Wireless-N Broadband Router
port translation for certain
application layer
"control/data" protocols
such as FTP, BitTorrent,
SIP, RTSP, file transfer
applications etc.
In order for these
protocols to work through
NAT or a firewall, either
the application has to
know about an
address/port number
combination that allows
incoming packets, or the
NAT has to monitor the
control traffic and open up
port mappings (firewall
pinhole) dynamically as
required. Legitimate
application data can thus
be passed through the
security checks of the
firewall or NAT that would
have otherwise restricted
the traffic for not meeting
its limited filter criteria.
59
