500分求telnet client 的VB源码或示例？

原来是有认证信息，有个简单的方法是拒绝所有认证，代码如下

Option Explicit

Private host As String

Private port As Integer

Private Sub Form_Load()

host = Trim(InputBox("输入主机地址，端口号用空格分割"))

Text1.Text = ""

Text1.Locked = True

If InStr(host, " ") >0 Then

port = Val(Mid(host, InStr(host, " ") + 1))

host = Left(host, InStr(host, " ") - 1)

End If

If port = 0 Then port = 23

Winsock1.Protocol = sckTCPProtocol

Winsock1.Connect host, port

End Sub

Private Sub Text1_Change()

Text1.SelStart = Len(Text1.Text)

End Sub

Private Sub Text1_KeyPress(KeyAscii As Integer)

Dim c As String

c = Chr(KeyAscii)

Winsock1.SendData c

End Sub

Private Sub Winsock1_DataArrival(ByVal bytesTotal As Long)

Dim s() As Byte

Dim l As Long

Winsock1.GetData s

ExplainCode s

End Sub

Private Sub Winsock1_Error(ByVal Number As Integer, Description As String, ByVal Scode As Long, ByVal Source As String, ByVal HelpFile As String, ByVal HelpContext As Long, CancelDisplay As Boolean)

Text1.Text = Text1.Text &vbCrLf &"Connect Error" &vbCrLf

End Sub

Private Function ExplainCode(ByRef s() As Byte) As String

Dim i As Long, j As Long

Dim l As Long

Dim k() As Byte

Dim db() As Byte, dbl As Long

ReDim k(UBound(s)) As Byte

Dim ss As String

dbl = -1

ExplainCode = vbNullChar

For i = 0 To UBound(s)

Select Case s(i)

Case 8

If i <UBound(s) - 1 Then

If s(i + 2) = 8 Then

ss = Left(Text1.Text, Len(Text1.Text) - 1)

Text1.Text = ss

i = i + 2

End If

End If

Case 255

If i <UBound(s) Then

Select Case s(i + 1)

Case 253

If i <UBound(s) - 1 Then

ReDim Preserve db(0 To dbl + 3)

db(dbl + 1) = s(i)

db(dbl + 2) = &HFC '所有特殊请求全部拒绝

db(dbl + 3) = s(i + 2)

dbl = dbl + 3

i = i + 2

End If

Case 250

For j = i To UBound(s)

If s(j) = 240 Then

Exit For

End If

Next j

i = j

Case 251

If i <UBound(s) - 1 Then

i = i + 2

End If

End Select

End If

Case 27

If i <UBound(s) - 1 Then

If s(i + 1) = &H5B Then

If s(i + 2) = &H48 Then

Text1.Text = Text1.Text &vbCrLf

i = i + 2

ElseIf s(i + 2) = &H4A Then

Text1.Text = ""

i = i + 2

Else

For j = i To UBound(s)

If s(j) = 109 Or s(j) = 75 Or s(j) = 74 Then

Exit For

End If

Next j

i = j

End If

End If

End If

Case Else

If i <UBound(s) Then

If s(i) = 10 And s(i + 1) = 13 Then

s(i) = 13

s(i + 1) = 10

End If

End If

k(l) = s(i)

l = l + 1

End Select

Next i

If dbl <>-1 Then Winsock1.SendData db

If l = 0 Then Exit Function

ReDim Preserve k(0 To l - 1) As Byte

ExplainCode = StrConv(k, vbUnicode)

Text1.Text = Text1.Text &ExplainCode

End Function

Linux 下流行的 telnet 实现有两个：

GNU 的 inetutils 中的实现 [1]

哈佛的 netkit-telnet [2]

1. http://ftp.gnu.org/gnu/inetutils/

2. http://ftp.de.debian.org/debian/pool/main/n/netkit-telnet/netkit-telnet_0.17.orig.tar.gz

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