Hi All,

I'm thinking about how I can debug this problem.
I enable logging for blocked packets (block log-all all). My pf.conf looks 
approximately so: 

scrub in on wlan0 all
rdr on wlan0 proto udp from any to (self) port 9870 -> 192.168.0.1 port 9870
block log-all all
pass on wlan0 all

The fragmented packets are not redirected to 192.168.0.1, but they are also not 
blocked since I don't see them in logs (with tcpdump -i pflog0). Where do they 
disappear? Are they just silently discarded by pf?

I also tried to add "log-all" to the scrub rule:

scrub in log-all on wlan0 all

--> I don't see anything from this rule in the logs as well!

My another question is about the option "set debug <level>" that one can write 
at the beginning of the pf.conf. What is this debug level for? I thought that 
there is only one way to debug pf rules: with this "log"/"log-all" keyword and 
pflog0 interface. Is this debug level some other kind of debugging? When I 
write the option "set debug none" in the pf.conf, I still can see all packets 
logged at the pflog0 interface. So, is it something different?

Thanks!
Aleksej.





-----Ursprüngliche Nachricht-----
Von: Spenst, Aleksej 
Gesendet: Dienstag, 14. Oktober 2014 16:03
An: Kristof Provost
Cc: freebsd-pf@freebsd.org
Betreff: AW: Fragmented packets are not redirected

Hi Kristof,

Thank you for your answer.
I read that "fragment reassemble" is the default behavior of scrub. So, "scrub 
in" and "scrub in fragment reassemble" is the same. But just to be sure I've 
also tried it already -> didn't help.

Regards,
Aleksej.


-----Ursprüngliche Nachricht-----
Von: Kristof Provost [mailto:kris...@sigsegv.be]
Gesendet: Dienstag, 14. Oktober 2014 15:57
An: Spenst, Aleksej
Cc: freebsd-pf@freebsd.org
Betreff: Re: Fragmented packets are not redirected

On 2014-10-14 09:33:44 (+0000), Spenst, Aleksej <aleksej.spe...@harman.com> 
wrote:
> It is clear that if the IP fragments are not reassembled at the server 
> they cannot be redirected since the redirection rule is written for 
> UDP packets. That is why I have this scrub rule at the very beginning 
> of my pf.conf:
> 
> scrub in on wlan0 all
> 
> I thought that this rule should reassemble all the incoming fragments.
> The reassembled UDP packets should be then correctly passed through 
> the rdr rule and redirected to my PC. But this does not happen.
> 
I think that you want 'scrub in on wlan0 all fragment reassemble'.

Regards,
Kristof



Von: Spenst, Aleksej 
Gesendet: Dienstag, 14. Oktober 2014 11:34
An: freebsd-pf@freebsd.org
Betreff: Fragmented packets are not redirected

Hi All,

I have one problem with redirection of the fragmented packets. My use case:

A mobile phone sends the RTP video stream to my server. The server has the pf 
installed. All RTP packets are redirected from the server to my PC:

|Mobile|------>---RTP---->-----|Server|------->---RTP--->-----|PC|

The small RTP packets are redirected to my PC without any problems.
The problem is with the large RTP packets that are fragmented and transmitted 
in several IP fragments. These IP fragments are not redirected to PC. The 
redirection rule at the server:

rdr on wlan0 proto udp from any to (self) port 9870 -> 192.168.0.1 port 9870

     | S e r v e r |
->--|wlan0      eth0|-->-------|PC 192.168.0.1|

It is clear that if the IP fragments are not reassembled at the server they 
cannot be redirected since the redirection rule is written for UDP packets. 
That is why I have this scrub rule at the very beginning of my pf.conf:

scrub in on wlan0 all

I thought that this rule should reassemble all the incoming fragments. The 
reassembled UDP packets should be then correctly passed through the rdr rule 
and redirected to my PC. But this does not happen. 

Do you have any ideas/tips?

Thanks a lot!
Aleksej.

_______________________________________________
freebsd-pf@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-pf
To unsubscribe, send any mail to "freebsd-pf-unsubscr...@freebsd.org"

Reply via email to