If your Jenkins instance runs on Tomcat and uses Atlassian Crowd as its user management system, you can provide your Jenkins users with Integrated Windows Authentication with the following add-on: https://marketplace.atlassian.com/plugins/com.cleito.iwaac

bruno_vincent, that is not really a solution. The plugin is $10 per user. That is expensive.
Tomcat itself can be configured to support Windows Authentication. How difficult would it be to tell Jenkins to use authentication context from tomcat?

Most but operate Jenkins with Jetty.

Ok, but Jetty can also be configured with SPNEGO http://www.eclipse.org/jetty/documentation/current/spnego-support.html .
How far is configuring SPNEGO in Jetty from getting implicit Windows Authentication in JENKINS ?

jcztery, price is always subjective but if you keep in mind that you can use the same plugin on all your Atlassian products (Jira, Confluence, Bamboo, Bitbucket, FishEye/Crucible) and custom web applications that use Crowd as their user management system, it's probably not that expensive. By the way, the add-on can be deployed on both Tomcat and Jetty.

bruno_vincent The price is prohibitive from my point of view. While our Jenkins is used locally by 10 people, JIRA and Confluence is used by around 2000. So we are looking at 4-5k to get this working. That is too much, that is why i do not consider it as a solution.
But thank you for mentioning it.
Since this is JENKINS JIRA, it would be good to understand what is involved in getting this to work without paid plugins. So that users like me could know the value provided by the paid plugins.

jcztery, FYI if your Jenkins is used by 10 people, then you would only need a 10 users license, which is 100$, not 4-5k. If you plan to install the plugin only on Jenkins then it has nothing to do with the number of Jira or Confluence users.

bruno_vincent, other teams occasionally connect to our Jenkins as well. BTW: what is your relationship to the aforementioned plugin?

jcztery The plugin has an option to restrict Integrated Windows Authentication to specific users, so in your case you could restrict the function to your own team of 10 people. I work for the vendor of this plugin. I understand that this might not be the right place to have a technical or functional discussion about the plugin so you might want to drop us a line at support@cleito.com if you have more questions.

Integrated Windows Authentication can be achieved using the following plugin: https://wiki.jenkins-ci.org/display/JENKINS/Negotiate+SSO+for+Windows