Guys, after a while trying to find a solution without interfering in iptables as suggested @arunm8489 , I found a solution. The solution proposed by @manandharbishes is ok but we need one more step by changing /etc/default/tomcat8 From: #AUTHBIND=no to AUTHBIND=yes

In the comments of this file, they say:

If you run Tomcat on port numbers that are all higher than 1023, then you

do not need authbind. It is used for binding Tomcat to lower port numbers.

(yes/no, default: no)

For you guys, this is the script I followed:

    $ nano /etc/tomcat8/server.xml
 change the port from 8080 to 80	
$ touch /etc/authbind/byport/80
$ chmod 500 /etc/authbind/byport/80
$ nano /usr/share/tomcat8/bin/setenv.sh
 CATALINAOPTS=”-Djava.net.preferIPv4Stack=true”
$ nano /usr/share/tomcat8/bin/startup.sh
 exec authbind –deep “$PRGDIR”/”$EXECUTABLE” start “$@”
$ nano /etc/default/tomcat8
 AUTHBIND=yes  

Thats it!

This question was answered by @mpatidar:

It’s workable solution. Let the port 8080 by default in server.xml

Run : sudo /sbin/iptables -t nat -I PREROUTING -p tcp --dport 80 -j REDIRECT --to-port 8080

This redirect traffic from port 80 to 8080 (default in tomcat) in Ubuntu 14.04 it is not possible to set the default port to 80 in server.xml.

To make this persistent: sudo apt-get install iptables-persistent

This package allows you to save iptables rules previously entered. Be sure to answered yes (save the current settings)

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