一.vsftpd说明:
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以外的其它目录,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
mail
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
mail
news
uucp
operator
games
nobody
更多linux ftp配置详解。