一、問題背景
沒事誰折騰這鬼玩意哦。。。還不是因為bug。
我們的應用，用戶頭像是存在ftp上的。之前的ftp服務器是一台windows，我們后台服務器程序收到用戶上傳頭像的請求時，會用一個ROOT/ROOT的賬戶，連接ftp服務器。
獲取到連接后，即進行上傳。
上傳：上傳文件則存放在ROOT用戶的home 目錄（在windows上裝的是server-U來充當ftp服務器，所以就是在Server-U里面配置了ROOT用戶的home目錄）。
上傳完成后，會得到一個ftp協議類型的url。范例如：
ftp://10.10.20.2/userphoto/user7.png。
客戶端拿到該url后，即用ftp客戶端的庫連接該url，獲取到文件流，下載下來，進行展示。
這兩天，ftp服務器從windows變到了redhat上。今天下午，測試突然報了個bug過來，說是用戶頭像不能正常展示了。what？於是開始查找問題。
梳理了半天，發現問題在於：linux上的ftp服務器，采用的是vsftpd軟件。因為配置文件沒配好的原因，利用前面的“ftp://10.10.20.2/userphoto/user7.png”就訪問不到圖片。
為什么說沒配好呢，一開始報的錯是：FTP 550 Failed to change directory
於是按照下面博文里的進行修改：https://blog.csdn.net/coreyC/article/details/80866533
沒想到一波三折。
二、匿名訪問
關於匿名訪問，如果不成功的話，那么，請首先去下載一個工具，winscp。
按照下面的方式去進行匿名訪問：
如果匿名登錄失敗的話，會提示具體的原因。
三、匿名上傳
錯誤提示1：553 Could not create file
這個提示，有一個原因是，匿名用戶的主目錄，主目錄的意思是，每個用戶登錄進去后所在的目錄，后續的讀取、上傳都會在這個目錄，相當於用戶的base目錄吧。
如果主目錄的權限不夠，就會提示這個問題，一般直接野蠻改為777權限。
至於主目錄在哪？ 在配置文件中通過以下選項進行配置：
anon_root=/data/ftp
如下圖所示，需要把主目錄權限改為777，即可匿名上傳：
修改權限的命令：
chmod 777 /data/ftp
下述的報錯也是同樣的問題：
500 OOPS: vsftpd: refusing to run with writable anonymous root
二、支持匿名訪問/上傳的配置文件
正確的配置貼一份，這份配置再加上，對目錄進行必要的權限設置，基本可以擺平大多數情況：
# 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).
# 這里需要打開，允許匿名訪問 anonymous_enable=YES
#https://blog.csdn.net/bluishglc/article/details/42399439
allow_writeable_chroot=YES
# # Uncomment this to allow local users to log in.
# 之前說到我們用ROOT/ROOT來訪問ftp，我們這里，ROOT/ROOT是我們的linux可以登錄的用戶名密碼。要允許這類用戶訪問ftp，需要開啟下面的選項 local_enable=YES # # Uncomment this to enable any form of FTP write command.
# 要允許寫入操作。否則應該不能上傳文件 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.
# 匿名上傳，需要配合write_enable=yes anon_upload_enable=YES
# # Uncomment this if you want the anonymous FTP user to be able to create # new directories.
# 允許匿名用戶創建目錄; anon_mkdir_write_enable=YES
#控制匿名用戶對文件和文件夾的刪除和重命名 anon_other_write_enable=YES
# # Activate directory messages - messages given to remote users when they # go into a certain directory. dirmessage_enable=YES # # The target log file can be vsftpd_log_file or xferlog_file. # This depends on setting xferlog_std_format parameter 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 # # The name of log file when xferlog_enable=YES and xferlog_std_format=YES # WARNING - changing this filename affects /etc/logrotate.d/vsftpd.log #xferlog_file=/var/log/xferlog # # Switches between logging into vsftpd_log_file and xferlog_file files. # NO writes to vsftpd_log_file, YES to xferlog_file 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. # 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(). #chroot_local_user=YES #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=YES # # This directive enables listening on IPv6 sockets. To listen on IPv4 and IPv6 # sockets, 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=YES tcp_wrappers=YES
#匿名用戶的根目錄。這個非常重要 anon_root=/home/ROOT
#匿名用戶不要密碼就靠這個 no_anon_password=YES
#本地用戶，如我們上傳用的用戶（ROOT/ROOT）的根目錄。當然，我們給匿名配了那么多，估計匿名也能上傳了。 local_root=/home/ROOT
#該選項暫時不太清楚 ftp_username=ROOT
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