获取IP

/// <summary>
/// 获取当前域名
/// </summary>
/// <returns></returns>
public static string GetCurrentDomain()
{
    string domain = System.Web.HttpContext.Current.Request.ServerVariables["SERVER_NAME"].ToString();
    int index = domain.IndexOf('.') + 1;
    return domain.Substring(index, domain.Length - index);
    //return "pifazhinan.com";
}

/// <summary>
/// 根据域名获取IP
/// </summary>
/// <param name="ToEmail"></param>
/// <param name="subject"></param>
/// <param name="body"></param>
/// <returns></returns>
public static string GetIPByHost(string host)
{
    host = GetDomainByHost(host);
    //Dns.GetHostAddresses(host);
    IPHostEntry dnstoip = new IPHostEntry();
    dnstoip = Dns.Resolve(host);
    string ip = dnstoip.AddressList[0].ToString();
    return ip;
}

/// <summary>
/// 获取用户真实IP地址
/// </summary>
/// <returns>返回用户真实IP</returns>
public static string GetUserRealIp()
{
    string user_IP = "";

    if (System.Web.HttpContext.Current.Request.ServerVariables["HTTP_VIA"] != null)
    {
        user_IP = System.Web.HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"].ToString();
    }
    else
    {
        user_IP = System.Web.HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"].ToString();
    }
    return user_IP;
}