Unable to access Jenkins server

EDIT 2

If running Jenkins on an Amazon EC2 instance, try setting HTTP_HOST to 0.0.0.0. You may not be able to bind the public interface IP directly.

EDIT 1

Check /etc/default/jenkins instead if you installed directly from the .deb package.

It appears Jenkins is listening on localhost (--httpListenAddress=127.0.0.1). In this configuration, Jenkins is not listening for connections from the network interface.

To resolve for Ubuntu, check the contents of /etc/init/jenkins.conf and append --httpListenAddress=x.x.x.x to JENKINS_ARGS (where x.x.x.x is the server's external IP address).