Installing and configuring FTP server vsftpd.
This article aims to detail the steps to set up an FTP file sharing server, using vsftpd (Very Secure FTP Daemon).
aptitude install vsftpd
After installing, the server starts automatically and listens on TCP port 21 by default.
You can check it within netstat:
# netstat -npl Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:21 0.0.0.0:* LISTEN 22468/vsftpd
If your host does not have a firewall, it is recommended to stop vsftpd before configuring.
The configuration file for this server is /etc/vsftpd.conf. You can find example configuration files in /usr/share/doc/vsftpd/EXAMPLE.
The configuration file has three option types:
- BOOLEAN OPTIONS - can be YES or NO;
- NUMERIC OPTIONS - e.g. time in seconds, port number
STRING OPTIONS - path to directory or file /var/run/vsftpd/;
If certain options are not present in the configuration file, the server will be use default parameters (see man vsftpd.conf).
By default, anonymous connections are not allowed.
If you enable this, only access to directory /srv/ftp/ is allowed:
For enabling anonymous uploading, set:
anon_upload_enable - allow file uploads from anonymous users (under certain conditions).
anon_mkdir_write_enable - allow directory creation.
anon_root=/data/directory - allow to change the default directory.
For enabling changes to ownership, set:
User access control
Access is enabled for authorized local users by default. To disable:
To enable write access:
Containment of users
User accounts can access files of the whole system which is not always desirable and can help to compromise the machine, they can be confined by changing vsftpd.conf :
The root of their FTP will be their home directory.
Nevertheless, an account can be used to connect outside of ftp: ssh, getty (terminal login) are examples . It will then still have access to the rest of the system by the shell. You can configure the services given as examples to block the account or to contain it, but the main solution is to disable the shell for the user.
For that we assign the user's shell to false , a simple binary which returns an error signal :
usermod -s /bin/false
Then, you need to add false to the shells list :
echo /bin/false >> /etc/shells