How to disable auto-start GUI (lightdm) on Ubuntu?

Create file /etc/int/lightdm.override and add line manual to it.

To start service manually use

$ sudo service lightdm start

To stop service manually use

$ sudo service lightdm stop

How to Enable or Disable Services in Ubuntu Systemd/Upstart

How can I deactivate the gnome desktop of my ubuntu server?

Ubuntu Linux stop / disable GNOME GUI ~ X.org

How to get LightDM automatically started at startup after disabling it (in Ubuntu MATE)?

LightDM

dbus_bus_request_name (): Connections are not allowed to own the service

Error on starting RIL daemon using dbus: “dbus_bus_request_name() failed (“Connection “connection_name” is not allowed to own the service “service_id” due to security policies in the configuration file”)”.

Solution

Make sure that access is granted in configuration file for user and group running the application

<!DOCTYPE busconfig PUBLIC 
"-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN"
"http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">

<busconfig>
<policy user="user">
<allow own="service_id"/>
</policy>

<policy group="group">
<allow own="service_id"/>
</policy>

<policy context="default">
<allow send_destination="service_id"/>
<allow receive_sender="service_id"/>
</policy>

</busconfig>

Copy configuration file into /etc/dbus-1/system.d.

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How to set up iperf for network performance testing?

IPv4 testing

Start server

$ iperf3 --server

Start client (UDP)

$ iperf3 --client ipv4_address --bandwidth 0 -n 32768M --length 8KB  
  --udp --port 5201 --parallel 8 --title 'test'

IPv6 testing

Start server

$ iperf3 --server -6

Start client (TCP)

$  iperf3 --client -6 ipv6_address --bandwidth 0 -n 32768M --length 8KB 
   --port 5201 --parallel 8 --title 'test'

How to install iperf under Linux?