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'''topic''' - Kurzbeschreibung
'''Authentifizierung über HTTP'''
 
== Beschreibung ==
== Beschreibung ==
; Stellt der Webserver fest, dass für eine angeforderte Datei Benutzername oder Passwort nötig sind
; Stellt der Webserver fest, dass für eine angeforderte Datei Benutzername oder Passwort nötig sind
Zeile 6: Zeile 7:
* Dieser prüft, ob die Angaben vorliegen, oder präsentiert dem Anwender einen Dialog, in dem Name und Passwort einzutragen sind, und überträgt diese an den Server.
* Dieser prüft, ob die Angaben vorliegen, oder präsentiert dem Anwender einen Dialog, in dem Name und Passwort einzutragen sind, und überträgt diese an den Server.
* Stimmen die Daten, wird die entsprechende Seite an den Browser gesendet.
* Stimmen die Daten, wird die entsprechende Seite an den Browser gesendet.
* Es wird nach RFC 2617 unterschieden in:
 
; Basic Authentication: Die Basic Authentication ist die häufigste Art der HTTP-Authentifizierung.
{| class="wikitable big options"
|+ [[RFC 2617]] unterscheidet
|-
| [[#Basic Authentication|Basic Authentication]] ||
|-
| [[#Digest Access Authentication|Digest Access Authentication]] ||
|}
 
=== Basic Authentication ===
Die Basic Authentication ist die häufigste Art der HTTP-Authentifizierung
* Der Webserver fordert eine Authentifizierung an, der Browser sucht daraufhin nach Benutzername/Passwort für diese Datei und fragt gegebenenfalls den Benutzer.
* Der Webserver fordert eine Authentifizierung an, der Browser sucht daraufhin nach Benutzername/Passwort für diese Datei und fragt gegebenenfalls den Benutzer.
* Anschließend sendet er die Authentifizierung mit dem Authorization-Header in der Form ''Benutzername:Passwort'' [[Base64]]-codiert an den Server.
* Anschließend sendet er die Authentifizierung mit dem Authorization-Header in der Form ''Benutzername:Passwort'' [[Base64]]-codiert an den Server.
* Base64 bietet keinen kryptographischen Schutz, daher kann dieses Verfahren nur beim Einsatz von [[Hypertext Transfer Protocol Secure|HTTPS]] als sicher angesehen werden.
* Base64 bietet keinen kryptographischen Schutz, daher kann dieses Verfahren nur beim Einsatz von [[Hypertext Transfer Protocol Secure|HTTPS]] als sicher angesehen werden.
; Digest Access Authentication: Bei der Digest Access Authentication sendet der Server zusätzlich mit dem WWW-Authenticate-Header eine eigens erzeugte zufällige Zeichenfolge ([[Nonce]]).
 
=== Digest Access Authentication ===
Bei der Digest Access Authentication sendet der Server zusätzlich mit dem WWW-Authenticate-Header eine eigens erzeugte zufällige Zeichenfolge ([[Nonce]]).
* Der Browser berechnet den [[Hashcode]] der gesamten Daten (Benutzername, Passwort, erhaltener Zeichenfolge, HTTP-Methode und angeforderter [[Uniform Resource Identifier|URI]]) und sendet sie im Authorization-Header zusammen mit dem Benutzernamen und der zufälligen Zeichenfolge zurück an den Server, der diese mit der selbst berechneten Prüfsumme vergleicht.
* Der Browser berechnet den [[Hashcode]] der gesamten Daten (Benutzername, Passwort, erhaltener Zeichenfolge, HTTP-Methode und angeforderter [[Uniform Resource Identifier|URI]]) und sendet sie im Authorization-Header zusammen mit dem Benutzernamen und der zufälligen Zeichenfolge zurück an den Server, der diese mit der selbst berechneten Prüfsumme vergleicht.
* Ein Abhören der Kommunikation nützt hier einem Angreifer nichts, da sich aufgrund der verwendeten [[Kryptologische Hashfunktion|kryptologischen Hashfunktion]] aus dem Hashcode die Daten nicht rekonstruieren lassen und für jede Anforderung anders lauten.
* Ein Abhören der Kommunikation nützt hier einem Angreifer nichts, da sich aufgrund der verwendeten [[Kryptologische Hashfunktion|kryptologischen Hashfunktion]] aus dem Hashcode die Daten nicht rekonstruieren lassen und für jede Anforderung anders lauten.
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===== Weblinks =====
===== Weblinks =====


= Access Control =
Access control refers to any means of controlling access to any resource. This is separate from authentication and authorization.
== Related Modules and Directives ==
There are three types of modules involved in the authentication and authorization process.  You will usually need to choose at least one module from each group.
* Authentication type (see the      <code>AuthType</code> directive)
** <code>mod_auth_basic</code>
** <code>mod_auth_digest</code>
* Authentication provider (see the  <code>AuthBasicProvider</code> and  <code>AuthDigestProvider</code> directives)
** <code>mod_authn_anon</code>
** <code>mod_authn_dbd</code>
** <code>mod_authn_dbm</code>
** <code>mod_authn_file</code>
** <code>mod_authnz_ldap</code>
** <code>mod_authn_socache</code>
* Authorization (see the      <code>Require</code> directive)
** <code>mod_authnz_ldap</code>
** <code>mod_authz_dbd</code>
** <code>mod_authz_dbm</code>
** <code>mod_authz_groupfile</code>
** <code>mod_authz_host</code>
** <code>mod_authz_owner</code>
** <code>mod_authz_user</code>
In addition to these modules, there are also  <code>mod_authn_core</code> and  <code>mod_authz_core</code>.  These modules implement core  directives that are core to all auth modules.
The module <code>mod_authnz_ldap</code> is both an  authentication and authorization provider.  The module  <code>mod_authz_host</code> provides authorization  and access control based on hostname, IP address or characteristics  of the request, but is not part of the authentication provider  system. For backwards compatibility with the mod_access, there is  a new module <code>mod_access_compat</code>.
You probably also want to take a look at the Access Control howto, which discusses the  various ways to control access to your server.
== Introduction ==
If you have information on your web site that is sensitive    or intended for only a small group of people, the techniques in    this article will help you make sure that the people that see    those pages are the people that you wanted to see them.
This article covers the "standard" way of protecting parts    of your web site that most of you are going to use.
=== Note: ===
If your data really needs to be secure, consider using    <code>mod_ssl</code> in addition to any authentication.
== The Prerequisites ==
The directives discussed in this article will need to go    either in your main server configuration file (typically in a    <code><Directory></code> section), or    in per-directory configuration files (<code>.htaccess</code> files).
If you plan to use <code>.htaccess</code> files, you will    need to have a server configuration that permits putting    authentication directives in these files. This is done with the    <code>AllowOverride</code> directive, which    specifies which directives, if any, may be put in per-directory    configuration files.
Since we're talking here about authentication, you will need    an <code>AllowOverride</code> directive like the    following:
AllowOverride AuthConfig
Or, if you are just going to put the directives directly in    your main server configuration file, you will of course need to    have write permission to that file.
And you'll need to know a little bit about the directory    structure of your server, in order to know where some files are    kept. This should not be terribly difficult, and I'll try to    make this clear when we come to that point.
You will also need to make sure that the modules    <code>mod_authn_core</code> and <code>mod_authz_core</code>    have either been built into the httpd binary or loaded by the    httpd.conf configuration file. Both of these modules provide core    directives and functionality that are critical to the configuration    and use of authentication and authorization in the web server.
== Getting it working ==
Here's the basics of password protecting a directory on your    server.
First, you need to create a password file. Exactly how you do    this will vary depending on what authentication provider you have    chosen. More on that later. To start with, we'll use a text password    file.
This file should be    placed somewhere not accessible from the web. This is so that    folks cannot download the password file. For example, if your    documents are served out of <code>/usr/local/apache/htdocs</code>, you    might want to put the password file(s) in    <code>/usr/local/apache/passwd</code>.
To create the file, use the <code>htpasswd</code> utility that    came with Apache. This will be located in the <code>bin</code> directory    of wherever you installed Apache. If you have installed Apache from    a third-party package, it may be in your execution path.
To create the file, type:
<code>htpasswd -c /usr/local/apache/passwd/passwords rbowen</code>   
<code>htpasswd</code> will ask you for the password, and    then ask you to type it again to confirm it:
<code># htpasswd -c /usr/local/apache/passwd/passwords rbowen</code>
<code>New password: mypassword</code>
<code>Re-type new password: mypassword</code>
<code>Adding password for user rbowen</code>   
If <code>htpasswd</code> is not in your path, of course    you'll have to type the full path to the file to get it to run.    With a default installation, it's located at    <code>/usr/local/apache2/bin/htpasswd</code>
Next, you'll need to configure the server to request a    password and tell the server which users are allowed access.    You can do this either by editing the <code>httpd.conf</code>    file or using an <code>.htaccess</code> file. For example, if    you wish to protect the directory    <code>/usr/local/apache/htdocs/secret</code>, you can use the    following directives, either placed in the file    <code>/usr/local/apache/htdocs/secret/.htaccess</code>, or    placed in <code>httpd.conf</code> inside a <Directory    "/usr/local/apache/htdocs/secret"> section.
AuthType Basic
AuthName "Restricted Files"
# (Following line optional)
AuthBasicProvider file
AuthUserFile "/usr/local/apache/passwd/passwords"
Require user rbowen
Let's examine each of those directives individually. The <code>AuthType</code> directive selects    the method that is used to authenticate the user. The most    common method is <code>Basic</code>, and this is the method    implemented by <code>mod_auth_basic</code>. It is important to be aware,    however, that Basic authentication sends the password from the client to    the server unencrypted. This method should therefore not be used for    highly sensitive data, unless accompanied by <code>mod_ssl</code>.    Apache supports one other authentication method:    <code>AuthType Digest</code>. This method is implemented by <code>mod_auth_digest</code> and was intended to be more secure. This is no    longer the case and the connection should be encrypted with <code>mod_ssl</code> instead.
The <code>AuthName</code> directive sets    the <dfn>Realm</dfn> to be used in the authentication. The realm serves    two major functions. First, the client often presents this information to    the user as part of the password dialog box. Second, it is used by the    client to determine what password to send for a given authenticated    area.
So, for example, once a client has authenticated in the    <code>"Restricted Files"</code> area, it will automatically    retry the same password for any area on the same server that is    marked with the <code>"Restricted Files"</code> Realm.    Therefore, you can prevent a user from being prompted more than    once for a password by letting multiple restricted areas share    the same realm. Of course, for security reasons, the client    will always need to ask again for the password whenever the    hostname of the server changes.
The <code>AuthBasicProvider</code> is,    in this case, optional, since <code>file</code> is the default value    for this directive. You'll need to use this directive if you are    choosing a different source for authentication, such as    <code>mod_authn_dbm</code> or <code>mod_authn_dbd</code>.
The <code>AuthUserFile</code>    directive sets the path to the password file that we just    created with <code>htpasswd</code>. If you have a large number    of users, it can be quite slow to search through a plain text    file to authenticate the user on each request. Apache also has    the ability to store user information in fast database files.    The <code>mod_authn_dbm</code> module provides the <code>AuthDBMUserFile</code> directive. These    files can be created and manipulated with the <code>dbmmanage</code> and <code>htdbm</code> programs. Many    other types of authentication options are available from third    party modules.
Finally, the <code>Require</code>    directive provides the authorization part of the process by    setting the user that is allowed to access this region of the    server. In the next section, we discuss various ways to use the    <code>Require</code> directive.
== Letting more than one person in ==
The directives above only let one person (specifically    someone with a username of <code>rbowen</code>) into the    directory. In most cases, you'll want to let more than one    person in. This is where the <code>AuthGroupFile</code> comes in.
If you want to let more than one person in, you'll need to    create a group file that associates group names with a list of    users in that group. The format of this file is pretty simple,    and you can create it with your favorite editor. The contents    of the file will look like this:
<code>GroupName: rbowen dpitts sungo rshersey</code> 
That's just a list of the members of the group in a long    line separated by spaces.
To add a user to your already existing password file,    type:
<code>htpasswd /usr/local/apache/passwd/passwords dpitts</code>   
You'll get the same response as before, but it will be    appended to the existing file, rather than creating a new file.    (It's the <code>-c</code> that makes it create a new password    file).
Now, you need to modify your <code>.htaccess</code> file or    <code><Directory></code> block    to look like the following:
AuthType Basic
AuthName "By Invitation Only"
# Optional line:
AuthBasicProvider file
AuthUserFile "/usr/local/apache/passwd/passwords"
AuthGroupFile "/usr/local/apache/passwd/groups"
Require group GroupName
Now, anyone that is listed in the group <code>GroupName</code>,    and has an entry in the <code>password</code> file, will be let in, if    they type the correct password.
There's another way to let multiple users in that is less    specific. Rather than creating a group file, you can just use    the following directive:
Require valid-user
Using that rather than the <code>Require user rbowen</code>    line will allow anyone in that is listed in the password file,    and who correctly enters their password.
== Possible problems ==
Because of the way that Basic authentication is specified,    your username and password must be verified every time you    request a document from the server. This is even if you're    reloading the same page, and for every image on the page (if    they come from a protected directory). As you can imagine, this    slows things down a little. The amount that it slows things    down is proportional to the size of the password file, because    it has to open up that file, and go down the list of users    until it gets to your name. And it has to do this every time a    page is loaded.
A consequence of this is that there's a practical limit to    how many users you can put in one password file. This limit    will vary depending on the performance of your particular    server machine, but you can expect to see slowdowns once you    get above a few hundred entries, and may wish to consider a    different authentication method at that time.
== Alternate password storage ==
Because storing passwords in plain text files has the above    problems, you may wish to store your passwords somewhere else, such    as in a database.
<code>mod_authn_dbm</code> and <code>mod_authn_dbd</code> are two    modules which make this possible. Rather than selecting <code>AuthBasicProvider file</code>, instead    you can choose <code>dbm</code> or <code>dbd</code> as your storage    format.
To select a dbm file rather than a text file, for example:
<Directory "/www/docs/private">
    AuthName "Private"
    AuthType Basic
    AuthBasicProvider dbm
    AuthDBMUserFile "/www/passwords/passwd.dbm"
    Require valid-user
</Directory>
Other options are available. Consult the    <code>mod_authn_dbm</code> documentation for more details.
== Using multiple providers ==
With the introduction of the new provider based authentication and    authorization architecture, you are no longer locked into a single    authentication or authorization method. In fact any number of the    providers can be mixed and matched to provide you with exactly the    scheme that meets your needs. In the following example, both the    file and LDAP based authentication providers are being used.
<Directory "/www/docs/private">
    AuthName "Private"
    AuthType Basic
    AuthBasicProvider file ldap
    AuthUserFile "/usr/local/apache/passwd/passwords"
    AuthLDAPURL ldap://ldaphost/o=yourorg
    Require valid-user
</Directory>
In this example the file provider will attempt to authenticate    the user first. If it is unable to authenticate the user, the LDAP    provider will be called. This allows the scope of authentication    to be broadened if your organization implements more than    one type of authentication store. Other authentication and authorization    scenarios may include mixing one type of authentication with a    different type of authorization. For example, authenticating against    a password file yet authorizing against an LDAP directory.
Just as multiple authentication providers can be implemented, multiple    authorization methods can also be used. In this example both file group    authorization as well as LDAP group authorization is being used.
<Directory "/www/docs/private">
    AuthName "Private"
    AuthType Basic
    AuthBasicProvider file
    AuthUserFile "/usr/local/apache/passwd/passwords"
    AuthLDAPURL ldap://ldaphost/o=yourorg
    AuthGroupFile "/usr/local/apache/passwd/groups"
    Require group GroupName
    Require ldap-group cn=mygroup,o=yourorg
</Directory>
To take authorization a little further, authorization container    directives such as    <code><RequireAll></code>    and    <code><RequireAny></code>    allow logic to be applied so that the order in which authorization    is handled can be completely controlled through the configuration.    See Authorization    Containers for an example of how they may be applied.
== Beyond just authorization ==
The way that authorization can be applied is now much more flexible    than just a single check against a single data store. Ordering, logic    and choosing how authorization will be done is now possible.
=== Applying logic and ordering ===
Controlling how and in what order authorization will be applied        has been a bit of a mystery in the past. In Apache 2.2 a provider-based        authentication mechanism was introduced to decouple the actual        authentication process from authorization and supporting functionality.        One of the side benefits was that authentication providers could be        configured and called in a specific order which didn't depend on the        load order of the auth module itself. This same provider based mechanism        has been brought forward into authorization as well. What this means is        that the <code>Require</code> directive        not only specifies which authorization methods should be used, it also        specifies the order in which they are called. Multiple authorization        methods are called in the same order in which the        <code>Require</code> directives        appear in the configuration.
With the introduction of authorization container directives        such as        <code><RequireAll></code>        and        <code><RequireAny></code>,        the configuration also has control over when the        authorization methods are called and what criteria determines when        access is granted.  See        Authorization Containers        for an example of how they may be used to express complex        authorization logic.
By default all        <code>Require</code>        directives are handled as though contained within a        <code><RequireAny></code>        container directive.  In other words, if        any of the specified authorization methods succeed, then authorization        is granted.
=== Using authorization providers for access control ===
Authentication by username and password is only part of the        story. Frequently you want to let people in based on something        other than who they are. Something such as where they are        coming from.
The authorization providers <code>all</code>,        <code>env</code>, <code>host</code> and <code>ip</code> let you        allow or deny access based on other host based criteria such as        host name or ip address of the machine requesting a        document.
The usage of these providers is specified through the        <code>Require</code> directive.        This directive registers the authorization providers        that will be called during the authorization stage of the request        processing. For example:
Require ip <var>address</var>
       
where <var>address</var> is an IP address (or a partial IP        address) or:
Require host <var>domain_name</var>
       
where <var>domain_name</var> is a fully qualified domain name        (or a partial domain name); you may provide multiple addresses or        domain names, if desired.
For example, if you have someone spamming your message        board, and you want to keep them out, you could do the        following:
<RequireAll>
    Require all granted
    Require not ip 10.252.46.165
</RequireAll>
Visitors coming from that address will not be able to see        the content covered by this directive. If, instead, you have a        machine name, rather than an IP address, you can use that.
<RequireAll>
    Require all granted
    Require not host host.example.com
</RequireAll>
And, if you'd like to block access from an entire domain,        you can specify just part of an address or domain name:
<RequireAll>
    Require all granted
    Require not ip 192.168.205
    Require not host phishers.example.com moreidiots.example
    Require not host ke
</RequireAll>
Using <code><RequireAll></code>        with multiple <code><Require></code> directives, each negated with <code>not</code>,        will only allow access, if all of negated conditions are true. In other words,        access will be blocked, if any of the negated conditions fails.
=== Access Control backwards compatibility ===
One of the side effects of adopting a provider based mechanism for        authentication is that the previous access control directives        <code>Order</code>,        <code>Allow</code>,        <code>Deny</code> and        <code>Satisfy</code> are no longer needed.        However to provide backwards compatibility for older configurations, these        directives have been moved to the <code>mod_access_compat</code> module.
=== Note ===
The directives provided by <code>mod_access_compat</code> have        been deprecated by <code>mod_authz_host</code>.        Mixing old directives like <code>Order</code>, <code>Allow</code> or <code>Deny</code> with new ones like        <code>Require</code> is technically possible        but discouraged. The <code>mod_access_compat</code> module was created to support        configurations containing only old directives to facilitate the 2.4 upgrade.        Please check the upgrading guide for more        information.
== Authentication Caching ==
There may be times when authentication puts an unacceptable load    on a provider or on your network.  This is most likely to affect users    of <code>mod_authn_dbd</code> (or third-party/custom providers).    To deal with this, HTTPD 2.3/2.4 introduces a new caching provider    <code>mod_authn_socache</code> to cache credentials and reduce    the load on the origin provider(s).
This may offer a substantial performance boost to some users.
== More information ==
You should also read the documentation for    <code>mod_auth_basic</code> and <code>mod_authz_host</code>    which contain some more information about how this all works.  The    directive <code><AuthnProviderAlias></code> can also help    in simplifying certain authentication configurations.
The various ciphers supported by Apache for authentication data are    explained in Password    Encryptions.
And you may want to look at the Access    Control howto, which discusses a number of related topics.
*


; Siehe auch
[[Kategorie:HTTP]]
* https://httpd.apache.org/docs/2.4/howto/access.html
[[Kategorie:Apache/HTTP/Sicherheit]]
</noinclude>


[[Kategorie:HTTP]]
[[Kategorie:HTTP]]
[[Kategorie:Apache/HTTP/Sicherheit]]
[[Kategorie:Apache/HTTP/Sicherheit]]
</noinclude>
</noinclude>

Aktuelle Version vom 2. November 2024, 16:15 Uhr

Authentifizierung über HTTP

Beschreibung

Stellt der Webserver fest, dass für eine angeforderte Datei Benutzername oder Passwort nötig sind
HTTP-Authentifizierung
meldet er das dem Browser mit dem Statuscode 401 Unauthorized und dem Header WWW-Authenticate.
  • Dieser prüft, ob die Angaben vorliegen, oder präsentiert dem Anwender einen Dialog, in dem Name und Passwort einzutragen sind, und überträgt diese an den Server.
  • Stimmen die Daten, wird die entsprechende Seite an den Browser gesendet.
RFC 2617 unterscheidet
Basic Authentication
Digest Access Authentication

Basic Authentication

Die Basic Authentication ist die häufigste Art der HTTP-Authentifizierung

  • Der Webserver fordert eine Authentifizierung an, der Browser sucht daraufhin nach Benutzername/Passwort für diese Datei und fragt gegebenenfalls den Benutzer.
  • Anschließend sendet er die Authentifizierung mit dem Authorization-Header in der Form Benutzername:Passwort Base64-codiert an den Server.
  • Base64 bietet keinen kryptographischen Schutz, daher kann dieses Verfahren nur beim Einsatz von HTTPS als sicher angesehen werden.

Digest Access Authentication

Bei der Digest Access Authentication sendet der Server zusätzlich mit dem WWW-Authenticate-Header eine eigens erzeugte zufällige Zeichenfolge (Nonce).

  • Der Browser berechnet den Hashcode der gesamten Daten (Benutzername, Passwort, erhaltener Zeichenfolge, HTTP-Methode und angeforderter URI) und sendet sie im Authorization-Header zusammen mit dem Benutzernamen und der zufälligen Zeichenfolge zurück an den Server, der diese mit der selbst berechneten Prüfsumme vergleicht.
  • Ein Abhören der Kommunikation nützt hier einem Angreifer nichts, da sich aufgrund der verwendeten kryptologischen Hashfunktion aus dem Hashcode die Daten nicht rekonstruieren lassen und für jede Anforderung anders lauten.
  • Authentication is any process by which you verify that someone is who they claim they are. Authorization is any process by which someone is allowed to be where they want to go, or to have information that they want to have. For general access control, see the Access Control How-To.
    • Related Modules and Directives
    • Introduction
    • The Prerequisites
    • Getting it working
    • Letting more than one person in
    • Possible problems
    • Alternate password storage
    • Using multiple providers
    • Beyond just authorization
    • Authentication Caching
    • More information


Anhang

Siehe auch

Links

Weblinks
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