Bug 41385 – pppd connection hangs when using deflate

• Product: Gentoo Linux
• Status: VERIFIED TEST-REQUEST

[Description volker.schindler 2004-02-12 08:59:30 UTC]

RELEASE:
ppp 2.4.1, ppp 2.4.2b3

SYMPTOMES:
ISP connection works well with new KNOPPIX live CD pppd 2.4.1.
With gentoo , the connection hangs after a few seconds (i.e. after ~100kB)
when transmitting an email to the ISP, but hangs typically after a few minutes
when doing a large download (e.g. emerge -f something).
After disconnecting and reconnecting to the ISP, the 'game' starts from the
beginning.

WORKAROUND
Setting the DEFLATE option to 0 (=nodeflate) cures the bug.
(in /etc/ppp/options or in kppp)

HINT:
Further observations show that the bug is due to misunderstanding
between pppd and the ISP. Turning on debug mode shows that
the pppd sends "deflate 14" challenges to the ISP by default, and
"deflate x-1" when "deflate x" is requested in the options file or by kppp.
Obviously, the daemon tells the ISP deflate 14 instead of 15, but actually performs deflate 15.
Thus, when disabling deflate compression by "deflate 0", the connection works normal.

I believe the bug resides inside the gentoo pppd, since providing the knoppix config files
to the gentoo host gives the same symptomes. On the other hand, the kernel sources for the used
gentoo kernel for ppp async and ppp deflate are not gentoo specific and were not changed for
years. However, I don't have time to further isolate the bug ;-)

Please reply since I otherwise believe my email was justified as spam and I will report to your
bug database.

I also spent hours to read several contributions of your forum and found a number of people
getting similar symptoms, but none of them provided a useful workaround.

Reproducible: Always
Steps to Reproduce:
PREFERED METHOD (shows bug after seconds)
1.use kppp to dial in to ISP (MODEM connection)
2.send an email with 200kB well compressed attachment
Actual Results:  
observe how all data transmission hangs
after disconnecting and redialing, the bug is reproduceable

SEE ATTACHMENT with PPPD DEBUG INFO SHOWING THE DEFLATE VARIABLE SETTING

Expected Results:  
GUESS ;-)
SUSE worked well
KNOPPIX worked well

Portage 2.0.49-r21 (default-x86-1.4, gcc-3.2.3, glibc-2.3.2-r9, 2.4.22-gentoo-r5)
=================================================================
System uname: 2.4.22-gentoo-r5 i686 AMD Athlon(tm) XP processor 1600+
Gentoo Base System version 1.4.3.10
ACCEPT_KEYWORDS="x86"
AUTOCLEAN="yes"
CFLAGS="-O2 -march=athlon-xp -pipe"
CHOST="i686-pc-linux-gnu"
COMPILER="gcc3"
CONFIG_PROTECT="/etc /usr/X11R6/lib/X11/xkb /usr/kde/2/share/config
/usr/kde/3.1/share/config /usr/kde/3/share/config /usr/share/config
/var/qmail/control"
CONFIG_PROTECT_MASK="/etc/gconf /etc/env.d"
CXXFLAGS="-O2 -march=athlon-xp -pipe"
DISTDIR="/usr/portage/distfiles"
FEATURES="autoaddcvs ccache sandbox"
GENTOO_MIRRORS="http://gentoo.linux.no 
http://www.die.unipd.it/pub/Linux/distributions/gentoo-sources 
http://ftp.uni-erlangen.de/pub/mirrors/gentoo http://gentoo.oregonstate.edu 
http://www.ibiblio.org/pub/Linux/distributions/gentoo"
MAKEOPTS="-j2"
PKGDIR="/usr/portage/packages"
PORTAGE_TMPDIR="/var/tmp"
PORTDIR="/usr/portage"
PORTDIR_OVERLAY=""
SYNC="rsync://rsync.gentoo.org/gentoo-portage"
USE="X apm arts avi berkdb crypt cups encode esd foomaticdb gdbm gif gpm gtk2
imlib java jpeg kde libg++ libwww mad mikmod motif mozilla mpeg ncurses nls
oggvorbis opengl oss pam pda pdflib perl png ppds python qt quicktime readline
sdl slang spell ssl svga tcpd truetype usb x86 xml2 xmms xv zlib"

[Comment 1 Heinrich Wendel (RETIRED) 2004-02-12 12:26:50 UTC]

this could be a bug in ppp or in your kernel. i just commited ppp-2.4.2 please try out this version, also try vanilla-sources-2.4.24. (i have no rights to remove you email)

[Comment 2 Heinrich Wendel (RETIRED) 2004-02-21 17:36:46 UTC]

any success?

[Comment 3 Heinrich Wendel (RETIRED) 2004-03-06 04:39:10 UTC]

any success?

[Comment 4 volker.schindler 2004-04-08 06:07:49 UTC]

Probably this bug can be closed:

I now use development-sources-2.6.4 for more than a week and as
a consequence deflate works fine together with ppp-2.4.2_beta3-r1.
I don't know what happens when used with ppp-2.4.1-r14, however,
since future ppp releases will be based on 2.4.2_beta3-r1,
it is just a question of time when this bug will disappear.

[Comment 5 Heinrich Wendel (RETIRED) 2004-04-08 10:11:35 UTC]

fine :)