Protocol Handlers

Overview

In order to use the clickable URLs generated by the Breakout utility when running in UI mode, we need to configure URL Handlers into the operating system so Firefox, Chrome and other browsers can handle these links.

Those Telnet and VNC URL handlers are usually not present by default on Windows, macOS or Linux.

These instructions have been tested using Windows 10 but we can assume other Windows version will also work. For other operating systems, similar instructions are available which will be added to this document over time.

For Windows 10

The following code snippets are Windows registry files that, when used properly, will make the modification required for the features outlined above.

The proper way to perform these changes is to open up a text file in Windows using e.g. Notepad, copy and paste the following sections into the text file, save those files to disk and then renaming the extension of the files from .txt to .reg.

Once the files are saved on the target computer, right click on each of the files and select “Merge”.

After merging the registry changes, close the browser and re-open the Breakout utility. Now, when clicking on a Telnet or VNC link it should automatically open Putty to the host and port from the connection URL from the Breakout lab detail page.

This document only outlines the use of Putty and UltraVNC as the Telnet and VNC clients, respectively. Changing the path will allow testing of other clients like SecureCRT but that’s outside the scope of this document.

In this particular case, the location of Putty was C:\Program Files\PuTTY\putty.exe and C:\Program Files\uvnc bvba\UltraVNC\vncviewer.exe

By replacing the Putty application .exe files in the examples below, other tools like SecureCRT should be usable as well.

Warning

Changing the registry can lead to a non-working system. We recommend to backup your registry and / or your entire computer so that the previous state can be restored, if needed.

Telnet URL Handler

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\telnet]
@="URL:Telnet Protocol"
"EditFlags"=dword:00000002
"FriendlyTypeName"="@C:\\Windows\\System32\\ieframe.dll,-907"
"URL Protocol"=""

[HKEY_CLASSES_ROOT\telnet\DefaultIcon]
@="C:\\Windows\\System32\\url.dll,0"

[HKEY_CLASSES_ROOT\telnet\shell]

[HKEY_CLASSES_ROOT\telnet\shell\open]

[HKEY_CLASSES_ROOT\telnet\shell\open\command]
@="\"C:\\Program Files\\PuTTY\\putty.exe\" %1"

SSH URL Handler

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\ssh]
@="URL:SSH Protocol"
"URL Protocol"=""
[HKEY_CLASSES_ROOT\ssh\shell]
[HKEY_CLASSES_ROOT\ssh\shell\open]
[HKEY_CLASSES_ROOT\ssh\shell\open\command]
@="C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe -Command \"$uri = [System.Uri]'%l';&\"${env:ProgramFiles}\\PuTTY\\putty.exe\" $uri.GetComponents([System.UriComponents]::UserInfo -bor [System.UriComponents]::Host, [System.UriFormat]::UriEscaped)\""

VNC URL Handler

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\vnc]
@="URL:VNC Protocol"
"URL Protocol"="http://www.uvnc.com/"

[HKEY_CLASSES_ROOT\vnc\DefaultIcon]

[HKEY_CLASSES_ROOT\vnc\shell]

[HKEY_CLASSES_ROOT\vnc\shell\open]

[HKEY_CLASSES_ROOT\vnc\shell\open\command]
@="cmd.exe /V /C \"set URL=%1& start \"\" \"C:\\Program Files\\uvnc bvba\\UltraVNC\\vncviewer.exe\" !URL:*://=!\""

Chrome Bypass Protocol Prompt

Having the URL handlers in place is OK but Chrome will prompt the user each time they click on a URL unless we bypass the prompt by adding the protocols into the protocol whitelist.

Telnet

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Chrome\URLWhitelist]
"1201"="telnet:*"

VNC

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Chrome\URLWhitelist]
"1202"="vnc:*"

For macOS

To be added.

For Linux

To be added.

References

Based on work found on StackOverflow

Similar, also includes instructions for Linux and macOS