Draytek Vigor130 User Manual page 73

S t a t e f u l P a c k e t I n s
S t a t e f u l P a c k e t I n s
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 modem not just
examine the header information also monitor the state of the connection.
U R L C o n t e n t F i l t e
U R L C o n t e n t F i l t e
To provide an appropriate cyberspace to users, Vigor modem equips with URL Content
Filter not only to limit illegal traffic from/to the inappropriate web sites but also prohibit
other web feature where malicious code may conceal.
Once a user type in or click on an URL with objectionable keywords, URL keyword blocking
facility will decline the HTTP request to that web page thus can limit user's access to the
website. You may imagine URL Content Filter as a well-trained convenience-store clerk
who won't sell adult magazines to teenagers. At office, URL Content Filter can also provide
a job-related only environment hence to increase the employee work efficiency. How can
URL Content Filter work better than traditional firewall in the field of filtering? Because it
checks the URL strings or some of HTTP data hiding in the payload of TCP packets while
legacy firewall inspects packets based on the fields of TCP/IP headers only.
On the other hand, Vigor modem can prevent user from accidentally downloading malicious
codes from web pages. It's very common that malicious codes conceal in the executable
objects, such as ActiveX, Java Applet, compressed files, and other executable files. Once
downloading these types of files from websites, you may risk bringing threat to your system.
p e c t i o n ( S P I )
p e c t i o n ( S P I )
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65 Vigor130 Series User's Guide