Linux Tips and Tricks

Start / Stop /Restart BIND DNS Server

Introduction

For testing purposes I am using Univention with bind9. The greater goal is to use AD/SAMBA from Univention. After testing for a couple of weeks suddenly some DNS addresses do not get resolved. The same problems occurred on Zentyal.

So far I couldn't find a reason for this misbehavior. However, a restart of the bind9 service seems to patch the problem.

Debian based Linux

Start the service

service bind9 start

Stop the service

service bind9 stop

Restart the service

service bind9 restart

Reload the service

This will become necessary of a configuration file is changed.

service bind9 reload

Check status

service bind9 status

Fedora based Linux

Start the service

systemctl start named

Stop the service

systemctl stop named

Restart the service

systemctl restart named

Check status

systemctl status named

 

Install network scanner on Archlinux

Install the drivers with pamac

run the commandline:

sudo brsaneconfig4 -a name=Brother model=MFC-9330CDW ip=192.168.1.108

check if it is working

scanimage -L
device `brother4:net1;dev0' is a Brother Brother MFC-9330CDW
device `v4l:/dev/video2' is a Noname Logitech BRIO virtual device
device `v4l:/dev/video0' is a Noname Logitech BRIO virtual devi

 

Install xrdp on Fedora 42

How to Set Up XRDP on Fedora 42 XFCE

Follow these steps for a reliable and quick XRDP setup with XFCE on Fedora 42:

  1. Install XRDP and XFCE (if not already installed)
sudo dnf install xrdp xorgxrdp

 

2. Enable and Start XRDP Service

sudo systemctl enable --now xrdp

 

3. Configure the Firewall

open Port 3389 for rdp

4. Set Up the XFCE Session for XRDP
Create a file named .Xclients in your home directory with the following content:

 echo "xfce4-session" > ~/.Xclients

 echo "xfce4-session" > ~/.Xclients
 chmod +x ~/.Xclients

6. Restart XRDP Services

sudo systemctl restart xrdp
sudo systemctl restart xrdp-sesman

 

7. Connect via RDP

  • Use Devolutions RDM or any RDP client.

  • Enter your Fedora machine's IP address and credentials.

 

Summary Table

Step Command/Action
Install XRDP sudo dnf install xrdp xorgxrdp
Enable & start service sudo systemctl enable --now xrdp
Firewall open port sudo firewall-cmd --permanent --add-port=3389/tcp; sudo firewall-cmd --reload
Configure session echo "xfce4-session" > ~/.Xclients; chmod +x ~/.Xclients
(Optional) SELinux fix sudo chcon --type=bin_t /usr/sbin/xrdp*
Restart XRDP sudo systemctl restart xrdp xrdp-sesman

This setup gives you a fast, graphical remote desktop on Fedora XFCE with minimal hassle.

 

Install send mail service on Fedora

Overview

This guide explains how to set up authenticated email sending from the command line on Fedora using msmtp (a lightweight SMTP client) and s-nail (a mailx-compatible mail utility). This method is ideal for scripts and system notifications in environments where only authenticated SMTP is allowed.

1. Install Required Packages

sudo dnf install -y msmtp s-nail

2. Configure msmtp

  1. Copy the example configuration (optional): 
    sudo cp /usr/share/doc/msmtp/msmtprc-system.example /etc/msmtprc
  2. Edit /etc/msmtprc and adjust to your SMTP provider: 
    sudo nano /etc/msmtprc

    Example configuration:

    defaults
auth           on
tls            on
tls_trust_file /etc/ssl/certs/ca-bundle.crt
logfile        /var/log/msmtp.log

account        default
host           mail.hosting.de
port           587
from           admin@simmy.org
user           admin@simmy.org
password       <super-secret>

  3. Set permissions to protect your password: 
    sudo chmod 600 /etc/msmtprc

3. Configure s-nail to Use msmtp

Add the following line to /etc/s-nail.rc or your ~/.mailrc:

set mta=/usr/bin/msmtp

4. Send a Test Email

echo "This is the body" | mail -s "Test Subject" recipient@example.com

5. Notes

References

Install send mail service on Debian

Overview

This guide explains how to set up authenticated email sending from the command line on Debian-based systems (including Proxmox Backup Server) using msmtp (a lightweight SMTP client) and s-nail (a mailx-compatible utility). This is ideal for system notifications, backup/email scripts, and environments with DMARC/SPF filtering where authenticated sending is required.

1. Install Required Packages

apt update
apt install -y msmtp s-nail

2. Configure msmtp

  1. Create/Edit the global configuration file:
    nano /etc/msmtprc
  2. Example /etc/msmtprc: 
    
defaults
auth           on
tls            on
tls_trust_file /etc/ssl/certs/ca-certificates.crt
logfile        /var/log/msmtp.log
syslog         LOG_MAIL

account        default
host           mail.hosting.de
port           587
from           admin@simmy.org
user           admin@simmy.org
password

    • Important: "from" and "user" should match your authenticated email address for DMARC/SPF.

     

  3. Example 2 /etc/msmtprc

    1. 
syslog LOG_MAIL

defaults
auth on
tls off
tls_trust_file /etc/ssl/certs/ca-certificates.crt
logfile /var/log/msmtp.log

account ucs-backup
host ucs-backup.simmy.ch
port 25
from pbs01@simmy.ch
account default : ucs-backup

    • Use only plain ASCII spaces (no tabs or Unicode spaces).

  4. Set strict permissions: 
    chmod 600 /etc/msmtprc

3. Configure s-nail or mailx to use msmtp

Add the following line to your /etc/s-nail.rc (system-wide) or ~/.mailrc (per user):

set mta=/usr/bin/msmtp

4. Send a Test Email

Use the mail command to test sending:

echo "This is the body" | mail -s "Test Subject" recipient@example.com

On success, no output is shown. Check /var/log/msmtp.log or /var/log/mail.log (if syslog is enabled) for debug info if not delivered.

5. Troubleshooting

Install xrdp on Fedora Xfce

Overview

This document describes how to install and configure the XRDP server on Fedora 43 with the Xfce desktop environment so that Windows, macOS, and Guacamole clients can connect via RDP. Each Linux user who should be able to log in via XRDP needs their own startwm.sh to launch Xfce correctly. 

Prerequisites

Install and Enable XRDP

Install XRDP and its Xorg backend, then enable and start the service. Fedora 40/41 XRDP documentation uses the same pattern and works on Fedora 43. [web:21][web:17]

sudo dnf install -y xrdp xorgxrdp
sudo systemctl enable --now xrdp
sudo systemctl status xrdp

Open the Firewall for RDP

If firewalld is running, open TCP port 3389 permanently and reload the firewall rules. [web:21][web:17]

sudo firewall-cmd --permanent --add-port=3389/tcp
sudo firewall-cmd --reload

Create startwm.sh for Each User

On Fedora, XRDP uses a per-user startup script named startwm.sh in the user's home directory to start the desktop session. Fedora's XRDP guide shows this pattern for multiple desktops; for Xfce the command is dbus-launch --exit-with-session /usr/bin/startxfce4. 

Repeat the following steps for each user account that should be able to log in via XRDP:

# as the target user (not root)
cat > ~/startwm.sh << 'EOF'
#!/bin/sh
export LANG=en_US.UTF-8
export LC_ALL=en_US.UTF-8
exec dbus-launch --exit-with-session /usr/bin/startxfce4
EOF

chmod 755 ~/startwm.sh

Explanation:

Optional: Global /etc/xrdp/startwm.sh

If you want a single configuration for all users, you can copy the same script to /etc/xrdp/startwm.sh so XRDP uses it globally. This approach is also referenced in XRDP discussions about custom session commands.

sudo cp /home/<username>/startwm.sh /etc/xrdp/startwm.sh
sudo chmod 755 /etc/xrdp/startwm.sh
sudo systemctl restart xrdp

Replace <username> with a real user name when copying from an existing script.

SELinux Considerations (Optional)

On some Fedora installations, SELinux can interfere with XRDP. Recent XRDP-on-Fedora guides use chcon to assign the bin_t type to XRDP binaries if SELinux denials occur. [web:17]

sudo chcon --type=bin_t /usr/sbin/xrdp
sudo chcon --type=bin_t /usr/sbin/xrdp-sesman
sudo systemctl restart xrdp

Testing with a Native RDP Client

Test XRDP with a standard RDP client before integrating with Guacamole. Fedora XRDP documentation uses Windows Remote Desktop as the reference client. [web:21]

  1. From a Windows machine, open Remote Desktop Connection (mstsc.exe).
  2. Enter the Fedora host name or IP (for example fedora-xfce.example.local) and connect. [web:21]
  3. Log in using a Fedora user that has a ~/startwm.sh configured.
  4. Verify that an Xfce desktop session appears and is usable.

Using XRDP from Guacamole

Once XRDP and Xfce are working locally, Guacamole can connect using the RDP protocol. The key is to match the security mode and certificate options so that negotiation succeeds.

image.png

Setting Value
Protocol RDP
Hostname IP Address
Port 3389
Username ${GUAC_USERNAME}
Password ${GUAC_PASSWORD}
Security Mode TLS
Ignore server certificate enable

Summary

Add a user to the sudoers group on Debian 13

usermod -aG sudo master

How to

Verify NFS export

Check NFS exports on nas05.simmy.ch from the Linux:

sudo showmount -e nas05.simmy.ch