Contemporary Controls CTRLink EIAR-10T, User Manual, Page: 44 / 78

Configuration
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4.3.1.8 Menu option "Firewall"
The firewall of the router offers two data filtering options:
•
a packet filter
•
a port filter
The packet filter always considers the IP addresses. It only passes IP
packets with permitted IP addresses, and blocks packets of illegal
addresses. As a rule, complete network(s) (areas) are enabled or
disabled in order to prohibit or permit individual hosts selectively as
required.
The router offers three preconfigured packet filters:
• Masqueraded networks
These subnets are masked externally, i.e. these networks appear
externally as a host.
•
Routed networks
Packets sent into these subnets are forwarded, but not masked.
• Trusted networks
Packets exchanged between these subnets are forwarded
unobstructed and are not masked. This makes sense, in particular,
with reference to the port filter and to the black/white lists (see
below).
In addition, the router keeps a black or white list of hosts for which the
access to the routed / masked networks is to be permitted / prohibited
explicitly.
A port filter assesses packets not by their source or target address, but
by their target port. For example, all packets aimed at a certain port are
discarded, or all packets of a certain port are transferred to another
computer.
CAUTION !!!
Any settings in the "Firewall" area pertain directly to the security
of your network.
Any modifications should therefore only be made if you have the
appropriate knowledge.
CAUTION