ZyXEL Communications eircom D1000, Руководство пользователя

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149
eircom D10
00 modem User’s Guide
Chapter 13 Firewall
Anti-Probing
If an outside user attempts to probe an unsupported port on your Device, an ICMP response packet
is automatically returned. This allows the outside user to know the Device exists. The Device
supports anti-probing, which prevents the ICMP response packet from being sent. This keeps
outsiders from discovering your Device when unsupported ports are probed.
ICMP
Internet Control Message Protocol (ICMP) is a message control and error-reporting protocol
between a host server and a gateway to the Internet. ICMP uses Internet Protocol (IP) datagrams,
but the messages are processed by the TCP/IP software and directly apparent to the application
user.
DoS Thresholds
For DoS attacks, the Device uses thresholds to determine when to drop sessions that do not
become fully established. These thresholds apply globally to all sessions. You can use the default
threshold values, or you can change them to values more suitable to your security requirements.
13.2 The Firewall General Screen
Use this screen to select the firewall protection level on the Device. Click Security > Firewall >
General to display the following screen.
Figure 100
Security > Firewall > General
The following table describes the labels in this screen.
Table 55
Security > Firewall > General
LABEL DESCRIPTION
High This setting blocks all traffic to and from the Internet. Only local network traffic and LAN to WAN
service (Telnet, FTP, HTTP, HTTPS, DNS, POP3, SMTP) is permitted.
Medium This is the recommended setting. It allows traffic to the Internet but blocks anyone from the
Internet from accessing any services on your local network.