Vsftpd FTP Server With Virtual Users ( Berkeley DB + PAM ) Vsftpd supports virtual users with PAM (pluggable authentication modules). A virtual user is a user login which does not exist as a real login on the system in /etc/passwd and /etc/shadow file. Virtual users can therefore be more secure than real users, because a compromised account can only use the FTP server but cannot login to system to use other services such as ssh or smtp. Required software Berkeley DB (version 4) databases pam_userdb.so Install Berkeley DB And Utilities Under RHEL / CentOS Type the following command: # yum install db4-utils db4 Create The Virtual Users Database To create a "db4" format file, first create a plain text files with the usernames and password on alternating lines. For e.g. create user called "tahaa" with password called "pass123456" and usman with password "pass345": # cd /etc/vsftpd # cat > vusers.txt S...