Draytek Vigor2850 Series, User Manual

Page: 126 / 387

Vigor2850 Series User’s Guide
116
S
S
t
t
a
a
t
t
e
e
f
f
u
u
l
l
P
P
a
a
c
c
k
k
e
e
t
t
I
I
n
n
s
s
p
p
e
e
c
c
t
t
i
i
o
o
n
n
(
(
S
S
P
P
I
I
)
)
Stateful inspection is a firewall architecture that works at the network layer. Unlike legacy
static packet filtering, which examines a packet based on the information in its header, stateful
inspection builds up a state machine to track each connection traversing all interfaces of the
firewall and makes sure they are valid. The stateful firewall of Vigor router not just examine
the header information also monitor the state of the connection.
D
D
e
e
n
n
i
i
a
a
l
l
o
o
f
f
S
S
e
e
r
r
v
v
i
i
c
c
e
e
(
(
D
D
o
o
S
S
)
)
D
D
e
e
f
f
e
e
n
n
s
s
e
e
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.
The below shows the attack types that DoS/DDoS defense function can detect: