Check If Port Is Open Or Closed On A Linux Server?
Answer : Solution 1: You can check if a process listens on a TCP or UDP port with netstat -tuplen . To check whether some ports are accessible from the outside (this is probably what you want) you can use a port scanner like Nmap from another system. Running Nmap on the same host you want to check is quite useless for your purpose. Solution 2: Quickest way to test if a TCP port is open (including any hardware firewalls you may have), is to type, from a remote computer (e.g. your desktop): telnet myserver.com 80 Which will try to open a connection to port 80 on that server. If you get a time out or deny, the port is not open :) Solution 3: OK, in summary, you have a server that you can log into. You want to see if something is listening on some port. As root, run: netstat -nlp this will show a listing of processes listening on TCP and UDP ports. You can scan (or grep) it for the process you're interest in,and/or the port numbers you expect to see. If the p...