浅浅的玩玩FTP

今天上午闲来没事，登录了很久没有登录过的Ubuntu，想找点事做做。玩啥呢？FTP吧。

首先查了一下资料，在linux下面比较流行、安全的FTP服务主要是vsftpd。

于是，不管了，直接终端输入

apt-get vsftpd

安装还挺快的，大概也就十几秒吧。

安装完以后，直接浏览器输入：

ftp://192.168.1.61

然后弹出来一个页面，让我输入一个用户名和密码。那我就输入一个系统里面有的用户呗，比如我就是用huangyiwei这个用户登录的，输入好了用户名和相应的密码后，就能浏览huangyiwei这个用户的home目录了。

到此，实现了FTP最简单的功能了。那何为“比较安全”呢？呵呵，这就要用到/etc/vsftp.conf文件了。废话不多说，现看看这个文件里面有什么东西把。

# 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 blah 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().
#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
#
# Debian customization
#
# Some of vsftpd's settings don't fit the Debian filesystem layout by
# default.  These settings are more Debian-friendly.
#
# 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/private/vsftpd.pem

是不是看的很刺激，至少对我这个英语不好的人来说，至少是这样的。玩嘛，那就要好好的玩，玩的尽兴一点才是。于是，硬着头皮，慢慢的看看这个文件，其实有些地方还是挺好理解的。

结合一下实际，在结合以下Google，总结如下：

1． 匿名服务器的连接（独立的服务器）
  Anonymous_enable=yes (允许匿名登陆)
  Dirmessage_enable=yes （切换目录时，显示目录下.message的内容）
  Local_umask=022 (FTP上本地的文件权限，默认是077)
  Connect_form_port_20=yes （启用FTP数据端口的数据连接）*
  Xferlog_enable=yes （激活上传和下传的日志）
  Xferlog_std_format=yes (使用标准的日志格式)
  Ftpd_banner=XXXXX （欢迎信息）
  Pam_service_name=vsftpd （验证方式）*
  Listen=yes （独立的VSFTPD服务器）*
  功 能：只能连接FTP服务器，不能上传和下传
  注：其中所有和日志欢迎信息相关连的都是可选项,打了星号的无论什么帐户都要添加，是属于FTP的基本 选项

2． 开启匿名FTP服务器上传权限，在配置文件中添加以下的信息即可：
  Anon_upload_enable=yes (开放上传权限)
  Anon_mkdir_write_enable=yes （可创建目录的同时可以在此目录中上传文件）
  Write_enable=yes (开放本地用户写的权限)
  Anon_other_write_enable=yes (匿名帐号可以有删除的权限)

3． 开启匿名服务器下传的权限，在配置文件中添加如下信息即可：
  Anon_world_readable_only=no
  注： 要注意文件夹的属性，匿名帐户是其它（other）用户要开启它的读写执行的权限。（R）读-----下传 （W）写----上传 （X）执行----如果不开FTP的目录都进不去

4．普通用户FTP服务器的连接（独立服务器），在配置文件中添加如下信息即可：
  Local_enble=yes （本地帐户能够登陆）
  Write_enable=no （本地帐户登陆后无权删除和修改文件）
  功能：可以用本地帐户登陆vsftpd服务 器，有下载上传的权限
  注：在禁止匿名登陆的信息后匿名服务器照样可以登陆但不可以上传下传

5． 用户登陆限制进其它的目录，只能进它的主目录。

  设置所有的本地用户都执行chroot：
  Chroot_local_user=yes （本地所有帐户都只能在自家目录）
  设置指定用户执行chroot：
  Chroot_list_enable=yes （文件中的名单可以调用）
  Chroot_list_file=/任意指定的路径/vsftpd.chroot_list
  注 意：vsftpd.chroot_list 是没有创建的需要自己添加，要想控制帐号就直接在文件中加帐号即可

6． 限制本地用户访问FTP
  Userlist_enable=yes (用userlistlai 来限制用户访问)
  Userlist_deny=no (名单中的人不允许访问)
  Userlist_file=/指定文件存放的路径/ （文件放置的路径）
  注：开启 userlist_enable=yes匿名帐号不能登陆

7． 安全选项
  Idle_session_timeout=600(秒) （用户会话空闲后10分钟）
  Data_connection_timeout=120（秒） （将数据连接空闲2分钟断）
  Accept_timeout=60（秒） （将客户端空闲1分钟后断）
  Connect_timeout=60（秒） （中断1分钟后又重新连接）
  Local_max_rate=50000（bite） （本地用户传输率50K）
  Anon_max_rate=30000（bite） （匿名用户传输率30K）
  Pasv_min_port=50000 （将客户端的数据连接端口改在
  Pasv_max_port=60000 50000—60000之间）
  Max_clients=200 （FTP的最大连接数）
  Max_per_ip=4 （每IP的最大连接数）
  Listen_port=5555 （从5555端口进行数据连接）

8． 查看谁登陆了FTP,并杀死它的进程
  ps –xf |grep ftp
  kill 进程号

Google真是个好东西，真不知道要是没她该怎么办。废话不多说，言归正题。看了上面那些解释，可能有人还是没什么感觉。那好，我就说说我做这个FTP服务器的流程吧。虽然我是菜鸟（可能菜鸟都算不上），但是如果能抛砖引玉，那还是很好的。

流程如下：

1、安装vsftpd服务（貌似这是一句废话）。

2、在vsftp.conf文件末尾加上如下内容：

anon_world_readable_only=No#匿名用户对他的默认文件夹具有只读权限
anon_root=/home/ftp#匿名用户的默认文件夹
user_config_dir=/etc/vsftpd.userconfig#正常登录的用户的配置
rsa_private_key_file=/etc/ssl/private/ssl-cert-snakeoil.key#这个是什么意思我也不是很清楚，还望高人指点……

 还是附上我自己的完整的配置吧，如下：

# 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=YES
#
# 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 HuangYiwei  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().
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
#
# Debian customization
#
# Some of vsftpd's settings don't fit the Debian filesystem layout by
# default.  These settings are more Debian-friendly.
#
# 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/private/vsftpd.pem
#
# This option specifies the location of the RSA key to use for SSL
# encrypted connections.
anon_world_readable_only=No
anon_root=/home/ftp
user_config_dir=/etc/vsftpd.userconfig
rsa_private_key_file=/etc/ssl/private/ssl-cert-snakeoil.key

 3、建立配置文件中需要的文件夹vsftpd.userconfig，此文件夹内存放用户的配置文件。比如huangyiwei用户，就用vi建立一个huangyiwei的文件，然后里面写上一些配置。这样做的好处是可以细化对用户的管理。比如在文件里面输入

local_root=/var/huangyiweidir

这样，我用huangyiwei这个用户登录FTP的时候就自动跳转的/var/huangyiweidir这个文件夹里面来了（前提是/var/huangyiweidir必须存在）。到此，有人可能会问，如果我cd到其他目录呢（如果浏览器访问的话，可以使用“回到上一级目录”）？如此一来，引出了下一个问题，怎样不让用户乱飘。

4、是否限定用户只在给他指定的目录下面。

# 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_local_user=YES
chroot_list_enable=YES
# (default follows)
chroot_list_file=/etc/vsftpd.chroot_list

此段配置所要表达的意思（从上往下）：允许用户改变他的根目录，允许改变根目录的用户列表启用，允许改变根目录的用户列表文件。在这个文件中，只用每行记录一个用户的登录名即可。

用户1
用户2
用户3
用户4

有一点需要注意，如果chroot_list_enable=NO，那么这个列表文件中存在的用户将不能改变自己的根目录。

5、还有一个过滤访问用户的功能，它用到了/etc/vsftpd.user_list这个文件。具体如何实现，大家Google去吧，困了，洗澡，睡了。