How to manage (Proxy) Re-Routing Packages?

[kf]

Hi,

WinPk-Filter:

it is possible to capture packes from a specific port an re-route it to an other ip?

Can i change the dest. & src IP-Address in the IP-Header?

Which stuff has to be modified?
Bye

[kf]

Hm… i tried to remote all destination informations like:

::ZeroMemory( &pIpHeader->ip_dst, sizeof(in_addr));

but the messages archive the goals?

Any ideas? 🙄

[Vadim Smirnov]

it is possible to capture packes from a specific port an re-route it to an other ip?

Can i change the dest. & src IP-Address in the IP-Header?

Which stuff has to be modified?

Yes this is possible and it is as simple as changing IP/TCP/UDP header and recalculating the checksums. Also if this is sort of redirect the reversed operation should be performed in reversed packets.

Internet Gateway sample http://www.ntkernel.com/w&p.php?id=31demonstrates the usage of WinpkFilter for implementing NAT solution.

[kf]

Hm, thx. That is an empty url?

EDIT: Sry the url is perfect 🙂

[kf]

The Source-code download requires an username & password ? 🙄

[kf]

I’ve found the source-code fore a new checksum.

Can i change the ip-address(es) and recompute the checksum is that everything i need?

::ZeroMemory( &pIpHeader->ip_dst, sizeof(in_addr));

::ZeroMemory( &pIpHeader->ip_src, sizeof(in_addr));



::RecalculateTCPChecksum( &PacketBuffer );

hmm whats wrong?

[kf]

Okay it works fine! Thx. That link was very helpful:
http://www.ntndis.com/forum/viewtopic.php?p=917&sid=d5925c2d83c622468d49c84caca81b75
http://www.ntkernel.com/forum/viewtopic.php?t=550&highlight=check+cheque+sum

So my last question (problem):

If i use the RecalculateIPChecksum() without changing the ip-address, the packages are droped in the pipeline?

RecalculateIPChecksum( &PacketBuffer );

Next, How can i enter an ip-adress? (to: pIpHeader->ip_dst)
e.g. 192.168.1.9 ?

[Author]

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