FreeBSD - How to check what services or port opening in tcp/udp

Platform :
FreeBSD

How to :
List/show what services or port is listening/opening.

Installation :
The command comes with base system.

FreeBSD - How to reduce TIME_WAIT connections

Routinely, I did a "netstat -an" on a FreeBSD box, a DNS server. The screen then shower with hundreds of "TIME_WAIT" connections. Seems like some malware infected clients are querying the server and causes the terminated TCP socket waiting to be shutdown, but not fast enough, to be efficient. Fortunately, the numbers of TIME_WAIT sockets accumulated are insignificant.

In order to reduce the number of socket waiting, tune the system value :