How to change tomcat 8 port

I am trying to change the Tomcat's port to 80 in Ubuntu 14.04 through this configuration [conf/server.xml]:

<Connector port="8080" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" />

to:

<Connector port="80" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" />

And I am receiving this error:

13-Oct-2015 18:09:10.626 SEVERE [main] org.apache.coyote.AbstractProtocol.init Failed to initialize end point associated with ProtocolHandler ["http-nio-80"] java.net.SocketException: Permission denied

What I am doing wrong? Or what is missing?

Thanks...

2 Answers

To run Tomcat on a port below 1024 in Ubuntu/Unix, the service needs root privileges. And that you do not want.

Use a port redirection via iptables

iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 8080

Start tomcat services using authbind this will allow user to start ports less than 1024 we do not need to redirect or iptables.

sudo apt-get install authbind -y

To install Authbind software

sudo chmod -R 755 /etc/authbind

group should be user group.

sudo chown -Rh root:group /etc/authbind

After that run the below commands

cd /etc/authbind/byuid

As an example lets imagne user id is 2000 you can use your user id number

sudo echo '0.0.0.0/0:1,1023' > 2000

That file should be own by user and group.

sudo chown : 2000

sudo chmod 700 2000

Add the below line in tomcat startup file $CATALINA_BASE/startup.sh

export JAVA_OPTS="$JAVA_OPTS -Djava.net.preferIPv4Stack=true"

For Starting tomcat using Authbind service startup.sh

Comment the below line

#$CATALINA_HOME/bin/startup.sh

Add This End as the end of the file

AUTHBIND_COMMAND="/usr/bin/authbind --deep /bin/bash -c "
$AUTHBIND_COMMAND $CATALINA_HOME/bin/startup.sh 

now you should be able to start tomcat services as user with less that 1024 ports.