【CentOS7】FTPサーバー構築手順

CentOS で FTP サーバーを構築する場合は大体「vsftpd」をインストールすると思います。

vsftpd とは

vsftpd「Very Secure Ftp Daemon」の略です。

Very Secureとあるようにセキュアにデータを送受信できるように設計されています。

具体的に何が「セキュア(安全)」なのでしょうか?

 

vsftpd の何がセキュアなのか?

  • SSL でデータの暗号化が可能
  • chroot が可能

 

vsftpd のインストール手順

yum コマンドでインストールします。

[root@test07 ~]# yum install vsftpd

 

以上でインストールは完了です。

 

vsftpd の設定

インストールが完了したら、今回は「/etc/vsftpd/vsftpd.conf」は以下のように編集します。

(完全ローカルの環境なので、ほとんどデフォルトのままです)

[root@test07 vsftpd]# vi /etc/vsftpd/vsftpd.conf

# 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=NO
#
# Uncomment this to allow local users to log in.
# When SELinux is enforcing check for SE bool ftp_home_dir
local_enable=YES
#
# Uncomment this to enable any form of FTP write command.
write_enable=NO
#
# 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.
# When SELinux is enforcing check for SE bool allow_ftpd_anon_write, allow_ftpd_full_access
#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
#
# 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/xferlog
#
# 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 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
#
# When "listen" directive is enabled, vsftpd runs in standalone mode and
# listens on IPv4 sockets. This directive cannot be used in conjunction
# with the listen_ipv6 directive.
listen=YES
#
# This directive enables listening on IPv6 sockets. By default, listening
# on the IPv6 "any" address (::) will accept connections from both IPv6
# and IPv4 clients. It is not necessary to listen on *both* IPv4 and IPv6
# sockets. If you want that (perhaps because you want to listen on specific
# addresses) then you must run two copies of vsftpd with two configuration
# files.
# Make sure, that one of the listen options is commented !!
listen_ipv6=NO

pam_service_name=vsftpd
userlist_enable=YES
tcp_wrappers=YES

 

 

 

今回は同セグメント内(192.168.1.0/24)からのみアクセスできるように設定します。

初めに「/etc/hosts.deny」ファイルに All Deny の設定を入れます。

[root@test07 ~]# vi /etc/hosts.deny
#
# hosts.deny This file contains access rules which are used to
# deny connections to network services that either use
# the tcp_wrappers library or that have been
# started through a tcp_wrappers-enabled xinetd.
#
# The rules in this file can also be set up in
# /etc/hosts.allow with a 'deny' option instead.
#
# See 'man 5 hosts_options' and 'man 5 hosts_access'
# for information on rule syntax.
# See 'man tcpd' for information on tcp_wrappers
#
vsftpd: ALL ← All deny の設定を入れます。

 

 

次に特定のセグメントからだけアクセスできるように設定を入れます。

[root@test07 ~]# vi /etc/hosts.allow
#
# hosts.allow This file contains access rules which are used to
# allow or deny connections to network services that
# either use the tcp_wrappers library or that have been
# started through a tcp_wrappers-enabled xinetd.
#
# See 'man 5 hosts_options' and 'man 5 hosts_access'
# for information on rule syntax.
# See 'man tcpd' for information on tcp_wrappers
#

vsftpd:192.168.1. ← 192.168.1.0/24 からのみ FTP アクセスを受け付けます。

 

 

vsftpd の自動起動の設定

デフォルトでは「vsftpd」サービスは自動起動は「無効」になっています。

[root@test07 ~]# systemctl list-unit-files | grep vsftpd
vsftpd.service     disabled
vsftpd@.service    disabled
vsftpd.target      disabled

 

「vsftpd」の自動起動を「有効」にします。

[root@test07 ~]# systemctl enable vsftpd
Created symlink from /etc/systemd/system/multi-user.target.wants/vsftpd.service to /usr/lib/systemd/system/vsftpd.service.
[root@test07 ~]# systemctl list-unit-files | grep vsftpd
vsftpd.service    enabled
vsftpd@.service   disabled
vsftpd.target     disabled

 

 

vsftpd サービスの開始

vsftpd サービスを開始します。

[root@test07 ~]# systemctl start vsftpd
[root@test07 ~]# systemctl status vsftpd
vsftpd.service - Vsftpd ftp daemon
Loaded: loaded (/usr/lib/systemd/system/vsftpd.service; enabled; vendor preset: disabled)
Active: active (running) since 日 2017-08-13 21:24:52 JST; 6s ago
Process: 10066 ExecStart=/usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf (code=exited, status=0/SUCCESS)
Main PID: 10067 (vsftpd)
CGroup: /system.slice/vsftpd.service
mq10067 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf

8月 13 21:24:52 test07 systemd[1]: Starting Vsftpd ftp daemon...
8月 13 21:24:52 test07 systemd[1]: Started Vsftpd ftp daemon.

 

 

 

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