User Authentication

Controlling who can access your site

Overview

Authentication, or "login", is the process by which a user lets Foswiki know who they are.

Authentication isn't just to do with access control. Foswiki uses authentication to keep track of who made changes, and manage a wide range of personal settings. With authentication enabled, users can personalise Foswiki and contribute as recognised individuals, instead of shadows.

Foswiki authentication is very flexible, and can either stand alone or integrate with existing authentication schemes. You can set up Foswiki to require authentication for every access, or only for changes. Authentication is also essential for access control.

Quick Authentication Test - Use the %USERINFO% macro to return your current identity:

Foswiki user authentication is split into four sections; password management, user mapping, user registration, and login management. Password management deals with how users personal data is stored. Registration deals with how new users are added to the wiki. Login management deals with how users log in.

Once a user is logged on, they can be remembered using a Client Session stored in a cookie in the browser (or by other less elegant means if the user has disabled cookies). This avoids them having to log on again and again.

Foswiki user authentication is configured through the Security Settings pane in the configure interface.

Please note FileAttachments are not protected by Foswiki User Authentication.

Password Management

As shipped, Foswiki supports the Apache 'htpasswd' password manager. This manager supports the use of .htpasswd files on the server. These files can be unique to Foswiki, or can be shared with other applications (such as an Apache webserver). A variety of password encodings are supported for flexibility when re-using existing files. See the descriptive comments in the Security Settings section of the configure interface for more details.

ALERT! Caution: Foswiki uses the .htpasswd file to also store the email addresses of registered users. If the .htpasswd file will be shared with another application, it is critical to preserve the email address stored as the last field in each line of the file.

You can easily plug in alternate password management modules to support interfaces to other third-party authentication databases.

The password manager is selected using the {PasswordManager} setting in configure.

User Mapping

Usually when you are using an external authentication method, you want to map from an unfriendly "login name" to a more friendly WikiName. Also, an external authentication database may well have user information you want to import to Foswiki, such as user groups.

By default, Foswiki supports mapping of usernames to wikinames, and supports Foswiki groups internal to Foswiki. If you want, you can plug in an alternate user mapping module to support import of groups etc.

The user mapping manager is selected using the {UserMappingManager} setting in configure.

User Registration

New user registration uses the password manager to set and change passwords and store email addresses. It is also responsible for the new user verification process. the registration process supports single user registration via the UserRegistration page, and bulk user registration via the BulkRegistration page (for admins only).

The registration process is also responsible for creating user topics, and setting up the mapping information used by the User Mapping support.

See Custom registration page for changing the user registration page.

Login Management

Login management controls the way users have to log in. There are three basic options; no login, login via a Foswiki login page, and login using the webserver authentication support. the login manager is selected using the {LoginManager} setting in configure.

No Login (select none)

Does exactly what it says on the tin. Forget about authentication to make your site completely public - anyone can browse and edit freely, in classic Wiki style. All visitors are given the WikiGuest default identity, so you can't track individual user activity.

ALERT! Note: This setup is not recommended on public websites for security reasons; anyone would be able to change system settings and perform tasks usually restricted to administrators.

Template Login (select Foswiki::LoginManager::TemplateLogin)

Template Login asks for a username and password in a web page, and processes them using whatever Password Manager you choose. Users can log in and log out. Client Sessions are used to remember users. Users can choose to have their session remembered so they will automatically be logged in the next time they start their browser.

Enabling Template Login

IDEA! By default, your Foswiki installation is probably already using TemplateLogin, HtPasswdUser and TopicUserMappingContrib as the default Login, Password and user mapping options.
  1. Using configure:
    1. Navigate to the Login tab on the Security and Authentication panel. Select the Foswiki::LoginManager::TemplateLogin login manager.
    2. Navigate to the Passwords tab. Select the appropriate PasswordManager for your system - the default is Foswiki::Users::HtPasswdUser.
      HELP There is also an EXPERT configure setting {TemplateLogin}{PreventBrowserRememberingPassword} that you can set to prevent Browsers from remembering username and passwords if you are concerned about public terminal usage.
  2. Verify that registration works by registering yourself with the System.UserRegistration topic. If there are problems, try these troubleshooting tips:
    1. Note: A standard Foswiki installation will not allow any new registrations unless there is a working SMTP configuration
    2. If your PasswordManager is HtPasswdUser (the default), check the .htpasswd file is being updated correctly with a new entry. If not, check {Htpasswd}{FileName} is correct (under Security and Authentication on the Password tab in configure), and that the webserver user has write permission.
  3. Create a new topic (in Sandbox web for example) to confirm that authentication works.
  4. Add users to the AdminGroup. Edit the AdminGroup topic in the Main web to include users that should have administrator status. Read defining adminstrator user(s) for more information.
    ALERT! This is a very important step, as users in this group can access all topics, independent of Foswiki access controls.

AccessControl has more information on setting up access controls.

ALERT! Foswiki AccessControls do not protect topic attachments unless the web server has been configured to do so using the viewfile script. Visit Foswiki:Support.ApacheConfigGenerator for examples using Apache.

TIP As Template Login uses a wiki page for its login prompt, there is a great deal of flexibility in customizing the login page for your purposes.

TIP The default new user template page is in System.NewUserTemplate. The same macros get expanded as in the template topics. You can create a custom new user topic by creating the NewUserTemplate topic in Main web, which will then override the default in System web. See UserForm for copy instructions.

Custom registration page

You can customize the default System.UserRegistration topic by first copying System.DefaultUserRegistration to UserRegistration in Main web. This will ensure that your changes will remain intact next time you upgrade.

A couple of common fields are hidden from normal view to make the registration page as lean as possible. You can unhide those fields on the page by removing EXCLUDED_ from the INCLUDE tags) or add new ones.

New fields may also be added. The name="" parameter of the <input> tags must start with: "Twk0..." (if this is an optional entry), or "Twk1..." (if this is a required entry). This ensures that the fields are carried over into the user home page correctly.

Enabling Apache Login

With Apache Login enabled, when Foswiki needs to authenticate the user, the standard HTTP authentication mechanism is used: the browser itself will prompt for a user name and password.

The advantage of this scheme is that if you have an existing website authentication scheme using Apache modules such as mod_auth_ldap or mod_auth_mysql you can just plug in to them directly.

The disadvantage is that because the user identity is cached in the browser, you can log in, but you can't log out again unless you restart the browser.

Foswiki maps the REMOTE_USER that was used to log in to the webserver to a WikiName using the table in WikiUsers?. This table is updated whenever a user registers, so users can choose not to register (in which case their webserver login name is used for their signature) or register (in which case that login name is mapped to their WikiName).

The same private .htpasswd file used in Foswiki Template Login can be used to authenticate Apache users, using the Apache Basic Authentication support.

ALERT! Do not use the Apache htpasswd program with .htpasswd files generated by Foswiki! htpasswd wipes out email addresses that Foswiki plants in the info fields of this file.

IDEA! Apache Login is required for Apache-based login methods such as mod_ldap

IDEA! You can use any Apache authentication module that sets the REMOTE_USER environment variable.

To setup Apache Login, perform the following steps:

  1. Configure Apache Login. Under the Security and Authentication pane on the Login tab in configure:
    1. Select Foswiki::LoginManager::ApacheLogin for {LoginManager}.
    2. Select Foswiki::Users::HtPasswdUser for {PasswordManager}.
    3. Select Foswiki::Users::TopicUserMapping for {UserMappingManager}.
    4. Save your settings.
    5. Configure your Apache settings for HTTP authentication. Use the Foswiki:Support.ApacheConfigGenerator tool or the foswiki/bin/.htaccess file to set the following Apache directives on the bin scripts:
       <FilesMatch "(attach|edit|manage|rename|save|upload|mail|logon|rest|.*auth).*">
       require valid-user
       </FilesMatch>
      You can also refer to the sample foswiki_httpd_conf.txt and bin/.htaccess.txt files to see how the appropriate Apache directives are specified.
  2. Verify that registration works by registering yourself with the System.UserRegistration topic. If there are problems, try these troubleshooting tips:
    1. Note: A standard Foswiki installation will not allow any new registrations unless there is a working SMTP configuration
    2. If your PasswordManager is HtPasswdUser (the default), check the .htpasswd file is being updated correctly with a new entry. If not, check {Htpasswd}{FileName} is correct (under Security and Authentication on the Password tab in configure), and that the webserver user has write permission.
  3. Create a new topic (in Sandbox web for example) to confirm that authentication works.
  4. Add users to the AdminGroup. Edit the AdminGroup topic in the Main web to include users that should have administrator status. Read defining adminstrator user(s) for more information.
    ALERT! This is a very important step, as users in this group can access all topics, independent of Foswiki access controls.

Logons via bin/logon

Any time a user requests a page that needs authentication, they will be forced to log on. It may be convenient to have a "logon" link as well, to give the system a chance to identify the user and retrieve their personal settings. It may be convenient to force them to log on.

The bin/logon script enables this. If you are using Apache Login, the bin/logon script must be setup in the bin/.htaccess file to be a script which requires a valid user. Once authenticated, it will redirect the user to the view URL for the page from which the logon script was linked.

Sessions

Foswiki uses the CPAN:CGI::Session and CPAN:CGI::Cookie modules to track sessions. These modules are de facto standards for session management among Perl programmers. If you can't use Cookies for any reason, CPAN:CGI::Session also supports session tracking using the client IP address.

You don't have to enable sessions to support logins in Foswiki. However it is strongly recommended. Foswiki needs some way to remember the fact that you logged in from a particular browser, and it uses sessions to do this. If you don;t enable sessions, Foswiki will try hard to remember you, but due to limitations in the browsers it may also forget you (and then suddenly remember you again later!). So for the best user experience, you should enable sessions.

There are a number of macros available that you can use to interrogate your current session. You can even add your own session variables to the Foswiki cookie. Session variables are referred to as "sticky" variables.

Getting, Setting, and Clearing Session Variables

You can get, set, and clear session variables from within Foswiki web pages or by using script parameters. This allows you to use the session as a personal "persistent memory space" that is not lost until the web browser is closed. Also note that if a session variable has the same name as a Foswiki preference, the session variables value takes precedence over the Foswiki preference. This allows for per-session preferences.

To make use of these features, use the tags:

%SESSION_VARIABLE{ "varName" }%
%SESSION_VARIABLE{ "varName" set="varValue" }%
%SESSION_VARIABLE{ "varName" clear="" }%

ALERT! Access controls cannot be modified in this way

Cookies and Transparent Session IDs

Foswiki normally uses cookies to store session information on a client computer. Cookies are a common way to pass session information from client to server. Foswiki cookies simply hold a unique session identifier that is used to look up a database of session information on the Foswiki server.

For a number of reasons, it may not be possible to use cookies. In this case, Foswiki has a fallback mechanism; it will automatically rewrite every internal URL it sees on pages being generated to one that also passes session information.

Username vs. Login Username

This section applies only if you are using authentication with existing login names (i.e. mapping from login names to WikiNames).

Foswiki internally manages two usernames: Login Username and Foswiki Username.

  • Login Username: When you login to the intranet, you use your existing login username. This name is normally passed to Foswiki by the REMOTE_USER environment variable, and used internally. Login Usernames are maintained by your system administrator.

  • Foswiki Username: Your name in WikiNotation, ex: JohnSmith, is recorded when you register using UserRegistration; doing so also generates a personal home page in the Main web.

Foswiki can automatically map an Intranet (Login) Username to a Foswiki Username if the {AllowLoginName} is enabled in configure. The default is to use your WikiName as a login name.

NOTE: To correctly enter a WikiName - your own or someone else's - be sure to include the Main web name in front of the Wiki username, followed by a period, and no spaces, for example Main.WikiUsername or %USERSWEB%.WikiUsername. This points WikiUsername to the Main web, where user home pages are located, no matter which web it's entered in. Without the web prefix, the name appears as a NewTopic? everywhere but in the Main web.

Changing Passwords

If your {PasswordManager} supports password changing, you can change and reset passwords using forms on regular pages.

If the {PasswordManager} does not support password changing, the ChangePassword and ResetPassword will show a simple message. This message is defined iby the setting CHANGEPASSWORDDISABLEDMESSAGE in DefaultPreferences. You can redefine this setting by copying it to SitePreferences and change it to include a link to the password management website of your organisation.

Changing E-mail Addresses

If the active {PasswordManager} supports storage and retrieval of user e-mail addresses, you can change your e-mail using a regular page. As shipped, this is true only for the Apache 'htpasswd' password manager.

If the {PasswordManager} does not support password changing, ChangeEmailAddress will guide the user to define the email address in the user topic.

Controlling access to individual scripts

You may want to add or remove scripts from the list of scripts that require authentication. The method for doing this is different for each of Template Login and Apache Login. TIP Any scripts listed as requiring authentication will not be usable by the Guest user. If you require that WikiGuest be allowed to edit topics on your site, edit and save must be removed from the list of scripts requiring authentication.
  • For Template Login, update the {AuthScripts} list using configure
  • For Apache Login, add/remove the script from .htaccess, or from the FilesMatch line in the Apache configuration.

How to choose an authentication method

One of the key features of Foswiki is that it is possible to add HTML to topics. No authentication method is 100% secure on a website where end users can add HTML, as there is always a risk that a malicious user can add code to a topic that gathers user information, such as session IDs. The Foswiki developers have been forced to make certain tradeoffs, in the pursuit of efficiency, that may be exploited by a hacker.

This section discusses some of the known risks. You can be sure that any potential hackers have read this section as well!

At one extreme, the most secure method is to use Foswiki via SSL (Secure Sockets Layer), with a login manager installed and Client Sessions turned off.

Using Foswiki with sessions turned off is a pain, though, as with all the login managers there are occasions where Foswiki will forget who you are. The best user experience is achieved with sessions turned on.

As soon as you allow the server to maintain information about a logged-in user, you open a door to potential attacks. There are a variety of ways a malicious user can pervert Foswiki to obtain another users session ID, the most common of which is known as a cross-site scripting attack. Once a hacker has an SID they can pretend to be that user.

To help prevent these sorts of attacks, Foswiki supports IP matching, which ensures that the IP address of the user requesting a specific session is the same as the IP address of the user who created the session. This works well as long as IP addresses are unique to each client, and as long as the IP address of the client can't be faked.

Session IDs are usually stored by Foswiki in cookies, which are stored in the client browser. Cookies work well, but not all environments or users permit cookies to be stored in browsers. So Foswiki also supports two other methods of determining the session ID. The first method uses the client IP address to determine the session ID. The second uses a rewriting method that rewrites local URLs in Foswiki pages to include the session ID in the URL.

The first method works well as long as IP addresses are unique to each individual client, and client IP addresses can't be faked by a hacker. If IP addresses are unique and can't be faked, it is almost as secure as cookies + IP matching, so it ranks as the fourth most secure method.

If you have to turn IP matching off, and cookies can't be relied on, then you may have to rely on the second method, URL rewriting. This method exposes the session IDs very publicly, so should be regarded as "rather dodgy".

Most Foswiki sites don't use SSL, so, as is the case with most sites that don't use SSL, there is always a possibility that a password could be picked out of the aether. Browsers do not encrypt passwords sent over non-SSL links, so using Apache Login is no more secure than Template Login.

Of the two shipped login managers, Apache Login is probably the most useful. It lets you do this sort of thing: wget --http-user=RogerRabbit --http-password=i'mnottelling http://www.example.com/bin/save/Sandbox/StuffAUTOINC0?text=hohoho,%20this%20is%20interesting i.e. pass in a user and password to a request from the command-line. However it doesn't let you log out.

Template Login degrades to url re-writing when you use a client like dillo that does not support cookies. However, you can log out and back in as a different user.

Finally, it would be really neat if someone was to work out how to use certificates to identify users.....

See Foswiki:Support.SupplementalDocuments for more information.


Related Topics: AdminDocumentationCategory, AccessControl
Topic revision: r1 - 12 Sep 2009 - 02:03:24 - ProjectContributor
 

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