No Security. Port 23
Telnet
Strong security. Port 22
SSH
Port 3389. Very secure
Remote Desktop (RDP)
Port 443
HTTPS
Port 123
NTP
Ports 1812 and 1813
RADIUS
Port 21
FTP data (incoming traffic)
Port 20
FTP control (outgoing traffic)
Port 67/68
DHCP
Port 53
DNS
Port 80
HTTP
Port 69
TFTP
Port 25
SMTP
Port 110
POP3