起因：最近在搗鼓Linux，配置vsftp的時候發現權限問題很坑，頭疼了一天，發現了一點小問題
常見的身份驗證方式：
1.使用系統的用戶認證
例如vsftp這種軟體，如果想建立一個可以登錄FTP的用戶我們建議不要給予該用戶可以登錄系統shell的權限
useradd -s /sbin/nologin xxx
使用段代碼我們可以指定該用戶沒有登錄系統shell的權限但是他可以作為一個用戶登錄FTP，默認情況下該用戶登錄到FTP服務器的目錄實在自己的家目錄下，那我們如果想給用戶指定他登錄到FTP服務所在的固定目錄，那我們可以在新建用戶的時候加入-d引數指定用戶的家目錄就可以實作
2.使用軟體本身的身份驗證機制
例如samba這樣的軟體，他雖然也需要在Linux系統建立用戶但是真正的身份驗證服務是由samba本身提供的，我們只需要在系統上建立賬戶然后使用smbpasswd -a給新建的用戶創建密碼
3.使用有公信力的第三方機構
例如Kerberos這樣的認證服務器，也可以提供身份認證
接下來說我遇到的坑
放上小弟的組態檔
# Example config file /etc/vsftpd/vsftpd.conf # # The default compiled in settings are fairly paranoid. This sample file # loosens things up a bit, to make the ftp daemon more usable. # Please see vsftpd.conf.5 for all compiled in defaults. # # READ THIS: This example file is NOT an exhaustive list of vsftpd options. # Please read the vsftpd.conf.5 manual page to get a full idea of vsftpd's # capabilities. # # Allow anonymous FTP? (Beware - allowed by default if you comment this out). anonymous_enable=NO allow_writeable_chroot=YES # Uncomment this to allow local users to log in. # When SELinux is enforcing check for SE bool ftp_home_dir local_enable=YES # # Uncomment this to enable any form of FTP write command. write_enable=YES # # Default umask for local users is 077. You may wish to change this to 022, # if your users expect that (022 is used by most other ftpd's) local_umask=022 # # Uncomment this to allow the anonymous FTP user to upload files. This only # has an effect if the above global write enable is activated. Also, you will # obviously need to create a directory writable by the FTP user. # When SELinux is enforcing check for SE bool allow_ftpd_anon_write, allow_ftpd_full_access anon_upload_enable=YES # # Uncomment this if you want the anonymous FTP user to be able to create # new directories. anon_mkdir_write_enable=YES # # Activate directory messages - messages given to remote users when they # go into a certain directory. dirmessage_enable=YES # # Activate logging of uploads/downloads. xferlog_enable=YES # # Make sure PORT transfer connections originate from port 20 (ftp-data). connect_from_port_20=YES # # If you want, you can arrange for uploaded anonymous files to be owned by # a different user. Note! Using "root" for uploaded files is not # recommended! # chown_uploads=YES # chown_username=whoever # # You may override where the log file goes if you like. The default is shown # below. xferlog_file=/var/log/xferlog # # If you want, you can have your log file in standard ftpd xferlog format. # Note that the default log file location is /var/log/xferlog in this case. xferlog_std_format=YES # # You may change the default value for timing out an idle session. #idle_session_timeout=600 # # You may change the default value for timing out a data connection. #data_connection_timeout=120 # # It is recommended that you define on your system a unique user which the # ftp server can use as a totally isolated and unprivileged user. #nopriv_user=ftpsecure # # Enable this and the server will recognise asynchronous ABOR requests. Not # recommended for security (the code is non-trivial). Not enabling it, # however, may confuse older FTP clients. #async_abor_enable=YES # # By default the server will pretend to allow ASCII mode but in fact ignore # the request. Turn on the below options to have the server actually do ASCII # mangling on files when in ASCII mode. The vsftpd.conf(5) man page explains # the behaviour when these options are disabled. # Beware that on some FTP servers, ASCII support allows a denial of service # attack (DoS) via the command "SIZE /big/file" in ASCII mode. vsftpd # predicted this attack and has always been safe, reporting the size of the # raw file. # ASCII mangling is a horrible feature of the protocol. #ascii_upload_enable=YES #ascii_download_enable=YES # # You may fully customise the login banner string: #ftpd_banner=Welcome to blah FTP service. # # You may specify a file of disallowed anonymous e-mail addresses. Apparently # useful for combatting certain DoS attacks. #deny_email_enable=YES # (default follows) #banned_email_file=/etc/vsftpd/banned_emails # # You may specify an explicit list of local users to chroot() to their home # directory. If chroot_local_user is YES, then this list becomes a list of # users to NOT chroot(). # (Warning! chroot'ing can be very dangerous. If using chroot, make sure that # the user does not have write access to the top level directory within the # chroot) chroot_local_user=YES local_root=/var/ftp #chroot_list_enable=YES # (default follows) #chroot_list_file=/etc/vsftpd/chroot_list # # You may activate the "-R" option to the builtin ls. This is disabled by # default to avoid remote users being able to cause excessive I/O on large # sites. However, some broken FTP clients such as "ncftp" and "mirror" assume # the presence of the "-R" option, so there is a strong case for enabling it. #ls_recurse_enable=YES # # When "listen" directive is enabled, vsftpd runs in standalone mode and # listens on IPv4 sockets. This directive cannot be used in conjunction # with the listen_ipv6 directive. listen=NO # # This directive enables listening on IPv6 sockets. By default, listening # on the IPv6 "any" address (::) will accept connections from both IPv6 # and IPv4 clients. It is not necessary to listen on *both* IPv4 and IPv6 # sockets. If you want that (perhaps because you want to listen on specific # addresses) then you must run two copies of vsftpd with two configuration # files. # Make sure, that one of the listen options is commented !! listen_ipv6=YES pam_service_name=vsftpd userlist_enable=NO tcp_wrappers=YES
關于檔案夾的屬主和屬組
本人實測的兩個Linux系統，Ubuntu16.04和redhat7.6
在Ubuntu里面安裝vsftp成功之后默認創建的用戶和組都是ftp
而Redhat默認創建的用戶和組是vsftp
Ubuntu
Redhat
本人一直覺得不能因為方便就把selinux關了，所以經過測驗，只有打開ftpd_full_access的bool值設定為on的時候可以實作正常的ftp功能，如果要允許任意用戶上傳檔案的話需要打開ftpd_anon_write,如果要使用FTP的被動模式需要打開ftpd_use_passive_mode
打開的陳述句可以參照
setsebool -P ftpd_full_access 1
同理我們也要在防火墻上放行FTP這個服務
命令參考
firewall-cmd --add-service=ftp firewall-cmd --add-service=ftp --permanent firewall-cmd --reload
如上第一條是臨時放行FTP服務，重啟之后失效，第二條是寫進底層，重啟之后任然生效但是必須重啟才可以生效，所以一二條搭配使用，或者執行二三條也可以達到同樣的效果
然后就是關于目錄的檔案夾權限設定，在Redhat上推薦把/var/ftp目錄的權限設定為755，屬主和屬組設定成vsftp
本地用戶上傳的檔案權限一般為644，檔案夾一般為755，這是因為組態檔中默認的權限掩碼umask=022的作用
暫時就這些，大佬們多多指正
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