Jenkins by default allows everyone to see your jobs. Securing jenkins is pretty easy:
0) Add two arguments to JENKINS_ARGS in /etc/default/jenkins
This should be near the end of the file. Once changed, restart, jenkins.
1) Install https://wiki.jenkins-ci.org/display/JENKINS/Role+Strategy+Plugin
2) Enable the plugin by going to the secure area:
3) Restart Jenkins.
4) Under configuration settings http://YOURDOMAIN:PORT/manage
Click on Manage Roles (could have changed, basically anything with roles)
Add a new group called “Anonymous” and uncheck everything. Then you want to add another group called “authenticated” and check everything. Jenkins will immediately prompt you for a login this way.