A question on modifying packet.

[Sami Halabi]

use netgraph.
In theory it should work.. in practice It worked for me once, but couldn't
repeat the success.

See ng_patch. Here is the code i tried:
kldload ng_patch
kldload ng_ipfw
/usr/sbin/ngctl -f- << SEQ
                 mkpeer ipfw: patch 300 in
                 name ipfw:300 src_dst_chg
                 msg src_dst_chg: setconfig { count=2 csum_flags=1
ops=[         \
                         { mode=1 value=0xc0a8e609 length=4 offset=12 }  \
                         { mode=1 value=0xc0a8e680 length=4 offset=16 } ] }
         SEQ
/sbin/ipfw add 600 netgraph 300 log ip from any to 239.0.0.19 dst-port 1234
in via vlan999

Sami
On 7/9/14, 1:01 PM, Niu Zhixiong wrote:

> Hi, all
> I have only one NIC. I want to capture packets from one certain ip address
> and change the both src and dst addresses and forward to other destination
> via the same NIC. It is possible? Is there any library to help me do this?
>
there is no library, but look at how natd does this using divert sockets.


>
> Regards,
> Niu Zhixiong
> －－－－－－－－－－－－－－－
>   kaiaixi at gmail.com
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