## Chapter 5. Configuring Guacamole

After installing Guacamole, it will be minimally configured to use the default authentication, which reads all users and connections from a single, monolithic user-mapping.xml file. You can modify this configuration if you need to use a different authentication module (such as the MySQL authentication, which is discussed in a separate chapter) or if you need to veer from the defaults.

Guacamole's configuration consists of two main pieces: a directory referred to as GUACAMOLE_HOME, which is the primary search location for configuration files, and guacamole.properties, the main configuration file used by Guacamole and its extensions.

## GUACAMOLE_HOME

Guacamole reads files from its own configuration directory by default, resorting to the classpath only when this directory cannot be found. When locating this directory, Guacamole will try, in order:

1. The directory specified within the system property guacamole.home.

2. The directory specified within the environment variable GUACAMOLE_HOME.

3. The directory .guacamole, located within the home directory of the user running the servlet container.

This directory will be referred to as GUACAMOLE_HOME elsewhere in the documentation.

Guacamole uses GUACAMOLE_HOME as the primary search location for configuration file like guacamole.properties. The structure of GUACAMOLE_HOME is rigorously defined, and consists of the following optional files:

guacamole.properties

The main Guacamole configuration file. Properties within this file dictate how Guacamole will connect to guacd, and may configure the behavior of installed authentication extensions.

logback.xml

Guacamole uses a logging system called Logback for all messages. By default, Guacamole will log to the console only, but you can change this by providing your own Logback configuration file.

extensions/

The install location for all Guacamole extensions. Guacamole will automatically load all .jar files within this directory on startup.

lib/

The search directory for libraries required by any Guacamole extensions. Guacamole will make the .jar files within this directory available to all extensions. If your extensions require additional libraries, such as database drivers, this is the proper place to put them.

## guacamole.properties

The Guacamole web application uses one main configuration file called guacamole.properties. This file is the common location for all configuration properties read by Guacamole or any extension of Guacamole, including authentication providers.

In previous releases, this file had to be in the classpath of your servlet container. Now, the location of guacamole.properties can be explicitly defined with environment variables or system properties, and the classpath is only used as a last resort. When searching for guacamole.properties, Guacamole will check, in order:

1. Within GUACAMOLE_HOME, as defined above.

2. The classpath of the servlet container.

The guacamole.properties file is optional and is used to configure Guacamole in situations where the defaults are insufficient, or to provide additional configuration information for extensions. There are three standard properties that are always available for use:

guacd-host

The host the Guacamole proxy daemon (guacd) is listening on. If omitted, Guacamole will assume guacd is listening on localhost.

guacd-port

The port the Guacamole proxy daemon (guacd) is listening on. If omitted, Guacamole will assume guacd is listening on port 4822.

guacd-ssl

If set to "true", Guacamole will require SSL/TLS encryption between the web application and guacd. By default, communication between the web application and guacd will be unencrypted.

Note that if you enable this option, you must also configure guacd to use SSL via command line options. These options are documented in the manpage of guacd. You will need an SSL certificate and private key.

Example 5.1. Example guacamole.properties

# Hostname and port of guacamole proxy
guacd-hostname: localhost
guacd-port:     4822

## Logging within the web application

By default, Guacamole logs all messages to the console. Servlet containers like Tomcat will automatically redirect these messages to a log file, catalina.out in the case of Tomcat, which you can read through while Guacamole runs. Messages are logged at four different log levels, depending on message importance and severity:

error

Errors are fatal conditions. An operation, described in the log message, was attempted but could not proceed, and the failure of this operation is a serious problem that needs to be addressed.

warn

Warnings are generally non-fatal conditions. The operation continued, but encountered noteworthy problems.

info

"Info" messages are purely informational. They may be useful or interesting to administrators, but are not generally critical to proper operation of a Guacamole server.

debug

Debug messages are highly detailed and oriented toward development. Most debug messages will contain stack traces and internal information that is useful when investigating problems within code.

Guacamole logs messages using a logging framework called Logback and, by default, will only log messages at the "info" level or higher. If you wish to change the log level, or configure how or where Guacamole logs messages, you can do so by providing your own logback.xml file within GUACAMOLE_HOME. For example, to log all messages to the console, even "debug" messages, you might use the following logback.xml:

<configuration>

<!-- Appender for debugging -->
<appender name="GUAC-DEBUG" class="ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
</encoder>
</appender>

<!-- Log at DEBUG level -->
<root level="debug">
<appender-ref ref="GUAC-DEBUG"/>
</root>

</configuration>

Guacamole and the above example configure only one appender which logs to the console, but Logback is extremely flexible and allows any number of appenders which can each log to separate files, the console, etc. based on a number of criteria, including the log level and the source of the message.

More thorough documentation on configuring Logback is provided on the Logback project's web site.

## Using the default authentication

Guacamole's default authentication module is simple and consists of a mapping of usernames to configurations. This authentication module comes with Guacamole and simply reads usernames and passwords from an XML file. If you wish to use this authentication mechanism, simply do not install and authentication extensions.

There are other authentication modules available. The Guacamole project provides database-backed authentication modules with the ability to manage connections and users from the web interface, and other authentication modules can be created using the extension API provided along with the Guacamole web application, guacamole-ext.

### user-mapping.xml

The default authentication provider used by Guacamole reads all username, password, and configuration information from a file called the "user mapping". By default, Guacamole will look for this file at GUACAMOLE_HOME/user-mapping.xml, but this can be overridden by specifying the location with the user-mapping property within guacamole.properties:

user-mapping: /path/to/user-mapping.xml

An example of a user mapping file is included with Guacamole, and looks something like this:

<user-mapping>

<!-- Per-user authentication and config information -->
<protocol>vnc</protocol>
<param name="hostname">localhost</param>
<param name="port">5900</param>
</authorize>

<!-- Another user, but using md5 to hash the password
(example below uses the md5 hash of "PASSWORD") -->
<authorize
encoding="md5">

<!-- First authorized connection -->
<connection name="localhost">
<protocol>vnc</protocol>
<param name="hostname">localhost</param>
<param name="port">5901</param>
</connection>

<!-- Second authorized connection -->
<connection name="otherhost">
<protocol>vnc</protocol>
<param name="hostname">otherhost</param>
<param name="port">5900</param>
</connection>

</authorize>

</user-mapping>

Each user is specified with a corresponding <authorize> tag. This tag contains all authorized connections for that user, each denoted with a <connection> tag. Each <connection> tag contains a corresponding protocol and set of protocol-specific parameters, specified with the <protocol> and <param> tags respectively.

When using BasicFileAuthenticationProvider, username/password pairs are specified with <authorize> tags, which each have a username and password attribute. Each <authorize> tag authorizes a specific username/password pair to access all connections within the tag:

<authorize username="USER" password="PASS">
...
</authorize>

In the example above, the password would be listed in plaintext. If you don't want to do this, you can also specify your password hashed with MD5:

<authorize username="USER"
password="319f4d26e3c536b5dd871bb2c52e3178"
encoding="md5">
...
</authorize>

After modifying user-mapping.xml, the file will be automatically reread by Guacamole, and your changes will take effect immediately. The newly-added user will be able to log in - no restart of the servlet container is needed.

#### Adding connections to a user

To specify a connection within an <authorize> tag, you can either list a single protocol and set of parameters (specified with a <protocol> tag and any number of <param> tags), in which case that user will have access to only one connection named "DEFAULT", or you can specify one or more connections with one or more <connection> tags, each of which can be named and contains a <protocol> tag and any number of <param> tags.

## Configuring connections

Each protocol supported by Guacamole has its own set of configuration parameters. These parameters typically describe the hostname and port of the remote desktop server, the credentials to use when connecting, if any, and the size and color depth of the display. If the protocol supports file transfer, options for enabling that functionality will be provided as well.

### VNC

The VNC protocol is the simplest and first protocol supported by Guacamole. Although generally not as fast as RDP, many VNC servers are adequate, and VNC over Guacamole tends to be faster than VNC by itself due to decreased bandwidth usage.

VNC support for Guacamole is provided by the libguac-client-vnc library, which will be installed as part of guacamole-server if the required dependencies are present during the build.

#### Network parameters

With the exception of reverse-mode VNC connections, VNC works by making outbound network connections to a particular host which runs one or more VNC servers. Each VNC server is associated with a display number, from which the appropriate port number is derived.

Parameter nameDescription
hostname

The hostname or IP address of the VNC server Guacamole should connect to.

port

The port the VNC server is listening on, usually 5900 or 5900 + display number. For example, if your VNC server is serving display number 1 (sometimes written as :1), your port number here would be 5901.

autoretry

The number of times to retry connecting before giving up and returning an error. In the case of a reverse connection, this is the number of times the connection process is allowed to time out.

#### Authentication

The VNC standard defines only password based authentication. Other authentication mechanisms exist, but are non-standard or proprietary. Guacamole supports only the password method.

Parameter nameDescription
password

The password to use when attempting authentication, if any. This parameter is optional.

#### Display settings

VNC servers do not allow the client to request particular display sizes, so you are at the mercy of your VNC server with respect to display width and height. However, to reduce bandwidth usage, you may request that the VNC server reduce its color depth. Guacamole will automatically detect 256-color images, but this can be guaranteed for absolutely all graphics sent over the connection by forcing the color depth to 8-bit. Color depth is otherwise dictated by the VNC server.

If you are noticing problems with your VNC display, such as the lack of a mouse cursor, the presence of multiple mouse cursors, or strange colors (such as blue colors appearing more like orange or red), these are typically the result of bugs or limitations within the VNC server, and additional parameters are available to work around such issues.

Parameter nameDescription
color-depth

The color depth to request, in bits-per-pixel. This parameter is optional. If specified, this must be either 8, 16, 24, or 32. Regardless of what value is chosen here, if a particular update uses less than 256 colors, Guacamole will always send that update as a 256-color PNG.

swap-red-blue

If the colors of your display appear wrong (blues appear orange or red, etc.), it may be that your VNC server is sending image data incorrectly, and the red and blue components of each color are swapped. If this is the case, set this parameter to "true" to work around the problem. This parameter is optional.

cursor

If set to "remote", the mouse pointer will be rendered remotely, and the local position of the mouse pointer will be indicated by a small dot. A remote mouse cursor will feel slower than a local cursor, but may be necessary if the VNC server does not support sending the cursor image to the client.

encodings

A space-delimited list of VNC encodings to use. The format of this parameter is dictated by libvncclient and thus doesn't really follow the form of other Guacamole parameters. This parameter is optional, and libguac-client-vnc will use any supported encoding by default.

Beware that this parameter is intended to be replaced with individual, encoding-specific parameters in a future release.

read-only

Whether this connection should be read-only. If set to "true", no input will be accepted on the connection at all. Users will only see the desktop and whatever other users using that same desktop are doing. This parameter is optional.

#### VNC Repeater

There exist VNC repeaters, such as UltraVNC Repeater, which act as intermediaries or proxies, providing a single logical VNC connection which is then routed to another VNC server elsewhere. Additional parameters are required to select which VNC host behind the repeater will receive the connection.

Parameter nameDescription
dest-hostThe destination host to request when connecting to a VNC proxy such as UltraVNC Repeater. This is only necessary if the VNC proxy in use requires the connecting user to specify which VNC server to connect to. If the VNC proxy automatically connects to a specific server, this parameter is not necessary.
dest-portThe destination port to request when connecting to a VNC proxy such as UltraVNC Repeater. This is only necessary if the VNC proxy in use requires the connecting user to specify which VNC server to connect to. If the VNC proxy automatically connects to a specific server, this parameter is not necessary.

#### Reverse VNC connections

Guacamole supports "reverse" VNC connections, where the VNC client listens for an incoming connection from the VNC server. When reverse VNC connections are used, the VNC client and server switch network roles, but otherwise function as they normally would. The VNC server still provides the remote display, and the VNC client still provides all keyboard and mouse input.

Parameter nameDescription
reverse-connect

Whether reverse connection should be used. If set to "true", instead of connecting to a server at a given hostname and port, guacd will listen on the given port for inbound connections from a VNC server.

listen-timeout

If reverse connection is in use, the maximum amount of time to wait for an inbound connection from a VNC server, in milliseconds. If blank, the default value is 5000 (five seconds).

#### Audio support

VNC does not provide any support for audio, but Guacamole's VNC support can provide audio support through a secondary network connection to a PulseAudio server running on the same machine as the VNC server. Guacamole will thus combine two separate streams (one graphical stream and one audio stream) from two distinct network sources into a single stream of Guacamole protocol data.

The following parameters are available for configuring the experimental audio support for VNC:

Parameter nameDescription
enable-audio

If set to "true", experimental sound support will be enabled. VNC does not support sound, but Guacamole's VNC support can include sound using PulseAudio.

Most Linux systems provide audio through a service called PulseAudio. This service is capable of communicating over the network. If PulseAudio is configured to allow TCP connections, Guacamole can connect to your PulseAudio server and combine its audio with the graphics coming over VNC.

Beware that you must disable authentication within PulseAudio in order to allow Guacamole to connect, as Guacamole does not yet support this. The amount of latency you will see depends largely on the network and how PulseAudio is configured.

audio-servername

The name of the PulseAudio server to connect to. This will be the hostname of the computer providing audio for your connection via PulseAudio, most likely the same as the value given for the hostname parameter.

If this parameter is omitted, the default PulseAudio device will be used, which will be the PulseAudio server running on the same machine as guacd.

### Important

Audio support within VNC is experimental. Please report any problems encountered while using the experimental audio support for VNC to the Guacamole team by opening an issue in JIRA.

If you are using the default authentication built into Guacamole, and you wish to grant access to a VNC connection to a particular user, you need to locate the <authorize> section for that user within your user-mapping.xml, and add a section like the following within it:

<connection name="Unique Name">
<protocol>vnc</protocol>
<param name="hostname">localhost</param>
<param name="port">5901</param>
</connection>

If added exactly as above, a new connection named "Unique Name" will be available to the user associated with the <authorize> section containing it. The connection will use VNC to connect to localhost at port 5901. Naturally, you will want to change some or all of these values.

If your VNC server requires a password, or you wish to specify other configuration parameters (to reduce the color depth, for example), you will need to add additional <param> tags accordingly.

Other authentication methods will provide documentation describing how to configure new connections. If the authentication method in use fully implements the features of Guacamole's authentication API, you will be able to add a new VNC connection easily and intuitively using the administration interface built into Guacamole. You will not need to edit configuration files.

#### Which VNC server?

The choice of VNC server can make a big difference when it comes to performance, especially over slower networks. While many systems provide VNC access by default, using this is often not the fastest method.

##### RealVNC or TigerVNC

RealVNC, and its derivative TigerVNC, perform quite well. In our testing, they perform the best with Guacamole. If you are okay with having a desktop that can only be accessed via VNC, one of these is likely your best choice. Both optimize window movement and (depending on the application) scrolling, giving a very responsive user experience.

##### TightVNC

TightVNC is widely-available and performs generally as well as RealVNC or TigerVNC. If you wish to use TightVNC with Guacamole, performance should be just fine, but we highly recommend disabling its JPEG encoding. This is because images transmitted to Guacamole are always encoded losslessly as PNG images. When this operation is performed on a JPEG image, the artifacts present from JPEG's lossy compression reduce the compressibility of the image for PNG, thus leading to a slower experience overall than if JPEG was simply not used to begin with.

##### x11vnc

The main benefit of using x11vnc is that it allows you to continue using your desktop normally, while simultaneously exposing control of your desktop via VNC. Performance of x11vnc is comparable to RealVNC, TigerVNC, and TightVNC. If you need to use your desktop locally as well as via VNC, you will likely be quite happy with x11vnc.

##### vino

vino is the VNC server that comes with the Gnome desktop environment, and is enabled if you enable "desktop sharing" via the system preferences available within Gnome. If you need to share your local desktop, we recommend using x11vnc rather vino, as it has proven more performant and feature-complete in our testing. If you don't need to share a local desktop but simply need an environment you can access remotely, using a VNC server like RealVNC, TigerVNC, or TightVNC is a better choice.

##### QEMU or KVM

QEMU (and thus KVM) expose the displays of virtual machines using VNC. If you need to see the virtual monitor of your virtual machine, using this VNC connection is really your only choice. As the VNC server built into QEMU cannot be aware of higher-level operations like window movement, resizing, or scrolling, those operations will tend to be sent suboptimally, and will not be as fast as a VNC server running within the virtual machine.

If you wish to use a virtual machine for desktop access, we recommend installing a native VNC server inside the virtual machine after the virtual machine is set up. This will give a more responsive desktop.

### RDP

The RDP protocol is more complicated than VNC and was the second protocol officially supported by Guacamole. RDP tends to be faster than VNC due to the use of caching, which Guacamole does take advantage of.

RDP support for Guacamole is provided by the libguac-client-rdp library, which will be installed as part of guacamole-server if the required dependencies are present during the build.

#### Network parameters

RDP connections require a hostname or IP address defining the destination machine. The RDP port is defined to be 3389, and will be this value in most cases. You only need to specify the RDP port if you are not using port 3389.

Parameter nameDescription
hostname

The hostname or IP address of the RDP server Guacamole should connect to.

port

The port the RDP server is listening on, usually 3389. This parameter is optional. If this is not specified, the default of 3389 will be used.

#### Authentication and security

RDP provides authentication through the use of a username, password, and optional domain.

Most RDP servers will provide a graphical login if the username, password, and domain parameters are omitted. One notable exception to this is Network Level Authentication, or NLA, which performs all authentication outside of a desktop session, and thus in the absence of a graphical interface. If your server requires NLA, you will need to manually choose this as your security mode, and you must provide a username and password.

All RDP connections are encrypted. Higher-grade encryption is available in the form of TLS, another possible security mode.

Parameter nameDescription
username

The username to use to authenticate, if any. This parameter is optional.

password

The password to use when attempting authentication, if any. This parameter is optional.

domain

The domain to use when attempting authentication, if any. This parameter is optional.

security

The security mode to use for the RDP connection. This mode dictates how data will be encrypted and what type of authentication will be performed, if any. By default, the server is allowed to control what type of security is used.

Possible values are:

rdp

Standard RDP encryption. This mode should be supported by all RDP servers.

nla

Network Level Authentication. This mode requires the username and password, and performs an authentication step before the remote desktop session actually starts. If the username and password are not given, the connection cannot be made.

tls

TLS encryption. TLS (Transport Layer Security) is the successor to SSL.

any

Allow the server to choose the type of security. This is the default.

ignore-cert

If set to "true", the certificate returned by the server will be ignored, even if that certificate cannot be validated. This is useful if you universally trust the server and your connection to the server, and you know that the server's certificate cannot be validated (for example, if it is self-signed).

disable-auth

If set to "true", authentication will be disabled. Note that this refers to authentication that takes place while connecting. Any authentication enforced by the server over the remote desktop session (such as a login dialog) will still take place. By default, authentication is enabled and only used when requested by the server.

If you are using NLA, authentication must be enabled by definition.

#### Session settings

RDP sessions will typically involve the full desktop environment of a normal user. Alternatively, you can manually specify a program to use instead of the RDP server's default shell, or connect to the administrative console.

Although Guacamole is independent of keyboard layout, RDP is not. This is because Guacamole represents keys based on what they do ("press the Enter key"), while RDP uses identifiers based on the key's location ("press the rightmost key in the second row"). To translate between a Guacamole key event and an RDP key event, Guacamole must know ahead of time the keyboard layout of the RDP server.

By default, the US English qwerty keyboard will be used. If this does not match the keyboard layout of your RDP server, keys will not be properly translated, and you will need to explicitly choose a different layout in your connection settings. If your keyboard layout is not supported, please notify the Guacamole team by opening an issue in JIRA.

Parameter nameDescription
client-name

When connecting to the RDP server, Guacamole will normally provide its own hostname as the name of the client. If this parameter is specified, Guacamole will use its value instead.

On Windows RDP servers, this value is exposed within the session as the CLIENTNAME environment variable.

console

If set to "true", you will be connected to the console (admin) session of the RDP server.

initial-program

The full path to the program to run immediately upon connecting. This parameter is optional.

server-layout

The server-side keyboard layout. This is the layout of the RDP server and has nothing to do with the keyboard layout in use on the client. The Guacamole client is independent of keyboard layout. The RDP protocol, however, is not independent of keyboard layout, and Guacamole needs to know the keyboard layout of the server in order to send the proper keys when a user is typing.

Possible values are:

en-us-qwerty

English (US) keyboard

de-de-qwertz

German keyboard (qwertz)

fr-fr-azerty

French keyboard (azerty)

it-it-qwerty

Italian keyboard

sv-se-qwerty

Swedish keyboard

failsafe

Unknown keyboard - this option sends only Unicode events and should work for any keyboard, though not necessarily all RDP servers or applications.

If your server's keyboard layout is not yet supported, this option should work in the meantime.

#### Display settings

Guacamole will automatically choose an appropriate display size for RDP connections based on the size of the browser window and the DPI of the device. The size of the display can be forced by specifying explicit width or height values.

To reduce bandwidth usage, you may also request that the server reduce its color depth. Guacamole will automatically detect 256-color images, but this can be guaranteed for absolutely all graphics sent over the connection by forcing the color depth to 8-bit. Color depth is otherwise dictated by the RDP server.

Parameter nameDescription
color-depth

The color depth to request, in bits-per-pixel. This parameter is optional. If specified, this must be either 8, 16, or 24. Regardless of what value is chosen here, if a particular update uses less than 256 colors, Guacamole will always send that update as a 256-color PNG.

width

The width of the display to request, in pixels. This parameter is optional. If this value is not specified, the width of the connecting client display will be used instead.

height

The height of the display to request, in pixels. This parameter is optional. If this value is not specified, the height of the connecting client display will be used instead.

dpi

The desired effective resolution of the client display, in DPI. This parameter is optional. If this value is not specified, the resolution and size of the client display will be used together to determine, heuristically, an appropriate resolution for the RDP session.

#### Device redirection

Device redirection refers to the use of non-display devices over RDP. Guacamole's RDP support currently allows redirection of audio, printing, and disk access, some of which require additional configuration in order to function properly.

Audio redirection will be enabled by default. If Guacamole was correctly installed, and audio redirection is supported by your RDP server, sound should play within remote connections without manual intervention.

Printing requires GhostScript to be installed on the Guacamole server, and allows users to print arbitrary documents directly to PDF. When documents are printed to the redirected printer, the user will receive a PDF of that document within their web browser.

Guacamole provides support for file transfer over RDP by emulating a virtual disk drive. This drive will persist on the Guacamole server, confined within the drive path specified. If drive redirection is enabled on a Guacamole SSH connection, users will be able to upload and download files as described in Chapter 9, Using Guacamole.

Parameter nameDescription
disable-audioAudio is enabled by default in both the client and in libguac-client-rdp. If you are concerned about bandwidth usage, or sound is causing problems, you can explicitly disable sound by setting this parameter to "true".
enable-printing

Printing is disabled by default, but with printing enabled, RDP users can print to a virtual printer that sends a PDF containing the document printed to the Guacamole client. Enable printing by setting this parameter to "true".

Printing support requires GhostScript to be installed. If guacd cannot find the gs executable when printing, the print attempt will fail.

enable-drive

File transfer is disabled by default, but with file transfer enabled, RDP users can transfer files to and from a virtual drive which persists on the Guacamole server. Enable file transfer support by setting this parameter to "true".

Files will be stored in the directory specified by the "drive-path" parameter, which is required if file transfer is enabled.

drive-path

The directory on the Guacamole server in which transferred files should be stored. This directory must be accessible by guacd and both readable and writable by the user that runs guacd. This parameter does not refer to a directory on the RDP server.

If file transfer is not enabled, this parameter is ignored.

console-audio

If set to "true", audio will be explicitly enabled in the console (admin) session of the RDP server. Setting this option to "true" only makes sense if the console parameter is also set to "true".

static-channels

A comma-separated list of static channel names to open and expose as pipes. If you wish to communicate between an application running on the remote desktop and JavaScript, this is the best way to do it. Guacamole will open an outbound pipe with the name of the static channel. If JavaScript needs to communicate back in the other direction, it should respond by opening another pipe with the same name.

Guacamole allows any number of static channels to be opened, but protocol restrictions of RDP limit the size of each channel name to 7 characters.

#### RemoteApp

Recent versions of Windows provide a feature called RemoteApp which allows individual applications to be used over RDP, without providing access to the full desktop environment. If your RDP server has this feature enabled and configured, you can configure Guacamole connections to use those individual applications.

Parameter nameDescription
remote-app

Specifies the RemoteApp to start on the remote desktop. If supported by your remote desktop server, this application, and only this application, will be visible to the user.

Windows requires a special notation for the names of remote applications. The names of remote applications must be prefixed with two vertical bars. For example, if you have created a remote application on your server for notepad.exe and have assigned it the name "notepad", you would set this parameter to: "||notepad".

remote-app-dir

The working directory, if any, for the remote application. This parameter has no effect if RemoteApp is not in use.

remote-app-args

The command-line arguments, if any, for the remote application. This parameter has no effect if RemoteApp is not in use.

If you are using the default authentication built into Guacamole, and you wish to grant access to a RDP connection to a particular user, you need to locate the <authorize> section for that user within your user-mapping.xml, and add a section like the following within it:

<connection name="Unique Name">
<protocol>rdp</protocol>
<param name="hostname">localhost</param>
<param name="port">3389</param>
</connection>

If added exactly as above, a new connection named "Unique Name" will be available to the user associated with the <authorize> section containing it. The connection will use RDP to connect to localhost at port 3389. Naturally, you will want to change some or all of these values.

If you want to login automatically rather than receive a login prompt upon connecting, you can specify a username and password with additional <param> tags. Other options are available for controlling the color depth, size of the screen, etc.

Other authentication methods will provide documentation describing how to configure new connections. If the authentication method in use fully implements the features of Guacamole's authentication API, you will be able to add a new RDP connection easily and intuitively using the administration interface built into Guacamole. You will not need to edit configuration files.

### SSH

Unlike VNC or RDP, SSH is a text protocol. Its implementation in Guacamole is actually a combination of a terminal emulator and SSH client, because the SSH protocol isn't inherently graphical. Guacamole's SSH support emulates a terminal on the server side, and draws the screen of this terminal remotely on the client.

SSH support for Guacamole is provided by the libguac-client-ssh library, which will be installed as part of guacamole-server if the required dependencies are present during the build.

#### Network parameters

SSH connections require a hostname or IP address defining the destination machine. SSH is standardized to use port 22 and this will be the proper value in most cases. You only need to specify the SSH port if you are not using the standard port.

Parameter nameDescription
hostname

The hostname or IP address of the SSH server Guacamole should connect to.

port

The port the SSH server is listening on, usually 22. This parameter is optional. If this is not specified, the default of 22 will be used.

#### Authentication

SSH provides authentication through passwords and public key authentication.

For Guacamole to use public key authentication, it must have access to your private key and, if applicable, its passphrase. If the private key requires a passphrase, but no passphrase is provided, you will be prompted for the passphrase upon connecting.

If no private key is provided, Guacamole will attempt to authenticate using a password, reading that password from the connection parameters, if provided, or by prompting the user directly.

Parameter nameDescription
username

The username to use to authenticate, if any. This parameter is optional. If not specified, you will be prompted for the username upon connecting.

password

The password to use when attempting authentication, if any. This parameter is optional. If not specified, you will be prompted for your password upon connecting.

private-key

The entire contents of the private key to use for public key authentication. If this parameter is not specified, public key authentication will not be used. The private key must be in OpenSSH format, as would be generated by the OpenSSH ssh-keygen utility.

passphrase

The passphrase to use to decrypt the private key for use in public key authentication. This parameter is not needed if the private key does not require a passphrase. If the private key requires a passphrase, but this parameter is not provided, the user will be prompted for the passphrase upon connecting.

#### Display settings

Guacamole's SSH support provides a display, but not in the same sense as a remote desktop protocol like VNC or RDP. The display is a terminal emulator, and thus provides options for configuring the font used and its size. In this case, the chosen font must be installed on the server, as it is the server that will handle rendering of characters to the terminal display, not the client.

Parameter nameDescription
font-name

The name of the font to use. This parameter is optional. If not specified, the default of "monospace" will be used instead.

font-size

The size of the font to use, in points. This parameter is optional. If not specified, the default of 12 will be used instead.

#### SFTP

Guacamole provides support for file transfer over SSH using SFTP, the file transfer protocol built into most SSH servers. If SFTP is enabled on a Guacamole SSH connection, users will be able to upload and download files as described in Chapter 9, Using Guacamole.

Parameter nameDescription
enable-sftp

Whether file transfer should be enabled. If set to "true", the user will be allowed to upload or download files from the SSH server using SFTP. Guacamole includes the guacctl utility which controls file downloads and uploads when run on the SSH server by the user over the SSH connection.

If you are using the default authentication built into Guacamole, and you wish to grant access to a SSH connection to a particular user, you need to locate the <authorize> section for that user within your user-mapping.xml, and add a section like the following within it:

<connection name="Unique Name">
<protocol>ssh</protocol>
<param name="hostname">localhost</param>
<param name="port">22</param>
</connection>

If added exactly as above, a new connection named "Unique Name" will be available to the user associated with the <authorize> section containing it. The connection will use SSH to connect to localhost at port 22. Naturally, you will want to change some or all of these values.

If you want to login automatically rather than receive a login prompt upon connecting, you can specify a username and password with additional <param> tags. Other options are available for controlling the font.

Other authentication methods will provide documentation describing how to configure new connections.

### Telnet

Telnet is a text protocol and provides similar functionality to SSH. By nature, it is not encrypted, and does not provide support for file transfer. As far as graphics are concerned, Guacamole's telnet support works in the same manner as SSH: it emulates a terminal on the server side which renders to the Guacamole client's display.

Telnet support for Guacamole is provided by the libguac-client-telnet library, which will be installed as part of guacamole-server if the required dependencies are present during the build.

#### Network parameters

Telnet connections require a hostname or IP address defining the destination machine. Telnet is standardized to use port 23 and this will be the proper value in most cases. You only need to specify the telnet port if you are not using the standard port.

Parameter nameDescription
hostname

The hostname or IP address of the telnet server Guacamole should connect to.

port

The port the telnet server is listening on, usually 23. This parameter is optional. If this is not specified, the default of 23 will be used.

#### Authentication

Telnet does not actually provide any standard means of authentication. Authentication over telnet depends entirely on the login process running on the server and is interactive. To cope with this, Guacamole provides non-standard mechanisms for automatically passing the username and entering password. Whether these mechanisms work depends on specific login process used by your telnet server.

The de-facto method for passing the username automatically via telnet is to submit it via the USER environment variable, sent using the NEW-ENVIRON option. This is the mechanism used by most telnet clients, typically via the -l command-line option.

Passwords cannot typically be sent automatically - at least not as reliably as the username. There is no PASSWORD environment variable (this would actually be a horrible idea) nor any similar mechanism for passing the password to the telnet login process, and most telnet clients provide no built-in support for automatically entering the password. The best that can be done is to heuristically detect the password prompt, and type the password on behalf of the user when the prompt appears. The prescribed method for doing this with a traditional command-line telnet is to use a utility like expect. Guacamole provides similar functionality by searching for the password prompt with a regular expression.

If Guacamole receives a line of text which matches the regular expression, the password is automatically sent. If no such line is ever received, the password is not sent, and the user must type the password manually. Pressing any key during this process cancels the heuristic password prompt detection.

If the password prompt is not being detected properly, you can try using your own regular expression by specifying it within the password-regex parameter. The regular expression must be written in the POSIX ERE dialect (the dialect typically used by egrep).

Parameter nameDescription
username

The username to use to authenticate, if any. This parameter is optional. If not specified, or not supported by the telnet server, the login process on the telnet server will prompt you for your credentials. For this to work, your telnet server must support the NEW-ENVIRON option, and the telnet login process must pay attention to the USER environment variable. Most telnet servers satisfy this criteria.

password

The password to use when attempting authentication, if any. This parameter is optional. If specified, your password will be typed on your behalf when the password prompt is detected.

username-regex

The regular expression to use when waiting for the username prompt. This parameter is optional. If not specified, a reasonable default built into Guacamole will be used. The regular expression must be written in the POSIX ERE dialect (the dialect typically used by egrep).

password-regex

The regular expression to use when waiting for the password prompt. This parameter is optional. If not specified, a reasonable default built into Guacamole will be used. The regular expression must be written in the POSIX ERE dialect (the dialect typically used by egrep).

#### Display settings

Guacamole's telnet support provides a display, but not in the same sense as a remote desktop protocol like VNC or RDP. The display is a terminal emulator, and thus provides options for configuring the font used and its size. In this case, the chosen font must be installed on the server, as it is the server that will handle rendering of characters to the terminal display, not the client.

Parameter nameDescription
font-name

The name of the font to use. This parameter is optional. If not specified, the default of "monospace" will be used instead.

font-size

The size of the font to use, in points. This parameter is optional. If not specified, the default of 12 will be used instead.

If you are using the default authentication built into Guacamole, and you wish to grant access to a telnet connection to a particular user, you need to locate the <authorize> section for that user within your user-mapping.xml, and add a section like the following within it:

<connection name="Unique Name">
<protocol>telnet</protocol>
<param name="hostname">localhost</param>
<param name="port">23</param>
</connection>

If added exactly as above, a new connection named "Unique Name" will be available to the user associated with the <authorize> section containing it. The connection will use telnet to connect to localhost at port 23. Naturally, you will want to change some or all of these values.

As telnet is inherently insecure compared to SSH, you should use SSH instead wherever possible. If Guacamole is set up to use HTTPS then communication with the Guacamole client will be encrypted, but communication between guacd and the telnet server will still be unencrypted. You should not use telnet unless the network between guacd and the telnet server is trusted.

### Parameter tokens

The values of connection parameters can contain "tokens" which will be replaced by Guacamole when used. These tokens allow the values of connection parameters to vary dynamically by the user using the connection, and provide a simple means of forwarding authentication information without storing that information in the connection configuration itself, so long as the remote desktop connection uses the same credentials as Guacamole.

Each token is of the form ${TOKEN_NAME}, where TOKEN_NAME is some descriptive name for the value the token represents. Tokens with no corresponding value will never be replaced, but should you need such text within your connection parameters, and wish to guarantee that this text will not be replaced with a token value, you can escape the token by adding an additional leading "$", as in "{TOKEN_NAME}".

${GUAC_USERNAME} The username of the current Guacamole user. When a user accesses this connection, this token will be dynamically replaced with the username they provided when logging in to Guacamole. ${GUAC_PASSWORD}

The password of the current Guacamole user. When a user accesses this connection, this token will be dynamically replaced with the password they used when logging in to Guacamole.

Note that these tokens are replaced dynamically each time a connection is used. If two different users access the same connection at the same time, both users will be connected independently of each other using different sets of connection parameters.

## Configuring guacd

guacd is configured with a configuration file called guacd.conf, by default located in /etc/guacamole. This file follows a simple, INI-like format:

#
# guacd configuration file
#

[daemon]

pid_file = /var/run/guacd.pid
log_level = info

[server]

bind_host = localhost
bind_port = 4822

#
# The following parameters are valid only if
# guacd was built with SSL support.
#

[ssl]

server_certificate = /etc/ssl/certs/guacd.crt
server_key = /etc/ssl/private/guacd.key

Configuration options are given as parameter/value pairs, where the name of the parameter is specified on the left side of an "=", and the value is specified on the right. Each parameter must occur within a proper section, indicated by a section name within brackets. The names of these sections are important; it is the pairing of a section name with a parameter that constitutes the fully-qualified parameter being set.

For the sake of documentation and readability, comments can be added anywhere within guacd.conf using "#" symbols. All text following a "#" until end-of-line will be ignored.

If you need to include special characters within the value of a parameter, such as whitespace or any of the above symbols, you can do so by placing the parameter within double quotes:

[ssl]

# Whitespace is legal within double quotes ...
server_certificate = "/etc/ssl/my certs/guacd.crt"

# ... as are other special symbols
server_key = "/etc/ssl/#private/guacd.key"

Note that even within double quotes, some characters still have special meaning, such as the double quote itself or newline characters. If you need to include these, they must be "escaped" with a backslash:

# Parameter value containing a double quote
parameter = "some\"value"

# Parameter value containing newline characters
parameter2 = "line1\
line2\
line3"

# Parameter value containing backslashes
parameter3 = "c:\\windows\\path\\to\\file.txt"

Don't worry too much about the more complex formatting examples - they are only rarely necessary, and guacd will complain with parsing errors if the configuration file is somehow invalid. To ensure parameter values are entered correctly, just follow the following guidelines:

1. If the value contains no special characters, just include it as-is.

2. If the value contains any special characters (whitespace, newlines, #, \, or "), enclose the entire value within double quotes.

3. If the value is enclosed within double quotes, escape newlines, \, and " with a backslash.

Table 5.1. guacd.conf parameters

SectionNameDescription
daemonpid_file

The name of the file in which the PID of the main guacd process should be written. This is mainly needed for startup scripts, which need to monitor the state of guacd, killing it if necessary. If this parameter is specified, the user running guacd must have sufficient permissions to create or modify the specified file, or startup will fail.

daemonlog_level

The maximum level at which guacd will log messages to syslog and, if running in the foreground, the console. If omitted, the default level of info will be used.

Legal values are debug, info, warning, and error.

serverbind_host

The host that guacd should bind to when listening for connections. If unspecified, guacd will bind to localhost, and only connections from within the server hosting guacd will succeed.

serverbind_port

The port that guacd should bind to when listening for connections. If unspecified, port 4822 will be used.

sslserver_certificate

The filename of the certificate to use for SSL encryption of the Guacamole protocol. If this option is specified, SSL encryption will be enabled, and the Guacamole web application will need to be configured within guacamole.properties to use SSL as well.

sslserver_key

The filename of the private key to use for SSL encryption of the Guacamole protocol. If this option is specified, SSL encryption will be enabled, and the Guacamole web application will need to be configured within guacamole.properties to use SSL as well.

You can also affect the configuration of guacd with command-line options. If given, these options take precendence over the system-wide configuration file:

-b HOST

Changes the host or address that guacd listens on.

This corresponds to the bind_host parameter within the server section of guacd.conf.

-l PORT

Changes the port that guacd listens on (the default is port 4822).

This corresponds to the bind_port parameter within the server section of guacd.conf.

-p PIDFILE

Causes guacd to write the PID of the daemon process to the specified file. This is useful for init scripts and is used by the provided init script.

This corresponds to the pid_file parameter within the daemon section of guacd.conf.

-L LEVEL

Sets the maximum level at which guacd will log messages to syslog and, if running in the foreground, the console. Legal values are debug, info, warning, and error. The default value is info.

This corresponds to the log_level parameter within the daemon section of guacd.conf.

-f

Causes guacd to run in the foreground, rather than automatically forking into the background.

If guacd was built with support for SSL, data sent via the Guacamole protocol can be encrypted with SSL if an SSL certificate and private key are given with the following options:

-C CERTIFICATE

The filename of the certificate to use for SSL encryption of the Guacamole protocol. If this option is specified, SSL encryption will be enabled, and the Guacamole web application will need to be configured within guacamole.properties to use SSL as well.

This corresponds to the server_certificate parameter within the ssl section of guacd.conf.

-K KEY

The filename of the private key to use for SSL encryption of the Guacamole protocol. If this option is specified, SSL encryption will be enabled, and the Guacamole web application will need to be configured within guacamole.properties to use SSL as well.

This corresponds to the server_key parameter within the ssl section of guacd.conf.