r33 - 13 Oct 2006 - 00:59:46 - TWikiContributorYou are here: TWiki >  TWiki Web > TWikiAccessControl

TWiki Access Control

Restricting read and write access to topics and webs, by Users and groups

TWiki Access Control allows you restrict access to single topics and entire webs, by individual user and by user Groups. Access control, combined with TWikiUserAuthentication, lets you easily create and manage an extremely flexible, fine-grained privilege system.

TIP Tip: TWiki:TWiki.TWikiAccessControlSupplement on TWiki.org has additional documentation on access control.

An Important Control Consideration

Open, freeform editing is the essence of WikiCulture - what makes TWiki different and often more effective than other collaboration tools. For that reason, it is strongly recommended that decisions to restrict read or write access to a web or a topic are made with great care - the more restrictions, the less Wiki in the mix. Experience shows that unrestricted write access works very well because:

  • Peer influence is enough to ensure that only relevant content is posted.
  • Peer editing - the ability for anyone to rearrange all content on a page - keeps topics focused.
  • In TWiki, content is transparently preserved under revision control:
    • Edits can be undone by the TWikiAdminGroup (the default administrators group; see #ManagingGroups).
    • Users are encouraged to edit and refactor (condense a long topic), since there's a safety net.
As a collaboration guideline:
  • Create broad-based Groups (for more and varied input), and...
  • Avoid creating view-only Users (if you can read it, you should be able to contribute to it).

Permissions settings of the webs on this TWiki site

Web Sitemap VIEW CHANGE
Listed DENY ALLOW DENY ALLOW
Preferences Home Main on       TWikiAdminGroup? , TWikiRegistrationAgent?
Preferences Home TWiki on       TWikiAdminGroup
Preferences Home DI on        
Preferences Home DI.EPL on       EplGroup
Preferences Home DI.FAST on       FastGroup
Preferences Home DI.FMHAS on       FmhasGroup
Preferences Home DI.TETIC on       TeticGroup
Preferences Home EL on       JoseCarlosRamalho,Main.JorgeGustavo,Main.JoseJoao,Main.JoaoSaraiva,Main.AlbertoSimoes,Main.PedroRangelHenriques,Main.DanielaCruz
Preferences Home Education on        
Preferences Home Education.ACMSD on       LuisSoaresBarbosa, JoseNunoOliveira
Preferences Home Education.ACS on        
Preferences Home Education.AeC on       JorgeSousaPinto
Preferences Home Education.Archive on       TWikiAdminGroup, StaffGroup, StudentsGroup
Preferences Home Education.CP on       JoseNunoOliveira, NunoMacedo
Preferences Home Education.CP0809 on        
Preferences Home Education.CP0910 on        
Preferences Home Education.CP1011 on        
Preferences Home Education.CP1112 on        
Preferences Home Education.CP1213 on        
Preferences Home Education.CP1314 on        
Preferences Home Education.CP1415 on        
Preferences Home Education.CP1617 on        
Preferences Home Education.CP1718 on        
Preferences Home Education.ClubeProgramacao on       AlcinoCunha, RuiMendes, VictorFonte, PauloSergioAlmeida
Preferences Home Education.Criptografia on       AlcinoCunha, JoseManuelValenca, ManuelBernardoBarbosa, JoseBacelarAlmeida, PaulaCristinaValenca?
Preferences Home Education.EL on       JoseCarlosRamalho,Main.JorgeGustavo,Main.JoseJoao,Main.JoaoSaraiva,Main.AlbertoSimoes,Main.PedroRangelHenriques,Main.DanielaCruz
Preferences Home Education.EL0708 on       JoseCarlosRamalho,Main.AlbertoSimoes,Main.PedroRangelHenriques,Main.DanielaCruz
Preferences Home Education.EL0809 on       JoseCarlosRamalho,Main.AlbertoSimoes,Main.PedroRangelHenriques,Main.DanielaCruz
Preferences Home Education.EL0910 on       JoseCarlosRamalho,Main.JorgeGustavo,Main.JoseJoao,Main.JoaoSaraiva,Main.AlbertoSimoes,Main.PedroRangelHenriques,Main.DanielaCruz
Preferences Home Education.EL1011 on       JoseCarlosRamalho,Main.JorgeGustavo,Main.JoseJoao,Main.JoaoSaraiva,Main.AlbertoSimoes,Main.PedroRangelHenriques,Main.DanielaCruz
Preferences Home Education.EM on        
Preferences Home Education.ERS on        
Preferences Home Education.LAD on       JoseCarlosRamalho, JoseJoao
Preferences Home Education.LC on        
Preferences Home Education.LI1 on       TWikiAdminGroup, JoseNunoOliveira
Preferences Home Education.LI10708 on        
Preferences Home Education.LI11011 on        
Preferences Home Education.LI11112 on       TWikiAdminGroup, JoseNunoOliveira
Preferences Home Education.MAPiICS on        
Preferences Home Education.MFES on       AlcinoCunha, LuisSoaresBarbosa, JoseNunoOliveira, JoaoSaraiva, JorgeSousaPinto, MariaJoaoFrade, JoseProenca, NunoMacedo
Preferences Home Education.MFES0910 on        
Preferences Home Education.MFES1011 on        
Preferences Home Education.MFES1112 on       AlcinoCunha, LuisSoaresBarbosa, JoseNunoOliveira, JorgeSousaPinto, MariaJoaoFrade
Preferences Home Education.MFES1213 on       AlcinoCunha, LuisSoaresBarbosa, JoseNunoOliveira, JorgeSousaPinto, MariaJoaoFrade
Preferences Home Education.MFES1314 on       AlcinoCunha, LuisSoaresBarbosa, JoseNunoOliveira, JorgeSousaPinto, MariaJoaoFrade
Preferences Home Education.MFES1415 on       AlcinoCunha, LuisSoaresBarbosa, JoseNunoOliveira, JorgeSousaPinto, MariaJoaoFrade
Preferences Home Education.MFES1617 on       AlcinoCunha, LuisSoaresBarbosa, JoseNunoOliveira, JoaoSaraiva, JorgeSousaPinto, MariaJoaoFrade, JoseProenca
Preferences Home Education.MFES1718 on       AlcinoCunha, LuisSoaresBarbosa, JoseNunoOliveira, JoaoSaraiva, JorgeSousaPinto, MariaJoaoFrade, JoseProenca
Preferences Home Education.MFES1819 on       AlcinoCunha, LuisSoaresBarbosa, JoseNunoOliveira, JoaoSaraiva, JorgeSousaPinto, MariaJoaoFrade, JoseProenca, NunoMacedo
Preferences Home Education.MFES1920 on       AlcinoCunha, LuisSoaresBarbosa, JoseNunoOliveira, JoaoSaraiva, JorgeSousaPinto, MariaJoaoFrade, JoseProenca, NunoMacedo
Preferences Home Education.MICEI on       MiCeiGroup
Preferences Home Education.MSM on       MsmGroup
Preferences Home Education.MapiFc on        
Preferences Home Education.MapiSCAM on       TWikiAdminGroup, JoaoSaraiva
Preferences Home Education.PE on       TWikiAdminGroup, JoaoSaraiva
Preferences Home Education.PED on       JoseCarlosRamalho
Preferences Home Education.PP2 on       StaffGroup
Preferences Home Education.PeC on        
Preferences Home Education.ProgramacaoImperativa on       JoseCarlosRamalho, NunoRodrigues, PedroRangelHenriques
Preferences Home Education.SEM on       LuisSoaresBarbosa, JorgeSousaPinto
Preferences Home Education.TPI on        
Preferences Home Events on        
Preferences Home Events.GTTSE on       GttseGroup
Preferences Home Events.GTTSE2007 on       GttseGroup
Preferences Home Events.JCC on       StaffGroup
Preferences Home Events.RULE2010 on       TWikiAdminGroup,Main.JoseFaria,Main.HassanAitKaci,Main.JorgeSousaPinto,Main.DaveReynolds
Preferences Home Events.RuleWorkshop on       TWikiAdminGroup, JorgeSousaPinto
Preferences Home JoseLuisSilva on       TWikiAdminGroup,Main.JoseLuisSilva
Preferences Home Personal on        
Preferences Home Personal.Alcino on       AlcinoCunha
Preferences Home Personal.Claudia on       ClaudiaNecco?
Preferences Home Personal.JFF off       JoaoFerreira
Preferences Home Personal.Jacome on        
Preferences Home Personal.Joao on       JoaoFernandes
Preferences Home Personal.Joost off       JoostVisser
Preferences Home Personal.Jorge on       JorgeSousaPinto, JoseNunoOliveira, LuisSoaresBarbosa
Preferences Home Personal.JorgeMendes on       JorgeMendes
Preferences Home Personal.JoseLuisSilva on       TWikiAdminGroup,Main.JoseLuisSilva
Preferences Home Personal.LSB on       LuisSoaresBarbosa
Preferences Home Personal.MBB on       ManuelBernardoBarbosa
Preferences Home Personal.Nuno on       NunoRodrigues
Preferences Home Personal.Olga on       OlgaPacheco
Preferences Home Personal.Pablo on       PabloBerdaguer, JoostVisser
Preferences Home Personal.PedroMartins on       PedroMartins
Preferences Home Personal.Tiago on        
Preferences Home Personal.Xana on       AlexandraSilva
Preferences Home Personal.Ze on       JoseProenca
Preferences Home Research on        
Preferences Home Research.APEX on       JoseCampos,Main.JoseLuisSilva
Preferences Home Research.Aviacc on       JorgeSousaPinto
Preferences Home Research.CROSS on       MariaJoaoFrade,Main.PedroRangelHenriques,Main.LuisSoaresBarbosa,Main.JorgeSousaPinto,Main.JoaoSaraiva,Main.JoseJoao,Main.JorgeGustavo,Main.JoseCampos,Main.AlbertoSimoes,Main.NunoRodrigues,Main.DanielaCruz,Main.JoaoPedroSilva,Main.NunoCarvalho
Preferences Home Research.Digitarq on       JoseCarlosRamalho, JoseMiguelFerreira? , LuisFerros?
Preferences Home Research.Doutoramentos on       ConceicaoBarbosa
Preferences Home Research.EVOLVE on       MariaJoaoFrade,Main.LuisSoaresBarbosa,Main.JorgeSousaPinto, AlcinoCunha, JoseNunoOliveira
Preferences Home Research.FATBIT on       AlcinoCunha, JoseNunoOliveira, JacomeCunha, JoaoSaraiva, HugoPacheco, NunoMacedo, JoaoFernandes, EricVanWyk
Preferences Home Research.IKF on       StaffGroup
Preferences Home Research.LerNet on       LerNetGroup
Preferences Home Research.MONDRIAN on       LuisSoaresBarbosa,Main.JoseNunoOliveira,Main.HugoMacedo,Main.JoseBernardoBarros,Main.ManuelAntonioMartins,Main.DirkHofmann,Main.AlexandreMadeira
Preferences Home Research.MathIS on       TWikiAdminGroup, PauloSilva, JoaoFerreira, LuisSoaresBarbosa, JoseNunoOliveira,Main.LuizLopes,Main.HugoMacedo
Preferences Home Research.Matisse on       TWikiAdminGroup, PauloSilva, JoaoFerreira, LuisSoaresBarbosa, JoseNunoOliveira,Main.LuizLopes,Main.HugoMacedo
Preferences Home Research.NASONI on       LuisSoaresBarbosa,Main.RenatoNeves,Main.AnaCarvalho
Preferences Home Research.OntXQuery on       VodaGroup
Preferences Home Research.PCVIA on       VodaGroup
Preferences Home Research.PURe on       StaffGroup
Preferences Home Research.QAIS on       LuisSoaresBarbosa, AlexandraSilva, LuisMonteiro, JoseNunoOliveira, RicardoAlmeida
Preferences Home Research.Rescue on       SimaoSousa, SimaoMeloDeSousa, RescueGroup
Preferences Home Research.VFS on       TWikiAdminGroup, JoseNunoOliveira, MiguelFerreira, SamuelSilva, ClaudiaNecco
Preferences Home Research.Voda on       VodaGroup
Preferences Home Sandbox on        

See TWikiAccessControl for details

Please Note:

  • A blank in the the above table may mean either the corresponding control is absent or commented out or that it has been set to a null value. The two conditions have dramatically different and possibly opposed semantics.
  • TWikiGuest is the guest account - used by unauthenticated users.
  • The TWiki web must not deny view to TWikiGuest; otherwise, people will not be able to register.

Note: Above table comes from SitePermissions

Authentication vs. Access Control

Authentication: Identifies who a user is based on a login procedure. See TWikiUserAuthentication.

Access control: Restrict access to content based on users and groups once a user is identified.

Users and Groups

Access control is based on the familiar concept of Users and Groups. Users are defined by their WikiNames. They can then be organized in unlimited combinations by inclusion in one or more user Groups. For convenience, Groups can also be included in other Groups.

Managing Users

A user can create an account in TWikiRegistration. The following actions are performed:

  • WikiName and encrypted password are recorded using the password manager if authentication is enabled.
  • A confirmation e-mail is sent to the user.
  • A user home page with the WikiName of the user is created in the Main web.
  • The user is added to the TWikiUsers topic.

The default visitor name is TWikiGuest. This is the non-authenticated user.

Managing Groups

Groups are defined by group topics located in the Main web, such as the TWikiAdminGroup. To create a new group, visit TWikiGroups and enter the name of the new group ending in Group into the "new group" form field. This will create a new group topic with two important settings:

  • Set GROUP = < list of Users and/or Groups >
  • Set ALLOWTOPICCHANGE = < list of Users and/or Groups >

The GROUP setting is a comma-separated list of users and/or other groups. Example:

  • Set GROUP = Main.SomeUser, Main.OtherUser, Main.SomeGroup

The ALLOWTOPICCHANGE setting defines who is allowed to change the group topic; it is a comma delimited list of users and groups. You typically want to restrict that to the members of the group itself, so it should contain the name of the topic. This prevents users not in the group from editing the topic to give themselves or others access. For example, for the TWikiAdminGroup topic write:

  • Set ALLOWTOPICCHANGE = Main.TWikiAdminGroup

ALERT! Note: TWiki has strict formatting rules. Make sure you have three spaces, an asterisk, and an extra space in front of any access control rule.

The Super Admin Group

By mistyping a user or group name in the settings, it's possible to lock a topic so that no-one can edit it from a browser. To avoid this, add the WikiNames of registered administrators to the super admin group topic called TWikiAdminGroup. The name of this topic is defined by the {SuperAdminGroup} configure setting. Example group setting:

  • Set GROUP= Main.ElizabethWindsor, Main.TonyBlair

Restricting Access

You can define who is allowed to read or write to a web or a topic. Note that some plugins may not respect access permissions.

  • Restricting VIEW blocks viewing and searching of content.
  • Restricting CHANGE blocks creating new topics, changing topics or attaching files.

Controlling access to a Web

You can define restrictions on who is allowed to view a TWiki web. You can restrict access to certain webs to selected Users and Groups, by:

  • authenticating all webs and restricting selected webs: Topic access in all webs is authenticated, and selected webs have restricted access.
  • authenticating and restricting selected webs only: Provide unrestricted viewing access to open webs, with authentication and restriction only on selected webs.

  • You can define these settings in the WebPreferences topic, preferable towards the end of the topic:
    • Set DENYWEBVIEW = < comma-delimited list of Users and Groups >
    • Set ALLOWWEBVIEW = < comma-delimited list of Users and Groups >
    • Set DENYWEBCHANGE = < comma-delimited list of Users and Groups >
    • Set ALLOWWEBCHANGE = < comma-delimited list of Users and Groups >

Be careful with empty values for any of these. In older versions of TWiki,

  • Set ALLOWWEBVIEW =
meant the same as not setting it at all. However since TWiki Dakar release, it means allow noone access i.e. prevent anyone from viewing the web. Similarly
  • Set DENYWEBVIEW =
now means do not deny anyone the right to view this web. See "How TWiki evaluates ALLOW/DENY settings" below for more on this.

Controlling access to a Topic

  • You can define these settings in any topic, preferable towards the end of the topic:
    • Set DENYTOPICVIEW = < comma-delimited list of Users and Groups >
    • Set ALLOWTOPICVIEW = < comma-delimited list of Users and Groups >
    • Set DENYTOPICCHANGE = < comma-delimited list of Users and Groups >
    • Set ALLOWTOPICCHANGE = < comma-delimited list of Users and Groups >

Remember when opening up access to specific topics within a restricted web that other topics in the web - for example, the WebLeftBar - may also be accessed when viewing the topics. The message you get when you are denied access should tell you what topic you were not permitted to access.

Be careful with empty values for any of these. In older versions of TWiki,

  • Set ALLOWTOPICVIEW =
meant the same as not setting it at all. However since TWiki Dakar release, it means allow no-one access i.e. prevent anyone from viewing the topic. Similarly
  • Set DENYTOPICVIEW =
now means do not deny anyone the right to view this topic. See "How TWiki evaluates ALLOW/DENY settings" below for more on this.

Controlling access to Attachments

Attachments are referred to directly, and are not normally indirected via TWiki scripts. This means that the above instructions for access control will not apply to attachments. It is possible that someone may inadvertently publicise a URL that they expected to be access-controlled.

The easiest way to apply the same access control rules for attachments as apply to topics is to use the Apache mod_rewrite module, and configure your webserver to redirect accesses to attachments to the TWiki viewfile script. For example,

    ScriptAlias /twiki/bin/ /filesystem/path/to/twiki/bin/
    Alias /twiki/pub/       /filesystem/path/to/twiki/pub/

    RewriteEngine on
    RewriteCond %{REQUEST_URI} !^/+twiki/+pub/+TWiki/+.+
    RewriteRule ^/+twiki/+pub/+([^/]+)/+((([^/]+)/+)+)(.+) /twiki/bin/viewfile/$1/$4?filename=$5 [L,PT]

That way all the controls that apply to the topic also apply to attachments to the topic. Other types of webserver have similar support.

Note: Images embedded in topics will load much slower since each image will be delivered by the viewfile script.

Controlling who can create top-level webs

Top level webs are a special case, because they don't have a parent web with a WebPreferences. So there has to be a special control just for the root level.
  • You can define these settings in the Main.%TWIKIPREFSTOPIC% topic, preferable towards the end of the topic:
    • Set DENYROOTCHANGE = < comma-delimited list of Users and Groups >
    • Set ALLOWROOTCHANGE = < comma-delimited list of Users and Groups >
Note that you do not require ROOTCHANGE access to rename an existing top-level web. You just need WEBCHANGE in the web itself.

How TWiki evaluates ALLOW/DENY settings

When deciding whether to grant access, TWiki evaluates the following rules in order (read from the top of the list; if the logic arrives at PERMITTED or DENIED that applies immediately and no more rules are applied). You need to read the rules bearing in mind that VIEW and CHANGE access may be granted/denied separately.

  1. If the user is a super-user
    • access is PERMITTED.
  2. If DENYTOPIC is set to a list of wikinames
    • people in the list will be DENIED.
  3. If DENYTOPIC is set to empty ( i.e. Set DENYTOPIC = )
    • access is PERMITTED i.e no-one is denied access to this topic
  4. If ALLOWTOPIC is set
    1. people in the list are PERMITTED
    2. everyone else is DENIED
      • Note that this means that setting ALLOWTOPIC to empty denies access to everyone except admins (unless DENYTOPIC is also set to empty, as described above)
  5. If DENYWEB is set to a list of wikiname
    • people in the list are DENIED access
  6. If ALLOWWEB is set to a list of wikinames
    • people in the list will be PERMITTED
    • everyone else will be DENIED
      • Note that setting ALLOWWEB to empty denies access to everyone except admins
  7. If you got this far, access is PERMITTED

Access Control quick recipes

Obfuscating Webs

Another way of hiding webs is to keep them hidden by not publishing the URL and by preventing the all webs search option from accessing obfuscated webs. Do so by enabling the NOSEARCHALL variable in WebPreferences:

  • Set NOSEARCHALL = on

This setup can be useful to hide a new web until content its ready for deployment, or to hide view access restricted webs.

ALERT! Note: Obfuscating a web without view access control is very insecure, as anyone who knows the URL can access the web.

Authenticate all Webs and Restrict Selected Webs

Use the following setup to authenticate users for topic viewing in all webs and to restrict access to selected webs. Requires TWikiUserAuthentication to be enabled.

  1. Restrict view access to selected Users and Groups. Set one or both of these variables in its WebPreferences topic:
    • Set DENYWEBVIEW = < list of Users and Groups >
    • Set ALLOWWEBVIEW = < list of Users and Groups >
    • Note: DENYWEBVIEW is evaluated before ALLOWWEBVIEW. Access is denied if the authenticated person is in the DENYWEBVIEW list, or not in the ALLOWWEBVIEW list. Access is granted in case DENYWEBVIEW and ALLOWWEBVIEW is not defined.

Authenticate and Restrict Selected Webs Only

Use the following setup to provide unrestricted viewing access to open webs, with authentication only on selected webs. Requires TWikiUserAuthentication to be enabled.

  1. Restrict view access to selected Users and Groups. Set one or both of these variables in its WebPreferences topic:
    • Set DENYWEBVIEW = < list of Users and Groups >
    • Set ALLOWWEBVIEW = < list of Users and Groups >
    • Note: DENYWEBVIEW is evaluated before ALLOWWEBVIEW. Access is denied if the authenticated person is in the DENYWEBVIEW list, or not in the ALLOWWEBVIEW list. Access is granted in case DENYWEBVIEW and ALLOWWEBVIEW is not defined.

Hide Control Settings

TIP Tip: To hide access control settings from normal browser viewing, you can put them into the topic-local settings. You can access those settings via the "More" screen, as explained in TWikiVariables.

Alternatively, place them in HTML comment markers, but this exposes the access setting during ordinary editing.

<!--
   * Set DENYTOPICCHANGE = Main.SomeGroup
-->

Related Topics: AdminDocumentationCategory, TWikiUserAuthentication, TWiki:TWiki.TWikiAccessControlSupplement

-- Contributors: TWiki:Main.PeterThoeny, TWiki:Main.MikeMannix, TWiki:Main.CrawfordCurrie

Edit | Attach | Printable | Raw View | Backlinks: Web, All Webs | History: r33 < r32 < r31 < r30 < r29 | More topic actions
 
DIUM
This site is powered by the TWiki collaboration platformCopyright © by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding TWiki? Send feedback
Note: Please contribute updates to this topic on TWiki.org at TWiki:TWiki.TWikiAccessControl