
40
Amazingly, all the address translation that occurs takes place
automatically in order to make web browsing and other
functions easier. This is also a way for large web hosting
services to speed up the network by having different devices
perform different functions.
TABLE 5. Packet Translation
Packet before Translation Packet After Translation
Source Destination Source Destination
IP Address
Port
Number
IP Address
Port
Number
IP Address
Port
Number
IP Address
Port
Number
To
Internet
10.2.100.1 1031 192.156.136.22 80 99.5.1.30 1032 192.156.136.22 80
From
Internet
192.156.136.22 80 99.5.1.30 1032 192.156.136.22 80 10.2.100.1 1031
TABLE 6. Well-known TCP Port Numbers
Port Number Description
1
TCP Port Service Multiplexer
(TCPMUX)
5 Remote Job Entry (RJE)
7ECHO
18 Message Send Protocol (MSP)
20 FTP-Data
21 FTP- Control
23 Telnet
25 Simple Mail Transfer Protocol (SMTP)
29 MSG ICP
37 Time
42 Host Name Server (Nameserv)
43 Whols
49 Login Host Protocol (Login)
53 Domain Name Server (DNS)
69 Trivial File Transfer Protocol (TFTP)
70 Gopher Service
79 Finger
80 HTTP
103 X.400 Standard
108 SNA Gateway Access Server
109 POP2
110 POP3
115 Simple File Transfer Protocol
118 SQL Services
119 Newsgroup (NNTP)
137 NetBIOS Name Service
139 NetBIOS Datagram Service
143 Interim Mail Access Protocol (IMAP)
150 NetBIOS Session Service
156 SQL Server
161 SNMP
179 Border Gateway Protocol (BGP)
190
Gateway Access Control Protocol
(GACP)
194 Internet Relay Chat (IRC)
197 Directory Location Services (DLS)
389
Lightweight Directory Access Protocol
(LDAP)
396 Novell Netware over IP
443 HTTPS
444
Simple Network Paging Protocol
(SNPP)
445 Microsoft-DS
458 Apple Quick Time
546 DHCP Client
547 DHCP Server
563 SNEWS
569 MSN
1080 Socks
TABLE 6. Well-known TCP Port Numbers
Port Number Description
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