Mail server domains DNS setup: SPF DMARC DKIM

Only texts to change in the records below: Client domain=”DOMAIN.TLD”, and generated DKIM key for DNS=”KEYFORTHEDNS”

SPF
@ TXT “v=spf1 ip4:46.4.107.162 include:_spf.google.com ~all”

DMARC
_dmarc TXT “v=DMARC1; p=none; rua=mailto:dmarc@DOMAIN.TLD”
Should be same domain otherwise need to allow rua email domain

DKIM
Generate both keys, use the key for DNS in the record:
default._domainkey.DOMAIN.TLD TXT “v=DKIM1; t=s; p=KEYFORTHEDNS”

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Create sdcard image file with Linux, fast and with progress bar

# pv -tpreb /dev/mmcblk0 | dd of=image_sdcard-1.img bs=16M

-t : Time elapsed
-p : Progress
-r : Rate of transfer
-e : ETA estimation
-b : Bytes counter

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On 30.5, root certificate for Comodo / Sectigo expired

Replace old certificate chain file CA by new one:
https://dtc2.nettitila.fi/new.cert_newroot2.ca

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check certificate validity with command line

openssl verify cert.pem

openssl verify -untrusted ca-bundle cert.pem

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Check SSL certificate content from command line

openssl x509 -text -noout -in /path/to/SSLCert.crt
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ISO images in Proxmox

are in:

/var/lib/vz/template/iso/

 

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Return to ap-get / dpkg when ssh connection cuts out

It’s good idea to use “screen”, so you can recover easily your session if the ssh connection breaks.

Otherwise just kill the dpkg process, then run

# dpkg --configure --pending
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grep string recursively and sort output files chronologically

Example: Searching the string “function ” recursively, then passing the list to ls which sorts by time:

grep -lir 'function ' . | xargs ls -lart
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turn off pc speaker under Linux

xset b off
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Proxmox host: add new guest IP with bridged network

Your Proxmox host run multiple Guests.

To add new Guest / VM IP using bridge, just do:

From the new Guest VM, /etc/network/interfaces:

[...]
auto eth0
iface eth0 inet static
 address MY-NEW-VM-IP
 netmask 255.255.255.255
 pointopoint MY-PROXMOX-HOST-IP
 gateway MY-PROXMOX-HOST-IP
[...]

Update Host /etc/network/interfaces , add a new route in the vmbr0 interface section:

[...]
auto vmbr0
[...]
 up ip route add MY-NEW-VM-IP/32 dev vmbr0
[...]

Then you need to run manually from the Proxmox Host command line:

route add MY-NEW-VM-IP/32 dev vmbr0

Should do it. You can also restart/reload networking on both Host and Guest

/etc/init.d/networking restart

You may need to use also ifdown/ifup for the Guest interface

ifdown --force eth0
ifup eth0
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