Packet interception / Mangling

[Julian Elischer]

cole at opteqint.net wrote:

>Hi
>
>I wanted to know if there are any libraries similar to pcap to intercept
>packets/mangle packets.
>  
>

how about pcap?  :-)

There are also two other mechinisms..
"divert sockets" (man divert) which is used in conjuction with teh ipfw 
packet fileter
and netgraph (man 4 netgraph, man ngctl, man ng_socket, man ng_ether)
which can do a lot of interesting thins.

>What im trying to do specifically is like link compression, and I would then
>need to check if the packet is then compressed and decompress, and so forth and
>so on.
>
>I would like to avoid having to use a ipfw divert to a port, and specifically
>check all traffic to the box using a library function or some kind of hook into
>the kernel.
>
>The FreeBSD version I will be using is 4.9 or 4.11, and would like to know if
>there are any such routines available, and whether it could be a userland
>daemon, or if i am going to need to write a kernel loadable module?
>
>If anyone has any ideas or suggestions, or knows anything about this, it would
>be a great help.
>
>Regards
>/Cole
>
>
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>  
>