FTP

FTP服务的工作原理？

CS模式

FTP服务的工作模式有几种？是什么？

主动模式

被动模式

vsftpd的用户类型有几种？是什么？

有三种用户类型

1、匿名用户

2、本地用户

3、虚拟用户

vsftpd的基本配置  ( /etc/vsftpd/vsftpd.conf )

 

不允许匿名访问

# Allow anonymous FTP? (Beware - allowed by default if you comment this out).
#anonymous_enable=YES
anonymous_enable=NO

本地用户可以访问

# Uncomment this to allow local users to log in.
local_enable=YES

可以进行写操作

# Uncomment this to enable any form of FTP write command.
write_enable=YES

上传后文件的权限掩码

# 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

禁止匿名用户上传

# 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.
#anon_upload_enable=YES
anon_upload_enable=NO

禁止匿名用户建立目录。

# Uncomment this if you want the anonymous FTP user to be able to create
# new directories.
#anon_mkdir_write_enable=YES
anon_mkdir_write_enable=NO

开启目录标语功能

# Activate directory messages - messages given to remote users when they
# go into a certain directory.

开启日志记录功能。

# Activate logging of uploads/downloads.
xferlog_enable=YES

使用20端口进行数据连接

# Make sure PORT transfer connections originate from port 20 (ftp-data).
connect_from_port_20=YES

禁止上传文件更改宿主

# 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_uploads=NO

Vsftpd的服务日志保存路径

#chown_username=whoever
#
# You may override where the log file goes if you like. The default is shown
# below.
xferlog_file=/var/log/vsftpd.log   #默认文件不存在，手动创建，入托更改vsftpd服务宿主用户是vsftpd，给用户对应写权限。

日志使用标准的记录格式

# If you want, you can have your log file in standard ftpd xferlog format
xferlog_std_format=YES

空闲连接超时时间

# You may change the default value for timing out an idle session.
#idle_session_timeout=600  #600是默认值

单次最大连续传输时间

# You may change the default value for timing out a data connection.
#data_connection_timeout=120  #默认值120

支撑Vsftpd服务的宿主用户为手动建立的Vsftpd用户

# 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
nopriv_user=vsftpd       #由此更改注意权限问题

支持异步传输功能。

# 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

支持ASCII模式的上传和下载功能。

# 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

Vsftpd的登陆标语。

# You may fully customise the login banner string:
ftpd_banner=This Vsftp server supports virtual users 

禁止用户登出自己的FTP主目录

# 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_list_enable=YES
chroot_list_enable=NO

禁止用户登陆FTP后使用"ls -R"的命令。

# (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
ls_recurse_enable=NO        #此命令会对服务器性能造成很大的开销。

设定该Vsftpd服务工作在StandAlone模式

# 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    #此模式就是该服务拥有自己的守护进程支持，在ps -A命令下我们将可用看到vsftpd的守护进程名

设定支持TCP Wrappers

tcp_wrappers=YES   ##可以实现主机访问控制

userlist_file中的用户将不得使用FTP

userlist_enable=YES