Question

when user=admin and pass=1234 login in page login.aspx login.

in page product.aspx how can access this user (that valid uset)without login aging

protected void btnligon_Click(object sender, EventArgs e)
{
    if (user.Text == "admin" && pass.Text == "12abAB!@")
        Response.Redirect("dialog1.aspx");
    else
        mess.InnerText = "login fail";
}

Answer 1

Suggest using Forms Authentication with the credentials in your web.config.

<authentication mode="Forms"> 
    <forms name="Auth"  requireSSL="false"
           loginUrl="~/login.aspx" defaultUrl="~/default.aspx" >
    <credentials passwordFormat="Clear">
         <user name="SomeUserName" password="SomePassword"/>    
    </credentials>
    </forms>
</authentication>
<authorization>
    <deny users="?" />
</authorization>