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Linux 下实现 FTP 服务的软件很多, 最常见的有 vsftpd,Wu-ftpd 和 Proftp 等.Red Hat Enterprise Linux 中默认安装的是 vsftpd。
访问 FTP 服务器时需要经过验证, 只有经过了 FTP 服务器的相关验证, 用户才能访问和传输文件.vsftpd 提供了 3 种 ftp 登录形式:
(1)anonymous(匿名帐号)
使用 anonymous 是应用广泛的一种 FTP 服务器. 如果用户在 FTP 服务器上没有帐号, 那么用户可以以 anonymous 为用户名, 以自己的电子邮件地址为密码进行登录. 当匿名用户登录 FTP 服务器后, 其登录目录为匿名 FTP 服务器的根目录 /var/ftp. 为了减轻 FTP 服务器的负载, 一般情况下, 应关闭匿名帐号的上传功能.
(2)real(真实帐号)
real 也称为本地帐号, 就是以真实的用户名和密码进行登录, 但前提条件是用户在 FTP 服务器上拥有自己的帐号. 用真实帐号登录后, 其登录的目录为用户自己的目录, 该目录在系统建立帐号时系统就自动创建.
(3)guest(虚拟帐号)
如果用户在 FTP 服务器上拥有帐号, 但此帐号只能用于文件传输服务, 那么该帐号就是 guest,guest 是真实帐号的一种形式, 它们的不同之处在于,geust 登录 FTP 服务器后, 不能访问除宿主目录以外的内容.
二 .FTP 相关配置文件说明
其相关配置文件有 /etc/vsftpd/vsftpd.conf, /etc/vsftpd.ftpusers, /etc/vsftpd.user_list, 在配置 FTP 服务器时, 主要是修改这些文件中的相关语句.
1.vsftpd.conf文件说明
# 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=YES // 是否允许 anonymous 登录 FTP 服务器, 默认是允许的.
#
# Uncomment this to allow local users to log in.
local_enable=YES // 是否允许本地用户登录 FTP 服务器, 默认是允许
#
# Uncomment this to enable any form of FTP write command.
write_enable=YES // 是否允许用户具有在 FTP 服务器文件中执行写的权限, 默认是允许
#
# 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 // 设置本地用户的文件生成掩码为 022, 默认是 077
#
# 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
#
# Uncomment this if you want the anonymous FTP user to be able to create
# new directories.
#anon_mkdir_write_enable=YES // 是否允许匿名账户在 FTP 服务器中创建目录
#
# Activate directory messages – messages given to remote users when they
# go into a certain directory.
dirmessage_enable=YES // 激活目录信息, 当远程用户更改目录时, 将出现提示信息
#
# Activate logging of uploads/downloads.
xferlog_enable=YES // 启用上传和下载日志功能
#
# Make sure PORT transfer connections originate from port 20 (ftp-data).
connect_from_port_20=YES // 启用 FTP 数据端口的连接请求
#
# 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/vsftpd.log // 设置日志文件的文件名和存储路径, 这是默认的
#
# If you want, you can have your log file in standard ftpd xferlog format
xferlog_std_format=YES// 是否使用标准的 ftpd xferlog 日志文件格式
#
# You may change the default value for timing out an idle session.
#idle_session_timeout=600 // 设置空闲的用户会话中断时间, 默认是 10 分钟
#
# You may change the default value for timing out a data connection.
#data_connection_timeout=120// 设置数据连接超时时间, 默认是 120 秒.
#
# 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 turning on ascii_download_enable enables malicious remote parties
# to consume your I/O resources, by issuing the command “SIZE /big/file” in
# ASCII mode.
# These ASCII options are split into upload and download because you may wish
# to enable ASCII uploads (to prevent uploaded scripts etc. from breaking),
# without the DoS risk of SIZE and ASCII downloads. ASCII mangling should be
# on the client anyway..
#ascii_upload_enable=YES
#ascii_download_enable=YES // 是否允许使用 ASCII 格式来上传和下载文件
#
# You may fully customise the login banner string:
#ftpd_banner=Welcome to blah FTP service.// 在 FTP 服务器中设置欢迎登录的信息.
#
# 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 // 如果希望用户登录后不能切换到自己目录��外的其它目录, 需要设置该项, 如果设置 chroot_list_enable=YES, 那么只允许 /etc/vsftpd.chroot_list 中列出的用户具有该功能. 如果希望所有的本地用户都执行者 chroot, 可以增加一行:chroot_local_user=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
pam_service_name=vsftpd // 设置 PAM 认证服务的配置文件名称, 该文件存放在 /etc/pam.d/ 目录下.
userlist_enable=YES // 用户列表中的用户是否允许登录 FTP 服务器, 默认是不允许
#enable for standalone mode
listen=YES // 使 vsftpd 处于独立启动模式
tcp_wrappers=YES // 使用 tcp_wrqppers 作为主机访问控制方式
2.vsftpd.ftpusers文件说明
这个文件是用来记录 ”不允许 ”登录到 FTP服务器的用户, 通常是一些系统默认的用户.
下面是该文件中默认的不允许登录的名单:
# Users that are not allowed to login via ftp
root // 默认情况下,root 和它以下的用户是不允许登录 FTP 服务器的. 可以将不允许登录的用户添加到这里来. 但切记每个用户都要单独占用一行.
bin
daemon
adm
lp
sync
shutdown
halt
news
uucp
operator
games
nobody
3.vsftpd.user_list文件说明
其实它的内容跟上面那个文件内容一样,只是在系统对文件 vsftpd.conf 进行检测时,会检测到 ”userlist_deny=YES”,因此这个文件必须存在.下面是这个文件的内容.
# vsftpd userlist
# If userlist_deny=NO, only allow users in this file
# If userlist_deny=YES (default), never allow users in this file, and
# do not even prompt for a password.
# Note that the default vsftpd pam config also checks /etc/vsftpd.ftpusers
# for users that are denied.
root
bin
daemon
adm
lp
sync
shutdown
halt
news
uucp
operator
games
nobody
本文永久更新链接地址:http://www.linuxidc.com/Linux/2015-10/123849.htm