NB1 User Guide YML780 Rev1
46 www.netcomm.com.au
The reason for this is that when using NAT, your publicly accessible IP address will
be used by and point to your router, which then needs to deliver all traffic to the
private IP addresses used by your PCs.
The Internet Assigned Numbers Authority (IANA) is the central coordinator for the
assignment of unique parameter values for Internet protocols. Port numbers range
from 0 to 65535, but only ports numbers 0 to 1023 are reserved for privileged serv-
ices and are designated as “well-known ports”. The registered ports are numbered
from 1024 through 49151. The remaining ports, referred to as dynamic ports or
private ports, are numbered from 49152 through 65535.
Examples of well-known and registered port numbers are shown in Table 4, for fur-
ther information, please see IANA’s website at: http://www.iana.org/assignments/
port-numbers
Well-know and registered Ports
Port Number Protocol Description
20 TCP FTP Data
21 TCP FTP Control
22 TCP & UDP SSH Remote Login Protocol
23 TCP Telnet
25 TCP SMTP (Simple Mail Transfer Protocol)
53 TCP & UDP DNS (Domain Name Server)
69 UDP TFTP (Trivial File Transfer Protocol)
80 TCP World Wide Web HTTP
110 TCP POP3 (Post Office Protocol Version 3)
119 TCP NEWS (Network News Transfer Protocol)
123 UDP NTP (Network Time Protocol)
161 TCP SNMP
443 TCP & UDP HTTPS
1503 TCP T.120
1720 TCP H.323
4000 TCP ICQ
7070 UDP RealAudio
