Normally applications should register themselves for all protocols they understand. This works great for http:, https: (webbrowsers) and mailto: (MUAs). You can even configure which program should "own" a protocol if you have more than one. Some programs don't bother registering for whatever reason. E.g., the makers of PuTTY refuse to register PuTTY as ssh: handler because there is no proper standard for ssh: URLs, yet. If you're like me and can't wait for that standard to be set in stone, then you could simply assume ssh: links will look a lot like telnet: links and use UrlConf to register PuTTY as ssh: protocol handler. UrlConf is a program to configure URL protocol handlers. If you want to make a click on a ssh://-link open PuTTY, or if you are curious what URL protocols your Windows supports out of the box then UrlConf can help you.....(free).....