Application of wireless technology in Linux

With the popularity of Wi-Fi, Linux has also added this row. In this article, Roman vichr explains how Linux can help many wireless tools and projects-and get help from these tools.

 

 

Linux-this universal, stable, scalable, changeable, and competitive platform has moved towards wireless. From desktop machines and servers that support wireless access to wireless access systems, it is becoming almost all common tools and has become a place in wireless solutions. Learn more about how Linux is promoting wireless networks.

　　Linux Wireless Access Point: build or purchase?

The basic question is: does the Linux system have the ability to combine with other access points in the wireless network to provide connections between fixed nodes and roaming wireless clients?

The actual installation of a wireless LAN is not that important. The key depends on what you purchased and whether it is supported in Linux. Check and ensure that you have hardware for a specific operating system driver. Note: If you want high performance (that is, Gigabit data transmission speed), it is wrong for you to choose wireless. Even if it is the latest standard, the transmission speed is less than 100 Mbps. Roaming poses another challenge: maintaining connections between different access points. To help achieve this, set the Wired Equivalent Privacy (WEP) Key to detect the access point that you can connect. Remember, in reality, the access point is mainly used as a bridge; that is, it should route data packets from one network to another.

This article focuses on various options and tools used to manage these access points. Basically, you need to choose whether to use the tool through wireless extensions. (Wireless expansion is the name of a common API that allows drivers to inform users about the spatial structure and statistical details of common wireless LANs .) For detailed instructions on how to install the Access Point Software in Linux, read the article to build a wireless access point in Linux. For a full overview of the wireless network structure and the bridge between the LAN and WLAN, please refer to Linux Wireless Access Point howto

　　Do not use wireless extensions

Some technologies can help you build a Linux wireless network without using wireless extensions, including Linux-IrDA and bluez, which are also Linux Bluetooth stacks. The Linux wireless network technology provides a detailed description of the two. Another choice is Rose (RadioNet open source environment; see references for more information), a platform for building 802.11 wireless access points. The advantage of Rose is that it can be compiled on any platform (such as MIPS, x86, arm, and PowerPC. The supported WLAN card is based on intersil prism chipset 2/2. 5/3. It also supports the 5 GHz frequency. The following are additional rose features:

　　Access Point Development Kit

802.11 protocol and security, MAC address filtering, IPv4 routing, firewall, radius, QoS, bridge, Nat, and DHCP. Other drivers such as 802.11a/g/h are also supported.

For good support and maintainability, the rose compiler is written in Python (with the available C compiler gzip, Python language versions 2.x -- 2.1 and 2.2 with the standard Python Library have been tested ).

Basically, using rose (and Linux 2.4 kernel) and a WLAN Card Based on 802.11 intersil prism, you can build a Linux-based Wireless Access Point

Select wireless extension

The advantage of wireless expansion is that a single set of tools can support all types of Wireless LAN regardless of their type (as long as the hardware driver Supports Wireless expansion ). Another advantage is that these parameters can be modified during use without restarting the driver (or Linux.

A set of Linux tools for operating wireless extensions are generally referred to as wireless tools. They use text interfaces and are very simple. In Linux implementation, the following are used:

Iwconfig: Basic wireless parameters.

Iwlist: Initialize Scan Frequency, list frequency, bit rate, and key.

Iwspy: gets the connection quality of each node.

Iwpriv: allows you to perform operations on wireless extensions that are specific to the Wi-Fi driver.

Ifrename: a standard-based name interface is allowed.

　　Ifplugd/waproamd

Waproamd is a roaming Background Program (roaming Daemon) of IEEE 802.11 compatible that supports Linux wireless extensions (V15 or later). It has been tested on Debian Linux. It is used to configure the WEP key based on the network found. The waproamd tool repeatedly scans wireless networks. When the NIC is associated with an available network, waproamd no longer scans, but connects the NIC card to the discovered access point. You can use the iwlist scan command to test scanning. As defined by the host AP driver, waproamd supports host_roaming. Do not forget to install the firewall when using waproamd. The tool itself cannot prevent intrusion.

　　Kwifimanager

Kwifimanager is a tool used to configure and monitor your wireless lan pc card in the KDE environment on Linux. It is written by KDE 3.x. It uses Linux kernel wireless extensions, so most wireless cards are supported by PCMCIA-CS packages. However, if your card uses a driver from the WLAN-ng project, there may be problems because these drivers are not compatible with wireless extensions. In either case, you can try or use the host AP driver for the same card, which is compatible with wireless extensions.

Kwifimanager is released as an RPM package; however, there are some prerequisites for installation. These prerequisites are QT Toolkit (version 3.0.3 or above), Kde 3.x, and glibc2.2. After these packages are available, the standard./configure make install will compile and install this tool. This application provides some Display Interfaces: signal quality, connection speed, current configuration, Access Point monitor, statistics viewer, and configuration Editor (the last display interface can only be accessed by the root user ).

Glink is a link monitor and configurator for 802.11b cards (these cards use linux kernels with wireless extensions), which is roughly equivalent to the kwifimanager tool in gnome.

　　Aphunter

Aphunter is written in Perl and can output an iwlist scan in a text file. You can use the perldoc-T./aphunter command to call up the tool documentation. This tool provides some switches to control its output and indicators.

　　Gkrellmwireless

This tool requires a Linux kernel with wireless extensions. This tool requires a C library for compilation. Of course, it is installed using (g) make. (In BSD, you need to add additional header files: if_wavelan_ieee.h and if_aironet_ieee.h for installation .) This tool displays wireless link quality, link level, and noise. Its latest version can display the level and noise in dBm units in Linux.

Collaboration capability issues

When deploying wireless networks on the Linux platform, it is important to consider the synergy between different cards using the Linux driver. You should also ensure that different hardware parts work collaboratively; they should all understand the signal of each other in the same spectrum. Don't forget that similar products may not be able to work collaboratively. For example, 802.11 and 802.11-FH products cannot work with 802.11-Ds products, and vice versa.

　　Chipset

Considering that some products may be supported while other products of the same brand may not, the use of multiple chipset in different wireless products may be a challenge. Sometimes, even cards of the same model number may use different chipsets, which makes it difficult to determine whether a card can be supported by Linux. However, most of the available 802.11b cards use the intersil prismii chipset, which is well supported by Linux.

The 802.11b specification is only an extension of 802.11-ds, which improves the speed, but in any case, both products can be in at least 2 MBS (802.11-Ds Mode) speed. The 802.11g standard is non-direct extension of 802.11b. It aims to increase the bandwidth without changing the frequency. When you try to make the 802.11a product work together (5 GHz in frequency), you must understand that they can only work together with products based on the exactly same chipset, rather than working directly with the 802.11b product, unless you have a device that can be used for both 802.11b and 802.11a. To fully review the wi-fi frequency and standard collaboration capabilities, read the 802.11g standard-IEEE and the ABCs of 802.11.

When considering your Linux wireless device driver, do not forget that the driver will not always implement all the features of the corresponding window driver. This limits the ability to work collaboratively. In Linux, security features are particularly easy to lag behind. The next section describes the enhancements and management details.

　　Networking flexibility and wireless Planning

To make wireless networks flexible and secure, some plans have been initiated, such as wireless freenetwork allocations and nodedb.com (see references for more information ). Basically, these are websites where people can list their locations and information about access points or fixed client connections, so that others can easily locate themselves based on a geographic directory service.

The soul of Linux-its openness, the spirit of users-owners and managers-has had an impact in some wireless programs, whether or not Linux is indeed part of that solution. In some plans, such as nodedb.com, Linux is only one of the platforms. In wiana and nocatauth plans, it is the backbone of the plan because it has the ability to allow users to customize permissions at the operating system level (that is, at the access point level.

　　Wiana

Wireless Assigned Numbers Authority, also known as the wiana Program (see references for more information), attempts to create a structure for wireless address management. The traditional IP address Registry relies on a static hierarchical structure, which cannot satisfy wireless applications. Wiana must deal with the special features of wireless networks. In wireless networks, nodes can be moved from one level to another just because of location changes. Under wiana's guidelines, the network is managed by users rather than providers. Large-scale wireless networks are based on different physical media than the traditional Internet that requires actual authentication for each address. The high cost of connection in traditional Internet makes wireless users no longer use the same method to obtain IP addresses. In wiana, these addresses are provided for free. Wiana also tries to focus on abuse and blocking. Wiana supports compatible wireless software and hardware that are subject to the mission statement provided by locustworld.com. The design of those hardware and software is fully compatible with any platform with 802.11 Wi-Fi. The main idea is to provide an open community wireless WAN, which is managed by users themselves to give users more flexibility.

　　Nocatauth

You can think that the plan named nocatauth is similar. It was initially built to support Sonoma County, California's 802.11b wireless network. This implementation method sets up the authentication code of the shared Internet service to a possible point (similar to wiana ). To use nocatauth following an open source code license, you must install the Perl programming language, GNU make, and gpgv in your Linux system.

　　The wireless future of Linux

Linux has become one of the optional platforms for products and solutions such as bluez (running on Linux kernel 2.4 and 2.6) and Linux-IrDA, and is also becoming a platform for mobile phones. As mobile phone hardware becomes more powerful and mature, it will provide a huge opportunity for smaller providers, they can create easy-to-use parts and provide users with more powerful control over the environment. Most Linux mobile phones have been used in Asia, where Linux is becoming the preferred 3G phone development platform. The reason is simple-the Linux method provides developers and consumers with greater flexibility and freedom.