How to check the process that is using a specific port?

Speficy the port number as you wish. Here we use 8080.

$ netstat -nlptu |awk '{print $4,$7}' | grep 8080

Setting up FTP server on linux

install vsftpd

> apt-get install vsftpd

More will be added here…

PPS: Question: How to write Markdown instruction with Markdown Language? Must be very inconvient…