Firewall; Basics For Firewall; Denial Of Service (Dos) Defense; Filter Setup - Draytek Vigor2760 Series User Manual

4 . 3 F i r e w a l l
4 . 3 F i r e w a l l
4 . 3 . 1 B a s i c s f
4 . 3 . 1 B a s i c s f
While the broadband users demand more bandwidth for multimedia, interactive applications,
or distance learning, security has been always the most concerned. The firewall of the Vigor
router helps to protect your local network against attack from unauthorized outsiders. It also
restricts users in the local network from accessing the Internet. Furthermore, it can filter out
specific packets that trigger the router to build an unwanted outgoing connection.
4 . 3 . 1 . 1
4 . 3 . 1 . 1
The DoS Defense functionality helps you to detect and mitigate the DoS attack. The attacks
are usually categorized into two types, the flooding-type attacks and the vulnerability attacks.
The flooding-type attacks will attempt to exhaust all your system's resource while the
vulnerability attacks will try to paralyze the system by offending the vulnerabilities of the
protocol or operation system.
The DoS Defense function enables the Vigor router to inspect every incoming packet based on
the attack signature database. Any malicious packet that might duplicate itself to paralyze the
host in the secure LAN will be strictly blocked and a Syslog message will be sent as warning, if
you set up Syslog server.
Also the Vigor router monitors the traffic. Any abnormal traffic flow violating the pre-defined
parameter, such as the number of thresholds, is identified as an attack and the Vigor router will
activate its defense mechanism to mitigate in a real-time manner.
Below shows the menu items for Firewall.
4 . 3 . 2 F i l t e r S e
4 . 3 . 2 F i l t e r S e
Filter Setup allows you to adjust settings of IP Filter and common options.
The Filter Setup contains Filter Rule and Default Rule configuration pages. When there is no
filter rule existed, the incoming packet will be filtered by the default filter rule.
4 . 3 . 2 . 1
4 . 3 . 2 . 1
The mode of the firewall operation is that the router will filter the incoming packets from
outside based on the applied filter rules one by one until matching with the set conditions.
Once the packet matches with the first filter rule, the other filter rules will be ignored and will
not be applied to the packet. Therefore, the sequence of the filter rules influence the operation
of the firewall significantly.
o r F i r e w a l l
o r F i r e w a l l
D e n i a l o f S e r v i c e
D e n i a l o f S e r v i c e
t u p
t u p
F i l t e r R u l e
F i l t e r R u l e
( D o S ) D e f e n s e
( D o S ) D e f e n s e
92 Vigor2760 Series User's Guide