如果用户名有3个attmept，如何阻止用户名？ [英] how to block username if the username have a 3 attmept?

问题描述

Private Sub CmdAdminLogin_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CmdAdminLogin.Click
    If Len(Trim(TxtAdminUserName.Text)) = 0 Then
        MessageBox.Show("Please enter user name", "Input Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
        TxtAdminUserName.Focus()
        Exit Sub
    End If
    If Len(Trim(TxtAdminPassword.Text)) = 0 Then
        MessageBox.Show("Please enter password", "Input Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
        TxtAdminPassword.Focus()
        Exit Sub
    End If



    Try
        Dim cn As New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" & My.Application.Info.DirectoryPath.ToString() & "\DbCPDRAS.accdb;Persist Security Info=False;")
        If cn.State = ConnectionState.Open Then
            cn.Close()
        End If
        cn.Open()
        Dim dr1 As OleDbDataReader
        Dim com As New OleDbCommand
        com.CommandText = "select [UserID],[Pass] from AdminInfo where UserID = @UName"

        ' UserName
        Dim UName As OleDbParameter = New OleDbParameter("@UName", OleDbType.VarWChar, 20)
        UName.Value = UCase(TxtAdminUserName.Text.ToString())
        com.Parameters.Add(UName)
        com.Connection = cn

        dr1 = com.ExecuteReader
        If dr1.Read Then
            If UCase(dr1("Pass")) = UCase(TxtAdminPassword.Text) Then
                cn.Close()
                CBformState.SelectedItem = "Admin"

                Dim obj As New FrmMain
                Me.Hide()
                obj.Show()
            Else
                Static Counter As Integer = 0
                MsgBox("Invalid Password   " & 2 - Counter & " Attempts left!", vbExclamation, "Login")

                TxtAdminPassword.Text = ""
                TxtAdminUserName.Text = ""
                Counter += 1
                If Counter = 3 Then Me.Close()
                cn.Close()
                LinkLabel2.Visible = True
                LinkLabel2.Text = "Forget Password"
                Return

            End If
        Else
            Static Counter1 As Integer = 0
            MsgBox("Invalid UserName and Password   " & 2 - Counter1 & " Attempts left!", vbExclamation, "Login")
            TxtAdminPassword.Text = ""
            TxtAdminUserName.Text = ""
            Counter1 += 1
            If Counter1 = 3 Then
                Me.Timer1.Interval = 1

                Me.Timer1.Start()

                CmdAdminLogin.Enabled = False

                TxtAdminUserName.Enabled = False

                TxtAdminPassword.Enabled = False

                If Me.Timer1.Interval = 3 Then

                    Me.Timer1.Stop()

                    MessageBox.Show("Login Available", "Message Box", MessageBoxButtons.OK, MessageBoxIcon.Information)

                    CmdAdminLogin.Enabled = True

                    TxtAdminUserName.Enabled = True

                    TxtAdminPassword.Enabled = True
                    cn.Close()
                End If

                Return
            End If

        End If

    Catch ex As Exception
        MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
    End Try
End Sub

推荐答案

对于单个应用程序会话：

保持一个包含尝试次数的类级整数。在每次失败时，将此数字增加1.当3次尝试结束时，将帐户锁定在数据库中并添加条件并显示相应的消息。



对于多会话：



在每次失败时，更新用户在数据库中的失败尝试。如果此数字超过3，则显示帐户锁定消息。



更新：以下是如何实现此功能的大纲。它在C＃中，但逻辑在VB中也是一样的。



在单个应用程序会话中：

For single application session:
Keep a class level integer that holds number of tries. On each failure increase this number by 1. When 3 tries are over, lock the account in database and add a condition do display appropriate message.

For multi-session:

On each failure, update failed attempts in database for the user. If this number goes above 3, display account locked message.

Update: Here is an outline on how to implement this. It is in C# but logic remains same in VB as well.

In single application session:

private int _failedAttempts;

        protected void LoginButtonClick(object sender, EventArgs e) {

            // Try user login here

            if (success)
            {
                // process ahead
            }
            else {
                _failedAttempts++;
            }

            if (_failedAttempts == 3) {

                // Update database for this user. Set account locked out.

                MessageBox.Show("Your account has been locked out.");
            }

        }

多个会话：

Multiple session:

private int _failedAttempts;

protected void LoginButtonClick(object sender, EventArgs e)
{

    // User table should have a failed attempt count field.

    // Check if value of that field is 3
    if (valueIs3)
    {
        MessageBox.Show("Your account has been locked out.");
    }
    else
    {
        // Try user login here

        if (success)
        {
            // set failed attempt field value as 0

            // process ahead
        }
        else
        {
            _failedAttempts = failedAttemptCountValueFromDatabase;
            // add one to failed attempts field

            _failedAttempts++;
        }

        if (_failedAttempts == 3)
        {

            // Update database for this user. Set account locked out.

            MessageBox.Show("Your account has been locked out.");
        }
    }

}

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