Delphi hook to redirect to different ip
- by Chris
What is the best way to redirect ANY browser to a different ip for specific sites?
For example if the user will type www.facebook.com in any browser he will be redirected to 127.0.0.1. Also the same should happen if he will type 66.220.146.11.
What I have until now is this:
using the winpkfilter I am able to intercept all the traffic on port 80, with type(in or out), source ip, destination ip and packet. My problem is to modify somehow the packet so the browser will be redirected.
This is the code that i have right now:
program Pass;
{$APPTYPE CONSOLE}
uses
SysUtils,
Windows,
Winsock,
winpkf,
iphlp;
var
iIndex, counter : DWORD;
hFilt : THANDLE;
Adapts : TCP_AdapterList;
AdapterMode : ADAPTER_MODE;
Buffer, ParsedBuffer : INTERMEDIATE_BUFFER;
ReadRequest : ETH_REQUEST;
hEvent : THANDLE;
hAdapter : THANDLE;
pEtherHeader : TEtherHeaderPtr;
pIPHeader : TIPHeaderPtr;
pTcpHeader : TTCPHeaderPtr;
pUdpHeader : TUDPHeaderPtr;
SourceIP, DestIP : TInAddr;
thePacket : PChar;
f : TextFile;
SourceIpString, DestinationIpString : string;
SourceName, DestinationName : string;
function IPAddrToName(IPAddr : string) : string;
var
SockAddrIn : TSockAddrIn;
HostEnt : PHostEnt;
WSAData : TWSAData;
begin
WSAStartup($101, WSAData);
SockAddrIn.sin_addr.s_addr := inet_addr(PChar(IPAddr));
HostEnt := gethostbyaddr(@SockAddrIn.sin_addr.S_addr, 4, AF_INET);
if HostEnt < nil then
begin
result := StrPas(Hostent^.h_name)
end
else
begin
result := '';
end;
end;
procedure ReleaseInterface();
begin
// Restore default mode
AdapterMode.dwFlags := 0;
AdapterMode.hAdapterHandle := hAdapter;
SetAdapterMode(hFilt, @AdapterMode);
// Set NULL event to release previously set event object
SetPacketEvent(hFilt, hAdapter, 0);
// Close Event
if hEvent < 0 then
CloseHandle(hEvent);
// Close driver object
CloseFilterDriver(hFilt);
// Release NDISAPI
FreeNDISAPI();
end;
begin
// Check the number of parameters
if ParamCount() < 2 then
begin
Writeln('Command line syntax:');
Writeln(' PassThru.exe index num');
Writeln(' index - network interface index.');
Writeln(' num - number or packets to filter');
Writeln('You can use ListAdapters to determine correct index.');
Exit;
end;
// Initialize NDISAPI
InitNDISAPI();
// Create driver object
hFilt := OpenFilterDriver('NDISRD');
if IsDriverLoaded(hFilt) then
begin
// Get parameters from command line
iIndex := StrToInt(ParamStr(1));
counter := StrToInt(ParamStr(2));
// Set exit procedure
ExitProcessProc := ReleaseInterface;
// Get TCP/IP bound interfaces
GetTcpipBoundAdaptersInfo(hFilt, @Adapts);
// Check paramer values
if iIndex > Adapts.m_nAdapterCount then
begin
Writeln('There is no network interface with such index on this system.');
Exit;
end;
hAdapter := Adapts.m_nAdapterHandle[iIndex];
AdapterMode.dwFlags := MSTCP_FLAG_SENT_TUNNEL or MSTCP_FLAG_RECV_TUNNEL;
AdapterMode.hAdapterHandle := hAdapter;
// Create notification event
hEvent := CreateEvent(nil, TRUE, FALSE, nil);
if hEvent <> 0 then
if SetPacketEvent(hFilt, hAdapter, hEvent) <> 0 then
begin
// Initialize request
ReadRequest.EthPacket.Buffer := @Buffer;
ReadRequest.hAdapterHandle := hAdapter;
SetAdapterMode(hFilt, @AdapterMode);
counter := 0;
//while counter <> 0 do
while true do
begin
WaitForSingleObject(hEvent, INFINITE);
while ReadPacket(hFilt, @ReadRequest) <> 0 do
begin
//dec(counter);
pEtherHeader := TEtherHeaderPtr(@Buffer.m_IBuffer);
if ntohs(pEtherHeader.h_proto) = ETH_P_IP then
begin
pIPHeader := TIPHeaderPtr(Integer(pEtherHeader) +
SizeOf(TEtherHeader));
SourceIP.S_addr := pIPHeader.SourceIp;
DestIP.S_addr := pIPHeader.DestIp;
if pIPHeader.Protocol = IPPROTO_TCP then
begin
pTcpHeader := TTCPHeaderPtr(Integer(pIPHeader) +
(pIPHeader.VerLen and $F) * 4);
if (pTcpHeader.SourcePort = htons(80)) or
(pTcpHeader.DestPort = htons(80)) then
begin
inc(counter);
if Buffer.m_dwDeviceFlags = PACKET_FLAG_ON_SEND
then
Writeln(counter, ') - MSTCP --> Interface')
else
Writeln(counter, ') - Interface --> MSTCP');
Writeln(' Packet size = ',
Buffer.m_Length);
Writeln(Format(' IP %.3u.%.3u.%.3u.%.3u --> %.3u.%.3u.%.3u.%.3u PROTOCOL: %u',
[byte(SourceIP.S_un_b.s_b1),
byte(SourceIP.S_un_b.s_b2),
byte(SourceIP.S_un_b.s_b3),
byte(SourceIP.S_un_b.s_b4),
byte(DestIP.S_un_b.s_b1),
byte(DestIP.S_un_b.s_b2),
byte(DestIP.S_un_b.s_b3),
byte(DestIP.S_un_b.s_b4),
byte(pIPHeader.Protocol)]
));
Writeln(Format(' TCP SRC PORT: %d DST PORT: %d',
[ntohs(pTcpHeader.SourcePort),
ntohs(pTcpHeader.DestPort)]));
//get the data
thePacket := pchar(pEtherHeader) +
(sizeof(TEtherHeaderPtr) + pIpHeader.VerLen * 4
+ pTcpHeader.Offset * 4);
{
SourceIpString :=
IntToStr(byte(SourceIP.S_un_b.s_b1)) + '.' +
IntToStr(byte(SourceIP.S_un_b.s_b2)) + '.' +
IntToStr(byte(SourceIP.S_un_b.s_b3)) + '.' +
IntToStr(byte(SourceIP.S_un_b.s_b4));
DestinationIpString :=
IntToStr(byte(DestIP.S_un_b.s_b1)) + '.' +
IntToStr(byte(DestIP.S_un_b.s_b2)) + '.' +
IntToStr(byte(DestIP.S_un_b.s_b3)) + '.' +
IntToStr(byte(DestIP.S_un_b.s_b4));
}
end;
end;
end;
// if ntohs(pEtherHeader.h_proto) = ETH_P_RARP then
// Writeln(' Reverse Addr Res packet');
// if ntohs(pEtherHeader.h_proto) = ETH_P_ARP then
// Writeln(' Address Resolution packet');
//Writeln('__');
if Buffer.m_dwDeviceFlags = PACKET_FLAG_ON_SEND then
// Place packet on the network interface
SendPacketToAdapter(hFilt, @ReadRequest)
else
// Indicate packet to MSTCP
SendPacketToMstcp(hFilt, @ReadRequest);
{
if counter = 0 then
begin
Writeln('Filtering complete');
readln;
break;
end;
}
end;
ResetEvent(hEvent);
end;
end;
end;
end.
