我正在将 ASP.NET MVC 5.1 应用程序从 MembershipProvider 迁移到 ASP.NET Identity v2.0。该应用程序的功能之一是用户模拟：管理员可以像在网站上注册的任何其他用户一样登录，而无需知道密码。

我用这段代码为 MembershipProvider 实现用户模拟这不适用于身份库。

如何在 ASP.NET Identity 中实现用户模拟（不是 IIS 模拟）？

我找到了解决这个问题的办法。

基本上，我使用管理员用户名添加声明，如果此声明存在，我就知道正在发生冒充行为。当管理员想要停止模拟时，系统会检索声明的原始用户名，删除旧的模拟 cookie 并为管理员创建一个新的 cookie：

[AuthenticateAdmin] // <- make sure this endpoint is only available to admins
public async Task ImpersonateUserAsync(string userName)
{
    var context = HttpContext.Current;

    var originalUsername = context.User.Identity.Name;

    var impersonatedUser = await userManager.FindByNameAsync(userName);

    var impersonatedIdentity = await userManager.CreateIdentityAsync(impersonatedUser, DefaultAuthenticationTypes.ApplicationCookie);
    impersonatedIdentity.AddClaim(new Claim("UserImpersonation", "true"));
    impersonatedIdentity.AddClaim(new Claim("OriginalUsername", originalUsername));

    var authenticationManager = context.GetOwinContext().Authentication;
    authenticationManager.SignOut(DefaultAuthenticationTypes.ApplicationCookie);
    authenticationManager.SignIn(new AuthenticationProperties() { IsPersistent = false }, impersonatedIdentity);
}

更多信息请参阅我的博文：使用 ASP.Net Identity 2 模拟用户.

Asp.Net Core 中的用户模拟

2017 年 7 月更新：这个主题非常流行，所以我研究了 Core 中的用户模拟，原理与更新的 API 非常相似。模仿方法如下：

    [Authorize(Roles = "Admin")] // <-- Make sure only admins can access this 
    public async Task<IActionResult> ImpersonateUser(String userId)
    {
        var currentUserId = User.GetUserId();

        var impersonatedUser = await _userManager.FindByIdAsync(userId);

        var userPrincipal = await _signInManager.CreateUserPrincipalAsync(impersonatedUser);

        userPrincipal.Identities.First().AddClaim(new Claim("OriginalUserId", currentUserId));
        userPrincipal.Identities.First().AddClaim(new Claim("IsImpersonating", "true"));

        // sign out the current user
        await _signInManager.SignOutAsync();

        // If you use asp.net core 1.0
        await HttpContext.Authentication.SignInAsync(cookieOptions.ApplicationCookieAuthenticationScheme, userPrincipal);
        // If you use asp.net core 2.0 (the line above is deprecated)
        await HttpContext.SignInAsync(cookieOptions.ApplicationCookieAuthenticationScheme, userPrincipal);

        return RedirectToAction("Index", "Home");
    }

这是阻止冒充的方法：

    [Authorize(Roles = "Admin")] // <-- Make sure only admins can access this 
    public async Task<IActionResult> StopImpersonation()
    {
        if (!User.IsImpersonating())
        {
            throw new Exception("You are not impersonating now. Can't stop impersonation");
        }

        var originalUserId = User.FindFirst("OriginalUserId").Value;

        var originalUser = await _userManager.FindByIdAsync(originalUserId);

        await _signInManager.SignOutAsync();

        await _signInManager.SignInAsync(originalUser, isPersistent: true);

        return RedirectToAction("Index", "Home");
    }

完整解释在我的博客中：http://tech.trailmax.info/2017/07/user-impersonation-in-asp-net-core/GitHub 上的完整代码示例：https://github.com/trailmax/AspNetCoreImpersonation