Playing with wireshark (current SVN version) I see a much more UDP packets having udp.checksum_bad == 1 (80 bad UP packets within 1600 TCP+UDP packets at all) than ever observed before (LAN, ThinkPad T41 with e1000 network card). Booting back into 2.6.18-gentoo-r5 I didn't have bad packets. Booting again into 2.6.19-r5 the problem appears again. The observed IP protocols affected by this problem are currently DNS, NTP but others too - and some TCP packets have bad checksum too. tfoerste@n22 ~ $ emerge --info Portage 2.1.1-r2 (default-linux/x86/2006.1, gcc-3.4.6, glibc-2.4-r4, 2.6.19-gentoo-r5 i686) ================================================================= System uname: 2.6.19-gentoo-r5 i686 Intel(R) Pentium(R) M processor 1700MHz Gentoo Base System version 1.12.6 Last Sync: Wed, 31 Jan 2007 11:20:01 +0000 ccache version 2.4 [enabled] app-admin/eselect-compiler: [Not Present] dev-java/java-config: 1.3.7, 2.0.31 dev-lang/python: 2.4.3-r4 dev-python/pycrypto: 2.0.1-r5 dev-util/ccache: 2.4-r6 dev-util/confcache: [Not Present] sys-apps/sandbox: 1.2.17 sys-devel/autoconf: 2.13, 2.61 sys-devel/automake: 1.4_p6, 1.5, 1.6.3, 1.7.9-r1, 1.8.5-r3, 1.9.6-r2, 1.10 sys-devel/binutils: 2.16.1-r3 sys-devel/gcc-config: 1.3.14 sys-devel/libtool: 1.5.22 virtual/os-headers: 2.6.17-r2 ACCEPT_KEYWORDS="x86" AUTOCLEAN="yes" CBUILD="i686-pc-linux-gnu" CFLAGS="-O2 -march=pentium-m -fomit-frame-pointer -pipe" CHOST="i686-pc-linux-gnu" CONFIG_PROTECT="/etc /usr/kde/3.5/env /usr/kde/3.5/share/config /usr/kde/3.5/shutdown /usr/share/X11/xkb /usr/share/config" CONFIG_PROTECT_MASK="/etc/env.d /etc/env.d/java/ /etc/gconf /etc/java-config/vms/ /etc/revdep-rebuild /etc/terminfo" CXXFLAGS="-O2 -march=pentium-m -fomit-frame-pointer -pipe" DISTDIR="/usr/portage/distfiles" FEATURES="autoconfig ccache distlocks metadata-transfer parallel-fetch sandbox sfperms strict" GENTOO_MIRRORS="http://pandemonium.tiscali.de/pub/gentoo/ http://85.25.128.62 http://ftp-stud.fht-esslingen.de/pub/Mirrors/gentoo/ http://linux.rz.ruhr-uni-bochum.de/download/gentoo-mirror/" LINGUAS="de en" MAKEOPTS="-j2" PKGDIR="/usr/portage/packages" PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --compress --force --whole-file --delete --delete-after --stats --timeout=180 --exclude='/distfiles' --exclude='/local' --exclude='/packages'" PORTAGE_TMPDIR="/var/tmp" PORTDIR="/usr/portage" PORTDIR_OVERLAY="/usr/local/portage" SYNC="rsync://rsync.de.gentoo.org/gentoo-portage" USE="x86 X aac acpi alsa alsa_cards_intel8x0 alsa_cards_intel8x0m alsa_pcm_plugins_adpcm alsa_pcm_plugins_alaw alsa_pcm_plugins_asym alsa_pcm_plugins_copy alsa_pcm_plugins_dmix alsa_pcm_plugins_dshare alsa_pcm_plugins_dsnoop alsa_pcm_plugins_empty alsa_pcm_plugins_extplug alsa_pcm_plugins_file alsa_pcm_plugins_hooks alsa_pcm_plugins_iec958 alsa_pcm_plugins_ioplug alsa_pcm_plugins_ladspa alsa_pcm_plugins_lfloat alsa_pcm_plugins_linear alsa_pcm_plugins_meter alsa_pcm_plugins_mulaw alsa_pcm_plugins_multi alsa_pcm_plugins_null alsa_pcm_plugins_plug alsa_pcm_plugins_rate alsa_pcm_plugins_route alsa_pcm_plugins_share alsa_pcm_plugins_shm alsa_pcm_plugins_softvol apache2 arts asf berkdb bitmap-fonts bluetooth bzip2 cairo cddb clamav cli cracklib crypt css cups dlloader dri dvd dvdr dvdread elibc_glibc exif fam fastbuild fortran gd gdbm gif gpm gtk gtk2 hdaps i8x0 iconv input_devices_evdev input_devices_joystick input_devices_keyboard input_devices_mouse ipv6 isdnlog jai java javascript jimi jpeg kernel_linux lcd_devices_bayrad lcd_devices_cfontz lcd_devices_cfontz633 lcd_devices_glk lcd_devices_hd44780 lcd_devices_lb216 lcd_devices_lcdm001 lcd_devices_mtxorb lcd_devices_ncurses lcd_devices_text libg++ linguas_de linguas_en logrotate madwifi mbox midi mikmod mmx mmxext mp3 mp4 mysql ncurses nls nptl nptlonly nsplugin opengl pam pcre pdf perl png ppds pppd python readline real reflection rtc samba session spl sse sse2 ssl subversion svg tcpd tiff truetype truetype-fonts type1-fonts udev unicode userland_GNU userlocales video_cards_radeon video_cards_vga win32codecs xml xorg xpm zlib" Unset: CTARGET, EMERGE_DEFAULT_OPTS, INSTALL_MASK, LANG, LC_ALL, LDFLAGS, PORTAGE_RSYNC_EXTRA_OPTS Reproducible: Always
For the NTP protocol: all server packets are ok, all NTP client packets have wrong checksum
in general: all UDP packets created by my localhost have a wrong check sum whereas the received UDP packets are ok
Which network hardware and driver is this? Is it reproducible on the latest development kernel, currently 2.6.20-rc6?
(In reply to comment #3) > Which network hardware and driver is this? 22 ~ # lspci | grep Ether 02:01.0 Ethernet controller: Intel Corporation 82540EP Gigabit Ethernet Controller (Mobile) (rev 03) 02:02.0 Ethernet controller: Atheros Communications, Inc. AR5212 802.11abg NIC (rev 01) dmesg gives: n22 ~ # dmesg | grep e100 e1000: 0000:02:01.0: e1000_probe: (PCI:33MHz:32-bit) 00:0d:60:7b:2d:9b e1000: eth0: e1000_probe: Intel(R) PRO/1000 Network Connection e1000: eth0: e1000_watchdog: NIC Link is Up 100 Mbps Full Duplex n22 ~ # dmesg | grep Think radeonfb: IBM Thinkpad R50/R51/T40/T41 detected, enabling workaround ibm_acpi: ThinkPad EC firmware 1RHT71WW-3.04 ibm_acpi: IBM ThinkPad ACPI Extras v0.13 It's an T41 which works like a charm with Linux (except this already solved bug: http://bugzilla.kernel.org/show_bug.cgi?id=7207) > Is it reproducible on the latest development kernel, currently 2.6.20-rc6? Unfortunately yes, I tested it with latest sources : 2.6.20-rc7-g190ff5b3 I switched back to 2.6.18-gentoo-r6.
b/c it's a problem of the vanilla kernel I filed a bug here : http://bugzilla.kernel.org/show_bug.cgi?id=7938
Thanks. It would be good to describe what makes you think the checksums are bad (i.e. describe the process you are using with wireshark) on the upstream bug as well.
As noted on the upstream bug, this is related to iptables_nat. It's not a 2.6.19 regression and it's not really a bug at all
