13 Technical issues

Some technical below-the-surface info.

13.1 The intranet tool

The intranet tool was developed for recent versions of Firefox, Google Chrome, Safari, and Edge. It will work with all browsers in the same way, with only minor differences. Internet Explorer is not supported.

The interface will use the preferred language setting of your web browser. Currently, only Dutch and English (the default) are available. Configure the language preferences in your web browser to choose the interface language.

It is not possible to use Raster in multiple tabs or windows of the same browser. When Raster is active in more than one browser window or tab, your project data will get damaged and you will likely lose all your work. The tool will warn you when it may already be running in another tab.

In rare cases you may see this warning even though no other instance of the Raster tool is active. This may happen, for example, when the browser crashed and could not exit cleanly. When this happens, make absolutely clear that Raster is not running elsewhere before continuing.

It is, however, possible to use Raster with two separate browsers on the same computer. For example, once in Firefox and once in Chrome. If the project is not private but shared (see Working with the intranet application), then it is possible to work on the same project simultaneously. Shared projects can also be viewed and edited from two computers simultaneously.

13.2 Computation of vulnerability levels

For malicious vulnerabilities the frequency depends on both the worst plausible attacker and the level of difficulty, as in the table below.

The following table describes the way that the Raster tool computes a vulnerability level from a frequency and impact class.

As can be seen from the table, the inner part for frequency and impact L, M, and H match expected damage, even though frequency and impact are not fully numerical. These three classes represent modest values, for which 'frequency times impact' assessment is suitable.

When impact is extremely high (V), it does not matter what the frequency is, as the risk is unacceptable at any probability. When frequency is extremely high (i.e. near certainty), we are almost certain that damage will arise, and are therefore obliged to prepare countermeasures. In this case the risk will also be unacceptable.

When the impact is extremely low (i.e. nearly absent, symbol U), we do not really care whether the incident happens; the risk will always be extremely low to us. The same consideration applies for situations where the frequency is extremely low.

These considerations are ambiguous when one of frequency or impact is V, and the other U. However, we do have a class for ambiguity, namely A.

When either the frequency or the impact is not known, the combination also cannot be known. In these combinations, we always want to preserve ambiguity, as we believe that information to be highly relevant to decision makers. When an undetermined value (the minus symbol in the table) is involved, the result must also be undetermined as that value could turn out to be ranked as ambiguous rather than simply unknown; until we assess the value of that factor, the result of the combination is still undetermined. When neither the value A nor – is appropriate, the combination is ranked as a `plain' unknown (symbol X).

The overall vulnerability score for a node is computed by taking the 'maximum' vulnerability score of all vulnerabilities on that node. The vulnerability levels, in order from lowest to highest, are:

(lowest)   -   U   L   M   H   X   A   V   (highest)

Note that here also the symbol – indicates the 'not yet analysed' level.

13.3 Creating iconsets

An iconset is a collection of cartoon-style images to create Raster diagrams. You can create your iconsets. Use the Default iconset as an example.

Each iconset should be stored in its own directory inside the iconset directory. The name of the directory should match the name of the iconset. The iconset must contain a description in JSON format; the file must be called iconset.json; e.g. for iconset Medical the description must be stored in iconset/Medical/iconset.json. See below for the definition of the the iconset.json file.

Icons have a type (either wired link, wireless link, equipment, unknown link or actor). There must be one or more icons for each type. For each icon there must be two files: the icon and its icon mask. If no mask is specified, the mask is assumed to have the same name as its icon but with -mask appended (and with the same extension). In addition to the icon and the mask, the first icon of each type must specify the template-image (the user drags the template from the toolbar onto the workspace to create new nodes). If no template image is specified, then the name is assumed to be the icon name with -template appended.


  • icon machine.png will have the default mask machine-mask.png, and the default template will be machine-template.png.
  • icon tube.jpeg will have the default mask tube-mask.jpeg, and the default template will be tube-template.jpeg.

Files for icons, masks and templates may be stored in the iconset directory (at the same level as iconset.json) or in subdirectories.

13.3.1 Creating icons and masks

Icon and mask images typically have transparent areas. The icon is displayed on a colored background. Some areas of the icon will have the background color. The mask image determined the extent and size of the background. Non-transparent areas of the mask will take the background color, transparent areas of the mask will remain transparent. The icon is drawn on top of its background.

  • Outlines and areas that must always be visible in the foreground color: include these in the icon.
  • Areas that should be visible in the background color: make these transparent in the icon, and non-transparent in the mask.
  • Areas that should always be transparent: make these transparent in the icon and in its mask.

13.3.2 iconset.json

This must be a valid JSON file, containing a single object. Some of the (sub-)fields are multi-language strings. Multi-language strings are objects in with property names are (capitalized) language codes, and property values are the string in that language. E.g. {"EN": "This is an example", "NL": "Dit is een voorbeeld"} Fields are mandatory, unless specified as optional.


  1. setDescription: Multilanguage string (optional), a phrase describing this iconset.
  2. icons: Array of icon descriptions; see below.

The first five icons in the array must be of types tEQT, tWRD, tWLS, tUNK, tACT, in that order. Any additional icons must be specified after these five.

Icon descriptions

  1. type: String, one of tWLS, tWRD, tEQT, tUNK, tACT.
  2. image: String, the name of the image file.
  3. mask: String (optional), the name of the mask file. Default = derived from the image filename.
  4. template: String (optional), the name of an image file that can be used as the template image. Default = derived from the image filename.
  5. name: Multi-language string (optional), description of this icon. Default = image filename.
  6. width: integer (optional), the default width of the icon in pixels. Default = 100. Allowed range is 20..200
  7. height: integer (optional), the default height of the icon in pixels. Default = 30. Allowed range is 10..100
  8. title: String (optional), location of the title, one of inside, below, topleft. Inside: the title is centered horizontally and vertically within the icon. Below: the title is drawn centered and below the icon. Topleft: the title is aligned to the left margin, and vertically aligned at the top. Default = inside.
  9. margin: String (optional), left and right margin of the title as a percentage of the icon width. Does not apply when title = below. Increase the margin to fit the title inside the icon. Default = 0.
  10. offsetConnector: real number between 0.00 and 1.00 (optional). The connector is always drawn at the top of the icon; this offset specifies its horizontal location: 0.00 means at the extreme left, 0.5 means centered, 1,0 means at the extreme right. Default = 0.5.
  11. maintainAspect: boolean (optional). If false, the width and height can be adjusted independently. Default = true.

Make sure that iconset.json is a valid JSON file. Raster will report parsing errors in the Developer tools|Console.

13.4 Project Groups

This section applies to the intranet tool, not to the standalone tool.

A group is a separate area in which projects can be stored on the web server. The group’s directory can be protected using the web server’s access authorization; a sample htaccess file is provided as an example. Although groups are mainly useful for Shared projects, all Private projects belong to a specific group as well.

The default group is called public_group and has no access control; the web server administrator can override this if required.

To create a new project group (called samplegroup in these instructions):

  1. Duplicate the public_group directory structure as a new directory samplegroup. All files should be readable by the web server; the directory SharedProjects should be writable.
  2. Set access permissions, if required.
  3. Add one or more iconsets, if required.
  4. Create a suitable project to be used as the template (starting point for new projects), if required.
  5. Inspect and modify the settings file group.json if required.

13.4.1 group.json

The settings for a group are stored in a JSON configuration file. Currently the file may contain these fields:

  • classroom: (boolean, default is false) If true, classroom functionality is enabled on this group. See below.
  • template: (string, default is “Project Template”) The name of the project that will be used as the starting point when a new project is created, instead of a blank project. Set to “” to disable the template.
  • iconsets: (array of strings, default is [“Default”]) The names of the available iconsets; the first set will be used for new projects. If a template is specified, the iconset in the template project takes precedence for new projects. See the Iconsets.md for details.
  • localonly: (boolean, default is false) If true, projects cannot be retrieved nor stored on the server. The template will still be used, if present. If this set, only private projects will be possible.

A template is most useful to define default iconset, vulnerabilities and labels, instead of the builtin defaults. It is possible, although perhaps less useful, to include services and nodes in the template.

If no shared project with the template name exists, an empty project (with builtin defaults) will be used instead.

The classroom option

For training purposes it may be useful to provide sample projects to the students, which the students should not be able to modify. This can be achieved by setting the classroom property to true. When classroom functionality is enabled, opening a shared project will create a new private copy instead. This way each student can open the projects provided by the course teacher, and make their own personal changes.

Students cannot set their private projects to shared, to prevent them from uploading their work for others to see. You can think of the classroom option as “can retrieve but cannot store”.

Note: when classroom functionality is enabled, shared projects will be called “Exercises” in the project library on the Projects toolbar.

The localonly option

When localonly is set to true, the server offers even less functionality. No project can be stored on the server, as is the case when classroom is true. But in addition, no projects will be retrieved from the server. The list of projects in the Projects toolbar will only show private projects. However, the template project will still be retrieved from the server if localonly is set.

You can think of the localonly option as “cannot retrieve and cannot store”.

Preparing the web server

To put the course materials (with the classroom option) and/or template on the web server, first temporarily disable the classroom and localonly properties by setting them to false in the group.json file. Then create your projects, and share them (in the project properties using the tool) to upload them to the server. Edit as required. Finally, when all is set, edit group.json again to set classroom or localonly options to true.

When either the classroom or localonly option is true, the SharedProjects directory on the web server can be made read-only.

Iconsets for project groups

Additional iconsets can be installed in two locations: either in the img/iconset directory or in the group’s directory. Iconsets installed in img/iconset are available to all groups on the server. Iconsets installed in a group’s directory are available to projects in that group only. In either case it is not sufficient to install the iconset files on the web server: it must also be explicitly enabled using the iconset field in group.json.

Installing a new iconset therefore requires two steps: copying the new set into the iconset directory (either under img or in de group’s directory), then edit the group.json file accordingly.

13.5 Standalone configuration

This section applies to the standalone tool, not to the intranet tool.

There are a few advanced settings that can be modified by editing the prefs.json configuration file. This file is stored in the user’s application data directory:

  • On Windows: %APPDIR% (most often C:\Users\«username»\AppData\Roaming\Raster).
  • On MacOS: Library/Application Support/Raster in the user’s home directory.

13.5.1 prefs.json

The file prefs.json is used by the Raster application to save user preferences between sessions. This is a plain JSON file, and the two relevant properties are:

  • disablehardwareacceleration: Set this to false to enable hardware acceleration. It is disabled by default for maximum compatibility.

  • iconsets: This is an array of strings that specifies the names of the available iconsets. The the first name will be used for new projects. To disable the “default” iconset and only allow iconset “myicons”, use the following line:

    "iconsets": ["myicons"]

13.5.2 iconsets

Each project will use one iconset for its diagrams. Two iconsets are provided: “Default” and “Classic”. You can create and add addition iconsets; see the file Iconsets.md for details. Additional iconset must be stored in the user’s application data directory, inside the iconset directory. The iconset directory does not exist by default; create it before adding custom iconsets.