Url Filter - Draytek VIGOR3300V+ User Manual

Enable Block Smurf
Enable Block Trace Route Activates the Block trace route function. The router will not
Enable Block SYN
Fragment
Enable Block Fraggle
Attack
Enable TCP Flag Scan
Enable Tear Drop
Enable Ping of Death
Enable Block ICMP
Fragment
Enable Block Unknown
Protocol
Click Apply to apply the settings when you finish the configuration.

4.4.3 URL Filter

The Internet contains a wide range of offenses or illegal materials. Unlike traditional media,
the Internet does not have any obvious tools to segregate materials based on URL strings or
content. URL content filtering systems are seen as tools that would provide the cyberspace
equivalent of the physical separations that are used to limit access to particular materials. By
rating a site as objectionable, and refusing to display it on user's browser, URL content filter
can prevent employee on SME from accessing inappropriate Internet resources.
Instead of traditional firewall inspects packets based on the fields of TCP/IP headers, the
URL content filter checks the URL strings or the payload of TCP/IP packets.
The URL content filter in the series of broadband security routers inspects every URL string
in the HTTP requestt. If the entire or part of the URL string (for instance,
http://www.draytek.com, as shown above) matches any activated rule, the first and the
Activates the Block Smurf function. The router will reject any
ICMP echo request destined for the broadcast address.
forward any trace route packets.
Activates the Block SYN fragment function. Any packets
having the SYN flag and fragmented bit sets will be dropped.
Activates the Block fraggle Attack function. Any broadcast
UDP packets received from the Internet are blocked.
Activates the Block TCP flag scan function. Any TCP packet
with an anomalous flag setting is dropped. These scanning
activities include no flag scan, FIN without ACK scan, SYN
FIN scan, Xmas scan and full Xmas scan.
Activates the Block Tear Drop function. This attack involves
the perpetrator sending overlapping packets to the target hosts
so that target host will hang once they re-construct the packets.
The routers will block any packets resembling this attacking
activity.
Activates the Block Ping of Death function. Many machines
may crash when receiving an ICMP datagram that exceeds the
maximum length. The router will block any fragmented ICMP
packets with a length greater than 1024 octets.
Activates the Block ICMP fragment function. Any ICMP
packets with fragmented bit sets are dropped.
Activates the Block Unknown Protocol function. The router
will block any packets with unknown protocol types.
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Vigor3300V+ Series User's Guide