blog.crox.net (Entries tagged as linux)

Disable WiFi Power Management on Raspbian 12 (Network Manager)

nospam@example.com (crox) — Fri, 15 Aug 2025 22:48:00 +0000

8 years later there are still issues on Raspberry Pi / Raspbian with WiFi power management causing disconnects and generally bad performance.

I've found a reliable method to disable WiFi Power Management for the on-board WiFi chip (brcmfmac) here: NetworkManager WiFi Power Saving.

Ensuring the EFI partition is mirrored on an Ubuntu install with root on software RAID 1

nospam@example.com (crox) — Sun, 04 May 2025 19:28:00 +0000

I found a working procedure here:

- Make sure both EFI partitions are mounted from /etc/fstab, eg. using /boot/eficopy in addition to /boot/efi. (Both partitions need to have the proper partition type GUID, i.e. C12A7328-F81F-11D2-BA4B-00A0C93EC93B or "EFI System".)

- Run dpkg-reconfigure grub-efi-amd64 and include both partitions when prompted.

libheif1 >= 1.18 on debian 12 bookworm (installing packages from backport in debian stable)

nospam@example.com (crox) — Fri, 02 May 2025 18:08:00 +0000

Add this line to /etc/apt/sources.list:

deb http://deb.debian.org/debian bookworm-backports main

Run:

# apt-get update
# apt install -t bookworm-backports libheif1

This solves the issues encountered when decoding HEIF (.heic) files produced by iPhone / iOS 18, causing for instance rendering in Nextcloud to fail.

This page has more details on using Backports.

BackupPC - binary garbage in XferLog.z / XferLog.z getting huge

nospam@example.com (crox) — Fri, 30 Dec 2022 18:32:00 +0000

I run a BackupPC instance that is still on Debian 10 / buster. The latest rsync package for Debian 10 has version number 3.1.3-6.

I recently noticed infrequent issues when backing up hosts that are either on Debian 11 / bullseye, or on Ubuntu 22.04 (which both ship rsync 3.2.3). The symptoms are as follows:

- backups take much longer than usual
- XferLog.z starts "normally", but after a certain point contains a lot of binary garbage, and gets much bigger than usual (hundreds of MB, or even in one case up to 12 GB)

After investigating and looking for information online, I came across these bug reports, which contain the explanation as well as a workaround: Debian Bug report #969463 and BackupPC issue #369.

=> The issue is caused by a combination of a change of default behaviour introduced with rsync 3.2.3, and a bug in File::RsyncP.

The solution that works for me (pending an update to Debian 11 and BackupPC 4) is to add the following line in the individual server config for each of the affected hosts:

$Conf{RsyncArgsExtra} = ['--no-msgs2stderr'];

Find large files in a BackupPC transfer log (sort files in XferLOG by size)

nospam@example.com (crox) — Sat, 13 Mar 2021 14:40:00 +0000

When your backups suddenly takes much longer to complete, it could be because large files that were previously excluded from the backup were renamed or relocated elsewhere. In order to identify those files, or just to sort the list of files by size, I use the following code (bash):

cd /tmp/
BackupPC_zcat /var/lib/backuppc/pc/mypc/XferLOG.99.z > xlog
for S in `cat xlog | sed -e 's/^[^/]*\/[0-9]*[ ]*//' | cut -f1 -d\  | egrep '^[0-9]+$' | egrep '[0-9]{9,}' | sort -n | uniq ` ; do fgrep " $S " xlog ; done

This will show the list of files bigger than 99999999 bytes (100 MB). Remove "| egrep '[0-9]{9,}'" to just list all instead.

Note: on Debian, BackupPC_zcat is in /usr/share/backuppc/bin/. I've added a symlink in /usr/local/bin/ so that I don't need to look for it every time.

Add HEIF support to Ubuntu Linux 18.04 (thumbnails / gimp) - preview and open HEIC files from iPhone directly in Ubuntu

nospam@example.com (crox) — Mon, 16 Mar 2020 22:10:00 +0000

Since Apple moved from JPEG to HEIF as default format about two years ago, there has been a lot of progress.

There is a very straightforward way to add minimal HEIC/HEIF support to Ubuntu:

sudo add-apt-repository ppa:strukturag/libheif
sudo apt-get install heif-gdk-pixbuf heif-gimp-plugin heif-thumbnailer

That's it! You don't even need to logout or restart, the new functionality is available immediately.

More details here and here.

IPv6 Neighbor discovery

nospam@example.com (crox) — Wed, 11 Jul 2018 06:12:00 +0000

Discover/list other hosts:

ping6 -I eth0 ff02::1
ip -6 neigh show

To connect to a host using the link-local address you need to specify which interface to use (see "zone index"):

ssh -6 fe80::a00:aaaa:bbbb:cccc%eth0

backuppc "no ping response" when ping works fine

nospam@example.com (crox) — Tue, 08 May 2018 17:20:00 +0000

It took me some time to figure this out, maybe it can be useful to someone else...

I kept getting "no ping" error for unknown reasons. It turned out that I had enabled DumpPreUserCmd and UserCmdCheckStatus for that specific host to check for an encrypted partition being mounted.

Due to some changes on the host after an upgrade, the script triggered by DumpPreUserCmd was returning an error... And for some reason this showed as a ping error in the web interface.

I eventually figured it out by checking the last lines of the LOG.** file in the pc/[host] directory, which looked like this:

2018-05-08 19:15:45 Output from DumpPreUserCmd: /[partition] is not mounted
2018-05-08 19:15:45 DumpPreUserCmd returned error status 256... exiting

How to solve Edimax EW-7612UAn v2 (7392:7822) power management issues on Raspberry Pi (Raspbian WiFi disconnect)

nospam@example.com (crox) — Sun, 12 Nov 2017 19:04:00 +0000

On Raspbian, you don't need to install the 8192cu driver manually, as it comes with the distribution

To avoid disconnection issues, you need however to disable power management. This needs to be done in two places. First, this is what I have in /etc/modprobe.d/8192cu.conf:
```
options 8192cu rtw_power_mgnt=0 rtw_enusbss=0
```

This alone did not prevent the issue. I also had to add this entry to /etc/network/interfaces:

auto wlan0
allow-hotplug wlan0
iface wlan0 inet dhcp
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
wireless-power off
iface default inet dhcp

Sources: https://github.com/xbianonpi/xbian/issues/217, https://www.kuerbis.org/2016/03/raspberry-pi-3-kurztipps-wlan-sleep-mode-verhindern/

Accessing iPhone (iOS 10.2.1) pictures from Ubuntu

nospam@example.com (crox) — Sun, 12 Mar 2017 15:40:03 +0000

Recent changes introduced with iOS 10 prevent you from mounting an iPhone on a regular Ubuntu installation.

The PPA by Martin Salbaba used to fix the issue, but it hasn't been updated in a while, and now when I connect my iPhone (running iOS 10.2.1) the pictures are no longer accessible, although the documents are still there.

This solution worked for me (Ubuntu 16.04):

- install libimobiledevice6 + dependencies from this PPA: https://launchpad.net/~martin-salbaba/+archive/ubuntu/ppa+libimobiledevice (follow the instructions there)

- install newer libimobiledevice version according to the "recipe" by A.B. here: http://askubuntu.com/questions/598940/libimobiledevice-1-2-ios-8-support-for-ubuntu-14-04-trusty

- install ifuse according to the same method:

cd ~/src/
git clone https://github.com/libimobiledevice/ifuse.git
cd ifuse/
sudo apt-get install libfuse2 libfuse-dev
./autogen.sh 
make
sudo checkinstall

You can now mount your iPhone like this:

mkdir ~/mnt
ifuse ~/mnt

I assume the same procedure would work for an iPad too.

Linux - extract data from an "OLE Compound" file

nospam@example.com (crox) — Mon, 05 Oct 2015 20:17:18 +0000

As seen here, 7-Zip can extract the contents:

$ file PGPexch.ole
PGPexch.ole: Composite Document File V2 Document, No summary info
$ 7z x PGPexch.ole

7-Zip [64] 9.20  Copyright (c) 1999-2010 Igor Pavlov  2010-11-18
p7zip Version 9.20 (locale=en_US.UTF-8,Utf16=on,HugeFiles=on,2 CPUs)

Processing archive: PGPexch.ole

Extracting  [1]CompObj
Extracting  [1]Ole
Extracting  CONTENTS
Extracting  [3]ObjInfo
Extracting  [2]OlePres000
Extracting  [3]MailStream

Everything is Ok

Files: 6
Size:       104336
Compressed: 108544
$ file CONTENTS
CONTENTS: PDF document, version 1.5
$

(If the OLE data is hidden in a WINMAIL.DAT file, you may have to extract it with tnef first.)

Add Ubuntu alongside a pre-installed Windows on an HP laptop (convert primary partition to extended/logical)

nospam@example.com (crox) — Sat, 03 Oct 2015 09:49:00 +0000

Recently I wanted to install Ubuntu next to a pre-installed Windows on a brand-new HP EliteBook.

The notebook came with four primary partitions, with Windows installed on the biggest one:

- sda1 (1 GB, NTFS, label=SYSTEM)
- sda2 (457 GB, NTFS)
- sda3 (16 GB, NTFS, label=HP_RECOVERY)
- sda4 (2 GB, FAT32)

In order to install Ubuntu it's not enough to resize the Windows partition, as you cannot have more than four primary partitions. Removing one of the other partitions is a bad idea according to several reports, as it might render the system unable to start, or prevent BIOS updates. So the idea is to convert the Windows partition to a logical one in addition to resizing it. Fortunately everything you need to do that is already included on the Ubuntu installation image.

1. Use gparted to resize and move the Windows partition. I resized it to 100 GB and added 10 MB free space before it (to leave some space to create the extended partition later on). This will take a while, depending on the performance of your hard drive.

2. Use fixparts to convert sda2 to a logical partition:

# fixparts /dev/sda

Type l then 2, write the changes to the disk with w.

3. Restart the computer without the Ubuntu install media so that Windows fixes itself. This will take even longer than the partition resize, be patient. Restart once more to make sure the Windows install is fine.

4. Proceed with installing Ubuntu, choose the option to "install Ubuntu alongside Windows".

OSMC NFS mount

nospam@example.com (crox) — Sun, 02 Aug 2015 14:19:46 +0000

It looks like you need some systemd "magic" to successfully mount an NFS share on OSMC. Adding "x-systemd.automount,noauto" to the mount options in /etc/fstab did the trick for me.

Enable IPv6 on OSMC (wired and wireless)

nospam@example.com (crox) — Sat, 01 Aug 2015 22:14:00 +0000

Despite having read the opposite, it looks like IPv6 is disabled by default on the latest OSMC release (2015.06-1). I've tried adding a sysctl.d file to set /proc/sys/net/ipv6/conf/eth0/disable_ipv6 to 0, but this did not help. It worked only when I ran the command manually. By going through numerous forum posts I eventually found out that you need to use the connmanctl CLI tool:

root@osmc:~# connmanctl
connmanctl> services
*AO Wired                ethernet_b827ebaabbcc_cable
connmanctl> config ethernet_b827ebaabbcc_cable --ipv6 auto preferred
connmanctl> quit
root@osmc:~#

This enables IPv6 with autoconfiguration, turns on Privacy Extensions and prefers these ephemeral addresses over the autoconfigured ones.

The same command works for wireless as well, you just need to select the appropriate interface (the service name will start with wifi_).

"help" will display basic usage info.

If for some reason you would like to disable IPv6, the command would be "config ... --ipv6 off".

BackupPC rsync error message "Internal hashtable error: illegal key supplied!"

nospam@example.com (crox) — Thu, 25 Jun 2015 09:08:03 +0000

While trying to restore two files with BackupPC I got the following error message:

Remote[1]: Internal hashtable error: illegal key supplied!
Remote[1]: rsync error: errors with program diagnostics (code 13) at hashtable.c(65) [Receiver=3.0.9]
Read EOF: 
Tried again: got 0 bytes
Done: 2 files, 760646 bytes
restore failed: Unable to read 4 bytes

Other restores worked flawlessly. All hosts involved were running the same version of Debian Linux, with the same version of rsync. The same two files could be restored as a zip file from the BackupPC web front-end.

After spending some time on the issue with a colleague we eventually found the explanation, albeit not the solution: one of the files was a hard link. It looks like we hit a bug similar to what is described here: http://sourceforge.net/p/backuppc/mailman/message/20762995/

> This results in one subtle bug that can't be easily fixed: if you
> switch the Xfer method from tar to rsync, old backups that have
> hardlinks stored with tar won't be correctly restored with rsync.
> The workaround is generate a tar file and extract it, or switch
> the Xfer method back to tar before you do the restore.

We did not switch Xfer method (we've always used rsync over ssh). Possibly the issue was caused by attempting to restore two hard links to the same file at once - more testing would be required to confirm this.