup.sh instead of directly calling catalina.sh start
  Entire copy of tomcat.service file that is executed with systemctl is below
• systemctl daemon-reload, stop and restart tomcat.
  
  

[Unit]
Description=Tomcat Server
After=network.target

[Service]
Type=forking

Environment=JAVA_HOME=/usr/local/jdk-14
Environment=CATALINA_HOME=/usr/local/tomcat9
Environment=CATALINA_BASE=/usr/local/tomcat9
Environment=CATALINA_PID=/usr/local/tomcat9/temp/tomcat.pid

ExecStart=/usr/local/tomcat9/bin/startup.sh
ExecStop=/usr/local/tomcat9/bin/shutdown.sh

RestartSec=12
Restart=always

User=tomcat
Group=tomcat

[Install]
WantedBy=multi-user.target

One of the references for this article is : https://support.code42.com/CP/Admin/On-premises/6/Configuring/Install_a_CA-signed_SSL_certificate_for_HTTPS_console_access. Credit to that page.

Miscellaneous

To check what program is running on what port:

lsof -i

For specific port:

lsof -i:443

If no results run via sudo since your might have no permission to certain processes