rspamd + DKIM

For RSA 2048
rspamadm dkim_keygen -b 2048 -s rsa -d domain.com -k /var/lib/rspamd/dkim/domain.com/rsa.key > /var/lib/rspamd/dkim/domain.com/rsa.pub

For key ED2551
rspamadm dkim_keygen -t ed25519 -s ed25519 -d domain.com -k /var/lib/rspamd/dkim/domain.com/ed25519.key > /var/lib/rspamd/dkim/domain.com/ed25519.pub

chown _rspamd:_rspamd -R /var/lib/rspamd/dkim/domain.com/

add to /var/lib/bind/domain.com.hosts
rsa._domainkey.domain.com. IN TXT (
"v=DKIM1; k=rsa; "
"p={PASTE_KEY_FROM rsa.pub}"
)
ed25519._domainkey.domain.com. IN TXT (
"v=DKIM1; k=ed25519;"
"p={PASTE_KEY_FROM ed25519.pub}"
)

/etc/rspamd/local.d/dkim_signing.conf
/etc/rspamd/local.d/dkim_signing.conf
domain {
…
domain.com {
selectors [
{
selector = “rsa”;
path = “/var/lib/rspamd/dkim/domain.com/rsa.key”;
},
{
selector = “ed25519”;
path = “/var/lib/rspamd/dkim/domain.com/ed25519.key”;
}
]
}
}

python error while loading shared libraries: libpython3.14.so.1.0: cannot open shared object file: No such file or directory

Rebuild .venv

rm -rf .venv
python3 -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt

Disk for Maildir with XFS in qemu

Create disk on hypervisor
qemu-img create -f qcow2 -o preallocation=metadata /var/lib/libvirt/images/bull-vmail2.qcow2 320G
Attach disk in console or virt-manager
virsh attach-disk bull /var/lib/libvirt/images/bull-vmail2.qcow2 vde \
--cache writeback \
--discard ignore \
--persistent

Create partition on attached disk
parted /dev/vde --script mklabel gpt
parted /dev/vde --script mkpart primary xfs 0% 100%

Format disk
mkfs.xfs -f -m reflink=0 /dev/vde1

Add entry to /etc/fstab
blkid
/dev/vde1: UUID="75c7522e-f196-442d-bd07-f997bed7d0cc" BLOCK_SIZE="512" TYPE="xfs" PARTLABEL="primary" PARTUUID="9b0f0bfe-1c6f-4d17-ab75-11de67a177da"

UUID=75c7522e-f196-442d-bd07-f997bed7d0cc /tmp/vmail xfs noatime,nodiratime,inode64,logbufs=8,allocsize=1m 0 0

Sending email without mail server – msmtp (light SMTP client)

apt install msmtp msmtp-mta

Config file /etc/msmtprc


defaults
auth on
tls on
tls_trust_file /etc/ssl/certs/ca-certificates.crt
logfile /var/log/msmtp.log
account default
host smtp.gmail.com
port 587
from twojemail@gmail.com
user twojemail@gmail.com
password "<secret>"

chmod 600 /etc/msmtprc
Test
echo "Test msmtp" | mail -s "Test" someone@gmail.com
Logs
tail -f /var/log/msmtp.log

dovecot

→ wymusza przeliczenie quota i zapis do clone.
doveadm quota recalc -u user@example.com

→ uruchom z verbose, aby zobaczyć szczegółowe operacje pluginów.
doveadm -Dv

UTC in Microsoft Windows

To dual boot with Windows, it is recommended to configure Windows to use UTC, rather than Linux to use localtime. (Windows by default uses localtime)

It can be done by a simple registry fix: Open regedit and add a DWORD value with hexadecimal value 1 to the registry HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation\RealTimeIsUniversal

You can do this from an Administrator Command Prompt running:

C:\>reg add "HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\TimeZoneInformation" /v RealTimeIsUniversal /d 1 /t REG_DWORD /f

pacman upgrade packages in ArchLinux

pacman upgrade packages in ArchLinux
sudo pacman -Syu
-S – Synchronizes packages
-y – Refreshes the package database
-u – Upgrades all installed packages

Remove a package (keep dependencies)
sudo pacman -R package_name

Remove a package and unneeded dependencies
sudo pacman -Rns package_name

Remove orphaned packages (unneeded dependencies)
sudo pacman -Rns $(pacman -Qdtq)

Remove a package and ignore dependencies
sudo pacman -Rdd package_name

Remove a package and its cache (free up disk space)
sudo pacman -R package_name && sudo pacman -Sc

For a more aggressive cleanup, remove all cached package files:
sudo pacman -R package_name && sudo pacman -Scc

To install packages from a previously saved list of packages, while not reinstalling previously installed packages that are already up-to-date, run:
pacman -S --needed - < pkglist.txt

EFI BOOT ENTRY

DELETE

To delete a menu entry using efibootmgr
first list the current boot entries with sudo efibootmgr
Identify the boot number of the entry you want to delete, then use the command:
sudo efibootmgr -b XXXX -B
replacing XXXX with the boot number of the entry you wish to remove.

ADD

To add a menu entry using efibootmgr, use the following command format:
sudo efibootmgr -c -d /dev/sdX -p NN -L "Label" -l "\EFI\path\to\boot\file.efi"
where /dev/sdX is your disk, NN is the partition number,
“Label” is the name you want for the boot entry,
and \EFI\path\to\boot\file.efi is the path to the EFI executable.

!!! Make sure the path to the boot file is correct and uses backslashes, as required by the EFI specification!!!

proxmox import vm from kvm

Create a new VM in the web interface (leave other settings as default)
copy VM disk to proxmox (ex. using terminal) and import it to newly created VM machine
qm importdisk machine_id_number /var/lib/vz/images/file.qcow local-zfs
qm rescan

Go to your new created VM in the proxmox web interface.
Go to the Hardware section of the newly created VM in the Proxmox web interface
Look for the Unused Disk and select it.
Then you have to add the disk by clicking on Edit on the top.

Reducing the size of a QEMU virtual disk (thin disk)

On all mounting points
dd if=/dev/zero of=/nul;sync;sync;sync;rm -f /nul;sync

Stop VM

Convert disk

qemu-img convert -O qcow2 -c disk1.qcow disk1.new.qcow