Linux System Services 3 FTP Service principle and VSFTPD service configuration

1 FTP

1 FTP is a fairly old and widely used Internet Protocol, FTP provides us with a reliable way to file sharing on the network

2 FTP is a CS architecture services, with a server and client, FTP using the TCP protocol as the underlying transport protocol, providing the reliability of data transmission, FTP standard port for 20,21,20 as the data interface, 21 for the instruction interface

3 All shared files are placed on the service side

2 FTP Mode

There are two modes of connection between FTP client and server side

1 active mode: Refers to the assumption that the client wants to request file sharing to the server, first the client sends a request to the service Port 21st, and then the server returns an instruction to ask the client what to do, and then the server through 20 ports to the client

2 because many of the computers now have firewalls, many of them will be rejected by the extranet, so the passive mode is now developed.

2 Passive mode: Refers to the assumption that the client wants to request file sharing to the server, first the client sends a request to the service Port 21st, and then the server returns an instruction to ask the client what to do. Next, the client sends the request to the server, and the server will send the data to the client

Passive mode is suitable for the vast majority of current hosts with a firewall installed

3 vsftpd

1 applications in Linux as an extensive FTP service program called VSFTPD,VSFTPD provides us with a fast, stable, and fairly secure FTP service

2 Use the following command to install VSFTPD

Yum Install-y vsftpd

3 VSFTPD of the relevant configuration files and directories are as follows

/ETC/VSFTPD/VSFTPD.CONF-VSFTPD Master configuration file

/etc/vsftpd/ftpusers-blacklist

/etc/vsftpd/user_list-Control List (by profile control is white list or blacklist)

/var/ftp-ftp shared Directory