How to use the command `create_ap` (with examples)

The create_ap command is a powerful utility that allows users to create software-based Access Points (AP) on their Linux machines. This tool is versatile and can be used to set up a variety of network configurations, enabling users to share their internet connection through Wi-Fi. create_ap supports both open and secure networks, and it can also facilitate internet sharing over different network interfaces. This command is particularly useful for users who need to quickly establish wireless networks without accessing hardware routers or modems.

Use case 1: Create an open network with no passphrase

Code:

create_ap wlan0 eth0 access_point_ssid

Motivation: Creating an open network is useful in scenarios where ease of access is prioritized over security, such as at a large event where a public network is needed, or in a secure environment where the network is isolated from external threats. An open network allows users to connect without needing to input a password, making it convenient for guest access.

Explanation:

• wlan0: This indicates the wireless network interface that will be used to create the access point.
• eth0: This specifies the wired network interface used for internet connectivity and sharing through the Wi-Fi access point.
• access_point_ssid: The service set identifier (SSID) for the new network. It’s the name that will appear to potential clients.

Example Output:

Configuring sharing for wlan0 via eth0
Starting Access Point service...
Success: AP is up at wlan0 with SSID 'access_point_ssid'

Use case 2: Use a WPA + WPA2 passphrase

Code:

create_ap wlan0 eth0 access_point_ssid passphrase

Motivation: Security is often a top priority in network configurations, especially in environments with sensitive data. By using a WPA/WPA2 passphrase, network integrity is enhanced by preventing unauthorized access to the network. This option is ideal for small businesses or home networks needing a secure connection.

Explanation:

• passphrase: A passphrase used for WPA/WPA2 encryption, ensuring that only users with the passphrase can connect to the AP.

Example Output:

Configuring sharing for wlan0 via eth0 with WPA/WPA2 encryption
Starting Access Point service...
Success: AP is up at wlan0 with SSID 'access_point_ssid' and secured with passphrase

Use case 3: Create an access point without Internet sharing

Code:

create_ap -n wlan0 access_point_ssid passphrase

Motivation: There are scenarios where users may wish to create a local network for device-to-device communication without internet access. This can be useful for hosting local multiplayer video games, sharing files internally, or testing network configurations.

Explanation:

• -n: A flag that disables Internet sharing, confining connectivity to local devices.
• Other arguments specify the wireless interface, SSID, and passphrase as explained earlier.

Example Output:

Configuring non-shared access point on wlan0
Success: Local only network is up with SSID 'access_point_ssid'

Use case 4: Create a bridged network with Internet sharing

Code:

create_ap -m bridge wlan0 eth0 access_point_ssid passphrase

Motivation: A bridged network setup allows for more cohesive interaction between the wireless and wired network devices. This ensures every device connected, either by wire or wireless, is on the same subnet, facilitating seamless communication which is crucial in environments that require connected services like printers.

Explanation:

• -m bridge: Indicates that a bridged network will be created.
• Eth0 is the interface with internet connectivity to be bridged with wlan0.

Example Output:

Bridging wlan0 with eth0...
Access Point is functioning with bridged networking
SSID is 'access_point_ssid' and protected by passphrase

Use case 5: Create a bridged network with Internet sharing and a pre-configured bridge interface

Code:

create_ap -m bridge wlan0 br0 access_point_ssid passphrase

Motivation: This setup is advantageous when using a pre-configured bridge interface like br0. It allows users to easily integrate the AP setup into existing complex network topologies without disrupting other configurations, saving time and reducing potential errors.

Explanation:

• The command specifies an existing bridge interface, br0, for greater control over network architecture.

Example Output:

Utilizing pre-configured bridge `br0` for access point sharing
Success: Bridged network 'access_point_ssid' is operational

Use case 6: Create an access port for Internet sharing from the same Wi-Fi interface

Code:

create_ap wlan0 wlan0 access_point_ssid passphrase

Motivation: Using the same Wi-Fi interface for creating an access point and sharing the internet is especially useful when resource constraints limit the availability of network interfaces. This use case is ideal for devices like laptops that often have a single wireless card.

Explanation:

• The command specifies the same interface for both the AP and Internet source, highlighting its dual role.

Example Output:

Configuring wlan0 for dual role as AP and Internet source
Access Point 'access_point_ssid' is active with WPA/WPA2 securing

Use case 7: Choose a different Wi-Fi adapter driver

Code:

create_ap --driver wifi_adapter wlan0 eth0 access_point_ssid passphrase

Motivation: Some network interface cards may require specific drivers to function optimally or to utilize certain features. Specifying a Wi-Fi adapter driver allows users to customize the AP setup, potentially increasing compatibility and performance.

Explanation:

• --driver wifi_adapter: Explicitly sets the Wi-Fi adapter driver to be used for initializing the AP.

Example Output:

Loading specified driver wifi_adapter for wlan0
Access Point with SSID 'access_point_ssid' successfully initialized using driver 'wifi_adapter'

Conclusion:

The create_ap command is a versatile tool that can cater to various network configurations and needs. Whether setting up a simple open network for ease of access or a more secure environment for sensitive data, this command provides a range of options to suit user requirements. By following these examples, users can effectively utilize create_ap to establish their own custom wireless networks with a high degree of control and security.