Multiple
applications use TCP protocol, but those applications are subdivided into
different sessions or port numbers for each application or computer/host.
Ports (TCP, UDP) May be thought of as tunnels or channels within a data
connection between computers. There are 65,536 possible ports for each of
the TCP and UDP protocols. When a single computer is communicating
with multiple servers or computers, only one channel may be used per application
(web browser, e-mail client, IM, streaming audio or video, and so
forth). While all that data is going to and from one computer (and the one IP
address for that computer), ports and protocols allow multiple data streams
to flow.
Services HTTP (web browsing), FTP (file transfers), POP3 (e-mail retrieval),
and SMTP (e-mail transmission) are all forms of data services. These and
many IM services use the TCP protocol to ensure complete data requests and
responses between computer and server. Voice chat and webcam services
typically use UDP.
Even if you don??™t embrace these terms and their significance, at least you??™ll be
familiar with their application and place in the configuration of your network and the
applications that communicate through it.
Firewall Settings for Popular IM and VoIP Services
In most cases of home networking, you won??™t have to touch a thing??”unless your software
firewall prompts you to authorize a specific application to connect, or your application
requires an inbound connection, which are usually blocked by both hardware
and software firewalls.
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