Iskratel SI3000, Руководство пользователя

Страница: 34 / 46

C. User Guide 28
4.7 Security
Si contains advanced security features that prevent other computers on the Internet from
connecting to your PCs. You should only change the default security settings if you have experience in
network configuration. In most cases you will not need to make any changes.
The following security features can be configured:
Š
“ Port Forwarding ”
Š
“ Parental Control/URL Filter ”
Š
“ DMZ Host ”
Š
“ IP Filter ”
To access these pages:
1. Select Configuration > Security . The following page opens.
Figure 4-28: Security setting page
2. To access and configure specific security feature, click the corresponding tab in this page.
4.7.1 IP Filter
Stateful Firewall
Settings on this page are actually Firewall settings. A stateful Firewall tracks the movement of packets over
a period of time. If an outgoing packet includes a request for responses from certain types of incoming
packet, the packet is tracked to ensure that only those types of incoming packets are allowed through the
Firewall. Other types of traffic are blocked. Each time outbound packets are sent from an inside host to an
outside host, the following stateful information is logged by the Firewall:
Š
source and destination addresses
Š
port details; protocol type and range of source and destination ports
Š
sequencing information
Š
additional flags for each connection associated with that particular inside host
All inbound packets are compared against this logged information and any manually configured address
and port details. These packets are only allowed through the Firewall if an appropriate connection exists or
if a filter explicitly allows that traffic. Address and port details are configured by defining Firewall validators
and filters. This makes it very difficult for hackers to break through the stateful Firewall, because they
would need to know addresses, port numbers, sequencing information and individual connection flags for
an inside host.