Questions about how to access someone else's wireless network often arise among novice information security professionals who want to understand the vulnerabilities of encryption protocols. Kali Linux is the industry standard for conducting network audits and testing infrastructure resilience to external influences. However, it's important to clarify: using these tools to connect to networks without the owner's permission is illegal and subject to criminal prosecution.
In this article, we'll cover the technical aspects of wireless interface monitoring, the process of handshaking, and vulnerability analysis techniques so you can understand the security mechanism and strengthen your own network. This knowledge is intended solely for legal testing (Pentest) and educational purposes. Understanding how it works deauthentication and brute-force passwords will allow you to properly configure your router.
Modern encryption methods like WPA3 make it much more difficult for attackers to exploit, but older protocols like WEP and WPA2 are still widely used and require attention. Capturing the 4-way handshake is a key step in the security audit process of WPA2 networks. We'll cover in detail the tools needed to simulate attacks so you can diagnose weaknesses in your infrastructure.
How a Wireless Adapter Works in Kali Linux
To get started with auditing tools, your network adapter must support two critical modes: Monitor Mode And Packet InjectionIn normal mode, the card only receives packets addressed to it, ignoring all other traffic, making it impossible to analyze the surrounding airwaves. Monitor mode allows the card to capture all packets within range, regardless of who they're intended for.
Most Wi-Fi modules built into laptops do not support the necessary functions or have proprietary drivers that prevent switching to listening mode. Security professionals often use external USB adapters based on Atheros AR9271, Ralink RT3070, or Realtek RTL8812AU chips.These devices are guaranteed to work with a set of utilities. aircrack-ng, included in the distribution.
The process of switching the interface to the desired mode is carried out through the terminal. First, it is necessary to stop processes that may be blocking the card, such as NetworkManager. Then, a command is used to enable monitor mode on a specific interface, for example, wlan0Successful completion of these actions is confirmed by the appearance of a new interface, usually with the suffix mon.
⚠️ Warning: Actively scanning and intercepting packets on other networks may be interpreted by your ISP or administrator as an attempt at unauthorized access. Only conduct tests on your own equipment or with written permission from the network owner.
Aircrack-ng Utilities and Airwave Scanning
The main tools for working with wireless networks in Kali Linux is a package Aircrack-ngIt is a suite of utilities for assessing the security of Wi-Fi networks, including tools for monitoring, attacking, testing, and hacking. The first step in the audit process is reconnaissance: it is necessary to locate the target network, determine its channel, encryption type, and the presence of connected clients.
A utility is used to detect networks. airodump-ngIt displays a list of all available access points (BSSID) and clients (STATION). The program's output displays columns for signal strength (PWR), number of data packets (#Data), and encryption type (ENC). Channel filtering allows you to focus on a specific frequency without having to spread your attention across the entire 2.4 GHz or 5 GHz range.
During the scan, it's important to pay attention to the presence of clients. If no devices are connected to the access point, it will be impossible to perform attacks (such as deauthentication to obtain a handshake). The scan command looks like this:
sudo airodump-ng wlan0mon --channel 6 --bssid 00:11:22:33:44:55 --write target_captureHere we specify the interface, the target network channel, its MAC address, and the file name for saving the results. Saving packets is necessary for subsequent analysis or for transmitting a handshake for brute-force attack. CAP save format is standard and supported by most analysis tools.
☑️ Preparing for scanning
Deauthentication methods and handshake interception
The key to testing WPA2 password strength is obtaining the four-way handshake. This process occurs when the client connects to the access point, when keys are exchanged to encrypt traffic. If the client is already connected, we need to force it to reconnect to intercept this.
A deauthentication attack is used for this purpose. The utility aireplay-ng Allows you to send a special control frame to the client's MAC address or broadcast it to the entire network, forcing devices to terminate the connection. Deauthentication does not require knowledge of a password and operates at the 802.11 protocol level.
As soon as the client attempts to automatically reconnect, it will go through the handshake procedure again, and if at that moment airodump-ng, the packets will be saved to a file. If the interception is successful, the message "WPA Handshake: [MAC address]" will appear in the upper right corner of the terminal window.
The command to perform a deauthentication attack looks like this:
sudo aireplay-ng --deauth 10 -a 00:11:22:33:44:55 -c 66:77:88:99:AA:BB wlan0monParameter --deauth 10 Specifies the number of deauthentication packets to send. Option -a specifies the MAC address of the access point, and -c — the victim's (client's) address. If you remove the option -c, packets will be sent to everyone, which may be noisier but more efficient.
⚠️ Warning: Sending mass deauthentication packets can cause a temporary denial of service (DoS) for all devices within the router's range. Be careful with the number of packets you send.
Vulnerability and brute-force password analysis
After successfully intercepting the handshake, the cryptanalysis phase begins. The intercepted file itself doesn't contain the password in plaintext. It contains a hash obtained by mathematically processing the password and the network SSID. The specialist's task is to find a string that, when hashed, will produce an identical result.
The method used for this is brute force (dictionary search). Utility aircrack-ng takes a list of common passwords (wordlist) and checks each of them. A popular list is rockyou.txt, which is often bundled with the Kali distribution. The brute-force speed depends on the processor and graphics card.
The process is started by a command that specifies the file with the intercepted handshake and the path to the dictionary:
aircrack-ng -w /usr/share/wordlists/rockyou.txt -b 00:11:22:33:44:55 target_capture-01.capIf the password is in the dictionary, the program displays it in the "KEY" field. If the password is complex, long, and doesn't contain dictionary words, a typical brute-force attack can take years. That's why Using complex passwords longer than 12 characters with a combination of case and special characters makes WPA2 virtually invulnerable to dictionary attacks..
| Tool | Purpose | Difficulty of use | Efficiency |
|---|---|---|---|
airmon-ng |
Managing adapter modes | Low | High |
airodump-ng |
Scanning and packet capturing | Average | High |
aireplay-ng |
Traffic generation and attacks | High | Depends on the purpose |
aircrack-ng |
Password checking (brute force) | Low | Depends on the dictionary |
Why is WEP cracked instantly?
The WEP protocol uses static encryption keys and the weak RC4 algorithm. It can be cracked by collecting approximately 10,000-20,000 IVS vectors, which takes anywhere from a few seconds to minutes, regardless of the password length.
Protecting your home network from unauthorized access
Understanding attack methods allows you to formulate effective defense measures. The first and most important step is to abandon the WPA/WPA2 protocol in favor of WPA3, if your hardware supports it. WPA3 uses the SAE (Simultaneous Authentication of Equals) protocol, which prevents real-time brute-force attacks and protects against even weak passwords.
If switching to WPA3 is not possible, you need to strengthen your password policy. Passwords must be unique, not used on other websites or services, and not a dictionary word. A password length of less than 8 characters is considered a critical vulnerability.It is also recommended to disable the WPS (Wi-Fi Protected Setup) function, as it often contains vulnerabilities that allow password verification to be bypassed.
Regularly updating your router's firmware patches software vulnerabilities that could allow remote code execution. MAC address filtering shouldn't be neglected; while it's not foolproof (addresses are easily spoofed), it does create an additional barrier to unauthorized access from neighbors.
Frequently Asked Questions (FAQ)
Is it possible to hack Wi-Fi from an Android phone?
Theoretically, it's possible if the phone is rooted and the chipset supports monitor mode. However, in practice, this is difficult to implement due to driver limitations. Specialized distributions such as Kali NetHunter, are designed for this purpose, but require specific equipment.
How long does it take to crack a password?
The time depends on the password complexity and hardware performance. A simple 6-digit numeric code can be brute-forced in seconds. An 8-character password (letters and numbers) can take several hours to brute-force on a GPU cluster. A password of 12+ random characters is virtually impossible to brute-force in a reasonable amount of time.
Is Kali Linux safe to use for a beginner?
Kali Linux is a tool for professionals. A beginner can accidentally damage their file system or disrupt their network infrastructure. It's recommended to begin learning in a virtual machine and only on your own hardware, strictly adhering to information security laws.
What should I do if the adapter doesn't see 5 GHz networks?
Not all adapters support the 5 GHz band. Make sure your Wi-Fi card is dual-band. Also, check that the driver isn't blocking high-frequency monitor mode. In some cases, switching the region in the settings may be necessary (iw reg set).