I'm looking for a way to automatically set a Socks5 proxy in Windows system settings / Internet explorer. I need some c# code to achieve this, as part of a greater SSH Tunnelling application.

I've been trying to get this working for about 2 weeks now, with no luck - I've brought the question up on stackoverflow and reddit with no good responses there either so now I'm offering a $50USD reward.

More detail here:
http://stackoverflow.com/questions/8866614/automatically-setting-internet-explorer-windows-to-use-a-socks5-proxy-using-c-sh

Cheers Eorl, that actually does look useful for a separate project :)
However I need to be able to control proxy settings system wide for this to work, not just for requests within the app itself

Except direct meddling with Microsoft's section of the registry is not supported and may break in future versions of windows. If you dont know that you probably shouldn't be programming real applications.

The right way is to find the Win32 API function that provides a supported interface, which appears to be InternetSetOption()

Check out http://msdn.microsoft.com/en-us/library/windows/desktop/aa385384(v=vs.85).aspx and then you'll have to do [DllImport]. Googling "c# internetsetoption" appears to turn up results from other people who've done similar.

Yeah changing a couple of proxy settings will break "future versions of windows" - better listen to Nath! ... not

I guess you dont read The Old New Thing, a blog by a senior Microsoft developer about (among other things) application compatibility problems. Go through the archives and there's many, many stories of applications that have either been broken or simply dont work right on all machines, simply because they with mess Windows internals instead of using Microsoft's supported API.

But if you want to be a "Works For Me" programmer, go right ahead.

I guess you dont read The Old New Thing, a blog by a senior Microsoft developer about (among other things) application compatibility problems. Go through the archives and there's many, many stories of applications that have either been broken or simply dont work right on all machines, simply because they with mess Windows internals instead of using Microsoft's supported API.

It has been a very common problem with games, especially in things like mods for Half-Life. It used to be a massive pain in the ass for a certain Counter-Strike mod (the name of which eludes me) which would not use the HL API to do something and instead used an unsupported custom way of doing things. Each new HL release, the mod would break horribly and they'd have to do a re-release a few days later once they figured out how to do it in the new version. It was a total pain in the ass for everyone.

So you can do things correctly once, or do them "incorrectly" multiple times. If you have unlimited spare time then it is probably not a hassle to do the registry hack.

Yeah changing a couple of proxy settings will break "future versions of windows" - better listen to Nath! ... not
My solution you can turn on off proxy in about 1-3 lines of code. Nathans is over complicated and a massive time waste.

It's actually your solution that's more complicated, just that the complications aren't visible until years later when they're causing unnecessary problems for the poor sap that's replaced you, your former company and Microsoft, or any/all three.
Nathan's solution is well worth the extra 10 minutes it might take to do it properly the first time.

Given that the registry is just a data-store, you have no way of knowing whether SetInternetOption() simply updates the registry and does nothing else; or whether it reaches out to tell active instances of IE that settings have changed. Or whether it will do that in the future, or provide some other key functionality that simply editing a data store cannot provide.

And of course, it actually looks pretty trivial to do the right way - eg http://www.pinvoke.net/default.aspx/wininet/internetsetoption.html assuming SetInternetOption is the right way to tell Windows about a SOCKS5 proxy - it might turn out there is no supported way to do so. But you want to establish that before going into unsupported territory.

Oh man... please tell me gamer doesn't program for a living.

As far as I can tell, it is supported via InternetSetOptions

InternetSetOption() with INTERNET_OPTION_PER_CONNECTION_OPTION

You then want a connection list with

INTERNET_PER_CONN_PROXY_SERVER
"Sets or retrieves a string containing the proxy servers."

The key bit being the that its servers - plural - ie the string format is not necessarily just an IP:port
The impression I get from http://support.microsoft.com/kb/226473 is that you can probably tell give it proxy "socks=socks://IP:port".

A simple app that spits out the results from InternetQueryOption() INTERNET_OPTION_PER_CONNECTION_OPTION should tell you the right format for the proxy string if you configure the SOCKS proxy through the GUI first. I assume its documented in MSDN somewhere, but so far my Google-fu is failing.

Got any other problems relating to health and fitness or metalwork that need addressing smashcrab? :)

fucking lol.

I knew gamer's first post was too good to be true, and then.... BAM he righted the world by being 'gamer' in the subsequent post

whilst that might be a suitable 'tweak' for one or two systems mate, it's a rubbish solution in an enterprise (or even serious Sml-Med Business) environment.

Sure, the solution might work, right up until the point where some innocuous windows update patch gets applied at 3am on a Sunday morning and nobody at the customer site has a clue as to why it suddenly stopped working.