How can I check if a port is listening on a Linux server?
This is what I'm doing:
mysql --host=localhost --port=9999 mysql -u root -p --execute="show tables;"
The command works (connecting to port 3306) no matter what I provide in --port argument. I have two mysql servers running on one machine, and want to connect to the second one by explicitly providing its port number. What's going on? Why does mysql ignore this parameter?
I have just finished setting up a Postfix mail server on a linux (ubuntu) platform. I have it sending and receiving email and it is not an open relay. It also supports secure smtp and imap.
Now this is a pretty beginner question but should I be leaving port 25 open? (since secure smtp is preferred). if so then why?
Also what about port 587?
Also should I require any authentication on either of these ports?
Please excuse my ignorance in this area :P
On the Windows platform, what native options to I have to check if a port (3306, for example) on my local machine (as in localhost), is being blocked?
What port(s) should I open/NAT to allow me to use Remote Desktop?