Write an FTP server (1)--Requirements analysis

An FTP server to have what function, take vsftpd for example, VSFTPD in addition to implement basic FTP command, also support control connection, parameter can be configured, breakpoint continued transmission and so on.

Most of the configuration and features of VSFTPD can be seen in its configuration file under Linux performing man 5 vsftpd.conf.

If you implement an FTP server, the following functions are implemented:

1. Standard FTP commands

Basic FTP File Transfer Protocol, you can refer to the RFC

A simplified Chinese version is included here:Https://github.com/zilandy/zFTP doc

2. Parameter configuration

Change the execution parameters by configuration file similar to vsftpd.conf

3. Idle Disconnect

The client is unresponsive, idle time is disconnected, and the resource is left to other users

such as: idle_session_timeout=600

4. Limit of connections

Total number of connections max_clients=50

Number of individual IP connections max_per_ip=5

5. Speed limit

Limitations of upload download speed

Local_max_rate=100 (KB)

6. Continuation of the breakpoint

The client also needs to configure the breakpoint to continue

Write an FTP server (1)--Requirements analysis