/docs/MyDocs

2013

====

 - glibc-1.17/1.19 (x86, kernel 2.6.32, gcc 4.4 & 4.7) have some problems with libm.

 All applications linked to libm (just linked, you don't need to call anything

 in library) are crashing during load. glibc-1.16 is fine.

 - Gnome 3.10 (even the fallback/classic mode) does not work without 3D. Hence,

 it is not possible to start it in NX session. LXDE is fast alternative for 

 remote access. It may be set as default WM using YaST (System/Sysconfig Editor).

 - OpenSSL-1.0.1e may cause problems with SASL-enabled qmail. OpenSSL-1.0.1f

 seems to work fine.

 - PTY allocation request failed on channel 0. /dev/pts should be mounted:

    none /dev/pts devpts gid=5,mode=620 0 0

 - Running google-earth

    LD_PRELOAD=/usr/lib32/opengl/nvidia/lib/libGLcore.so.195.36.15:/usr/lib32/opengl/nvidia/lib/libGL.so.195.36.15 googleearth

2016

====

 - R420 wifi has some timeouts configured (embedded?) causing packet loss on 

 high latency networks (USA). I.e. from my PC there will be large latency,

 but all packets will be delivered and on R420 were will be packet loss...

 - There is some problems with gpg acting as ssh-agent. After script-restarting

 and killing, not all keys are working (sometimes none, sometimes some). Just 

 killing it manually and restarting with 'pass' helps.

 - Duplicity occasionaly crashes with librsync 2.0.0 due to this bug.

    https://github.com/librsync/librsync/issues/50

 the patch is in net-libs/librsync-2.0.0-r1

 - USB3 support in Linux is buggy. There is two modes how USB storage can 

 operate

    1. New USB Attached SCSI (UAS) mode

    2. Legacy usb-storage mode

 The UAS mode is slightly faster, but may cause write faults and kernel

 crashes with some of the devices. This is not visible with FAT32, but

 very well visible if copying multiple big files to ExFAT or Ext4. The

 only solution is to enforce legacy mode. The USB Vendor/Device IDs of 

 misbehaving devices should be listed in the parameters of usb-storage

 kernel module. I.e. add the following to quirks.conf in /etc/modprobe.d 

    options usb-storage quirks=0x18a5:0x0411:u

 And re-load usb-storage module (and re-insert device). You should see in 

 dmesg:

    usb 10-1.2: UAS is blacklisted for this device, using usb-storage instead

 - Missing Bluetooth keyboard (from headset) on Xorg startup. 

    The only way arround is seems to enable autodection for both NVIDIA

    and AMD layouts and use Multi-seat. The xorg.conf should be splitted

    in two files.

	https://wiki.gentoo.org/wiki/Multiseat

 - mod_python complains "python_handler: Can't get/create interpreter".

    The problem is in the dist/version.sh file which runs git, but since 

    the distribution doesn't have the .git repository structure, the error 

    is generated. I fixed version.sh by just replacing the offending line 

    with an empty definition:

	#GIT=`git describe --always`

	GIT=

    The problem is fixed in mod_python-3.5.0-r1

2017

==== 

 - revdep-rebuild complains on some utf8 character conversion. Python is crap,

 there is still old revdep-rebuild.sh which is just working. Changing locale 

 does not help to python scum.

 - another set of problems related to systemd-less setup of Gentoo 

    1. /etc/X11/xinit/xinitrc.d/90-consolekit causes problems for X startup even if exit 

    put as a first line.

    2. XDG_RUNTIME_DIR is required by gnome-keyring and other Gnome related services.

    It can be set in the /etc/env.d like:

        XDG_RUNTIME_DIR="/tmp/.runtime-$USER"

 - qmail-smtpd complains about 'failed to map segment from shared object'

    The default limits on the shared memory segment set by 'softlimit' utility of the daemontools 

    in the 'supervise/qmail-smtpd/run' is low for the nowdays large libraries and should be increased

    by setting SOFTLIMIT_OPTS in the conf-smtpd. This currently works

        SOFTLIMIT_OPTS="-m 64000000"

 - qmail doesn't receive mails from gmail and there is the following messages in the log

    Technical details of temporary failure: TLS Negotiation failed

    TLS connection failed: error:1408A0C1:SSL routines:SSL3_GET_CLIENT_HELLO:no shared cipher (#4.3.0)

 This is due to protocol incompatibility after fixing the 'Poodle' problem. tlsserverciphers should be

 adjusted to include protocols supported by both qmail and gmail.

    ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-DSS-AES128-GCM-SHA256:kEDH+AESGCM:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-DSS-AES128-SHA256:DHE-RSA-AES256-SHA256:DHE-DSS-AES256-SHA:DHE-RSA-AES256-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA:AES256-SHA:AES:CAMELLIA:DES-CBC3-SHA:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!PSK:!aECDH:!EDH-DSS-DES-CBC3-SHA:!EDH-RSA-DES-CBC3-SHA:!KRB5-DES-CBC3-SHA

 - ssh/login has long delay

    This is caused by 'pam_ck_connector.so' module from consolekit (systemd). I guess this happens if

    SystemD is not used to boot system. It is completely fine just to comment out this module in 

    'system-auth'.

 - owncloud clients complain that "file transfer failed" because file is "locked". This is server-side

 problem which may occur during updates, etc. Solution:

    1. Put owncloud in maintenance mode by setting 'maintenance' to 'true' in  'config/config.php' 

    This is optional is system is not highly loaded...

    2. Empty table 'oc_file_locks' table 

        sqlite /var/lib/owncloud/data   (on darksoft.org: sqlite3 /home/temp/owncloud/data/owncloud.db)

            DELETE FROM oc_file_locks;

    3. Restore standard operation mode, by setting 'maintenance' to 'false'

 Owncloud suggests using Redis as more robust database solution

    https://central.owncloud.org/t/file-is-locked-how-to-unlock/985

 - Annoying evolution in Ubuntu trying to connect here and there. Don't possible to uninstall as will destroy

 complete gnome. But possible to disable

        cd /usr/share/dbus-1/services

        sudo ln -snf /dev/null  org.gnome.evolution.dataserver.AddressBook.service  

        sudo ln -snf /dev/null  org.gnome.evolution.dataserver.Calendar.service 

        sudo ln -snf /dev/null  org.gnome.evolution.dataserver.Sources.service 

        sudo ln -snf /dev/null  org.gnome.evolution.dataserver.UserPrompter.service 

 - OpenOffice crashes on Microsoft *x formats with xmlsec in backtrace

        Rebuild gpgme and libgpg-error.

2018

====

 - Duplicity needs pgp key when running from cron. There are some mm bug in the latest version 0.7.17 (last version

 known to work 0.7.10, but 0.7.11 - 0.7.16 are not checked). Downgrading to 0.7.10 should be fine.

 - In Fedora28 everything starts hanging if mellanox drivers are installed. Network manager has some problems with

 Mellanox drivers. Mellanox cards has to be configured manually and to prevent automatic configuration we need to remove 

 configuration in '/etc/sysconfig/network-scripts/ifcfg-ib*' and set udev rules preventing NM takeover

    ENV{INTERFACE}=="ib[0-9]*" ENV{NM_UNMANAGED}="1"

    ENV{ID_NET_DRIVER}=="mlx4_*", ENV{NM_UNMANAGED}="1"

 - Broadcom NetXtreme II is incompatible with PLX switches.

 - Letsencrypt certbot complains on handle_modules on OpenSuSE 13.1. Change

    handle_mods=False => handle_modules=False

 in 

    /opt/eff.org/certbot/venv/lib64/python2.7/site-packages/certbot_apache/override_suse.py

 - On Gentoo, problems building PDF from latex source using Font Awesome (high quality pictograms):

    In /usr/share/texmf-dist/tex/latex/fontawesome/fontawesome.sty

        \newfontfamily{\FA}{Font Awesome 5 Free}

2019

====

 - I have problems writting on SDCard/ExFAT in Linux. It is unclear that the reason, but situation is looking very similar

 o 'gridlocked' SD card: reading is OK, writting also, but data is lost after remount. This pretty much cross-platform.

    * I have tried Gentoo (kernel 4.8), CentOS 7.5, Fedora 28. 

    * Stable and bleading edge version of fuse-extfat.

    * DeLock USB3 Multi-card reader connected to USB 3.1, USB 3.0, USB 2.0

    * I tried disabling UAS mode as described above (but actually it is not used anyway, the driver can be unloaded)

 Either way, the situation is the same and looks exactly like gridlocked card.

 - Tethering is not working with some (old?) Android phones.

    * Phone is able to connect, but no internet available. 

    * It seems this is kind of incompatibility between old and new ways to implement tethering. 

    * To enable back-ward compatibility, you need to  add 'dun' to the APN type field. In other words the APN type field should be default,dun,supl. 

 - Recent (post 1.6) Java doesn't play well with old IPMI firmwares. Only solution to run Firefox with old version of Java in the docker.

        docker run -ti -e DISPLAY=$DISPLAY -e XAUTHORITY=$XAUTHORITY  -v /tmp/.X11-unix:/tmp/.X11-unix ftso/docker-oracle-java6-firefox firefox

  - While connecting (ssh) to raspbian system (and probably older Debian systems in general), there is curious problem with cyrillic names on the mounts. 

  You get question marks if you 'ls', but it is enough to pipe it trough cat (ls | cat) to get properly readable text. The fix is too install Russian 

  Unicode locale using:

        sudo dpkg-reconfigure locales

  - udisks-glew doesn't allow umask/dmask on exfat. Simple patch udisks (v1) fixes it.

  - openvpn connection problems (OpenVPN seems connected, but packets go trough). 

    * Check 'cipher' warnings. OpenVPN in different distributions reverts to different default cipher (CentOS 8: AES-256-GCM). This would be the effect

    if different ciphers are selected. Better to select implicitely.

  - gnupg-agent serving ssh keys starts asking passwords for the keys which passwords are already stored in gnome-keyring

    * This happens under heavy load (not clear who is responsible: gnupg or gnome-keyring). 

    * Mostly, dsa & rsa keys are affected. The problem does not happen with ED25519 keys and native gnupg key (while it is also actually RSA)

    * No remedy currenlty known

  - Gnome eco-system (e.g. gnome-terminal) starts gvfs processes with automouting which slows down 'File Openning' dialogs and may create many processes

  in 'D' state confusing load average computation. Best remedy is to disable 'gvfs' automounter and kill exisitng 'gvfs*' processes (they will be restarted

  but without automount and would not cause more problems)

        gsettings set org.gnome.desktop.media-handling automount false

        gsettings set org.gnome.desktop.media-handling automount-open false 

        kill -9 $(ps xa | grep gvfs | awk '{ print $1 }')

 - Large loadavg reported by 'uptime' and /proc/loadavg.

    * This likely normal. For uptime, not only 'Running' processes are counted, but also processes in 'uninterruptible sleep' ('D' state in ps). This generally

    mean tasks waiting for I/O, but could be a bunch of stalled things (like process monitoring unavailable NFS mount, some crappy 'gvfs' stuff, etc.)

2020

====

 - ANSIBLE hangs on gather facts. I guess there are many reasons, some:

    * Stalled NFS mounts

    * sg_inq hangs on some IPMI devices, e.g. sg_inq /dev/sd1 on ipepdvcompute2. Temporarily remedy is to disable gathering hardware facts:

        ANSIBLE_GATHER_SUBSET="!hardware" ansible ...

2021

====

 - By default feed-scanning is not working with Browther MFC-L2710DW (Ubuntu 20.04). But it works with the Brother drivers. The drivers are

 configured with the following command: 

	sudo brsaneconfig4 -a name=BrotherScanner model=MFC-L2710DW ip=192.168.43.227

 - Intel WiFi cards seems to have problems with some WiFi bridges on 802.11n standard and only solution is to disable 802.11n support in

 /etc/modprobe.d/iwlwifi.conf:

    options iwlwifi 11n_disable=1

2022

====

  - Linux router terminates idle ssh connections

    * Long-standing problem affecting manly raspbian systems. Likely related iptables MASQUERADE (but migth be (or might not) NOT  SNAT rules).

    In both cases, it could be caused by idle connection timeouts or missing packets (as all running over Wifi). Or both or something else...

    * We can try to setup 'KeepAliveServer' messages to prevent connection getting idle.

    * One usable (while inconvinient) work-around for now to use VPN connections which working without such problems.

    * The issue and fix is unclear, but it worth trying to send Alive messages from ssh client using 'ServerAliveInterval' directive and debug

    with 'conntrack -E --proto tcp --orig-port-dst 22' when it gets happening often.

 - Broken connection between Fritzbox and Debian ipsec installation

    * Some problems with conntrac which can be partially solved by keeping periodic traffic on tunnel (keep-alive is not working for some reason).

    Just ping'ing (e.g. every 10 mins) helps for a while. 

    * If ping fails, connection can be recovered by resetting conntrack status 'conntrack -F' (or reconnecting ipsec first)

 - Homeassistant latency problems

    * Problem is with HDD connected via USB hub (I guess we need to replace USB hub here)

2023

====

  - Canon LBP6000 printer problems: 'lp1' interface registered and immedeately disappears

    * We need Canon drivers as there is proprietary protocol (and printer does not support standard PostScript)

    * We can't install via standard cups setup (it will install printer via wrong protocol), but should use lpadmin/ccpdadmin instead

	mkdir /var/ccpd; lpadmin -p LBP6000 -m CNCUPSLBP6018CAPTK.ppd -v ccp:/var/ccpd/fifo0 -E; ccpdadmin -p LBP6000 -o /dev/usb/lp1; systemctl start ccpd

    * Status: captstatusui -P LBP6000    

  - vlc doesn't see UPNP resources on non-default network interface (i.e. it will not discover resources on WiFi if we have Ethernet connected)

    * SmartPI pulseaudio server is configured on Ethernet IP and we need Ethernet enabled to be able to stream audio to 'Sven' speakers

    * So to enable ASGARD discovery, we need to configure routing of multicast packages (UPNP/DLNA uses 239.255.255.250) on SmartPI via 'smcroute' service and also increase 'ttl' of multicast packets in PREROUTING mangle table

    => It also seems have problem playing both sound and subtitles from Samba share while streaming. Better to copy one (or better both) to local storage