Re: (OT kinda) Newly-discovered TCP flaw
On Thursday 11 August 2016 15:31:37 Lisi Reisz wrote:
> On Thursday 11 August 2016 20:06:26 Gene Heskett wrote:
> > On Thursday 11 August 2016 15:44:24 Doug wrote:
> > > On 08/11/2016 12:50 PM, Gene Heskett wrote:
> > > > On Thursday 11 August 2016 12:47:09 Nicolas George wrote:
> > > > CC:ing emc-developers, and trinity-users who may not yet be
> > > > aware of this tcp attack vector thats quite dangerous. And my
> > > > post to trinity-users was in error, so this corrects it.
> > > >
> > > >> Le quintidi 25 thermidor, an CCXXIV, Gene Heskett a écrit :
> > > >>> to add should be changed to forward slashes:
> > > >>
> > > >> You are wrong, sysctl supports both slashes and dots as
> > > >> separators.
> > > >>
> > > >> Regards,
> > > >
> > > > I changed it back Nicolas, and sysctl -p now returns:
> > > > root@coyote:/etc/init.d# sysctl -p
> > > > sysctl: cannot stat /proc/sys//net.ipv4.tcp_challenge_ack_limit:
> > > > No such file or directory
> > > >
> > > > Put the slashes back and I get this:
> > > > root@coyote:/etc/init.d# sysctl -p
> > > > .net.ipv4.tcp_challenge_ack_limit = 999999999
> > > >
> > > > Which I assume is the correct response. And yet the echo shows
> > > > all dots.
> > > >
> > > > WTH? Ahh, my bad, no damned biscuit, an extra leading slash
> > > > snuck in. But if a dot and a slash are the same to sysctl, I
> > > > should have a file in the wrong place? But I do not. /net is
> > > > empty. It is in the right place now. And cats the correct value.
> > > >
> > > > Sorry about the confusion everybody.
> > > >
> > > > Cheers, Gene Heskett
> > >
> > > Running PCLOS. I put in the original command with dots. When I run
> > > sysctl.p from a root environment I get no response, but no error
> > > either. Don't know the significance of that.
> > >
> > > --doug
> >
> > Neither do I Doug, sorry. See the announcement on /. today & read
> > the link to the post from the guys that found it that is in the
> > story, UCsomething IIRC, see below. A closer read may answer it.
> >
> > <https://ucrtoday.ucr.edu/39030>
> >
> > And please keep things like this on the list you read it from. A PM
> > is unfair to the other readers of the list you read it on, so I'll
> > cc the three lists it was cross posted to as it sounds pretty
> > serious to me.
> >
> > And I just noted that the sysctl command you quoted above is
> > incorrect, its sysctl -p, not sysctl.p.
> >
> > Maybe that helps?
>
> I copied and pasted the commands exactly, and ran them as root, and
> got an echo of net.ipv4.tcp_challenge_ack_limit = 999999999 in
> response to the first and a blank return in response to the second. I
> don't know the significance.
>
> Lisi
cat that file Lisi. Thats in /proc/sys/net.ipv4.tcp_challenge_ack_limit.
I think we did as we were told if it contains those 9 9's.
Cheers, Gene Heskett
--
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-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>
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