您还可以通过向浏览器返回“Strict-Transport-Security”报头来使用HSTS。浏览器必须支持这一点(目前主要是Chrome和Firefox支持)，但这意味着一旦设置好，浏览器将不会通过HTTP向站点发出请求，而是在发出请求之前将它们转换为HTTPS请求。尝试结合从HTTP重定向:

protected void Application_BeginRequest(Object sender, EventArgs e)
{
  switch (Request.Url.Scheme)
  {
    case "https":
      Response.AddHeader("Strict-Transport-Security", "max-age=300");
      break;
    case "http":
      var path = "https://" + Request.Url.Host + Request.Url.PathAndQuery;
      Response.Status = "301 Moved Permanently";
      Response.AddHeader("Location", path);
      break;
  }
}

不了解HSTS的浏览器将忽略头文件，但仍然会被switch语句捕获并发送到HTTPS。

如果你不能在IIS中设置这个，我会做一个HTTP模块，为你重定向:

using System;
using System.Web;

namespace HttpsOnly
{
    /// <summary>
    /// Redirects the Request to HTTPS if it comes in on an insecure channel.
    /// </summary>
    public class HttpsOnlyModule : IHttpModule
    {
        public void Init(HttpApplication app)
        {
            // Note we cannot trust IsSecureConnection when 
            // in a webfarm, because usually only the load balancer 
            // will come in on a secure port the request will be then 
            // internally redirected to local machine on a specified port.

            // Move this to a config file, if your behind a farm, 
            // set this to the local port used internally.
            int specialPort = 443;

            if (!app.Context.Request.IsSecureConnection 
               || app.Context.Request.Url.Port != specialPort)
            {
               app.Context.Response.Redirect("https://" 
                  + app.Context.Request.ServerVariables["HTTP_HOST"] 
                  + app.Context.Request.RawUrl);    
            }
        }

        public void Dispose()
        {
            // Needed for IHttpModule
        }
    }
}

然后将其编译为DLL，将其作为项目的引用添加到web.config中:

 <httpModules>
      <add name="HttpsOnlyModule" type="HttpsOnly.HttpsOnlyModule, HttpsOnly" />
 </httpModules>

如果SSL支持在您的站点中不可配置(例如。应该能够打开/关闭https) -你可以在任何你希望保护的控制器/控制器动作上使用[RequireHttps]属性。

这是基于@特洛伊·亨特的更全面的回答。将这个函数添加到Global.asax.cs中的WebApplication类中:

    protected void Application_BeginRequest(Object sender, EventArgs e)
    {
        // Allow https pages in debugging
        if (Request.IsLocal)
        {
            if (Request.Url.Scheme == "http")
            {
                int localSslPort = 44362; // Your local IIS port for HTTPS

                var path = "https://" + Request.Url.Host + ":" + localSslPort + Request.Url.PathAndQuery;

                Response.Status = "301 Moved Permanently";
                Response.AddHeader("Location", path);
            }
        }
        else
        {
            switch (Request.Url.Scheme)
            {
                case "https":
                    Response.AddHeader("Strict-Transport-Security", "max-age=31536000");
                    break;
                case "http":
                    var path = "https://" + Request.Url.Host + Request.Url.PathAndQuery;
                    Response.Status = "301 Moved Permanently";
                    Response.AddHeader("Location", path);
                    break;
            }
        }
    }

(要在本地构建中启用SSL，请在项目的Properties dock中启用它)

请使用HSTS (HTTP严格传输安全)

从http://www.hanselman.com/blog/HowToEnableHTTPStrictTransportSecurityHSTSInIIS7.aspx

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <system.webServer>
        <rewrite>
            <rules>
                <rule name="HTTP to HTTPS redirect" stopProcessing="true">
                    <match url="(.*)" />
                    <conditions>
                        <add input="{HTTPS}" pattern="off" ignoreCase="true" />
                    </conditions>
                    <action type="Redirect" url="https://{HTTP_HOST}/{R:1}"
                        redirectType="Permanent" />
                </rule>
            </rules>
            <outboundRules>
                <rule name="Add Strict-Transport-Security when HTTPS" enabled="true">
                    <match serverVariable="RESPONSE_Strict_Transport_Security"
                        pattern=".*" />
                    <conditions>
                        <add input="{HTTPS}" pattern="on" ignoreCase="true" />
                    </conditions>
                    <action type="Rewrite" value="max-age=31536000" />
                </rule>
            </outboundRules>
        </rewrite>
    </system.webServer>
</configuration>

原答案(2015年12月4日取代)

基本上

protected void Application_BeginRequest(Object sender, EventArgs e)
{
   if (HttpContext.Current.Request.IsSecureConnection.Equals(false) && HttpContext.Current.Request.IsLocal.Equals(false))
   {
    Response.Redirect("https://" + Request.ServerVariables["HTTP_HOST"]
+   HttpContext.Current.Request.RawUrl);
   }
}

它会被放到global。asax。cs(或global。asax。vb)

我不知道如何在web.config中指定它

对于上面的@Joe，“这是给我一个重定向循环。在我添加代码之前，它工作得很好。有什么建议吗?——乔11月8日11月4点13分

这种情况也发生在我身上，我认为发生的情况是有一个负载均衡器在Web服务器前终止SSL请求。因此，我的Web站点总是认为请求是“http”，即使原始浏览器要求它是“https”。

I admit this is a bit hacky, but what worked for me was to implement a "JustRedirected" property that I could leverage to figure out the person was already redirected once. So, I test for specific conditions that warrant the redirect and, if they are met, I set this property (value stored in session) prior to the redirection. Even if the http/https conditions for redirection are met the second time, I bypass the redirection logic and reset the "JustRedirected" session value to false. You'll need your own conditional test logic, but here's a simple implementation of the property:

    public bool JustRedirected
    {
        get
        {
            if (Session[RosadaConst.JUSTREDIRECTED] == null)
                return false;

            return (bool)Session[RosadaConst.JUSTREDIRECTED];
        }
        set
        {
            Session[RosadaConst.JUSTREDIRECTED] = value;
        }
    }