Sorry!! I didn't see the -n :o
yes, with ping -n it works perfectly, the only problem is the DNS request for
every ping.
Ibrahim,
From: ibrahim.me...@alumnos.upm.es
To: jam...@nau.edu
CC: nox-dev@noxrepo.org
Subject: RE: [nox-dev] Adding DNS functionality to nox
Date: Fri, 26 Aug 2011 14:02:39 +0200
It takes about 45 sec to respond, and it sends dns request for every ping!
however, nslookup responds in 0 sec. Also, no more unknown host messages.
Ibrahim,
Subject: Re: [nox-dev] Adding DNS functionality to nox
From: jam...@nau.edu
Date: Fri, 26 Aug 2011 04:24:53 -0700
CC: nox-dev@noxrepo.org
To: ibrahim.me...@alumnos.upm.es
What's the behavior with "ping -n <host>" ?
-- Murphy
On Aug 26, 2011, at 4:05 AM, ibrahim mun wrote:Hi Murphy, Christian, All,
The problem is partially solved. I've added the following code to
pyswitch.packet_in_callback
# drop packets to dns 10.0.0.2
iph=packet.find("ipv4")
udph=packet.find("udp")
if iph!= None and udph!= None:
if iph.dstip==ipstr_to_int("10.0.0.2") and udph.dstport==53:
return CONTINUE
Now I can always ping but:
1. I have dns request for every ping (not cached?).
2. It takes a lot of time to respond to ping, while as you suggested, nslookup
responds immediately. it seems something should be timed out before ping
responds.
This is the traffic on "h3-eth0" for one " ping pc4"
http://codepad.org/DBZg46yB
And this is the expanded DNS reply packet as show in wireshark:
http://codepad.org/NEkkGH06
Thank you,
Ibrahim
Subject: Re: [nox-dev] Adding DNS functionality to nox
From: jam...@nau.edu
Date: Thu, 25 Aug 2011 13:34:58 -0700
CC: chest...@dca.fee.unicamp.br; nox-dev@noxrepo.org
To: ibrahim.me...@alumnos.upm.es
What is generating these ICMP messages? You should be able to stop them by
dropping the packets you're intercepting. It strikes me as totally possible
that they are causing the problem.
Also, I might try testing using nslookup or dig instead of ping.
-- Murphy
On Aug 25, 2011, at 9:55 AM, ibrahim mun wrote:Hi Christian,
Wireshark shows standard dns replays, and that's why ping works sometimes. The
only irregularity I see are icmp "port unreachable" packets, generated because
nothing is listening on 10.0.0.2:53. but I think it's not the problem!
Thanks for you help.
Ibrahim
From: chest...@dca.fee.unicamp.br
Date: Thu, 25 Aug 2011 10:13:38 -0300
Subject: Re: [nox-dev] Adding DNS functionality to nox
To: ibrahim.me...@alumnos.upm.es
Hi Ibrahim,
I would try to trace back where the problem might be.
As you pointed, this could be due to:- nox and my reply packet, - mininet, -
linux caches dns.- ?
For the first possibility, have you tried to capture the DNS traffic with
wireshark to see if they are correctly decoded?
-Christian
On Thu, Aug 25, 2011 at 07:22, ibrahim mun <ibrahim.me...@alumnos.upm.es> wrote:
Hi again,
One last question in this thread :) , about weird dns functionality:
In mininet I have a single switch (s1), 4 hosts (h2,h3,h4,h5) (10.0.0.2 ->
10.0.0.5)
resolve.conf points to 10.0.0.2 as dns server, but actually nox catchs dns
requests matching with dst port 53, builds the response packet and sends it to
the asker with src ip 10.0.0.2.
first, I restart /etc/init.d/nscd, then
xterm h3
h3>> ping -c2 pc4
it works correctly for one time
====================================
= PING pc4 (10.0.0.4) 56(84) bytes of data.
= 64 bytes from 10.0.0.4: icmp_seq=1 ttl=64 time=19.9 ms
= 64 bytes from 10.0.0.4: icmp_seq=2 ttl=64 time=3.39 ms
=
= --- pc4 ping statistics ---
= 2 packets transmitted, 2 received, 0% packet loss, time 1007ms
= rtt min/avg/max/mdev = 3.391/11.660/19.929/8.269 ms
====================================
then, for 3 to 5 times, it gives
====================================
= ping: unknow host pc4
====================================
Then it works again for one time.
Observations:
1.. host sends dns request at every ping, even those with unknow host
2. I changed TTL in the dns reply (the time to be cached) and it has no effect.
I don't know where is the problem (nox and my reply packet, mininet, how linux
caches dns)..
Thanks,
Ibrahim
From: ibrahim.me...@alumnos.upm.es
To: jam...@nau.edu
CC: nox-dev@noxrepo.org
Subject: RE: [nox-dev] Adding DNS functionality to nox
Date: Fri, 19 Aug 2011 15:17:58 +0200
Hi murphy,
Thank you very much, I stupidly thought that 0 is a special value which means
*full packet* instead of *zero bytes*, I've Added flows for both src and dst
ports with higher priorty than pyswitch rules and finally it responses :D
thank you again!
Ibrahim
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Christian
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