Scope
SpycerMediaGateway, CentOS 7.7
FTP only no SSH thus no SFTP for the defined users.
Landing point after login defined by local_root, same landing point for all FTP users.
User is 'jailed' to landing point and below.
Linux User
Add a Linux user / password for FTP login; useraddd, passwd
Deny SSH access
In /etc/ssh/ssh_config add DenyUsers robert, enter additional users using space as delimiter. It is good to add this under the entry PasswordAuthentication yes for clarity.
Restart ssh systemctl restart sshd
vsftpd.conf
Configure /etc/vsftpd/vsftpd.conf
What are significant:
chroot_local_user=NO
chroot_list_enable=YES
allow_writeable_chroot=yes
userlist_enable=YES
local_root=/media/vol0/(the mount point to land at after user login)
Restart the service after update systemctl restart vsftpd.service
/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=YES 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 # # Activate logging of uploads/downloads. xferlog_enable=YES # # Make sure PORT transfer connections originate from port 20 (ftp-data). connect_from_port_20=NO # # 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 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=NO 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. To listen on IPv4 and IPv6 # sockets, you must run two copies of vsftpd with two configuration files. # Make sure, that one of the listen options is commented !! #listen_ipv6=YES allow_writeable_chroot=yes pam_service_name=vsftpd userlist_enable=YES tcp_wrappers=YES #user_sub_token=$USER #local_root=/home/$USER/ftp local_root=/media/vol0/pebble anon_root=/media/vol0/ port_promiscuous=YES pasv_promiscuous=YES use_sendfile=no
chroot_list
Add the new Linux users to the chroot_list.
/etc/vsftpd/chroot_list :
rsapp robert sf_pebble_staging_ftp
Test
Using FileZila or equivalent.
Stats
[root@smgw-100948 vsftpd]# netstat -a | grep ftp tcp 0 0 0.0.0.0:ftp 0.0.0.0:* LISTEN tcp 0 0 smgw-100948-ces:ftp 10.170.3.192:64797 ESTABLISHED tcp 0 0 smgw-100948-ces:ftp 10.170.3.192:64795 ESTABLISHED tcp 0 0 smgw-100948-ces:ftp 10.170.3.192:64798 ESTABLISHED
Additional Resources
https://help.ubuntu.com/community/vsftpd
https://linuxize.com/post/how-to-setup-ftp-server-with-vsftpd-on-centos-8/
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