Public bug reported:
Hello, I am using a vpn pptp connection to ipredator.se. Heavy use of the pptp completely freezes my computer. Usually the freeze happens within a few minutes. Then both the caps lock and scroll lock led will be blinking. Magic sysrq keys to not work anymore. CTRL-ALT-F1 etc to switch to a terminal window does not work either and the machine does not respond to a ping on the eth0 interface's ip address anymore. In short words: totally and utterly frozen. I think that the pptp kernel module is not handling the queueing of a larger number of packets correctly (might be interesting if that could be exploited). Architecture is amd64. The computer is a Dell Latitude D830. I can reproduce this freeze with the pptp vpn connection running both over the ethernet interface eth0, as well as over the wireless ethernet interface wlan0. At first I always used the vpn pptp service with network-manager. This is when I first noticed the freezes. The freezes happen when I heavily use the pptp vpn connection at the airport, hotel or some other hotspot, or when working from a client's site, when I have to access some disk images or larger pdf manuals, or open a couple of tabs at the same moment in firefox, etc. /var/log/syslog then shows as the last message before the freeze of the machine: Dec 17 03:12:08 tuxtux pptp[20321]: anon warn[decaps_gre:pptp_gre.c:426]: discarding bogus packet 2650122 (expecting 2648136) Dec 17 03:12:08 tuxtux pptp[20321]: anon warn[decaps_gre:pptp_gre.c:426]: discarding bogus packet 2650123 (expecting 2648136) Dec 17 03:12:08 tuxtux pptp[20321]: anon warn[decaps_gre:pptp_gre.c:426]: discarding bogus packet 2650124 (expecting 2648136) Dec 17 03:12:08 tuxtux pptp[20321]: anon warn[decaps_gre:pptp_gre.c:426]: discarding bogus packet 2650125 (expecting 2648136) That messages is repeated a couple of hundred times before the syslog entries stops and the machine freezes. Not being satisfied with a not really working pptp vpn I decided to resort to the beloved command line interface to investigate further. Configuration needed to reproduce: /etc/ppp/options.pptp: lock noauth refuse-pap refuse-eap refuse-chap refuse-mschap nobsdcomp nodeflate /etc/ppp/ipredator: pty "pptp vpn.ipredator.se --nolaunchpppd" remotename ipredator ipparam ipredator lock noproxyarp noauth nobsdcomp nodeflate defaultroute replacedefaultroute name USERNAMEFORPPTPSERVICE require-mppe-128 persist refuse-pap refuse-eap refuse-chap refuse-mschap noipx lcp-echo-interval 30 lcp-echo-failure 4 /etc/ppp/chap-secrets USERNAMEFORPPTPSERVICE ipredator PASSWDFORPPTPSERVICE vpn.ipredator.se /etc/ppp/ip-up does not contain any customisations. With that I can start the pptp vpn on the command line as root like that # while : ; do pon ipredator nodetach debug ; done using channel 1 Using interface ppp0 Connect: ppp0 <--> /dev/pts/1 sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x3e93cf02> <pcomp> <accomp>] rcvd [LCP ConfReq id=0x1 <asyncmap 0x0> <auth chap MS-v2> <magic 0x70400b12> <pcomp> <accomp>] sent [LCP ConfAck id=0x1 <asyncmap 0x0> <auth chap MS-v2> <magic 0x70400b12> <pcomp> <accomp>] rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x3e93cf02> <pcomp> <accomp>] sent [LCP EchoReq id=0x0 magic=0x3e93cf02] rcvd [LCP EchoReq id=0x0 magic=0x70400b12] sent [LCP EchoRep id=0x0 magic=0x3e93cf02] rcvd [CHAP Challenge id=0x6e <XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX>, name = "pptpd"] sent [CHAP Response id=0x6e <YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY>, name = "USERNAMEFORPPTPSERVICE"] rcvd [LCP EchoRep id=0x0 magic=0x70400b12] rcvd [CHAP Success id=0x6e "S=ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ"] CHAP authentication succeeded sent [CCP ConfReq id=0x1 <mppe +H -M +S -L -D -C>] rcvd [CCP ConfReq id=0x1 <mppe +H -M +S -L -D -C>] sent [CCP ConfAck id=0x1 <mppe +H -M +S -L -D -C>] rcvd [CCP ConfAck id=0x1 <mppe +H -M +S -L -D -C>] MPPE 128-bit stateless compression enabled sent [IPCP ConfReq id=0x1 <compress VJ 0f 01> <addr 0.0.0.0>] rcvd [IPCP ConfReq id=0x1 <compress VJ 0f 01> <addr 93.182.153.2>] sent [IPCP ConfAck id=0x1 <compress VJ 0f 01> <addr 93.182.153.2>] rcvd [IPCP ConfNak id=0x1 <addr 93.182.153.41>] sent [IPCP ConfReq id=0x2 <compress VJ 0f 01> <addr 93.182.153.41>] rcvd [IPCP ConfAck id=0x2 <compress VJ 0f 01> <addr 93.182.153.41>] replacing old default route to eth0 [192.168.254.1] local IP address 93.182.153.41 remote IP address 93.182.153.2 Script /etc/ppp/ip-up started (pid 2867) Script /etc/ppp/ip-up finished (pid 2867), status = 0x0 So far so good. Now when the computer freezes it looks like that in syslog (please see that attached file) I noticed that I can (mostly) avoid the freezes if I change the line from the file /etc/ppp/ipredator from: pty "pptp vpn.ipredator.se --nolaunchpppd" to pty "pptp vpn.ipredator.se --nolaunchpppd --timeout 0.3" I also tried with: pty "pptp vpn.ipredator.se --nolaunchpppd --timeout 0.5" but then the freezes still happened, but with timeout 0.3 it seems to work. However with the setting "timeout 0.3" the overall pptp vpn connection's speed seems to suffer. I hope that is enough information to debug this problem. I ran memtest86 for a few hours before investigating this in the first place. RAM seems ok. This computer never freezes unless the pptp connection is running. A quick search at google yielded these other bug reports: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=424511 http://lists.opensuse.org/opensuse-bugs/2010-08/msg00772.html http://sourceforge.net/mailarchive/forum.php?thread_name=20100806004326.GK3802%40us.netrek.org&forum_name=pptpclient-devel http://comments.gmane.org/gmane.comp.misc.pptpclient.devel/2858 http://www.mail-archive.com/linux-il@cs.huji.ac.il/msg22678.html http://lists.debian.org/debian-devel/2007/05/msg00464.html BR. Max. ProblemType: Bug DistroRelease: Ubuntu 10.10 Package: pptp-linux 1.7.2-5 ProcVersionSignature: Ubuntu 2.6.35-31.63-generic 2.6.35.13 Uname: Linux 2.6.35-31-generic x86_64 Architecture: amd64 Date: Sat Dec 17 10:33:07 2011 InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release amd64 (20101007) ProcEnviron: LANGUAGE=de_DE:en LANG=de_DE.utf8 LC_MESSAGES=de_DE.UTF-8 SHELL=/bin/bash SourcePackage: pptp-linux ** Affects: pptp-linux (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug maverick -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/905659 Title: pptp vpn connection, heavily used, completely freezes the computer To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/pptp-linux/+bug/905659/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
