Sunday, July 27, 2014

Linux FTP (vsftpd) Interview Questions & Answers

In Linux Like operating system vsftpd(Very Secure FTP Daemon) is ftp server , which provides the features of downloading and uploading files to the ftp space. In this article we will discuss most common ftp server interview questions along with the Answers.

Q:1 What does VSFTPD Stands for ?
Ans: VSFTPD stands for Very Secure FTP Daemon.
Q:2 What are the defaults ports used in linux ftp server ?
Ans: Port 20 – This is the data transfer port. All the all subsequent data transfers between the client and server are done using this port.
Port 21 – On this port control connection is established. All commands we send and the ftp server’s responses to those commands will go over the control connection, but any data sent back (such as “ls” directory lists or actual file data in either direction) will go over the data connection.
Q:3 What are most common features of vsftpd ?
Ans:some of the Common Features are listed below :
  • 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
Q:4 What is the configuration file of vsftpd ?
Ans: ‘/etc/vsftp/vsftpd.conf’
Q:5 How to restart the service of ftp server in linux ?
Ans: Service vsftpd restart or /etc/init.d/vsftpd restart
Q:6 Which Users tare not allowed to login via ftp ?
Ans: Users mentioned in the file ‘/etc/vsftpd/ftpusers’ are not allowed to login via ftp.
Q:7 How to disable standard ftpd xferlog log format and enable default vsftpd log ?
Ans : Edit the file ‘ /etc/vsftpd/vsftpd.conf’ & make the below changes:
  • xferlog_std_format=NO
  • log_ftp_protocol=YES
The default vsftpd log file is /var/log/vsftpd.log

Q:8 What is default directory for ftp / Anonymous user ?
Ans : ‘/var/ftp’ is the default directory for ftp or Anonymous user
Q:9 How to change the default directory for ftp / Anonymous user ?
Ans: Edit the file ‘/etc/vsftpd/vsftpd.conf’ and change the below directive :
  • anon_root=/<Path-of-New-Directory>
After making above change either restart or reload vsftpd service.
Q:10 How to disable Anonymous user in vsftpd ?
Ans: Edit the conf file ‘/etc/vsftpd/vsftpd.conf’ and chnage below directive and restart the ftp service.
  • anonymous_enable=NO
Q:11 What is chroot environment in ftp server ?
Ans: chroot environment prevents the user from leaving its home directory means jail like environment where users are limited to their home directory only. It is the addon security of ftp server.
Q:12 How to enable chroot environment in vsftpd server ?
Ans : To enable chroot environment edit the file ‘/etc/vsftpd/vsftpd.conf’ and enable the below directives :
  • chroot_list_enable=YES
  • chroot_list_file=/etc/vsftpd.chroot_list
The chroot_list_file variable specifies the file which contains users that are chroot.
Q:13 How to enable only limited/allowed users are able to login via ftp ?
Ans: This can be done by editing the file ‘/etc/vsftpd/vsftpd.conf’ and add the below directives :
  • userlist_enable=YES
  • userlist_file=/etc/vsftpd.user_list
  • userlist_deny=NO
The file specified by userlist_file will now contain users that are able to login.
Q:14 How to set ftp banner in linux ?
Ans: Open the file ‘/etc/vsftpd/vsftpd.conf’ and set the below directive :
  • ftpd_banner= “Enter New Banner Here”
Q:15 How To limit the data transfer rate, number of clients & connections per IP for local users ?
Ans: Edit the ftp server’s config file(/etc/vsftpd/vsftpd.conf) and set the below directives :
  • local_max_rate=1000000 # Maximum data transfer rate in bytes per second
  • max_clients=50 # Maximum number of clients that may be connected
  • max_per_ip=2 # Maximum connections per IP

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