Parameters in /webaccess/

In this section, we will describe all the parameters currently used by the ThinLinc Web Access client. These configuration parameters reside in /opt/thinlinc/etc/conf.d/webaccess.hconf.

/webaccess/cert

The path to the certificate file to be used for TLS encryption.

Note

This certificate may be downloaded by connecting clients to be installed in their browsers. Make sure that this file does not contain a private key.

/webaccess/certkey

The path to the certificate private key file used for TLS encryption.

/webaccess/gnutls_priority

The GnuTLS priority string is used to select the order and availability of TLS versions, ciphers, key exchange, MAC, compression, signature and elliptic curve algorithms for TLS sessions. See GnuTLS priority strings for possible values.

/webaccess/logging/logfile

The file to use for logging tlwebaccess messages. By default, this is /var/log/tlwebaccess.log.

/webaccess/login/password

Allow logging in using traditional username and password. Enabled by default. If disabled, only OIDC login is available.

/webaccess/login_page

The URL which is used to redirect back to the Web Access login page on the master server. The default value is /, which redirects to the current server. This parameter needs to be changed when ThinLinc Web Access is used in a cluster setup.

/webaccess/listen_port

The local port for this service to listen on. The default port used is 300.

/webaccess/server_tokens

If set to true, Web Access includes the ThinLinc version, as well as Python version information in the “Server” response header field. If set to false, the “Server” response header will not include any version information. The default value is true.

Note

Disabling server_tokens might make it easier to work with some security scanners that raise alerts when this type of version information is included. But note that hiding version information does nothing to make your server more secure.

/webaccess/trusted_proxies

A space-separated list of proxies that should be considered trusted when handling the X-Forwarded-For HTTP header. Each entry in the list needs to be a valid IP address in either IPv4 or IPv6 format.

For more information on how this feature works and important security implications, see Forwarding client IP addresses.

Parameters in /webaccess/branding/

This section describes the parameters used for customizing the Web Access login page. Read more in Custom branding.

/webaccess/branding/background

The path to a background image to be displayed on the Web Access login page. Any path on the local filesystem works. This background will appear only on large screens, surrounding the central box on the login page.

The background image will be stretched to cover the entire page. A semi-transparent white overlay will be applied on top of the background. The image formats SVG, PNG, JPEG, GIF, and WEBP are supported. The file must be readable by a non-privileged user. No background image is used by default.

The path to the logo to be displayed on the Web Access login page. Any path on the local filesystem works. If this logo used, it will be displayed in place of the ThinLinc logo. A smaller variant of the ThinLinc logo will then appear below the login button.

Maximum displayed width and height is 360 px, it will be scaled down if larger. It is recommended to pick a logo that fits well on a white background. The image formats SVG, PNG, JPEG, GIF, and WEBP are supported. The file must be readable by a non-privileged user. Only the ThinLinc logo is used by default.

/webaccess/branding/title

A short string to be displayed in the browser window or tab title. This is empty by default.

Parameters in /webaccess/hsts/

This section describes the parameters used for HSTS in Web Access. Read more in Configuring HSTS headers.

/webaccess/hsts/allow_browser_preload

Requirements: policy=permanent and subdomains_included=true

With allow_browser_preload enabled, it is indicated to the browser that the intention is to add the domain, and subdomains, to the browsers’ lists. This would result in the HSTS policy being enabled at the first visit to the domain or subdomain.

Note

Only use this option if you are sure to support HTTPS for domains and subdomains. It may be difficult to remove domains and subdomains from the preload list.

/webaccess/hsts/policy

Note the warnings about enabling HSTS policy, see Configuring HSTS headers. The results should be considered permanent once enabled and are difficult to reverse. The only way to disable the HSTS policy is to wait for the specified duration, as described below, to pass until visiting the domain again.

  • Off: The default value. The HSTS header will not be sent.

  • Testing: Before setting the policy to permanent, it is recommended to test if the policy works for the intended domains to verify they support HTTPS. This value indicates to the browser that it should only remember this domain for 10 minutes.

  • Permanent: This value indicates that browsers will remember this domain for 2 years. This duration is refreshed every time a domain is revisited, which is why it should be viewed as permanent.

/webaccess/hsts/subdomains_included

The HSTS policy will be applied to the included subdomains of the ThinLinc host if enabled.

Note

It is recommended to verify that all subdomains support HTTPS before enabling this. In order to verify, set policy=testing, restart the service and then visit Web Access in the browser to enable the HSTS policy.

Parameters in /webaccess/oidc/<provider>

OpenID Connect (OIDC) providers are configured in separate sections identified by <provider>. Each section configures one provider. See OpenID Connect for setup instructions and examples.

The following four parameters are required for OIDC authentication to function:

All other parameters are optional and have sensible defaults. Detailed parameter descriptions are provided below.

/webaccess/oidc/<provider>/button_text

Optional parameter for setting custom text for the login button displayed on the Web Access login page. If not set, the button text defaults to <provider>, which is the identifier specified in the configuration section name.

/webaccess/oidc/<provider>/client_id

Specifies the client identifier assigned by the provider. The client ID is obtained during application registration at the provider.

This parameter is required and has no default value.

/webaccess/oidc/<provider>/client_secret_path

Specifies the path to a file containing the client secret. The file must contain only the secret value with no labels, comments, or additional formatting. The file must not be readable or writable by others than the file owner.

This parameter is required and has no default value.

/webaccess/oidc/<provider>/discovery_url

Specifies the OIDC discovery endpoint URL. The discovery URL provides the OIDC provider metadata. ThinLinc automatically retrieves endpoint URLs and signing keys from this URL. The URL must end with /.well-known/openid-configuration.

This parameter is required and has no default value.

/webaccess/oidc/<provider>/icon_path

Optional parameter for setting the path to a custom icon for the login button. We recommend using SVG files, but if not, the icon should be at least 20×20. The image formats SVG, PNG, JPEG, GIF, and WEBP are supported. The file must be readable by a non-privileged user. No icon is displayed by default.

/webaccess/oidc/<provider>/prompt

Optional parameter that controls authentication prompts shown at the provider.

Possible values:

  • none - Silent authentication (no prompts)

  • login - Always prompt for credentials

  • consent - Show consent screen

  • select_account - Show account selection interface

No prompt parameter is set by default, this leaves the behavior up to the provider. For details on prompt parameter behavior, refer to OpenID Connect Core 1.0 - Authentication Request.

Note

When set to none, silent authentication only succeeds if the user has an existing session at the provider. The consent value prompts for user consent on the first login, then subsequent logins follow silent authentication if consent has been granted.

/webaccess/oidc/<provider>/scope

Optional parameter for additional OAuth 2.0 scopes to be requested from the provider. The openid scope is always requested from the provider, the scopes specified here are requested in addition to it. The scopes control which claims are included. The value is a space-separated list of additional scope identifiers. Consult your provider’s documentation for available scopes.

/webaccess/oidc/<provider>/username_claim

The claim that contains the username. The value of this claim must be reliable, unique and match a Linux username on the ThinLinc server exactly. There is no universal username claim that works for all providers. See Username mapping for requirements and tips on how to approach this.

This parameter is required and has no default value.