Basic concepts of Linux VSTP (1)

FTP Overview:

File Transfer protocol Files Transfer Protocol, the FTP service is divided into two roles of server and client.

Transfer mode for FTP server:
Active mode: The server actively connects the client to establish the data link
Passive mode: The FTP server waits for the client to establish a data link

VSFTP Port number:

Command Channel port:

Data Channel port:

VSFTP Supported Accounts:

• 
  

  • Anonymous account

  • Local accounts (which local accounts are on the Linux system)

  • Virtual Account

Configuration file for Vsftp:

/etc/vsftpd/vsftpd.conf #主配置文件

/etc/vsftpd/ftpusers #黑名单

/etc/vsftpd/user_list #白/blacklist (default blacklist)

Note :/var/ftp/ The default shared directory, permissions cannot be changed.

How the Vsftp works:

The specific working procedure for the FTP service is as follows.

① when the FTP client makes a request, the system dynamically assigns a port (such as 1032).

② if the FTP server hears the request on port 21, port 1032 of the FTP client and port 21 of the FTP server

An FTP session connection is established between the

③ when data needs to be transferred, the FTP client then dynamically opens a 2nd port on port 20 connected to the FTP server

(such as 1033), so that data can be transmitted between the two ports. When the data transfer is complete, the two ports

is automatically turned off.

④ when the FTP client disconnects from the FTP server, the dynamically allocated port on the client is automatically freed.

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Vsftp Common configuration and meaning description.

Anonymous	Anonymous_enable=yes	Enable anonymous Access
	anon_umask=022	Permission mask for files uploaded by anonymous users
	Anon_root=/var/ftp	Anonymous user's FTP root directory
	Anon_upload_enable=yes	Allow uploading of files
	Anon_mkdir_write_enable=yes	Allow Directory creation
	Anon_other_write_enable=yes	Open Other write rights
	Anon_max_rate=0	Limit the maximum transfer rate in bytes
Local user	Local_enable=yes	Whether to enable Local system users
	local_umask=022	Permission mask for files uploaded by local Users
	Local_root=/var/ftp	To set the FTP root directory for Local Users
	Chroot_local_user=yes	Whether to imprison the user in the home directory
	Local_max_rate=0	Limit Maximum transfer rate (Bytes/sec)
                global configuration
listen_address=192.168.4.1	Set the Listening IP address
Listen_port=21	Set the port number for listening to the FTP service
Write_enable=yes	Whether Write permission is enabled
Download_enable=yes	Whether to allow file download
Dirmessage_enable=yes	The contents of the. message file (if present) when the user switches into the directory.
Xferlog_enable=yes	Enable Xferlog logging, default logging to/var/log/xferlog file
Xferlog_std_format=yes	Enable standard Xferlog log format, if disabled, will use VSFTPD's own log format
Connect_from_port_20=yes	Allow server active mode (data connection is established from Port 20)
Pasv_enable=yes	Allow Passive mode connection
pasv_max_port=24600	Set the server maximum port number for passive mode
pasv_min_port=24500	Set the server minimum port number for passive mode
Pam_service_name=vsftpd	Set the Pam file location for user authentication (the corresponding file name in the/etc/pam.d/directory)
	Userlist_enable=yes	Whether to enable the User_list user list file
	Userlist_deny=yes	Whether to prohibit user accounts in the user_list list file
	Max_clients=0	Maximum number of clients allowed to connect at the same time (0 is unlimited)
	Max_per_ip=0	For clients from the same IP address, the maximum number of concurrent connections (0 is unrestricted) is allowed.
	Tcp_wrappers=yes	Whether to enable Tcp_wrappers host access control (the application of TCP wrappers will be explained in the subsequent course)

Vsftp start-up and shutdown and join boot start:

Start:

[Email protected] ~]# service vsftpd Restart

Shut down:

[[email protected] ~]# service vsftpd Stop

Boot start:

[email protected] ~]# chkconfig dhcpd on

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