[Winpcap-users] Use of WinPcap library to make NAT program

[Loris Degioanni]

WinPcap can be used to write software like bridges or routers, but only 
user level ones: you capture the frames from an interface, you perform 
your processing and you send them to the other interface(s).
Next version of WinPcap will provide better support for this, since it 
will be possible to configure it not to receive the packets that it just 
sent.
Note that some link layers (e.g. PPP and VPN connections) work only in 
receive mode, so you'll not be able to transmit on them.

If you want to write a "real" nat (able to process the packets before 
they get delivered to TCP/IP stack), you will have to use one of the 
options that the Windows operating system provides:

- NDIS intermediate drivers (you can find information and sample code in 
the microsoft DDK)
- Filter-Hook Drivers 
(http://msdn.microsoft.com/library/default.asp?url=/library/en-us/network/hh/network/fltrref_16b29dd7-dd36-4f22-a828-24a6820dfeb3.xml.asp)
- Other mechanisms? (for example, 
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/rras/rras/packet_filtering_reference.asp)

Loris


kwyjibo at ono.com wrote:
> I would prefer a freeware or open source solution... Do anybody know one?
> 
> Vadim Smirnov wrote:
> 
>> May be this is an option for you http://www.ntkernel.com/w&p.php?id=7
>>
>> Winpcap is a protocol driver and not really suitable for packet filtering
>> solution.
>> -----Original Message-----
>> From: winpcap-users-bounces at winpcap.org
>> [mailto:winpcap-users-bounces at winpcap.org] On Behalf Of kwyjibo at ono.com
>> Sent: Friday, November 04, 2005 5:21 PM
>> To: winpcap-users at winpcap.org
>> Subject: [Winpcap-users] Use of WinPcap library to make NAT program
>>
>> Hi,
>>
>> Is this library a good choice to programme a software router with NAT
>> capabilities? If not, what would be a good choice?
>>
>> Thanks in advance.
>>
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>>  
>>
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