Ubuntu為Tomcat啟用80埠
一、tomcat部署除錯

Update the package repository

sudo apt-get update  
sudo apt-get upgrade --show-upgrades 

Install the authbind package

sudo apt-get install authbind  

This package allows non-root users to bind to ports below 1024. Install the tomcat7 package

sudo apt-get install tomcat7  
 

The tomcat7-docs, tomcat7-examples,and tomcat7-admin packages aren’t required to deploy and maintain a web application. These packages can be skipped unless they are truly needed.

A new user “tomcat7” with primary group “tomcat7” will be created.

Enable authbind
Open a text editor like vim and load the default tomcat configuration file

vi /etc/default/tomcat7

Remove the comment hash “#” in front of the authbind property and set the value to “yes”

AUTHBIND=yes

Create authbind bind permission files for ports 80 and 443. Authbind will loop through the directory structure and try to find a byPort file referencing the port number attempting to be bound. Authorization will be granted if the user attempting to bind has execute permission.

touch /etc/authbind/byport/80  
touch /etc/authbind/byport/443  
chmod 0755 /etc/authbind/byport/80  
chmod 0755 /etc/authbind/byport/443  
chown tomcat7:tomcat7 /etc/authbind/byport/80  
chown tomcat7:tomcat7 /etc/authbind/byport/443  

Change the Tomcat Port from 8080/8443 to 80/443
Open a text editor like vim and load the server configuration file

vi /etc/tomcat7/server.xml 

Find the connector for port 8080 to port 80 and the redirect port from 8443 to 443:

<Connector port="80" protocol="HTTP/1.1"   
connectiontimeout="20000" uriencoding="UTF-8"   
redirectport="443">  
</Connector>  

Restart the Tomcat service

sudo service tomcat7 restart  

View the catalina.out log after restart and look for any errors. If you see permission denied errors, then you may have missed a step like:
Forgetting to uncomment the AuthBind setting and putting it to “yes”
Forgetting to restart the tomcat7 service as sudo

便捷方法：
什麼配置檔案不改，執行如下命令

iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to-port 8080

因為linux限制了1-1024埠的使用許可權，只有root使用者才可以訪問1024以下的埠號，所以不能用上面的方法實現，可以使用防火牆對映tomcat監聽的埠到80埠。