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Firewall
The firewall is a kind of software that interrupts the data between the
Internet and your computer. It is the TCP/IP equivalent of a security gate at
the entrance to your company. All data must pass through it, and the firewall
(functions as a security guard) will allow only authorized data to be passed
into the LAN.
What the firewall can do? It can：
deny or permit any packet from passing through explicitly.
distinguish between various interfaces and match on the following
fields:
To keep track of the performance of IP Filter, a logging device is used. The
device supports logging of the TCP/UDP and IP packet headers and the first
129 bytes of the packet (including headers) whenever a packet is
successfully passed through or blocked, and whenever a packet matches a
rule being setup for suspicious packets.
An example for firewall setup：
Internet
This picture shows the most common and easiest way to employ the
firewall. Basically, you can install a packet-filtering router at the Internet
gateway and then configures the filter rule in the router to block or filter
protocols and addresses. The systems behind the router usually have a
direct access to the Internet; however some dangerous services such as
NIS and NFS are usually blocked.
For the security of your router, set the firewall is an important issue.
source and destination IP address
port
Firewall Protection
Router
Wireless IAD User Manual
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