Today, almost any user can give an answer to the question of what an IP network scanner is. This is a sniffer program that identifies a specific computer terminal on a local network or when establishing an Internet connection. But here is how this system works, some can only guess.
What is a network scanner?
Programs or commands of this type can conditionally be divided into several classes, depending on the defined parameters.
Obviously, a software network scanner should work in several modes, including determining internal and external IP addresses of connected devices, running a diagnostic system, recognizing wireless networks and having access to resources based on HTTP and FTP protocols.
Windows Scan Tools
To determine IP-addresses in Windows-systems, there is a special tool already built into the OS.
As a rule, IP addresses in their current use by providers are set automatically. In the network settings, this setting is simply installed (Obtain IP address automatically). At the same time, the subnet mask and gateway are set in the same mode. The DNS server (primary and alternative) is not involved, in some cases their addresses need to be entered manually, especially if the settings are made through Google services.
But you can recognize any internal address using the simplest ping command, entered in the corresponding console with the internal address of the local computer or terminal connected, for example, to the corporate network.
You can view all the addresses of devices currently connected via one of the network protocols using the ipconfig command.
Many people underestimate the command line, and here, when adding an addition to the main command in the form of release6 or renew, you can use the space bar to automatically apply the IPv6 protocol or even update the configuration to obtain the DHCP server settings.
External request based on ping command
As for external requests by the ping command, they are mostly made only by the provider or network administrator.
The disadvantage of this method is the determination of the external IP address of a device connected to the Internet. In this case, the internal address can be hidden or assigned automatically.
And in the case of checking virtual WLAN networks, there is only pinging of a router or ADSL modem. Its address in no way matches the address of the local terminal.
WiFi Scanner
Let's move on to the software products directly. You probably don’t need to say that in the same Google Play market you can download a free utility that can recognize virtual networks located near the user.
But, if you thoroughly rummage around on the Internet, you can find not just a network scanner, but a whole software package that allows you to crack a password or even act as a so-called anonymizer, which is somewhat reminiscent of using virtual proxy servers and access protocols. The essence of the question is to determine an unused address and connect to it. Thus, any scanner of IP addresses on the network determines them based on the ones allocated by the provider, although the service itself, provided that a virtual proxy server is activated, can only guess about it.
The simplest programs
Among all that can be found on the Internet today, the most popular are the following:
- Free WiFi Detector (scanner for public wireless networks);
- Net Scan - scanner of local ports and IP addresses;
- In S SIDer - a tool for wireless networks;
- Angry IP Scanner is a system for checking free addresses that are not involved in local connections.
Any network scanner of the above type works on the same principle. This is the definition of the external IP of the connected device, no matter, the mobile is a device, a desktop computer or a laptop.
All applications related to the category of programs that are commonly called “Windows 7 Network Scanner” use a hidden ping command, which the user does not know about. True, an external request is carried out not in the form of an operation performed by Windows, but based on our own developments, taking into account the protocol used and the DHCP server.
At the same time, there may be failures in the connection option of the proxy server. You can change these settings in the network or network adapter settings, which prohibits the use of proxies for local addresses (IPv4 protocol settings at least).
At the same time, mobile applications of this type are very popular. In the simplest case, the following example can be given. A man came to a cafe and urgently needed to write a message or send an email. He does not know the password for accessing the virtual network (or does not want to ask). If there is a corresponding application installed on the smartphone or tablet, the network scanner will work automatically, determining the nearest wireless system (or several).
Depending on the software product, there may also be the possibility of passwordless access to the network. But this is clearly illegal. Needless to say, today there is a residually large number of so-called crackers, to which sometimes applications of this type are also ranked.
But no one understands that the scanner of network IP addresses determines only the source through which the Internet is connected and the network is accessed (network adapter based on Ethernet, Wi-Fi network using a router as a router).
Conclusion
The worst part is that no program of this type can scan the hosts configuration file, which stores information about accesses to standard addresses, when scanning internal and external addresses. Sometimes its contents may have records blocking certain resources, and access to these settings on Windows systems has the highest priority even in relation to DNS or proxy servers.
Therefore, when installing a network scanner, it is worth considering the feasibility of using such a software product. Unfortunately, applications in the form of scanners that are not controlled by Windows can cause conflicts at the system level (the operation of some dynamic libraries necessary for the correct functioning of Windows, and even device drivers, is blocked).
In addition, one should pay attention to the legality of penetration into a certain virtual network, not to mention the installed software, taken from unofficial (pirated) sources.