Ubuntu Server / vsftpd로 FTP 서버 구축하기
차례
vsftpd
vsftpd(Very Secure FTP Daemon)는 유닉스와 리눅스에서 사용할 수 있는 가벼운 FTP 서버입니다. 주요 특징은 다음과 같습니다.
- Virtual IP configurations
- Virtual users
- Standalone or inetd operation
- Powerful per-user configurability
- Bandwidth throttling
- Per-source-IP configurability
- Per-source-IP limits
- IPv6
- Encryption support through SSL integration
설치
vsftpd는 우분투 패키지에 포함되어 있으므로 다음과 같이 명령하여 설치할 수 있습니다.
apt install vsftpd
방화벽을 사용 중이라면 다음과 같이 명령하여 포트를 열어줍니다.
ufw allow ftp
주요 기본 설정은 다음과 같습니다.
- 익명 사용자 접속 불가
- 사용자는 읽기 전용으로 접속
- 다른 폴더 보기 가능
설정 파일은 /etc/vsftpd.conf입니다.
# 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=NO # # 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. 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(). # (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 rsa_private_key_file=/etc/ssl/private/ssl-cert-snakeoil.key ssl_enable=NO # # Uncomment this to indicate that vsftpd use a utf8 filesystem. #utf8_filesystem=YES서
서버 부팅 시 자동으로 시작하게 하려면 다음과 같이 명령합니다.
systemctl enable vsftpd
설정 변경 후 적용시키려면 서비스를 다시 시작합니다.
systemctl restart vsftpd
주요 설정
사용자 쓰기 가능하게 하기
사용자는 읽기 전용으로 접속하므로 파일을 업로드하거나 삭제하는 것이 불가능합니다. 쓰기 가능하게 하려면 다음 코드에서 주석(#)을 제거합니다.
#write_enable=YES
사용자 홈 디렉토리를 벗어나지 못하게 하기
사용자는 홈 디렉토리를 벗어나서 다른 디렉토리나 파일 목록을 볼 수 있습니다. 다운로드나 업로드는 불가능하나 목록을 보는 거 자체가 문제가 될 수 있습니다. 접속한 사용자가 홈 디렉토리를 벗어나지 못하게 하려면 다음 코드에서 주석을 제거하고...
#chroot_local_user=YES
다음 코드를 추가합니다.
allow_writeable_chroot=YES
익명 사용자 접속
익명 사용자, 즉 누구나 접속할 수 있게 하려면 다음 설정 코드에서 No를...
anonymous_enable=NO
YES로 변경합니다.
anonymous_enable=YES
읽기 전용으로 /srv/ftp에 접속됩니다.
익명 사용자에게 업로드, 쓰기 권한 부여
익명 사용자가 업로드와 쓰기가 가능하게 하려면 두 가지 작업을 해야 합니다.
설정 파일 수정
설정 파일에서 다음 두 코드에서 주석을 제거합니다.
#anon_upload_enable=YES
#anon_mkdir_write_enable=YES
디렉토리 권한 설정
예를 들어 /srv/ftp/pub 디렉토리에 업로드와 쓰기가 가능하게 하고 싶다면, 디렉토리를 만들고...
mkdir /srv/ftp/pub
쓰기 가능하게 권한을 부여하거나...
chmod 777 /srv/ftp/pub
ftp 사용자에게 소유권을 부여합니다.
chown ftp:ftp /srv/ftp/pub