一.vsftpd說明:

LINUX下實現FTP服務的軟體很多,最常見的有vsftpd,Wu-ftpd和Proftp等.Red Hat Enterprise Linux中預設安裝的是vsftpd.

訪問FTP伺服器時需要經過驗證,只有經過了FTP伺服器的相關驗證,使用者才能訪問和傳輸檔案.vsftpd提供了3種ftp登入形式:

(1)anonymous(匿名帳號)

使用anonymous是應用廣泛的一種FTP伺服器.如果使用者在FTP伺服器上沒有帳號,那麼使用者可以以anonymous為使用者名稱,以自己的電子郵件地址為密碼進行登入.當匿名使用者登入FTP伺服器後,其登入目錄為匿名FTP伺服器的根目錄/var/ftp.為了減輕FTP伺服器的負載,一般情況下,應關閉匿名帳號的上傳功能.

(2)real(真實帳號)

real也稱為本地帳號,就是以真實的使用者名稱和密碼進行登入,但前提條件是使用者在FTP伺服器上擁有自己的帳號.用真實帳號登入後,其登入的目錄為使用者自己的目錄,該目錄在系統建立帳號時系統就自動建立.

(3)guest(虛擬帳號)

如果使用者在FTP伺服器上擁有帳號,但此帳號只能用於檔案傳輸服務,那麼該帳號就是guest,guest是真實帳號的一種形式,它們的不同之處在於,geust登入FTP伺服器後,不能訪問除宿主目錄以外的內容.

二.FTP相關配置檔案說明

其相關配置檔案有/etc/vsftpd/vsftpd.conf, /etc/vsftpd.ftpusers, /etc/vsftpd.user_list,在配置FTP伺服器時,主要是修改這些檔案中的相關語句.

1.vsftpd.conf檔案說明

# 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 //是否允許anonymous登入FTP伺服器,預設是允許的.

#

# Uncomment this to allow local users to log in.

local_enable=YES //是否允許本地使用者登入FTP伺服器,預設是允許

#

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

write_enable=YES //是否允許使用者具有在FTP伺服器檔案中執行寫的許可權,預設是允許

#

# 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 //設定本地使用者的檔案生成掩碼為022,預設是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 //是否允許匿名賬戶在FTP伺服器中建立目錄

#

# Activate directory messages - messages given to remote users when they

# go into a certain directory.

dirmessage_enable=YES //啟用目錄資訊,當遠端使用者更改目錄時,將出現提示資訊

#

# Activate logging of uploads/downloads.

xferlog_enable=YES //啟用上傳和下載日誌功能

#

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

connect_from_port_20=YES //啟用FTP資料埠的連線請求

#

# 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 //設定日誌檔案的檔名和儲存路徑,這是預設的

#

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

xferlog_std_format=YES//是否使用標準的ftpd xferlog日誌檔案格式

#

# You may change the default value for timing out an idle session.

#idle_session_timeout=600 //設定空閒的使用者會話中斷時間,預設是10分鐘

#

# You may change the default value for timing out a data connection.

#data_connection_timeout=120//設定資料連線超時時間,預設是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 //是否允許使用ASCII格式來上傳和下載檔案

#

# You may fully customise the login banner string:

#ftpd_banner=Welcome to blah FTP service.//在FTP伺服器中設定歡迎登入的資訊.

#

# 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 //如果希望使用者登入後不能切換到自己目錄以外的其它目錄,需要設定該項,如果設定chroot_list_enable=YES,那麼只允許/etc/vsftpd.chroot_list中列出的使用者具有該功能.如果希望所有的本地使用者都執行者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 //設定PAM認證服務的配置檔名稱,該檔案存放在/etc/pam.d/目錄下.

userlist_enable=YES //使用者列表中的使用者是否允許登入FTP伺服器,預設是不允許

#enable for standalone mode

listen=YES //使vsftpd 處於獨立啟動模式

tcp_wrappers=YES //使用tcp_wrqppers作為主機訪問控制方式

2.vsftpd.ftpusers檔案說明

這個檔案是用來記錄"不允許"登入到FTP伺服器的使用者,通常是一些系統預設的使用者.

下面是該檔案中預設的不允許登入的名單:

# Users that are not allowed to login via ftp

root //預設情況下,root和它以下的使用者是不允許登入FTP伺服器的.可以將不允許登入的使用者新增到這裡來.但切記每個使用者都要單獨佔用一行.

bin

daemon

adm

lp

sync

shutdown

halt

mail

news

uucp

operator

games

nobody

3.vsftpd.user_list檔案說明

其實它的內容跟上面那個檔案內容一樣,只是在系統對檔案vsftpd.conf 進行檢測時,會檢測到"userlist_deny=YES",因此這個檔案必須存在.下面是這個檔案的內容.

# 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