I'll update this post whenever I see fits, A.K.A. when I have other bits of information which don't require a whole post.

Operations on files and directories

Move files to the current/parent directory in Linux

Current dir

find . -type f -exec mv {} . \;

Parent dir

find . -type f -exec mv {} .. \;

Recursive chmod on files and dirs

To change all the directories to 755 (-rwxr-xr-x):

find /var/www/blog -type d -exec chmod 755 {} \;

To change all the files to 644 (-rw-r--r--):

find /var/www/blog -type f -exec chmod 644 {} \;

Certbot

Certbot cli

/etc/letsencrypt/cli.ini

When renewing, use the same private key as the existing certificate. (default: False):

reuse-key = True

Common commands

Register single domain:

certbot certonly --standalone -d domain.tld --dry-run

• Remove “–dry-run” when ok.

Renew single domain:

certbot renew --cert-name domain.tld --dry-run

• Remove “–dry-run” when ok.

Revoke certificate:

certbot revoke --cert-path /etc/letsencrypt/archive/${YOUR_DOMAIN}/cert1.pem

Check certificate's expiry date:

cat /etc/letsencrypt/live/domain.tld/cert.pem | openssl x509 -noout -enddate

GIT

To reset your git repository to given commit id, do:

git reset --hard <commit-id>
git push origin master --force

Ignoring files that are already tracked

git update-index --assume-unchanged <your file here>

Delta Chat Mail sieve

require ["fileinto"];
# rule:[DeltaChat]
if header :contains "Chat-Version" "1.0"
{
	fileinto "DeltaChat";
	stop;
}

Postfix mail queue

To view postfix mail queue in case of problems and remove a particular message from it, do as follows:

# mailq

-Queue ID-  --Size-- ----Arrival Time---- -Sender/Recipient-------
6DCF32201B*    4824 Thu Oct 19 22:54:44  roughnecks@woodpeckersnest.eu
                                         debian@spacenet.it

-- 4 Kbytes in 1 Request.

# postsuper -d 6DCF32201B

postsuper: 6DCF32201B: removed
postsuper: Deleted: 1 message

To delete all emails in the queue, use this command:

# postsuper -d ALL

Check Preferred Outgoing IP (when multiple are set on <interface>)

curl ifconfig.me

The correct command to add a new Linux user (in this case without a shell)

adduser --shell /usr/sbin/nologin <username>

I always forget which command is the complete one, useradd or adduser

I am most productive at night, when there is finally silence - apart from background music. The last couple hours of this Wednesday brought some nice additions to the @wpn support MUC:

• chat is not XMPP only anymore, but it got bridged to Matrix, via "matterbridge".
• a bot is now sending "BOFH excuses" to the chat, once a day.

XMPP MUC can be reached from: https://invite.woodpeckersnest.space/#status@chat.woodpeckersnest.space?join

Matrix room can be reached from: https://matrix.to/#/#wpn:matrix.org

Bridged chat means that everything being written in any of those rooms, gets relayed to the other by bots: there are in fact 2 bots connected to the 2 rooms, one is an XMPP bot and the other is a Matrix one, operated by "matterbridge", as I said earlier.

About "BOFH excuses", they are some fortune cookies from the relative Linux package, which are all about "Bastard Operators From Hell" excuses.. They are some short funny sentences about IT which an imaginary Operator (sysop, sysadmin, you name it) could say as excuse to justify issues.

Example?

BOFH excuse #266:
All of the packets are empty.

I have the same script running on gemini, at gemini://woodpeckersnest.space/cgi-bin/bofh

Basically it's some python spaghetti which runs the fortune command, does some formatting to the resulting text and sends it over gemini, or in the case of @wpn chat, over webhook to one other bot, which then posts its content to XMPP. It's more complicated to explain than do it 😀

P.S. @wpn support MUC is not publicly listed, so even if I'm posting links which may be used to join it, it should be treated as limited to @wpn users only.

gemlog

Beszel Setup

Interesting project at https://github.com/henrygd/beszel

Collects resource statistics from one or more systems, display CPU/RAM/DISK/NET/DOCKER information and be alerted in case "event" happens.

These days I set up beszel HUB on my VPS and beszel-agent on the same VPS, on our chatmail server and even on my desktop PC at home on WSL2: so now I'm monitoring 3 systems from a web interface and I'm being notified if one of them becomes unreachable or has exceeded %resources for every type of monitor.

This is my compose.yaml for the HUB and agent on "woodpeckersnest.eu":

services:
  beszel:
    image: 'henrygd/beszel'
    container_name: 'beszel'
    networks:
      beszel:
        ipv4_address: 172.30.0.2
    restart: unless-stopped
    ports:
      - '8090:8090'
    volumes:
      - beszel_data:/beszel_data
    environment:
      DISABLE_PASSWORD_AUTH: false

  beszel-agent:
    image: "henrygd/beszel-agent"
    container_name: "beszel-agent"
    networks:
      beszel:
        ipv4_address: 172.30.0.3
    restart: unless-stopped
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock:ro
    environment:
      PORT: 45876
      KEY: "SECRET"
      FILESYSTEM: /dev/sda3
      
networks:
  beszel:
    name: "beszel"
    external: true

volumes:
   beszel_data:
       external: true
       name: "beszel_data"

I created a named docker volume and a custom network beforehand:

docker volume create --name beszel_data

docker network create --subnet=172.30.0.0/16 --gateway=172.30.0.1 beszel

I didn't want to run the agent with network_mode: host, so here's a bridged setup. Network stats on my VPS won't be relevant, since the only net beszel can monitor is the docker bridged one, but I don't care very much.

For chatmail and home desktop I'm running the binary agent, respectively in a systemd unit for chatmail and with a bash script for my PC.

The systemd unit looks like this:

# /etc/systemd/system/beszel-agent.service
[Unit]
Description=Beszel Agent Service
After=network.target

[Service]
Environment="PORT=45876"
Environment="KEY=SECRET"
ExecStart=/home/chatmail/bin/beszel-agent
User=chatmail
Restart=always

[Install]
WantedBy=multi-user.target

The HUB has also got (automatic) backups, locally or on S3 - I tested both without issues. Beszel (both HUB and agent) take almost no CPU/RAM to do their job and stats are easy to read. Even the management tool is quite straightforward and has got the basic stuff right - I skipped OAUTH entirely though, while managing users manually.

Still young project but already recommended 😍

If you're interested in setting this up on WSL2, here I opened a discussion about this topic.. No need to repeat myself 😀

shout-out to "mforester@rollenspiel.social" who posted about beszel on the fediverse and gave me the idea to try it.

After some failed attempt at this, I think I found the right way to "mount" a remote WebDAV folder under Windows' Explorer.

Initially my baby steps took me here: https://note.woodpeckersnest.space/share/0TJT81fgI8Jy

After following that tutorial I didn't succeed, so I investigated further. I can say that everythig looks correct until you get to point 9.

The address they tell you have to enter isn't correct in my experience and they aren't even using https for the URL. What worked for me was instead something like:

\\webdav.woodpeckersnest.space@SSL\folder

You have to input the network-path-stile address which is common in Windows, as in: double backslash, FQDN of your WebDAV server, "@SSL" and then the path (folder) where you have access to files in your WebDAV server, with a backslash preceding it.

That's it, a prompt will ask for username and password and then a new Network Path (WebFolder) will be connected in Explorer, just below your local drives.

You can then browse, copy, upload, delete (and so on) whatever content you like.

EDIT: Just found out I couldn't rename files/folders from Windows or Total Commander (Android)

Fixed by setting nginx virtualhost like this:

server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    server_name  webdav.woodpeckersnest.space;


    # HTTPS configuration
    ssl_certificate /etc/letsencrypt/live/webdav.woodpeckersnest.space/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/webdav.woodpeckersnest.space/privkey.pem;

    access_log /var/log/nginx/webdav/access.log;
    error_log /var/log/nginx/webdav/error.log;

  location / {
    set $destination $http_destination;

    if ($destination ~* ^https(.+)$) {
         set $destination http$1;
    }

    proxy_set_header   Destination $destination;
    proxy_set_header   X-Real-IP $remote_addr;
    proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header   Host $host;
    proxy_pass         http://127.0.0.1:17062/;
    proxy_http_version 1.1;
    proxy_set_header   Upgrade $http_upgrade;
    proxy_set_header   Connection "upgrade";
  }

  client_max_body_size 0;

}

Now I'm quite happy 😀

Here's my configuration, working fine with my Android 9 Phone

server.conf

root@pandora:~# cat /etc/wireguard/wg0.conf
[Interface]
# specify generated private key for server
PrivateKey = <sekret>
# IP address for VPN interface
Address = 172.16.100.1/32, fd42:42:42::1/64
MTU = 1420
# UDP port WireGuard server listens
ListenPort = 51820

# possible to set any commands after WireGuard starts/stops
# set routing rules like follows to access to local network via VPN session
PostUp = iptables -A FORWARD -i wg0 -j ACCEPT; iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE; ip6tables -A FORWARD -i wg0 -j ACCEPT; ip6tables -t nat -A POSTROUTING -o eth0 -j MASQUERADE;
PostDown = iptables -D FORWARD -i wg0 -j ACCEPT; iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE; ip6tables -D FORWARD -i wg0 -j ACCEPT; ip6tables -t nat -D POSTROUTING -o eth0 -j MASQUERADE;

[Peer]
# REDMI
# specify public key for client
PublicKey = <sekret>
# clients' VPN IP addresses you allow to connect
# possible to specify subnet ⇒ [172.16.100.0/24]
AllowedIPs = 172.16.100.6/32, fd42:42:42::6/128
PersistentKeepalive = 25

client.conf

root@pandora:~# cat /etc/wireguard/redmi.conf
[Interface]
#Private IP Address
Address = fd42:42:42::6/128, 172.16.100.6/32
#Client's Private Key
PrivateKey = <sekret>
#Server's listening port
ListenPort = 51820

[Peer]
#Server's Public Key
PublicKey = <sekret>
AllowedIPs = ::0/0, 0.0.0.0/0
#Server's IP:port
Endpoint = woodpeckersnest.space:51820

sysctl.conf

root@pandora:~# sysctl -p
net.ipv4.ip_forward = 1
net.ipv6.conf.all.forwarding = 1
net.ipv6.conf.eth0.accept_ra = 2

Here are a few tweaks that make my "converse.js" experience better:

Remove link from banner: I accidentally used to click that and be teleported to converse.js official webclient, so I thought it could be misleading for unaware users using my locally hosted version of the software.

Search and replace/remove the href bit in converse.min.js, under the dist directory:

<a class="brand-heading" href="https://conversejs.org" target="_blank" rel="noopener">

In the "converse.min.css" file, search for this string and fill it with the following code to have unread MUCs underlined and colored in red:

.list-item.unread-msgs

.list-item.unread-msgs{font-weight:700; text-decoration: underline red;}

Fix color for toolbar-utilities when in 1:1 chats: find this line in "converse.min.css"

.fas:hover svg{fill:var(--chat-head-color)}

and replace with:

.fas:hover svg{fill:var(--chat-toolbar-btn-color)}

Raise minimum chat text area: find this bit in "converse.min.css"

min-height:var(--chat-textarea-height);

and replace with custom value in pixels, e.g.

min-height:120px;

Set a smaller line height for chats list: find the first occurrence of this code in "converse.min.css"

.conversejs .items-list .list-item

and continue until you find:

height:2.5em

substitute it with something like height:2.0em

Removing a space in quoted reply for "actions" plugin: find the following string in your conversejs/dist/plugins/actions/action.js

return ">" + nick + ' : '

remove the offending space

return ">" + nick + ': '

Changing from :smiley: to :thumbsup: emoji for the "Like" actions plugin function: find the following string in your conversejs/dist/plugins/actions/action.js

actions_reactions: [
                                    {name: 'like', label: 'Like', emoji: ':smiley:', icon_class: 'fa fa-check'},

and replace with:

actions_reactions: [
                                    {name: 'like', label: 'Like', emoji: ':thumbsup:', icon_class: 'fa fa-check'},

Fix background-color for screencast plugin icon: replace the class in row #25 in screencast.js

<button class="plugin-screencast"

<button class="btn"

I recently moved from OVH to Contabo for my VPS: since setting up everything from scratch looked like a hard challenge, I moved everything using rsync.

Firstly, some preparations:

• installed the same kernel I had on OVH
• rebooted Contabo
• installed rsync on Contabo

Then I switched to the OVH shell:

• created a exclude.txt file with all the directory and file I didn't want to move:

/boot/
/etc/modules
/etc/fstab
/etc/mtab
/etc/netconfig
/etc/networks
/etc/network/
/etc/ssh/
/etc/cloud/
/etc/cloud-release
/etc/grub.d/
/etc/host.conf
/etc/hostname
/etc/hosts
/etc/hosts.allow
/etc/hosts.deny
/etc/init.d/cloud-config
/etc/init.d/cloud-final
/etc/init.d/cloud-init
/etc/init.d/cloud-init-local
/etc/initramfs-tools/
/etc/default/grub
/etc/default/grub.d/
/etc/kernel/
/etc/kernel-img.conf
/lib/modules/
/lost+found/
/sys/
/proc/
/dev/
/tmp/
/var/cache/
/var/log/journal/
/mnt/
/root/.ssh/

• moved it to /root/exclude.txt

• stopped all the running services

  systemctl stop <service>

• now we can begin rsync-ing: you have to have access to the root user on destination VPS

  rsync -avzP --exclude-from=/root/exclude.txt / root@CONTABO_IP:/

• after that, I edited /etc/fstab to add support for quota, like I had on OVH

• then I searched and grepped /etc for my OVH IP address, because I knew it was set somewhere on some config file

  grep -r “OVH IP” /etc/*

• and substituted it with the new Contabo IP, where necessary.

Finally, I could reboot Contabo:

reboot

Once up & running again, I changed all DNS entries from OVH to Contabo IP.. And waited 😀

• Last but not least, I edited etc/hosts manually to reflect the new Domain Name address and also set up the hostname

  hostnamectl set-hostname <new-hostname>

Done!

EDIT! A detail I missed to mention is that your destination host's root password will be changed, after rsync-ing, to the one of the source host!!

Remember: don't ever use special characters in your DB's users password!!

I have been troubleshooting a migration from mariadbd to pgsql for several hours, until I tried changing my password, which, weirdly enough, was working to connect roundcube but gave errors with pgloader. Once I successfully migrated using the same password with those special characters, roundcube wouldn't connect with pgsql, so I made another fighting round! Finally changed my pgsql password to some letters and numbers only and BAM!, it worked.

Then I stopped mariadbd and disabled the service; now I have more than 200MB RAM freed¹.

¹ See previous post.