Simple Principle and introduction of Serv-U (FTP software)

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Section 1 FTP principles and concepts
A shared download site is what we call an FTP server. FTP is short for file transfer protocol, which is used to transfer files between two computers.
The FTP protocol can work in two ways: Port and PASV. The Chinese meaning is active and passive.
The active connection process is that the client sends a connection request to the FTP port of the server (21 by default). The server accepts the connection and establishes a command link. When data needs to be transmitted, the server sends a connection request from Port 20 to the idle port of the client and establishes a data link to transmit data.
PASV (passive) connection process: the client sends a connection request to the FTP port of the server (21 by default). The server accepts the connection and establishes a command link. When data needs to be transmitted, the client sends a connection request to the idle port of the server and establishes a data link to transmit data.
Because the server actively connects to the client when data is transmitted by port, if the client is behind the firewall or NAT gateway, the file cannot be transmitted by port with the FTP server on the Internet. In this case, PASV is required. Almost all FTP client software supports these two methods. A special example is IE, which uses port by default. If you want to enable PASV in IE, open IE and choose tools> Internet Options> advanced from the menu, hook up before "use Passive FTP" (supported only by ie6.0 or above ).
An FTP server is a computer that provides FTP storage space on the Internet. It can be a dedicated server or a personal computer. When it provides this service, users can connect to the server to download files, and allow users to transfer their files to the FTP server.
You can log on to an FTP server in two ways: Anonymous logon and authorized account and password logon.
In general, anonymous login can only download FTP server files, and the transmission speed is relatively slow, of course, this needs to be set on the FTP server, for such users, FTP needs to be limited, it is not suitable to enable excessive permissions, and the bandwidth is as small as possible.
The administrator needs to authorize the account and password to log on. The administrator needs to inform netizens of the account and password, and set these accounts, such as the resources they can access and download and upload speeds, similarly, administrators need to restrict such accounts and reduce their permissions as much as possible. If not necessary, do not grant the account administrator permissions.
A Personal FTP server is an FTP service built on a personal computer using FTP-specific software. It has the following advantages over a Professional FTP Server:
1. Complete functions.As you know, a dedicated FTP server only provides a certain service and is no longer required. Unlike a personal server, what can the owner do if he wants to do it.
2. flexible configuration.It is no longer subject to disk space restrictions. For example, if the disk space is insufficient, you can purchase another disk. Now, the price of large-capacity hard disks is not expensive, which can provide a place for netizens to stream files.
3. Have Full Management permissions.The machine is by its own side, and all the work can be done by itself.
Of course, there are still many shortcomings between individual FTP servers and dedicated FTP servers, mainly reflected in the following aspects:
1. Relatively Small bandwidth.Although broadband is widely used, the fastest speed of broadband is only 10 M. There is a big gap between it and the bandwidth calculated by the dedicated FTP several g or even T.
2. The opening time is not fixed.Because it is a personal computer, it is regarded as an FTP server, and the performance is not very stable. Generally, it cannot be opened 24 × 7.
3. Use your valuable bandwidth and disk space.
Although the Personal FTP server has many disadvantages, it is a matter of benefit to establish a personal FTP server. He can provide his favorite items to netizens for download, at the same time, you can upload the users in the east and west regions you need.
Section 2 Introduction to Serv-u ftp Server
There are a variety of software for building FTP servers, among which FTP functions in IIS and Serv-u ftp server are commonly used.
FTP in IIS is a non-Professional FTP software, but many people are familiar with it because it is integrated into Windows 2000. Here we will mainly introduce the latter Serv-u ftp server. Serv-U is an FTP server program that runs on Windows 95/98/2000/me and Windows NT4.0. With it, your PC can be simulated as an FTP server. That is to say, computer users in your connected network can access your PC, you can copy, move, or delete files or folders on your computer through the FTP protocol (file transfer protocol) to do everything permitted by permissions. The FTP protocol specifies the standard communication mode between computers so that files can be exchanged between different types of computers, operating systems, and computers of different formats. It can create a user account in the simplest way, and divide a certain area in the hard disk space to store files, allowing users to use various FTP client software (such as CuteFTP, WS_FTP, etc) upload or download the required files.

Many FTP servers and client software can be used in different systems. Serv-U is used in PCs that run MS-windows and have installed Winsock version 1.1 compatible with TCP/IP protocol, this includes almost all Windows operating systems.
Serv-U consists of two parts: Engine and user interface. Serv-uengine (servudaemon.exe) is actually a resident background program, and is also the heart of the Serv-U software. It is responsible for processing FTP commands from various FTP client software, it is also responsible for executing various file transfer software. We can stop and start the Serv-U engine, that is, the slave engine. The Serv-U engine can run as a local system service on any Windows platform. The system service starts to run as the operating system starts, and then we can run the user interface program. In Win NT/2000, Serv-U is automatically installed as a system service, but in win 9x/Me, you need to select "auto start" on the "server" Panel to convert it into a system service.
Serv-u (servuadmin.exe) is the Serv-uadministrator, responsible for interaction with the Serv-U engine. It allows users to configure Serv-U, including creating a domain, defining a user, and telling the server whether access is allowed. The easiest way to start a Serv-U administrator is to directly tap the "U" icon in the system bar. Of course, you can also run it from the Start Menu.
It is necessary to clarify some important concepts in Serv-U: each running Serv-U engine can be used to run multiple "virtual" FTP servers, in the Administrator program, each "virtual" FTP server is called a "domain". Therefore, it is very useful for the server to have to create multiple domains. Each domain has its own "user", "group", and settings. Generally, the "Setup Wizard" will set up the initial domain and user account when you run the application for the first time. The relationships between servers, domains, and users can be found in the following table:
* Serv-U Server
* Domain 1
* User Account 1
* User Account 2
* User Account 3
* Domain 2
* User Account 1
* User Account 2
* Domain 3
* User Account 1
* User Account 1
Serv-u ftp server is a sharing software that can be used for 30 days without registration. It is a professional FTP server software and can be used to build a professional FTP server, currently, FTP services for Internet use this software. It has the following features:
Supports multi-user access;
Anonymous Users are supported, and the number of user logins can be limited at any time;
You can manage each user separately or by group;
You can limit the download or upload speed;
Security management for directories or files;
Supports virtual directories;
Prohibit or allow access to IP addresses;
Ease of installation and management;
Multiple FTP servers can be created on one computer.

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