C# HttpListener without using netsh to register a

Question

My application uses a small webserver to server up some files and have a web interface for administration remotely. Right now the user has to use netsh to register the URI like so

netsh http add urlacl url=http://+:1233/ user=Chris-PC\Chris

Which is no fun for the average user. I'd like the program to be able to listen on any port specified by the user from my program without the end-user needing to using command prompt. Is there anyway to accomplish this short of just using Process.Start and running command prompt myself?

Answer 1

I wrote this to elevate perms and add http ACL entries through netsh.

Users will get prompted to make changes top their system but it's better than nothing. You might want to do this in response to an AddressAccessDeniedException

public static class NetAclChecker
{
    public static void AddAddress(string address)
    {
        AddAddress(address, Environment.UserDomainName, Environment.UserName);
    }

    public static void AddAddress(string address, string domain, string user)
    {
        string args = string.Format(@"http add urlacl url={0} user={1}\{2}", address, domain, user);

        ProcessStartInfo psi = new ProcessStartInfo("netsh", args);
        psi.Verb = "runas";
        psi.CreateNoWindow = true;
        psi.WindowStyle = ProcessWindowStyle.Hidden;
        psi.UseShellExecute = true;

        Process.Start(psi).WaitForExit();
    }
}

Answer 2

If you are using an HTTPListener, you have to use httpconfig.exe or netsh to configure your HTTPListener, because:

A. AFAIK There is no API for doing this from C#, only the command line tools

B. By default only SYSTEM or the local Administrators group can listen to http prefixes

So... if your app is running under the user's account, you need to explicitly grant access (using httpcfg.exe or netsh) because your HTTPHandler uses the HTTP.sys to share ports with the running webserver (so you can host your own web app on port 80 while IIS is running on port 80 as well).

A better solution might be to use an actual embedded web server to listen on the port you need. This won't work if another application (e.g. IIS) is already using the port, but since this DOESN'T use the HTTP.sys for port-sharing, there are no security restrictions about what user account is opening /listening on the port. Because you want the user to specify their own port, it seems acceptable to run on another port besides port 80.

My company makes a commercial product called the Neokernel Web Server (http://www.neokernel.com) that runs ASP.NET and lets you programmatically start/stop the server and set configurations; you can embed and distribute this assembly with the application.

There is also the Cassini source code which you can modify and embed, it's free but has a couple of drawbacks like no logging or SSL support.