Shulou(Shulou.com)06/02 Report--

I. introduction to FTP

1. File transfer Protocol (File Transfer Protocol,FTP) is a set of standard protocols for file transfer over the network. It works at the seventh layer of the OSI model and the fourth layer of the TCP model, that is, the application layer. It uses TCP transport instead of UDP. Before establishing a connection with the server, the client has to go through a "three-way handshake" process to ensure that the connection between the client and the server is reliable and connection-oriented. Provide reliable guarantee for data transmission.

2.FTP connection and transmission mode

By default, the FTP server communicates with the client using port 2010 21 of the TCP protocol. Port 20 is based on establishing a data connection and transferring file data: port 21 is used to establish a control connection and transmit FTP control commands

FTP data connection is divided into active mode and passive mode.

3.FTP user Typ

Anonymous users (ftp) and local users

4. Software package-> vsftpd 2 access FTP service 1. Anonymous access

Host directory is / var/ftp,FTP root permissions do not allow anonymous users or other users to write (otherwise 505 error will be reported)

two。 Enable anonymous user configuration and launch vsftpd [root @ localhost ~] # yum install vsftpd # install ftp [root @ localhost ~] # chown ftp/ var/ftp/pub/ # to give write permission to / pub/ In order to upload data vim / etc/vsftpd/vsfpd.confanonymous_enable=YES # allow anonymous users to access write_enable=YES # enable write access to the server-the global option anon_upload_enable=YES # allows anonymous users to upload files anon_other_write_enable=YES # allows anonymous users other write permissions, including deletion, renaming, upload directory anon_mkdir_write_enable=YES # allows anonymous users to create directories 3. FTP service for user authentication

a. Basic local user authentication

Vim / etc/vsftpd/vsftp.conflocallocal_enable=YES # enable local user permissions write_enable=YES # enable write permissions chroot_local_user=YES # turn on all host directories fasten in the host directory B. Use the user_list user list file. When the vsftpd server opens the "loacl_emable" configuration item, by default all system users except root can log in to this FTP server. To open up FTP services to a small number of system users, you need to open list control related configuration items. Userlist_enable 、 usrlist_deny . Vim / etc/vsftpd/vsftpd/confchroot_local_user=YES # enable usr_list user list chroot_list_enable=YES # disable the user vim / etc/vsftpd/user_list # in the user_list list how to add the local member caoguojihunterlaya that can access the FTP service

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