how i restrict the user who enter the site without login

<pre lang="xml">&lt;authentication mode=&quot;Forms&quot;&gt;
            &lt;forms defaultUrl=&quot;Secured/Default.aspx&quot; loginUrl=&quot;Login.aspx&quot;&gt;
      &lt;/forms&gt;
        &lt;/authentication&gt;</pre>

<pre lang="xml">&lt;system.web&gt;
            &lt;authorization&gt;
                &lt;deny users=&quot;?&quot;/&gt;
            &lt;/authorization&gt;
        &lt;/system.web&gt;</pre>
in the code behind
<pre lang="cs">protected void btn_Submit_Click(object sender, EventArgs e)
        {
            if (TextBox1.Text == &quot;UserName&quot;)
            {
                if (TextBox2.Text == &quot;Password&quot;)
                {
                   // Response.Redirect(&quot;~/Secured/Secured2.aspx&quot;);
                    FormsAuthentication.RedirectFromLoginPage(TextBox1.Text, false);
                }
                else
                {
                    Label1.Text = &quot;Enter Correct Password&quot;;
                }
            }
            else
            {
                Label1.Text = &quot;Enter Correct User Name&quot;;
            }
        }</pre>
<pre lang="sql">Use Forms Authentication for that
try this link
Link [^]</pre>

I think you need to read up a bit on authentication and how it works in an IIS environment. What you are asking for should not be handled only in code and SQL Server. You should incorporate built in IIS authentication processes to achieve your goal.
Check out some of these links.

You should read this:

Scott Gu's Blog Entry[^]

Use Forms Authentication.
Use some thing like this at web.config

<location path="secure">
    <system.web>
      <authorization>
        <deny users="?"/>
        <deny users="jhon"/>
      </authorization>
    </system.web>
  </location>

secure is a folder which contains your secure webforms.

<authentication mode="Forms">
      <forms loginUrl="Default.aspx"
           protection="All"
           timeout="30"
           name=".ASPXAUTH"
           path="/"
           requireSSL="false"
           slidingExpiration="true"
           defaultUrl="default.aspx"
           cookieless="UseDeviceProfile"
           enableCrossAppRedirects="false" >
        <credentials passwordFormat="Clear">
          <user name="kim" password="kim@123"/>
          <user name="jhon" password="jhonn"/>
        </credentials>
      </forms>
    </authentication>

Now at server side code

Default.aspx is your login form, Drag Two TextBoxes and a Button
at click event of button write following code. Default2.aspx is destination page. Secure is a folder which can have webforms which you wants to make secure

if 

(FormsAuthentication.Authenticate(

TextBox1.Text, TextBox2.Text))
        {
            

FormsAuthentication.SetAuthCookie(
                 

this.TextBox1.Text.Trim(), false);

            

FormsAuthenticationTicket ticket1 

=
               new 

FormsAuthenticationTicket(
                    1,             

                      // version
                    

this.TextBox1.Text.Trim(),   // 

get username  from the form
                    DateTime.Now,  

                      // issue 

time is now
                    

DateTime.Now.AddMinutes(10),       

  // expires in 10 minutes
                    false,      // 

cookie is not persistent
                    "HR"           

                   // role 

assignment is stored
                // in userData
                    );
            HttpCookie cookie1 = 

new HttpCookie(
              

FormsAuthentication.FormsCookieNam

e,
              

FormsAuthentication.Encrypt(ticket

1));
            

Response.Cookies.Add(cookie1);

            // 4. Do the redirect. 
            String returnUrl1;
            // the login is 

successful
            if 

(Request.QueryString["ReturnUrl"] 

== null)
            {
                returnUrl1 = 

"Default2.aspx";
            }

            //login not 

unsuccessful 
            else
            {
                returnUrl1 = 

Request.QueryString["ReturnUrl"];
            }
            

Response.Redirect(returnUrl1);

        }