lkml.org 
[lkml]   [1999]   [Feb]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: PPP bug
Date
Andrew Snare wrote the following:
>
> --pgp-sign-Multipart_Mon_Feb__8_15:11:52_1999-1
> Content-Type: text/plain; charset=US-ASCII
>
> >>>>> "Dick" == Richard B Johnson <root@chaos.analogic.com> writes:
>
> Dick> The +++ sequence in a packet can't affect the modem because
> Dick> you need at least 500ms (lowest you can set it) of quiet after
> Dick> the sequence to change its mode. The data strings will never
> Dick> be the last thing sent, so you can't get 500ms between
> Dick> characters no matter how hard you try.
>
> This is partially true. Unfortunately (I believe) Hayes patented the
> idea of there having to be a pause before and after the +++ sequence,
> and some manufacturers (namely Rockwell) simply look for any +++
> sequence as a break sequence regardless of timing. Experience is that
> roughly 40% of people on IRC are susceptible to this problem, so these
> modems are fairly wide-spread. To test a host (with permission,
> of-course:) use:
>
> % ping -p 2b2b2b415448300d <hostname>

*laughs and laughs*

501.damien@kinder:/home/damien>> ping -p 2b2b2b415448300d axe
PATTERN: 0x2b2b2b415448300d
PING axe (203.35.182.2): 56 data bytes
ping: sendto: Network is unreachable
ping: wrote axe 64 chars, ret=-1
ping: sendto: Network is unreachable
ping: wrote axe 64 chars, ret=-1
ping: sendto: Network is unreachable
ping: wrote axe 64 chars, ret=-1
ping: sendto: Network is unreachable
ping: wrote axe 64 chars, ret=-1
ping: sendto: Network is unreachable
ping: wrote axe 64 chars, ret=-1
ping: sendto: Network is unreachable
ping: wrote axe 64 chars, ret=-1

--- axe ping statistics ---
7 packets transmitted, 0 packets received, 100% packet loss

Boom! :) Ahh well. This -IS- a cheaparse modem afterall :)

Also figures that BSD compression on my ppp link should've died
sometime before that. :/

> If it replies, the host is fine. If it doesn't, it's got a faulty
> modem. This was all covered in depth a while back on the Bugtraq
> mailing lists (search the geek-girl archives... I think "Old school
> DoS" was the subject). The only solution if you've got one of these
> modems is to change break character from + to something else, or
> (preferably) disable it entirely with AT S2=255. An interesting
> side-effect of the bug is that you can "patch" people's modems for
> them if they're buggy with something like (untested):
>
> % ping -p 2b2b2b415453323d323535204f300d

Don't have time to do the ascii on this one... This does the S2
command?

--
CaT (cat@zip.net.au) URL: http://www.zip.com.au/dev/null

There was farting in the air that night,
It lit so bright,
Fernando...


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:50    [W:0.189 / U:0.372 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site