A common security practice is to allow only authenticated requests to pass through the inner firewall of the DMZ servers. The Independent Gateway supports the traditional Tableau Server authentication methods, but it also includes configuration properties that allow integrating an Apache httpd loadable module for custom authentication.
For example, by configuring SAML on Tableau Server and configuring a custom authentication module, you can require all users to authenticate with your IdP at the Independent Gateway. Only those users who are authenticated will then be able to access Tableau Server, which can then authenticate and authorize user access.
For a more detailed explanation of this authentication scheme, see Pre-authentication with an AuthN module(Link opens in a new window) in the Enterprise Deployment Guide.
To configure the authentication module, you must complete the following steps:
- Generate authentication module configuration files. When setup is complete, each module and its configuration directives will be treated as Include options making the included files logically part of the overall httpd configuration.
- Copy the configuration files to each computer running Independent Gateway. All files must be copied to the same locations on each Independent Gateway computer. Each file maps to a configuration property that is managed by Tableau Server.
- Set the configuration properties with the
tsm configuration setcommand on Tableau Server.
Do not edit the httpd configuration file (httpd.conf) on the Independent Gateway, since Independent Gateway includes logic to update httpd configuration based on changes made with TSM commands on Tableau Server.
Example authentication module configuration
For an end-to-end authentication module configuration example, see Example authentication configuration: SAML with external IdP(Link opens in a new window) in the Enterprise Deployment Guide. The example describes how to setup and configure SAML with Okta IdP and Mellon authentication module for a Tableau Server on Linux deployment running in AWS. Although the example describes the process for Linux, the configuration example is also useful for Tableau Server on Windows.
The following table describes the various configuration files that you may reference. Each file maps to a configuration property that is set onTableau Server. You only need to define the properties necessary to formulate your custom authentication configuration. Skip any configuration properties that are not needed.
|gateway.tsig.authn_module_block||Appears at the end of the set of normally loaded Apache httpd modules. The intent is that the file includes one or more
|gateway.tsig.authn_global_block||Appears after all of the
|gateway.tsig.authn_globalbottom_block||Appears at the very bottom of the configuration file, again at the global level. The intent is to provide a place for any configuration directives needed by the custom module that must specifically come after various other directives. (You are unlikely to need this.)|
|gateway.tsig.authn_location_block||Appears inside a
|gateway.tsig.authn_directory_block||This appears inside a
Appears inside one or two
<Location "/tsighk"> block
In addition to the expected
<Location "/"> block for normal request traffic, there is also a
<Location "/tsighk"> block used to service internal Independent Gateway housekeeping (HK) requests. These HK requests have their own authentication guards and will not work with typical custom SSO solutions.
You may need to explicitly exclude your custom module from attempting authentication for the HK URL path.
To determine whether you need to exclude your module, first configure the module. Then look for HK requests in the Independent Gateway access log. You should see at least a status check once or twice a minute. If those requests are receiving a 200 response code, things are probably OK. On the other hand, if those requests receive a 3xx response code (redirecting to your custom authentication provider), then you need to do something about it.
Possible solutions include:
<Location "/tsighk">block contains the directive
AuthType None, and that may be sufficient.
- The Independent Gateway httpd.conf has the standard Apache httpd directive
ProxyPreserveHost(Link opens in a new window) On. If there is an unusual circumstance that requires it to be Off or some other value, that value can be set with the TSM configuration item
- You might need some module-specific directives to disable your authentication module for
<Location "/tsighk">. You can't directly modify that block in the httpd.conf file. Instead, you can make another
<Location "/tsighk">block in your
gateway.tsig.authn_global_blockfile and let Apache httpd logically merge them. For example, some versions of mod_auth_mellon, a popular open source authentication module, requires
MellonEnable Offfor sections where it doesn't apply, even if
AuthType Noneis set in those sections.
- When creating an additional
<Location "/tsighk">section, as described in the previous bullet, you may find that the order of appearance of the various sections in the httpd.conf file makes a difference in how they affect each other. The standard
<Location "/tsighk">section appears before the standard
<Location "/">section. If your experimentation shows that some different order is needed, you might have to define another
<Location "/">section in your
gateway.tsig.authn_global_blockblock in addition to another
<Location "/tsighk">section, in which case you might not need anything in a
Troubleshoot custom authentication module configuration
A handy way to understand how the Independent Gateway will compose the httpd.conf file is to set the TSM configuration items with values that point to empty files on your Independent Gateway computers. (The files must exist, but they can be empty.) You can then look at the Independent Gateway's httpd.conf file to get a concrete understanding of where the
Include directives for the various configuration files will actually appear.
Configuration problems in the Independent Gateway httpd.conf can result in the
tsig-httpd service being unable to start. Other configuration problems may interfere with receiving configuration updates from the Independent Gateway companion service on the Tableau Server cluster. One way to recover, after you've fixed whatever caused the problem, is to copy
TSIG_DATA/config/httpd.conf, and then restart the
For more troubleshooting tips, see Troubleshooting Tableau Server Independent Gateway(Link opens in a new window) in the Enterprise Deployment Guide (EDG). The EDG provides example deployment of Tableau Server on Linux. The troubleshooting steps are useful for Windows or Linux versions of Tableau Server.