Permissions in XNAT for accessing and manipulating data are governed through each user's account. A user must have a valid and enabled account in order to log in and work with data in XNAT.
An XNAT can be set to allow guest access to allow users to view and download public data without an account, such as in XNAT Central. By default, this setting is turned off, and must be enabled by an Administrator.
There are three ways in which a user account can be created:
In a standard XNAT installation, user accounts must be created by either the user themselves or by the site administrator. Users will be given the option of registering for an account when they first visit the site.
The User Registration form collects the necessary data for the creation of your account including First & Last Name, Email, and Username. Once you have registered for an account, your new account may need to be enabled by an administrator (depending on how the site is configured). Once an administrator has enabled your account, you will receive a Welcome email at the email address you entered on the registration page.
An existing project owner may wish to invite you to join XNAT with the purpose of granting you access to their project data. If they do so, you will receive an email from XNAT with a specially coded link called a Project Access Request. Clicking on that link will take you to a customized version of the account registration page, where you can either log in with an existing account, or create a new one.
By default, if you join XNAT with a project access request, XNAT is configured to allow you get access immediately without any additional Administrator approval required. (This setting may be different in your XNAT. See Administering Users.)
An XNAT Administrator has full capabilities of managing user access, including creating, enabling or disabling user accounts.
See: Administering Users
If your XNAT has been set up to use an LDAP server as an authentication method, you will be able to log in using a valid LDAP account, even if you have never registered an account in that XNAT before.
Having a valid user account in XNAT gives you access to the web application and its primary functions, but not keys to the kingdom. Access to any data in XNAT is governed on a project-by-project basis.
See: Understanding User Roles and Permissions
After creating your account, if you decide that you want to change your password or associate a different email address with your account, you can click on your username in the top navigation bar. After entering and confirming your new password or email address, simply click 'Submit' to change it.
For security reasons, you cannot change your username once it has been created.
For security reasons, each XNAT has a defined period of time in which a user session can remain active. You will see this reflected in the top navigation bar as an "Auto-Logout" countdown. The default time limit in XNAT is 15 minutes, but this can be changed in the Admin settings.
If the timer reaches 0:00, your session will automatically end and you will be redirected to the login page. However, any user activity involving a new page load – even a simple page refresh – will result in this counter being reset to the full time limit. Additionally, the user can click on the "Renew" link in the top navigation to renew the session without leaving or refreshing your current page.
After a certain period of time of inactivity (the default setting in XNAT is 1 year, though this can be changed), your account will go dormant. This means that this account must be re-enabled by an XNAT administrator. If you attempt to log in with a dormant account, you will receive a notice to this effect, with a link to send the XNAT administrator your request.