NetworkManager Trackability Reduction

MAC address randomization
How to mask your hardware MAC address to limit tracking on and across networks.

MAC address randomization

Available configurations

There are three different aspects of MAC address randomization in NetworkManager, each with their own configuration flag:

WiFi scanning


WiFi connections


Ethernet connections


Mode options

Generate a new random MAC address every time a connection is activated
Assign each connection a random MAC address that will be maintained across activations
Use the MAC address already assigned to the interface (such as from macchanger), or the permanent address if none is assigned
Use the MAC address permanently baked into the hardware

Setting a default configuration

It’s best to create a dedicated configuration file, such as /etc/NetworkManager/conf.d/99-random-mac.conf, to ensure package updates do not overwrite the configuration. In general, I recommend the following:



This configuration randomizes all MAC addresses by default. These settings can of course be overridden on a per-connection basis.

After editing the file, run sudo nmcli general reload conf to apply the new configuration.

Per-connection overrides

Connection-specific settings take precedence over configuration file defaults. They can be set through nm-connection-editor (“Network Connections”), a DE-specific network settings GUI, nmtui, or nmcli.

Look for “Cloned MAC address” under the “Wi-Fi” or “Ethernet” section:

nm-connection-editor screenshot

In addition to the four mode keywords, you can input an exact MAC address to be used for that connection.

For a home or other trusted network, it can be helpful to use stable or even permanent, as MAC address stability can help avoid being repeatedly served a new IP address and DHCP lease (though not all DHCP servers work this way).

For public networks with captive portals (webpages that must be accessed to gain network access), the stable setting can help prevent redirection back to the captive portal after a brief disconnection or roaming to a different access point.

Seeing the randomized MAC address

Activate the connection in question, and then look for GENERAL.HWADDR in the output of nmcli device show. This represents the MAC address currently in use by the interface, whether randomized or not. It is also visible as “Hardware Address” (or similar) in NetworkManager GUIs under active connection details.

$ nmcli device show
GENERAL.DEVICE:                         enp5s0
GENERAL.TYPE:                           ethernet
GENERAL.HWADDR:                         XX:XX:XX:XX:XX:XX

GENERAL.DEVICE:                         wlp3s0
GENERAL.TYPE:                           wifi
GENERAL.HWADDR:                         XX:XX:XX:XX:XX:XX


Remove static hostname to prevent hostname broadcast
How to avoid broadcasting a persistent and likely unique software identifier.

Remove static hostname to prevent hostname broadcast

$ sudo hostnamectl hostname "localhost"

An empty (blank) hostname is also an option, but a static hostname of “localhost” is less likely to cause breakage. Both will result in no hostname being broadcasted to the DHCP server.

Disabling transient hostname management

It’s best to create a dedicated configuration file, such as /etc/NetworkManager/conf.d/01-transient-hostname.conf, to ensure package updates do not overwrite the configuration:


This will prevent NetworkManager from setting transient hostnames that may be provided by some DHCP servers. This will have no visible effect except with an empty static hostname.

After editing the file, run sudo nmcli general reload conf to apply the new configuration. Run sudo hostnamectl --transient hostname "" to reset the transient hostname.


Disable sending hostname to DHCP server
How to limit hostname exposure. Imperfect and hacky — prefer removing static hostname instead.

Disable sending hostname to DHCP server

Due to being leaky, this configuration is virtually useless without also randomizing MAC addresses by default. Your MAC address and hostname will not be correlated starting with the second connection, assuming the first connection used a random MAC address.

Create /etc/NetworkManager/dispatcher.d/no-wait.d/ as follows:


if [ "$(nmcli -g 802-11-wireless.cloned-mac-address c show "$CONNECTION_UUID")" = 'permanent' ] \
        || [ "$(nmcli -g 802-3-ethernet.cloned-mac-address c show "$CONNECTION_UUID")" = 'permanent' ]
    nmcli connection modify "$CONNECTION_UUID" \
            ipv4.dhcp-send-hostname true \
            ipv6.dhcp-send-hostname true
    nmcli connection modify "$CONNECTION_UUID" \
            ipv4.dhcp-send-hostname false \
            ipv6.dhcp-send-hostname false

The script must have specific file permissions and a symlink to take effect:

$ cd /etc/NetworkManager/dispatcher.d/

$ sudo chown root:root no-wait.d/

$ sudo chmod 744 no-wait.d/

$ sudo ln -s no-wait.d/ ./

This script will be automatically triggered on connection events to modify the connection’s dhcp-send-hostname settings. If the connection’s cloned MAC address is explicitly overridden to permanent, the hostname will be sent to the DHCP server on future connections. In all other cases, the hostname will be masked on future connections, so the DHCP server will only see the MAC address.

Verifying proper operation

After initiating first connection with a network:

$ nmcli c show <connection> | grep dhcp-send-hostname
ipv4.dhcp-send-hostname:                no
ipv6.dhcp-send-hostname:                no

<connection> can be the connection name (usually the SSID for WiFi networks) or UUID, obtained from nmcli c show [--active].

Recall that these setting values are set based on the previous connection activation and take effect for the next connection activation.