How I see port number in Linux System?

I always forget the port number of FTP or SSH server, is there any command that I can see the port number anytime?

I always forget the port number of FTP or SSH server, is there any command that I can see the port number anytime?
Hi Williams,
You don’t need to remember all the port numbers in Linux. You just need to know about one file that contains all the port numbers in Linux.
# less /etc/services
This file shows you all the port numbers, which is used in the Linux system
The most important ports are listed below..
NAME UDP TCP
FTP 20 21
TELNET 23 23
SMTP 25 25
http 80 80
POP3 110 110
IMAP 143 143
IMAP3 220 220
HTTPS 443 443
SMTPS 465 465
DHCP client 546 546
DHCP server 547 547
POP3S 995 995
NFS 2049 4049
PROXY 8081 8081
Britnu Salu