Intercepting a packet, changing it and re-injecting into the network

[Max Laier]

On Friday 22 December 2006 16:43, Fabrício Barros Cabral wrote:
> I'm developing a network application which needs *to intercept* a
> packet (not just *copy* a packet, like libpcap does), move this packet
> into my application (userland), do some checking in the packet and
> according with some heuristics, the application may change the payload
> and re-inject the modified packet into the network. Note that
> sometimes, I'll change the payload, drop the packet or just let it go.
>
> So, how can a I do that in FreeBSD? I can use 6.1, 7.1, any version.

Sounds like you are looking for divert(4) sockets.  Look at natd(8) for an 
example useage.

-- 
/"\  Best regards,                      | mlaier at freebsd.org
\ /  Max Laier                          | ICQ #67774661
 X   http://pf4freebsd.love2party.net/  | mlaier at EFnet
/ \  ASCII Ribbon Campaign              | Against HTML Mail and News
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 187 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/freebsd-net/attachments/20061222/4a51e22a/attachment.pgp