If you use NetScaler you will want to see these guides. The NetScaler How To Guides show administrators how to get NetScaler up and configured by providing instructions for common scenarios and some not so common ones.
So, REMOTE_ADDR will, return the IP of the form page, NOT the visitor?that is correct. Although you could run into issues if the user is behind a proxy server. You could also try using HTTP_X_FORWARDED_FOR, but again, it's not 100%, but it can help out some.
REMOTE_ADDR is pointless as is SCRIPT_NAME
So, REMOTE_ADDR will, return the IP of the form page, NOT the visitor?
<%
<!-- #include virtual ="sha.asp" -->
if request.form = "" then ' no form submit
tstamp = now()
passcode = Session.SessionID & tstamp & "some_secret_word"
session("passcode")=passocde
end if
<input type="hidden" name="stamp" value="<%=tstamp%>">
<input type="hidden" name="passcode" value="<%=sha(passcode)%>">
%>
<!-- #include virtual ="sha.asp" -->
<%
if request.form<>"" then
if request.form("passcode")= sha(Session.SessionID&request.form("stamp")&"some_secret_word") then ' ok to process form
end if
%>
<%
' See the VB6 project that accompanies this sample for full code comments on how
' it works.
'
' ASP VBScript code for generating a SHA256 'digest' or 'signature' of a string. The
' MD5 algorithm is one of the industry standard methods for generating digital
' signatures. It is generically known as a digest, digital signature, one-way
' encryption, hash or checksum algorithm. A common use for SHA256 is for password
' encryption as it is one-way in nature, that does not mean that your passwords
' are not free from a dictionary attack.
'
' If you are using the routine for passwords, you can make it a little more secure
' by concatenating some known random characters to the password before you generate
' the signature and on subsequent tests, so even if a hacker knows you are using
' SHA-256 for your passwords, the random characters will make it harder to dictionary
' attack.
'
' NOTE: Due to the way in which the string is processed the routine assumes a
' single byte character set. VB passes unicode (2-byte) character strings, the
' ConvertToWordArray function uses on the first byte for each character. This
' has been done this way for ease of use, to make the routine truely portable
' you could accept a byte array instead, it would then be up to the calling
' routine to make sure that the byte array is generated from their string in
' a manner consistent with the string type.
'
' This is 'free' software with the following restrictions:
'
' You may not redistribute this code as a 'sample' or 'demo'. However, you are free
' to use the source code in your own code, but you may not claim that you created
' the sample code. It is expressly forbidden to sell or profit from this source code
' other than by the knowledge gained or the enhanced value added by your own code.
'
' Use of this software is also done so at your own risk. The code is supplied as
' is without warranty or guarantee of any kind.
'
' Should you wish to commission some derivative work based on this code provided
' here, or any consultancy work, please do not hesitate to contact us.
'
' Web Site: http://www.frez.co.uk
' E-mail: sales@frez.co.uk
Private m_lOnBits(30)
Private m_l2Power(30)
Private K(63)
Private Const BITS_TO_A_BYTE = 8
Private Const BYTES_TO_A_WORD = 4
Private Const BITS_TO_A_WORD = 32
m_lOnBits(0) = CLng(1)
m_lOnBits(1) = CLng(3)
m_lOnBits(2) = CLng(7)
m_lOnBits(3) = CLng(15)
m_lOnBits(4) = CLng(31)
m_lOnBits(5) = CLng(63)
m_lOnBits(6) = CLng(127)
m_lOnBits(7) = CLng(255)
m_lOnBits(8) = CLng(511)
m_lOnBits(9) = CLng(1023)
m_lOnBits(10) = CLng(2047)
m_lOnBits(11) = CLng(4095)
m_lOnBits(12) = CLng(8191)
m_lOnBits(13) = CLng(16383)
m_lOnBits(14) = CLng(32767)
m_lOnBits(15) = CLng(65535)
m_lOnBits(16) = CLng(131071)
m_lOnBits(17) = CLng(262143)
m_lOnBits(18) = CLng(524287)
m_lOnBits(19) = CLng(1048575)
m_lOnBits(20) = CLng(2097151)
m_lOnBits(21) = CLng(4194303)
m_lOnBits(22) = CLng(8388607)
m_lOnBits(23) = CLng(16777215)
m_lOnBits(24) = CLng(33554431)
m_lOnBits(25) = CLng(67108863)
m_lOnBits(26) = CLng(134217727)
m_lOnBits(27) = CLng(268435455)
m_lOnBits(28) = CLng(536870911)
m_lOnBits(29) = CLng(1073741823)
m_lOnBits(30) = CLng(2147483647)
m_l2Power(0) = CLng(1)
m_l2Power(1) = CLng(2)
m_l2Power(2) = CLng(4)
m_l2Power(3) = CLng(8)
m_l2Power(4) = CLng(16)
m_l2Power(5) = CLng(32)
m_l2Power(6) = CLng(64)
m_l2Power(7) = CLng(128)
m_l2Power(8) = CLng(256)
m_l2Power(9) = CLng(512)
m_l2Power(10) = CLng(1024)
m_l2Power(11) = CLng(2048)
m_l2Power(12) = CLng(4096)
m_l2Power(13) = CLng(8192)
m_l2Power(14) = CLng(16384)
m_l2Power(15) = CLng(32768)
m_l2Power(16) = CLng(65536)
m_l2Power(17) = CLng(131072)
m_l2Power(18) = CLng(262144)
m_l2Power(19) = CLng(524288)
m_l2Power(20) = CLng(1048576)
m_l2Power(21) = CLng(2097152)
m_l2Power(22) = CLng(4194304)
m_l2Power(23) = CLng(8388608)
m_l2Power(24) = CLng(16777216)
m_l2Power(25) = CLng(33554432)
m_l2Power(26) = CLng(67108864)
m_l2Power(27) = CLng(134217728)
m_l2Power(28) = CLng(268435456)
m_l2Power(29) = CLng(536870912)
m_l2Power(30) = CLng(1073741824)
K(0) = &H428A2F98
K(1) = &H71374491
K(2) = &HB5C0FBCF
K(3) = &HE9B5DBA5
K(4) = &H3956C25B
K(5) = &H59F111F1
K(6) = &H923F82A4
K(7) = &HAB1C5ED5
K(8) = &HD807AA98
K(9) = &H12835B01
K(10) = &H243185BE
K(11) = &H550C7DC3
K(12) = &H72BE5D74
K(13) = &H80DEB1FE
K(14) = &H9BDC06A7
K(15) = &HC19BF174
K(16) = &HE49B69C1
K(17) = &HEFBE4786
K(18) = &HFC19DC6
K(19) = &H240CA1CC
K(20) = &H2DE92C6F
K(21) = &H4A7484AA
K(22) = &H5CB0A9DC
K(23) = &H76F988DA
K(24) = &H983E5152
K(25) = &HA831C66D
K(26) = &HB00327C8
K(27) = &HBF597FC7
K(28) = &HC6E00BF3
K(29) = &HD5A79147
K(30) = &H6CA6351
K(31) = &H14292967
K(32) = &H27B70A85
K(33) = &H2E1B2138
K(34) = &H4D2C6DFC
K(35) = &H53380D13
K(36) = &H650A7354
K(37) = &H766A0ABB
K(38) = &H81C2C92E
K(39) = &H92722C85
K(40) = &HA2BFE8A1
K(41) = &HA81A664B
K(42) = &HC24B8B70
K(43) = &HC76C51A3
K(44) = &HD192E819
K(45) = &HD6990624
K(46) = &HF40E3585
K(47) = &H106AA070
K(48) = &H19A4C116
K(49) = &H1E376C08
K(50) = &H2748774C
K(51) = &H34B0BCB5
K(52) = &H391C0CB3
K(53) = &H4ED8AA4A
K(54) = &H5B9CCA4F
K(55) = &H682E6FF3
K(56) = &H748F82EE
K(57) = &H78A5636F
K(58) = &H84C87814
K(59) = &H8CC70208
K(60) = &H90BEFFFA
K(61) = &HA4506CEB
K(62) = &HBEF9A3F7
K(63) = &HC67178F2
Private Function LShift(lValue, iShiftBits)
If iShiftBits = 0 Then
LShift = lValue
Exit Function
ElseIf iShiftBits = 31 Then
If lValue And 1 Then
LShift = &H80000000
Else
LShift = 0
End If
Exit Function
ElseIf iShiftBits < 0 Or iShiftBits > 31 Then
Err.Raise 6
End If
If (lValue And m_l2Power(31 - iShiftBits)) Then
LShift = ((lValue And m_lOnBits(31 - (iShiftBits + 1))) * m_l2Power(iShiftBits)) Or &H80000000
Else
LShift = ((lValue And m_lOnBits(31 - iShiftBits)) * m_l2Power(iShiftBits))
End If
End Function
Private Function RShift(lValue, iShiftBits)
If iShiftBits = 0 Then
RShift = lValue
Exit Function
ElseIf iShiftBits = 31 Then
If lValue And &H80000000 Then
RShift = 1
Else
RShift = 0
End If
Exit Function
ElseIf iShiftBits < 0 Or iShiftBits > 31 Then
Err.Raise 6
End If
RShift = (lValue And &H7FFFFFFE) \ m_l2Power(iShiftBits)
If (lValue And &H80000000) Then
RShift = (RShift Or (&H40000000 \ m_l2Power(iShiftBits - 1)))
End If
End Function
Private Function AddUnsigned(lX, lY)
Dim lX4
Dim lY4
Dim lX8
Dim lY8
Dim lResult
lX8 = lX And &H80000000
lY8 = lY And &H80000000
lX4 = lX And &H40000000
lY4 = lY And &H40000000
lResult = (lX And &H3FFFFFFF) + (lY And &H3FFFFFFF)
If lX4 And lY4 Then
lResult = lResult Xor &H80000000 Xor lX8 Xor lY8
ElseIf lX4 Or lY4 Then
If lResult And &H40000000 Then
lResult = lResult Xor &HC0000000 Xor lX8 Xor lY8
Else
lResult = lResult Xor &H40000000 Xor lX8 Xor lY8
End If
Else
lResult = lResult Xor lX8 Xor lY8
End If
AddUnsigned = lResult
End Function
Private Function Ch(x, y, z)
Ch = ((x And y) Xor ((Not x) And z))
End Function
Private Function Maj(x, y, z)
Maj = ((x And y) Xor (x And z) Xor (y And z))
End Function
Private Function S(x, n)
S = (RShift(x, (n And m_lOnBits(4))) Or LShift(x, (32 - (n And m_lOnBits(4)))))
End Function
Private Function R(x, n)
R = RShift(x, CInt(n And m_lOnBits(4)))
End Function
Private Function Sigma0(x)
Sigma0 = (S(x, 2) Xor S(x, 13) Xor S(x, 22))
End Function
Private Function Sigma1(x)
Sigma1 = (S(x, 6) Xor S(x, 11) Xor S(x, 25))
End Function
Private Function Gamma0(x)
Gamma0 = (S(x, 7) Xor S(x, 18) Xor R(x, 3))
End Function
Private Function Gamma1(x)
Gamma1 = (S(x, 17) Xor S(x, 19) Xor R(x, 10))
End Function
Private Function ConvertToWordArray(sMessage)
Dim lMessageLength
Dim lNumberOfWords
Dim lWordArray()
Dim lBytePosition
Dim lByteCount
Dim lWordCount
Dim lByte
Const MODULUS_BITS = 512
Const CONGRUENT_BITS = 448
lMessageLength = Len(sMessage)
lNumberOfWords = (((lMessageLength + ((MODULUS_BITS - CONGRUENT_BITS) \ BITS_TO_A_BYTE)) \ (MODULUS_BITS \ BITS_TO_A_BYTE)) + 1) * (MODULUS_BITS \ BITS_TO_A_WORD)
ReDim lWordArray(lNumberOfWords - 1)
lBytePosition = 0
lByteCount = 0
Do Until lByteCount >= lMessageLength
lWordCount = lByteCount \ BYTES_TO_A_WORD
lBytePosition = (3 - (lByteCount Mod BYTES_TO_A_WORD)) * BITS_TO_A_BYTE
lByte = AscB(Mid(sMessage, lByteCount + 1, 1))
lWordArray(lWordCount) = lWordArray(lWordCount) Or LShift(lByte, lBytePosition)
lByteCount = lByteCount + 1
Loop
lWordCount = lByteCount \ BYTES_TO_A_WORD
lBytePosition = (3 - (lByteCount Mod BYTES_TO_A_WORD)) * BITS_TO_A_BYTE
lWordArray(lWordCount) = lWordArray(lWordCount) Or LShift(&H80, lBytePosition)
lWordArray(lNumberOfWords - 1) = LShift(lMessageLength, 3)
lWordArray(lNumberOfWords - 2) = RShift(lMessageLength, 29)
ConvertToWordArray = lWordArray
End Function
Public Function SHA256(sMessage)
Dim HASH(7)
Dim M
Dim W(63)
Dim a
Dim b
Dim c
Dim d
Dim e
Dim f
Dim g
Dim h
Dim i
Dim j
Dim T1
Dim T2
HASH(0) = &H6A09E667
HASH(1) = &HBB67AE85
HASH(2) = &H3C6EF372
HASH(3) = &HA54FF53A
HASH(4) = &H510E527F
HASH(5) = &H9B05688C
HASH(6) = &H1F83D9AB
HASH(7) = &H5BE0CD19
M = ConvertToWordArray(sMessage)
For i = 0 To UBound(M) Step 16
a = HASH(0)
b = HASH(1)
c = HASH(2)
d = HASH(3)
e = HASH(4)
f = HASH(5)
g = HASH(6)
h = HASH(7)
For j = 0 To 63
If j < 16 Then
W(j) = M(j + i)
Else
W(j) = AddUnsigned(AddUnsigned(AddUnsigned(Gamma1(W(j - 2)), W(j - 7)), Gamma0(W(j - 15))), W(j - 16))
End If
T1 = AddUnsigned(AddUnsigned(AddUnsigned(AddUnsigned(h, Sigma1(e)), Ch(e, f, g)), K(j)), W(j))
T2 = AddUnsigned(Sigma0(a), Maj(a, b, c))
h = g
g = f
f = e
e = AddUnsigned(d, T1)
d = c
c = b
b = a
a = AddUnsigned(T1, T2)
Next
HASH(0) = AddUnsigned(a, HASH(0))
HASH(1) = AddUnsigned(b, HASH(1))
HASH(2) = AddUnsigned(c, HASH(2))
HASH(3) = AddUnsigned(d, HASH(3))
HASH(4) = AddUnsigned(e, HASH(4))
HASH(5) = AddUnsigned(f, HASH(5))
HASH(6) = AddUnsigned(g, HASH(6))
HASH(7) = AddUnsigned(h, HASH(7))
Next
SHA256 = LCase(Right("00000000" & Hex(HASH(0)), 8) & Right("00000000" & Hex(HASH(1)), 8) & Right("00000000" & Hex(HASH(2)), 8) & Right("00000000" & Hex(HASH(3)), 8) & Right("00000000" & Hex(HASH(4)), 8) & Right("00000000" & Hex(HASH(5)), 8) & Right("00000000" & Hex(HASH(6)), 8) & Right("00000000" & Hex(HASH(7)), 8))
End Function
%>
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