Ubuntu 14.04 下FTP服务器的搭建--锁定用户目录，解决vsftpd: refusing to run with writable root inside chroot()
FTP服务器的搭建，我要实现的需求是：
不允许匿名访问，因为我的机器不想让谁都能登录上来，随便获取文件，
需要锁定一个目录，因为在家里，我需要给媳妇下载一些电影 韩剧之类的东西，媳妇会来我机器下载，但是我不想让他随意操作我的东西。
万一删除我的配置文件，我就惨了（吐槽一下韩剧：媳妇问我，你都没看过韩剧怎么知道它不好看呢，我说：我没吃过屎 但是知道它一定不好吃！）
另外，需要本机也能访问，因为我要做一些关于FTP的测试。
不单独建立FTP用户，FTP也使用ubuntu桌面的用户进行登录和操作，
我还不希望FTP开始启动。
好了 我们开始安装，很简单。
sudo apt-get install vsftpd
30秒内估计就能安装完。
下面开始配置：
首先备份配置文件。
linux@ubuntu:/etc/init$ cd /etc/
linux@ubuntu:/etc$ sudo cp vsftpd.conf vsftpd.conf.old
接下来就是开始配置了
咱们就针对需求来：
1. 不允许匿名访问，因为我的机器不想让谁都能登录上来，随便获取文件，
配置如下：
23 anonymous_enable=NO
2.需要锁定一个目录，因为在家里，我需要给媳妇下载一些电影 韩剧之类的东西，
媳妇会来我机器下载，但是我不想让他随意操作我的东西。
万一删除我的配置文件，我就惨了
配置如下：
152 local_root=/home/linux/公共的/FTP共享文件
备注：[FTP共享文件] 这个文件夹是我新建出来的
另外，需要本机也能访问，因为我要做一些关于FTP的测试。
配置如下：
26 local_enable=YES
不单独建立FTP用户，FTP也使用ubuntu桌面的用户进行登录和操作，
配置如下：
120 #chroot_local_user=YES
121 chroot_list_enable=YES
122 # (default follows)
123 chroot_list_file=/etc/vsftpd.chroot_list
这里需要/etc/vsftpd.chroot_list 这个文件，如果没有请新建：
sudo gedit /etc/vsftpd.chroot_list
内容如下（例如我桌面的用户名为linux）：
duoduo
其实就是把你的用户名写进去
我还不希望FTP开始启动。 一会单独说！
贴出我的配置文件。
# Example config file /etc/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.
#
#
# Run standalone? vsftpd can run either from an inetd or as a standalone
# daemon started from an initscript.
listen=YES
#
# Run standalone with IPv6?
# Like the listen parameter, except vsftpd will listen on an IPv6 socket
# instead of an IPv4 one. This parameter and the listen parameter are mutually
# exclusive.
#listen_ipv6=YES
#
# Allow anonymous FTP? (Disabled by default)
anonymous_enable=NO
#
# Uncomment this to allow local users to log in.
local_enable=YES
#
# Uncomment this to enable any form of FTP write command.
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.
#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
#
# Activate directory messages - messages given to remote users when they
# go into a certain directory.
dirmessage_enable=YES
#
# If enabled, vsftpd will display directory listings with the time
# in your local time zone. The default is to display GMT. The
# times returned by the MDTM FTP command are also affected by this
# option.
use_localtime=YES
#
# Activate logging of uploads/downloads.
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
#
# You may override where the log file goes if you like. The default is shown
# below.
#xferlog_file=/var/log/vsftpd.log
#
# If you want, you can have your log file in standard ftpd xferlog format.
# Note that the default log file location is /var/log/xferlog in this case.
#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 linuxidc's 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 restrict local users to their home directories. See the FAQ for
# the possible risks in this before using chroot_local_user or
# chroot_list_enable below.
#chroot_local_user=YES
#
# 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().
# (Warning! chroot'ing can be very dangerous. If using chroot, make sure that
# the user does not have write access to the top level directory within the
# 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
#
# Customization
#
# Some of vsftpd's settings don't fit the filesystem layout by
# default.
#
# This option should be the name of a directory which is empty. Also, the
# directory should not be writable by the ftp user. This directory is used
# as a secure chroot() jail at times vsftpd does not require filesystem
# access.
secure_chroot_dir=/var/run/vsftpd/empty
#
# This string is the name of the PAM service vsftpd will use.
pam_service_name=vsftpd
#
# This option specifies the location of the RSA certificate to use for SSL
# encrypted connections.
rsa_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
# This option specifies the location of the RSA key to use for SSL
# encrypted connections.
rsa_private_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
#
local_root=/home/linux/公共的/FTP共享文件
现在可以重启FTP了。
linux@ubuntu:/etc$ sudo service vsftpd restart
vsftpd stop/waiting
vsftpd start/running, process 303
OK 看到这些 证明配置文件没有问题，FTP启动了
下面直接访问FTP 看看：
linux@ubuntu:/etc$ ftp 127.0.0.1
Connected to 127.0.0.1.
Welcome to linux's FTP service.
Name (127.0.0.1:linux): duoduo
Please specify the password.
Password:
OOPS: vsftpd: refusing to run with writable root inside chroot()
Login failed.
Service not available, remote server has closed connection
ftp>
居然报了一个500的错误
vsftpd: refusing to run with writable root inside chroot()
其实这里是需要特殊说明的，原因出在这里
120 #chroot_local_user=YES
121 chroot_list_enable=YES
122 # (default follows)
123 chroot_list_file=/etc/vsftpd.chroot_list
我们用
chroot_list_enable=YES 和 chroot_list_file=/etc/vsftpd.chroot_list配合使用，使得只有在vsftpd.chroot_list中配置的用户才能登录FTP。
对于这要的配置有一个特殊的要求，就是vsftpd.chroot_list里面配置的用户，对于前面local_root配置的目录不能有写的权限！
也就是/home/linux/公共的/FTP共享文件 这个文件夹 对于linux这个用户不能有写的权限，
我们为了额操作方便可以这么做：
sudo chown -R root:root /home/linux/公共的/FTP共享文件/
这样，linux这个用户对于/home/linux/公共的/FTP共享文件没有写权限了，
现在重启FTP 重新登录看看：
linux@ubuntu:/etc$ ftp 127.0.0.1
Connected to 127.0.0.1.
Welcome to linux's FTP service.
Name (127.0.0.1:linux): duoduo
Please specify the password.
Password:
Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp>
OK FTP 好了 可以登录了
但是我刚才 sudo chown -R root:root /home/linux/公共的/FTP共享文件/ 这个操作 还带来了一个麻烦。就是FTP共享文件在我桌面登录时，不能任意复制粘贴操作文件了，但是我还要必须保持linux用户对[FTP共享文件] 这个文件夹不可写。这该怎么办呢？
其实很简单，
cd /home/linux/公共的/FTP共享文件
sudo mkdir FTPFILES
sudo chown -R linux:duoduo FTPFILES
这样 就保持了 FTP共享文件 文件夹linux用户不可写，但duoduo用户用可以在桌面登录时任意操作文件了，只不过此时的随意范围在FTPFILES文件夹范围呢了。
这样基本FTP服务基本搭建完成了。
对了 忘记了一点。就是不让FTP服务开机启动。操作如下：
linux@ubuntu:/etc/init$ cd /etc/init/
linux@ubuntu:/etc/init$ sudo cp vsftpd.conf vsftpd.conf.old
编辑配置文件
sudo gedit /etc/init/vsftpd.conf
将#start on runlevel [2345] or net-device-up IFACE!=lo 修改为start on runlevel [345] 如下：
#start on runlevel [2345] or net-device-up IFACE!=lo
start on runlevel [345]
stop on runlevel [!2345]
这次重启FTP 重启系统 彻底完成。
这里建议大家查一下：chroot_local_user chroot_list_enable=YES chroot_list_file=/etc/vsftpd.chroot_list 相关的资料，这里面灵活性配置很高的。