Chapter 4: Web Configuration
Firewall
The firewall is a kind of software that interrupts the dat a betwe en 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 (fun ctions as a security
guard) will allo
w only authorized data to be passed into the LAN.
ssing through explicitly
ces and match on the following fields:
ress
ce of IP Filter, a logging device is used. The device
of the TCP/UDP and IP packet hea ders and the first 129 bytes of
ver a packet is successfully passed through or
henever a pa cket matches a rule being setup for suspicious packets.
What the firewall can do? It can:
deny or permit any packet from pa
distinguish between various interfa
source and destination IP add
port
To keep track of the performan
supports logging
the packet (includi ng headers) whene
blocked, and w
An example for firewall setup:
This picture shows the most common and ea siest 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 ro uter usually have a direct access to the Internet; however
some dangerous service s such as NIS and NFS are usually blocked.
For the security of your router, set the firewall is an important issue.
g
rovides a way for the users to define rules to
based on source MAC address and/or
ss. When bridge filtering is e nabled, each p acket is examined
ned filter rules sequentially, and when a matched is determined,
ge packet filtering rule s to block those
ls and MAC addresses.
Firewall – Bridge Filterin
The bridge filtering mechanism p
allow/deny packets through the bridge
destination MAC addre
against the each defi
the packets will be blocked.
This page all ows you to define the brid
redundant packets with specific protoco
Choose Disabled to disable the
bridge filtering function. Click Enabled
to monitor and block redundant
packets.
To initiate the Bridge Filtering rules,
select the Enabled radio b utton an
click Apply.
Click Add to configure a new bridge
filtering rule.
Note that the Add option is available
only when there i
d
s a bridge mode PVC
on this device.