This page has been robot translated, sorry for typos if any. Original content here.

Install also configure the FTP server. Part 1

By the measure of increasing the availability of the Internet and local area networks, many users begin to want or need to share files with other people. In principle, this is also allowed to be done using "shared access" using the built-in capabilities of the operating system. But through the Internet it is dangerous also requires the installation of a VPN, only on the local network - it does not allow you to limit the download speed in any way; your computer may exist approximately paralyzed with the active download of impressive files. In order to avoid all these problems, you should install an FTP server, which will allow you to flexibly control the volume of traffic, centrally manipulate the lists of available files by users as well, it is only similar to use programs with downloads after the break (for example, ReGet) to download files.

To further understand some of the settings, consider what the blast is the FTP work algorithm.
FTP (File Transport Protocol), created specifically for file transfer, works on a pair of ports. The client connects to the server (by default on the 21st port) also sends commands to it, only for file transfer the server connects to the customer, also files are already transferred through this channel. This mode (the server connects to the client) is called "PORT", and it cannot be used by users accessing the Internet through NAT, so the mode was invented where the customer personally installs the second association for transferring files - this is called "PASV" or "passive FTP -protocol".

Only since version 5.5, Microsoft Internet Explorer learned to work in PASV mode (the corresponding option is allowed to be enabled in its parameters). But the "PORT" mode did not give up at all - in advanced FTP clients (such as CuteFTP, FTP-Voyager and even Total Commander) it is allowed to specify the range of ports for PORT mode, which will forward these clients to NAT to your machine as well to request the server connects specifically to these ports.

Eat a pair of data transfer options - Binary is also ASCII. In the "Binary" mode, any data is transmitted, but a little slower; in "ASCII" mode, only text files can be transferred. The transfer mode is selected by the customer, and the ASCII mode for TXT, HTML, INI files and other explicitly text files is also usually automatically set. It is better to always use the "Binary" mode for all files.

FTP can own various extensions in the schedule of protection against traffic interception. Interception protection can exist by duplicated methods, depending on the required level of security.

Firstly, it is allowed to use encrypted passwords (OTP-MD5), as a result of which no password will be transmitted over the communication channel, only its hash, and with the addition of pore - therefore, attackers will not be able to find out the password, only by adding pore re-sending a copy of the hash from the attackers will not be accepted. This will not allow attackers to log into a personal FTP account.

Secondly, it is possible to encrypt all FTP traffic (FTP SSL / TLS). This will not allow attackers to get all the files that you transferred. But I note that the standard clients originally present in Windows (Internet Explorer also ftp.exe) do not have any of these methods of protection against interception, so users of your FTP server will need to use alternative FTP clients - CuteFTP or FTP-Voyager.

Well, we got the initial information about the features of the FTP protocol, only now it is time to move on to creating your own FTP server as well. We will talk about how to perform this operation on the sample program Serv-U in another element of our material.