Setting Path Permissions

For security reasons, Corda Server™ can only read Image Template files, data files and Web documents from authorized locations. Likewise, it can only write image and document files to authorized locations. By default, Corda Server can only read from its document root directory and subdirectories, and the localhost (127.0.0.1) domain. It can only write to the \images folder of the document root directory.

You must authorize any other locations to which you want Corda Server to have read or write access. For example, suppose that you wanted to load a Web document from a Web application server located at http://webapp.mycompany.com. Corda Server needs permission to retrieve data from this location. Likewise, you must authorize Corda Server to load an Image Template file from C:\InetPub on the system on which Corda Server is loaded.

Control which locations Corda Server can read or write from by editing the path.xml file. This file is located in the config directory. Edit it in a text editor (such as Microsoft* Notepad) or in Corda Server Administrator.

The Need for Security

To convince you of the need for a path.xml file and to keep you from defeating the purpose of this file, we should point out two ways by which an insecure server can be abused.

First of all, without Corda Server built-in security settings, Corda Server's save capabilities can be used to overwrite crucial system files. For example, Corda® Embedder's saveToCordaServer method allows a programmer to save images for future use to the machine running the Corda Server. A hacker can easily use this method to save an image over a system file, thus crashing the server, or to save an unrestricted number of files to disk, making you run short on critical disk space.

Note: You also need to specify a password to save images to Corda Server, so this could only happen if the password were insecure.

To prevent this from occurring, the path.xml file controls the directories to which Corda Server can write files. By default, the only directory to which images and documents can be saved is the images folder inside of the document root directory. Unless you have a really good reason to add another location, leave it this way.

The second security issue is that Corda Server can read files from URLs. Although this flexibility is one of Corda Server's most attractive features, it also presents several security risks. First of all, it makes it possible that the server can be used for denial of service attacks, by repeatedly requesting large documents from other Web servers.

It also creates the possibility of parasites—outside users that "hi-jack" another organization's Corda Server to generate their Corda images.

To prevent such abuse, the path.xml file allows you to specify a list of valid callback domains. The term callback describes any request that Corda Server makes to an outside resource for information (Image Template files, data, etc.)

Modifying path.xml

To add or remove path and URL permissions for Corda Server, modify the path.xml file.

To add permission to read from a specified URL

  1. Log in to Corda Server Administrator and go to the Security > Path / URL Permissions screen.

    The textbox on this screen contains the contents of the path.xml file. Edit the file directly in this textbox.

  2. Copy the following text (which also appears at the top of the page in Corda Server Administrator and paste it immediately above the last line:

    <Map Name=" MyAppServer " Path=" appservername.mycompany.com " Action=" allowDomain "/>

  3. Replace MyAppServer (the value of the Name attribute) with the name you want to give to this mapping.

    This name is for descriptive purposes only and is entirely up to you. In fact, this step is entirely optional.

  4. Replace appservername.mycompany.com (the value of the Path attribute) with the DNS name or IP address of the host from which Corda Server can read files.

    This allows Corda Server to read any file that comes from the specified host. For example, specifying www.mycoolstats.com lets Corda Server read from sources such as http://www.mycoolstats.com/data/110899.html, http://www.mycoolstats.com/renderer?name=bar&image_template=26, etc.

    Corda Server also supports wildcards. For instance, *.corda.com would allow any host in the corda.com domain (www.corda.com, popchart.corda.com, etc.). Similarly, 10.0.*.* allows Corda Server to read from any IP address that begins with 10.0.

  5. Click the Submit Changes button. You do not need to restart Corda Server.

To add permission to read from a specified local path

  1. Log in to Corda Server Administrator and go to the Security > Path / URL Permissions screen.

    The textbox on this screen contains the contents of the path.xml file. Edit the file directly in this textbox.

  2. Copy the following text and paste it immediately above the last line:

    <Map Name=" Read " Path=" ./path " Action=" Load "/>

    Note: This text is different from the text that appears in Corda Server Administrator.

  3. Replace Read (the value of the Name attribute) with the name you want to give to this mapping.

    This name is for descriptive purposes only, and is entirely up to you. In fact, this step is entirely optional.

  4. Replace ./path (the value of the Path attribute) with the local path from which you want to allow Corda Server to read files.

    If you precede the path with ./, Corda Server assumes it to be relative to the document root. Otherwise, it assumes the path to be an absolute path, accessible to the machine on which Corda Server is running. Put a wildcard at the end of a path to indicate that Corda Server has permission to read from any of the path's subdirectories.

    For example, setting this value to F:\InetPub\mydata\* lets Corda Server read anything from the F:\InetPub\mydata directory, as well as any of its subdirectories. Similarly, setting this value to ./data lets Corda Server read from the \data directory in the document root, but none of its subdirectories.

  5. Click the Submit Changes button. You do not need to restart Corda Server.