FTP Interview Questions and Answers

[Nimy]

1. What is FTP ?
FTP stands for File Transfer Protocol. It is used as one of the most common means of copying files between servers over the Internet.
An FTP server allows clients to connect to it either anonymously or with a username and password combination. After successful authentication, files can be transferred back and forth between the server and client. The files are neither encrypted nor compressed.
2. What are the defaults ports used by linux ftp server ?
Port 20 for Data transfer. All the all subsequent data transfers between the client and server are done using this port.
Port 21 for control connection. All commands we send and the ftp server’s responses to those commands will go over the control connection, but any data sent back will go over the data connection.
3. What does VSFTPD Stands for ?
VSFTPD stands for Very Secure FTP Daemon.
4. What is the Difference between TFTP and FTP Server ?
TFTP means Trivial File Transfer Protocol which uses User Datagram Protocol (UDP) whereas FTP uses Transmission Control Protocol (TCP). FTP uses port number 20 for Data and 21 for control by default whereas TFTP uses port 69 by default.
5. Differenciate Active FTP and Passive FTP ?
In active FTP, client uses a random port to connect to server’s port 21 inorder to establish connection. Server then opens data connection from server’s port 20 to client’s computer on a random port. For passive FTP, the connection is initiated from the FTP client. ie, Client uses random port to open data connection.
6. How many TCP connections are used by Active and Passive FTP respectively ?
Both Active and Passive FTP uses two TCP connections each.
7. How can we deny specific users access to the FTP server ?
Add their usernames to the /etc/vsftpd/ftpusers file inorder to deny specific users access to the FTP server. By default, system users such as root and nobody are included in this list.
8. What is meaning of max_clients parameter ?
Maximum number of clients that can connect at one time.
If set to 0, the number of clients is unlimited.

[MarvinClifs]

I am accessing my external ftp server web server through ftp client cute ftp , its connect to my ftp server but I am unable to open any folder in my ftp server. there is time out message showing, but in my linux server it would oprn very quickly.