Key authentication module¶

The authkey module for GeoServer allows for a very simple authentication protocol designed for OGC clients that cannot handle any kind of security protocol, not even the HTTP basic authentication.

For these clients the module allows a minimal form of authentication by appending a unique key in the URL that is used as the sole authentication token. Obviously this approach is open to security token sniffing and must always be associated with the use of HTTPS connections.

A sample authenticated request looks like:

http://localhost:8080/geoserver/topp/wms?service=WMS&version=1.3.0&request=GetCapabilities&authkey=ef18d7e7-963b-470f-9230-c7f9de166888

Where authkey=ef18d7e7-963b-470f-9230-c7f9de166888 is associated to a specific user (more on this later). The capabilities document contains backlinks to the server itself, linking to the URLs that can be used to perform GetMap, GetFeatureInfo and so on. When the authkey parameter is provided the backlinks will contain the authentication key as well, allowing any compliant WMS client to access secured resources.

Limitations¶

The authkey module is meant to be used with OGC services. It won’t work properly against the administration GUI, nor RESTConfig.

Key providers¶

Key providers are responsible for mapping the authentication keys to a user. The authentication key itself is a UUID (Universal unique Identifier). A key provider needs a user/group service and it is responsible for synchronizing the authentication keys with the users contained in this service.

Key provider using user properties¶

This key provider uses a user property UUID to map the authentication key to the user. User properties are stored in the user/group service. Synchronizing is simple since the logic has to search for users not having the property UUID and add it. The property value is a generated UUID.

UUID=b52d2068-0a9b-45d7-aacc-144d16322018

If the user/group service is read only, the property has to be added from outside, no synchronizing is possible.

Key provider using a property file¶

This key provider uses a property file named authkeys.properties. The default user/group service is named default. The authkeys.properties for this service would be located at

$GEOSERVER_DATA_DIR/security/usergroup/default/authkeys.propeties

A sample file looks as follows:

# Format is authkey=username
b52d2068-0a9b-45d7-aacc-144d16322018=admin
1825efd3-20e1-4c18-9648-62c97d3ee5cb=sf
ef18d7e7-963b-470f-9230-c7f9de166888=topp

This key provider also works for read only user/group services. Synchronizing adds new users not having an entry in this file and removes entries for users deleted in the user/group service.

Key provider using an external web service¶

This key provider calls an external URL to map the authentication key to the user. This allows GeoServer to integrate into an existing security infrastructure, where a session token is shared among applications and managed through dedicated web services.

The web service URL and some other parameters can be specified to configure the mapper in details:

Option	Description
`Web Service URL, with key placeholder`	the complete URL of the key mapping webservice, with a special placeholder ({key}) that will be replaced by the current authentication key
`Web Service Response User Search Regular Expression`	a regular expression used to extract the username from the webservice response; the first matched group (the part included in parentheses) in the regular expression will be used as the user name; the default (^\s(.)\s*$) takes all the response text, trimming spaces at both ends
`Connection Timeout`	timeout to connect to the webservice
`Read Timeout`	timeout to read data from the webservice

The mapper will call the webservice using an HTTP GET request (webservice requiring POST are not supported yet), replacing the {key} placeholder in the configured URL with the actual authentication key.

If a response is received, it is parsed using the configured regular expression to extract the user name from it. New lines are automatically stripped from the response. Some examples of regular expression that can be used are:

Regular Expression	Usage
`^\\s(.)\\s*$`	all text trimming spaces at both ends
`^.?\"user\"\\s:\\s\"([^\"]+)\".$`	json response where the username is contained in a property named user
`^.?<username>(.?)</username>.*$`	xml response where the username is contained in a tag named username

Synchronizing users with the user/group service is not supported by this mapper.

Configuration¶

Configuration can be done using the administrator GUI. There is a new type of authentication filter named authkey offering the following options.

URL parameter name. This the name of URL parameter used in client HTTP requests. Default is authkey.
Key Provider. GeoSever offers the providers described above.
User/group service to be used.

Some of the key providers can require additional configuration parameter. These will appear under the Key Provider combobox when one of those is selected.

After configuring the filter it is necessary to put this filter on the authentication filter chain(s).

Note

The administrator GUI for this filter has button Synchronize. Clicking on this button saves the current configuration and triggers a synchronize. If users are added/removed from the backing user/group service, the synchronize logic should be triggered.

Provider pluggability¶

With some Java programming it is possible to programmatically create and register a new key to user name mapper that works under a different logic. For example, you could have daily tokens, token generators and the like.

In order to provide your custom mapper you have to implement the org.geoserver.security.AuthenticationKeyMapper interface and then register said bean in the Spring application context. Alternatively it is possible to subclass from org.geoserver.security.AbstractAuthenticationKeyMapper. A mapper (key provider) has to implement

/**
 *
 * Maps a unique authentication key to a user name. Since user names are
 * unique within a {@link GeoServerUserGroupService} an individual mapper
 * is needed for each service offering this feature.
 *
 * @author Andrea Aime - GeoSolution
 */
public interface AuthenticationKeyMapper extends BeanNameAware {

    /**
     * Maps the key provided in the request to the {@link GeoServerUser} object
     * of the corresponding user, or returns null
     * if no corresponding user is found
     *
     * Returns <code>null</code> if the user is disabled
     *
     * @param key
     * @return
     */
    GeoServerUser getUser(String key) throws IOException;

    /**
     * Assures that each user in the corresponding {@link GeoServerUserGroupService} has
     * an authentication key.
     *
     * returns the number of added authentication keys
     *
     * @throws IOException
     */
    int synchronize() throws IOException;

    /**
     * Returns <code>true</code> it the mapper can deal with read only u
     * user/group services
     *
     * @return
     */
    boolean supportsReadOnlyUserGroupService();

    String getBeanName();

    void setUserGroupServiceName(String serviceName);
    String getUserGroupServiceName();

    public GeoServerSecurityManager getSecurityManager();
    public void setSecurityManager(GeoServerSecurityManager securityManager);

}

The mapper would have to be registered in the Spring application context in a applicationContext.xml file in the root of your jar. Example for an implementation named com.mycompany.security.SuperpowersMapper:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
  <bean id="superpowersMapper" class="com.mycompany.security.SuperpowersMapper"/>
</beans>

At this point you can drop the authkey jar along with your custom mapper jar and use it in the administrator GUI of the authentication key filter.