Eicon Networks Eicon 1550, Руководство пользователя, Страница: 70 / 157

Security 70
After creating the first filter, the filter page should look like this:
Since the Eicon 1550/1551 automatically changed the last filter to one that drops all
traffic, you must create a second filter (before the last one) that allows all other traffic
through, as shown below. Without the second filter, all traffic would essentially be
barred.
Example: Allowing incoming traffic only from a specific network
This example shows how to allow the Eicon 1550/1551 to only accept incoming data
from a specific network (112.111.212.0). Incoming data from all other networks is
dropped. However, outgoing traffic is not affected. This requires defining two filters.
• Define the first filter to forward only incoming traffic from 112.111.212.0, as shown
below.
• Define the second filter to forward all outgoing traffic.The filter should state ‘Forward
outgoing datagrams being sent from anywhere that contain any protocol,’ as shown
below.
The third and last filter (the default filter) will drop all traffic. Incoming data that does
not originate from 112.111.212.0 will pass through the first two filters and will be
dropped by the last filter. All outgoing data will pass through the first filter but will be
caught by the second.
First filter
Second filter