Centos FTP server system suite

1. vsftpd, commonly used centos FTP server suite; vsftpd is a centos FTP server program that is the most popular in the Linux release version; it is small, light, secure, and easy to use; it can give full play to its own characteristics and be used most importantly. Currently, the ftpd kits commonly used in open-source operating systems include ProFTPD, pureftpd, and wuftpd; which centos FTP server suite is better and which one is the most familiar to you is the best;

 

2. Explanation of centos FTP user management; management of users by centos FTP server is based on/etc/passwd and/etc/group by default, therefore, we must understand the management of Linux users and user groups. The management of users and user groups is the foundation of all applications. Some brothers do not want to understand the basic things, it turns out that this learning method is the most unwise to build a variety of servers. Although you may have started the centos FTP server in a few minutes, when you encounter problems, you may not be able to know where the error occurred; therefore, the foundation is extremely important. recommended Article: Linux User and user group management overview

 

2.1 anonymous centos ftp users and user groups; when we access the centos FTP, we may not consider the identity of the user to log on, if his FTP allows anonymous login; for example we typed in a browser; ftp://mirrors.kernel.org or FTP: // ftp: ftp@mirrors.kernel.org

 

We will find that the above two lines can finally access, and the display results are exactly the same, and finally jump to the ftp://mirrors.kernel.org address; then when we access this centos FTP, is there a user and password? Yes, it is also necessary. It is only necessary to allow anonymous access on the server side, while the username and password for anonymous access are all ftp. It is only because of anonymous access, he doesn't feel like he has a user name and password. The second address is to centos ftp users, the password is also centos FTP to access the ftp://mirrors.kernel.org;

 

If we use the centos FTP command to connect to mirrors.kernel.org, we will find that we need to enter the user centos FTP and password centos FTP to access; In the centos FTP server, the anonymous user name and password are both centos ftp. This user can be found in/etc/passwd in your operating system. There may be a line similar to the following; ftp: X: 14: 50: FTP user:/var/ftp:/sbin/nologin

 

Note:/etc/passwd is the configuration file of the System user./etc/group is the configuration file of the System user group. You can use) management overview and related documents to learn some basic user management knowledge. In the centos FTP user line, we can see seven fields, each field is separated by a comma;

 

Centos FTP is the username X is the password field, which is hidden; 14 is the UID field of the user, which can be set by yourself. Do not use the same UID as other users; otherwise, system security problems may occur; 50 use the GID of the user group, which can be set by yourself. Do not share the GID of centos FTP with other user groups; otherwise, the system will be fully affected; centos FTP user is the user Description field; /var/FTP is the home directory of FTP users and can be defined by yourself;

 

/Sbin/nologin this is the user login shell, which can also be defined,/sbin/nologin indicates that the system cannot be logged on; system virtual accounts (also known as pseudo users) are generally set in this way. For example, change/sbin/nologin of centos ftp users to/bin/bash, so that centos ftp users can log on to the system as real users through local or remote tools SSH or telnet.

 

This is not safe for the system. If you think that a user does not have to log on to the system, you can only grant the centos FTP account permissions, that is to say, only give him the centos FTP permission, instead of setting his shell to/bin/Bash;

 

Understanding about the centos FTP user group: When we view/etc/group, we will find a similar one. FTP: X: 50:/etc/group is the management configuration file of the user group, the above line indicates that the user group FTP, X is the password segment, and 50 is the GID. We know that the centos FTP user in/etc/passwd belongs to the centos FTP user group, because the gid in the centos FTP user line is the same as the gid in the centos FTP user group;

 

2.2 whether anonymous centos ftp users and centos FTP user groups can be deleted normally, the rows of centos ftp users and user groups cannot be deleted in/etc/passwd and/etc/group., because centos FTP servers require them to manage centos ftp users by default.

 

Although it cannot be deleted, it can be modified for centos ftp users and centos FTP user groups in/etc/passwd and/etc/group; for example, you can change the Home Directory of centos ftp users, or change the UID of centos ftp users ...... the premise is that you understand user management. system user management is one of the foundations of all applications. Maybe Linux beginners do not understand the importance of user management, but you will find this truth slowly.

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