macchanger

View the current and permanent MAC addresses of a interface

$ macchanger [[-s|--show]] [interface]

$ macchanger [[-r|--random]] [interface]

$ macchanger [[-r|--random]] [[-b|--bia]] [interface]

$ macchanger [[-m|--mac]] [XX:XX:XX:XX:XX:XX] [interface]

$ macchanger [[-l|--list]]

$ macchanger [[-p|--permanent]] [interface]

macchanger [options] interface
Common usage includes:
macchanger [-s|-r|-e|-p|-m MAC|-b] interface

-s, --show
    Displays the current MAC address of the specified interface without changing it.

-r, --random
    Assigns a completely random MAC address to the interface. This includes both the vendor (OUI) and device-specific bytes.

-e, --another
    Assigns a MAC address from a random vendor (Organizationally Unique Identifier - OUI) while keeping the last three bytes (device identifier) random.

-p, --permanent
    Resets the MAC address of the interface to its original, permanent hardware address (Burned-In Address - BIA) as assigned by the manufacturer.

-m MAC, --mac=MAC
    Sets the MAC address of the interface to a specific user-provided value (e.g., 00:11:22:33:44:55). The format must be colon-separated hexadecimal pairs.

-b, --bia
    Assigns a random MAC address but preserves the original vendor (OUI) bytes of the current MAC address, randomizing only the last three device-specific bytes.

-a, --bia
    An alias for -b, --bia, assigning a random MAC address while preserving the original vendor (OUI) bytes and randomizing the device-specific bytes.

--help
    Displays a help message with all available options and usage instructions.

--version
    Shows the program's version information.

The macchanger command-line utility allows users to easily view and modify the Media Access Control (MAC) address of a specified network interface. A MAC address is a unique identifier assigned to network interfaces for communications within a network segment, acting as a hardware address. While typically burned into the network adapter's firmware, macchanger enables its temporary alteration, often referred to as 'MAC spoofing'.

Users leverage macchanger for various purposes, including enhancing privacy by anonymizing their network presence, bypassing network access controls (like MAC address filtering on Wi-Fi networks), or for security testing and penetration testing scenarios. The changes made by macchanger are usually temporary and do not persist across system reboots unless configured otherwise through system scripts or network management tools. It typically requires superuser (root) privileges to operate, as modifying network interface settings is a privileged operation.

Changing the MAC address with macchanger has several considerations:
1. Root Privileges: It requires superuser (root) privileges to execute.
2. Temporary Change: MAC address changes are typically temporary and do not persist across system reboots. For persistence, additional configuration (e.g., network manager scripts, init scripts) is required.
3. Network Disruption: The network interface usually needs to be brought down before changing its MAC address and brought back up afterwards, causing a brief network disconnection.
4. Driver Compatibility: Not all network drivers or hardware might fully support MAC address spoofing, potentially leading to errors or unstable network behavior.
5. Legal and Ethical Use: While useful for privacy and security testing, MAC spoofing can be misused for malicious activities. Users should be aware of and comply with local laws and network policies.

To effectively change a MAC address, the network interface generally needs to be temporarily deactivated. A common sequence of commands is:

1. Bring down the interface:
sudo ip link set dev eth0 down (or sudo ifconfig eth0 down)

2. Change the MAC address:
sudo macchanger -r eth0 (for a random MAC)
or
sudo macchanger -m 00:11:22:33:44:55 eth0 (for a specific MAC)

3. Bring up the interface:
sudo ip link set dev eth0 up (or sudo ifconfig eth0 up)

Replace eth0 with your actual network interface name (e.g., wlan0, enp0s3).

Since macchanger's changes are not persistent across reboots, you can make them permanent by:

1. Network Manager Dispatcher Scripts: For systems using NetworkManager, create a script in /etc/NetworkManager/dispatcher.d/ that runs macchanger when the interface comes up.
2. Systemd Services: Create a custom systemd service unit that executes macchanger on boot.
3. Distribution-Specific Network Configuration Files: Edit network configuration files (e.g., /etc/network/interfaces for Debian/Ubuntu, /etc/sysconfig/network-scripts/ifcfg-* for RHEL/CentOS) to include a MAC address setting.
4. rc.local / init scripts: Add commands to /etc/rc.local or similar init scripts for older systems, though this method is less common in modern Linux distributions.

macchanger emerged as a popular open-source utility within the Linux ecosystem, primarily driven by the increasing awareness of network privacy and security. Its development focused on providing a straightforward command-line interface for manipulating network interface MAC addresses, a capability often desired by privacy advocates, penetration testers, and system administrators. It became a staple in many ethical hacking and network analysis toolkits, offering a simple yet powerful way to anonymize or change network identities on the fly. Its continued relevance highlights the ongoing need for flexible network configuration tools.

ip(8), ifconfig(8), iwconfig(8), arp(8)