Kernelnewbies Digest, Vol 48, Issue 10
mohanty bhagaban
bhagaban181 at gmail.com
Mon Nov 10 08:54:04 EST 2014
Hi ,
How to get access to min kenel git as i need to add some patches for
reviews.
Bhagaban
On Sat, Nov 8, 2014 at 10:30 PM, <kernelnewbies-request at kernelnewbies.org>
wrote:
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> Today's Topics:
>
> 1. Re: Eudyptula challenge status (Drew Fustini)
> 2. RE: lots of connections in SYN_RECV state (Puneet Agarwal)
> 3. Re: lots of connections in SYN_RECV state
> (Valdis.Kletnieks at vt.edu)
> 4. Re: lots of connections in SYN_RECV state (Dave Tian)
> 5. RE: lots of connections in SYN_RECV state (Puneet Agarwal)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 7 Nov 2014 11:04:28 -0600
> From: Drew Fustini <pdp7pdp7 at gmail.com>
> Subject: Re: Eudyptula challenge status
> To: Dan <qsdconsulting at gmail.com>
> Cc: kernelnewbies <kernelnewbies at kernelnewbies.org>
> Message-ID:
> <
> CAEf4M_B6W3GJ8P_ShhpoL8QqtGEZ7h18p92BxuH0foQOQYj2Wg at mail.gmail.com>
> Content-Type: text/plain; charset=UTF-8
>
> Yup, I submitted my current task 4 weeks ago, sent a note last week,
> and got reply the next day (Nov 1) with same sentiment: relax -
> everything is ok, it's a slow process, and it's not a race.
>
> On Tue, Nov 4, 2014 at 8:59 PM, Dan <qsdconsulting at gmail.com> wrote:
> > Ramon Fried <ramon.fried <at> tandemg.com> writes:
> >
> >>
> >>
> >> Hey all.
> >> Tasks are pending for a long time. Anyone has Info regarding the queue?
> >> Thanks.
> >> Ramon
> >>
> >>
> >> _______________________________________________
> >> Kernelnewbies mailing list
> >> Kernelnewbies <at> kernelnewbies.org
> >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
> >>
> >
> >
> > I've been on challenge 5 for about a month and a half. I sent him a
> follow
> > up email a few weeks ago and he replied "Relax, things are slow, there's
> no
> > rush..."
> >
> > His response times before that were usually less than 2 days.
> >
> >
> >
> > _______________________________________________
> > Kernelnewbies mailing list
> > Kernelnewbies at kernelnewbies.org
> > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>
>
>
> ------------------------------
>
> Message: 2
> Date: Fri, 7 Nov 2014 23:11:26 +0530
> From: Puneet Agarwal <puneet.agr at outlook.com>
> Subject: RE: lots of connections in SYN_RECV state
> To: Dave Tian <dave.jing.tian at gmail.com>, Silvan Jegen
> <me at sillymon.ch>
> Cc: "kernelnewbies at kernelnewbies.org"
> <kernelnewbies at kernelnewbies.org>
> Message-ID: <SNT153-W7011B59E54B5FD99A3604699850 at phx.gbl>
> Content-Type: text/plain; charset="iso-8859-1"
>
> I use linux kernel 2.6. I have enabled SYN cookies already. But that does
> not seem to solve the problem. Overall request latency is very high with
> these many half open connections.
>
> Thanks and Regards
> Puneet
> ----------------------------------------
> > Subject: Re: lots of connections in SYN_RECV state
> > From: dave.jing.tian at gmail.com
> > Date: Fri, 7 Nov 2014 23:49:35 +0800
> > CC: puneet.agr at outlook.com; kernelnewbies at kernelnewbies.org
> > To: me at sillymon.ch
> >
> > Latest kernel provides a TCP SYN Cookie feature to defense from SYN
> flooding.
> >
> > -daveti
> >
> >
> >> On Nov 6, 2014, at 11:58 PM, Silvan Jegen <me at sillymon.ch> wrote:
> >>
> >> 2014-11-06 16:15,Puneet Agarwal:
> >>> Is there a way to check the reason, why they do not answer to the
> >>> SYN-ACK's?
> >>
> >> I don't think so. After all, they just don't answer and they won't tell
> >> you why (AFAIK there is no way to ask them why either)...
> >>
> >> You could try to check for patterns in the incoming IP addresses to see
> >> from how many different places these connections are being made. I think
> >> that way it should be possible to figure out from which geographic
> >> location these problematic connections are coming from as well. What you
> >> would do with these findings I am not sure though.
> >>
> >> If these connection negatively impact the performance of your servers
> >> you should definitely look into to countermeasures mentioned in the RFC
> >> here.
> >>
> >> http://tools.ietf.org/html/rfc4987
> >>
> >>
> >> _______________________________________________
> >> Kernelnewbies mailing list
> >> Kernelnewbies at kernelnewbies.org
> >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
> >
>
>
>
> ------------------------------
>
> Message: 3
> Date: Fri, 07 Nov 2014 13:10:05 -0500
> From: Valdis.Kletnieks at vt.edu
> Subject: Re: lots of connections in SYN_RECV state
> To: Puneet Agarwal <puneet.agr at outlook.com>
> Cc: Dave Tian <dave.jing.tian at gmail.com>, Silvan Jegen
> <me at sillymon.ch>, "kernelnewbies at kernelnewbies.org"
> <kernelnewbies at kernelnewbies.org>
> Message-ID: <9736.1415383805 at turing-police.cc.vt.edu>
> Content-Type: text/plain; charset="us-ascii"
>
> On Fri, 07 Nov 2014 23:11:26 +0530, Puneet Agarwal said:
>
> > I use linux kernel 2.6. I have enabled SYN cookies already. But that
> does not
> > seem to solve the problem. Overall request latency is very high with
> these many
> > half open connections.
>
> So, out of curiosity, where are all these half open connections coming
> from? Are they from addresses in your local network? Outside sites that
> *should* be connecting? Places you've never heard and and probably
> *shouldn't*
> be connecting?
>
> (Also, if you have properly implemented syncookies, you shouldn't *have*
> any
> half-open connections. That's the whole point of syncookies....)
>
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> ------------------------------
>
> Message: 4
> Date: Sat, 8 Nov 2014 07:48:14 +0800
> From: Dave Tian <dave.jing.tian at gmail.com>
> Subject: Re: lots of connections in SYN_RECV state
> To: Valdis.Kletnieks at vt.edu
> Cc: Puneet Agarwal <puneet.agr at outlook.com>, Silvan Jegen
> <me at sillymon.ch>, kernelnewbies at kernelnewbies.org
> Message-ID: <3C9C05E5-9B76-4C85-ABB5-D6A9D345E871 at gmail.com>
> Content-Type: text/plain; charset=utf-8
>
> Oops, my bad. I remember seeing sth on LWN for the 3.x kernel talking
> about a new feature related with TCP SYN. Thought this pretty old stuff was
> the one?
>
> -daveti
>
>
> > On Nov 8, 2014, at 12:58 AM, Valdis.Kletnieks at vt.edu wrote:
> >
> > On Fri, 07 Nov 2014 23:49:35 +0800, Dave Tian said:
> >> Latest kernel provides a TCP SYN Cookie feature to defense from SYN
> flooding.
> >
> > If by "latest" you mean "since Andi Kleen submitted a patch for 2.1.44",
> > back in July 1997....
>
>
>
>
> ------------------------------
>
> Message: 5
> Date: Sat, 8 Nov 2014 07:35:30 +0530
> From: Puneet Agarwal <puneet.agr at outlook.com>
> Subject: RE: lots of connections in SYN_RECV state
> To: "Valdis.Kletnieks at vt.edu" <valdis.kletnieks at vt.edu>
> Cc: Dave Tian <dave.jing.tian at gmail.com>, Silvan Jegen
> <me at sillymon.ch>, "kernelnewbies at kernelnewbies.org"
> <kernelnewbies at kernelnewbies.org>
> Message-ID: <SNT153-W6599D6BF8CD3550AB9FB9899820 at phx.gbl>
> Content-Type: text/plain; charset="iso-8859-1"
>
> These connections are from outside the network, and the IP's are
> legitimate ones which should be connecting.
> I don't know whether the IP's which I could see are the real ones or
> spoofed ones.
>
> sysctl -a says
> net.ipv4.tcp_syncookies = 1
>
> cat /proc/sys/net/ipv4/tcp_syncookies also gives 1
>
> Isn't this sufficient to enable syncookies?
>
> Thanks and Regards
> Puneet
> ----------------------------------------
> > To: puneet.agr at outlook.com
> > CC: dave.jing.tian at gmail.com; me at sillymon.ch;
> kernelnewbies at kernelnewbies.org
> > Subject: Re: lots of connections in SYN_RECV state
> > From: Valdis.Kletnieks at vt.edu
> > Date: Fri, 7 Nov 2014 13:10:05 -0500
> >
> > On Fri, 07 Nov 2014 23:11:26 +0530, Puneet Agarwal said:
> >
> >> I use linux kernel 2.6. I have enabled SYN cookies already. But that
> does not
> >> seem to solve the problem. Overall request latency is very high with
> these many
> >> half open connections.
> >
> > So, out of curiosity, where are all these half open connections coming
> > from? Are they from addresses in your local network? Outside sites that
> > *should* be connecting? Places you've never heard and and probably
> *shouldn't*
> > be connecting?
> >
> > (Also, if you have properly implemented syncookies, you shouldn't *have*
> any
> > half-open connections. That's the whole point of syncookies....)
> >
>
>
>
> ------------------------------
>
> _______________________________________________
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>
> End of Kernelnewbies Digest, Vol 48, Issue 10
> *********************************************
>
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