transparent udp proxy

[Hooman Fazaeli]

On 10/31/2014 2:18 PM, Andrey V. Elsukov wrote:
> On 31.10.2014 12:50, Hooman Fazaeli wrote:
>> Hi,
>>
>> I my setup, I use a fwd rule to forward all udp traffic to my local proxy:
>>
>> ipfw add 10 fwd localhost,7000 udp from any to any recv em1
>>
>> The proxy needs to know the original destination address of forwarded
>> datagrams, but
>> there seems to be no way to obtain that address.
>>
>> Using recvmsg with IP_RECVDSTADDR does not help because it returns
>> next-hop address
>> instead of original destination. This is because udp_input() overwrites
>> packet's destination
>> with next-hop address before doing ip_savecontrol.
> Hi,
>
> udp_input() doesn't overwrite destination address. Probably you have NAT
> that does this.
>
There is no NAT stuff.
I checked that on 8.4 source: http://fxr.watson.org/fxr/source/netinet/udp_usrreq.c?v=FREEBSD8#L461


-- 

Best regards.
Hooman Fazaeli