Siemens SLI-5310 - Manual (Page 96)

ADSL Router User Manual
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:
‹ source and destination IP address
‹ port
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:
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.
Firewall – IP Filtering
This page allows you to specify the IP packet filtering rules to prevent the services
accessed from the Internet hosts or limit the Internet access for local hosts.
Choose Disabled to disable the
firewall function. Click Enabled to
invoke the settings that you set in this
web page.
To initiate the IP Filtering, select the
Enabled radio button and click Apply.
Select the direction to filter
packets: Inbound means the data is
transferred from outside onto your
computer. Outbound means the data
is transferred from your computer onto
outside through Internet. Please
choose Outbound traffic or Inbound
traffic as the direction for filtering
packets.
Click Add to add a new IP Filtering
rule.
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