Sapido Gr-1100, Руководство пользователя

Страница: 76 / 294

76
The following sections will explain in more detail about DoS Defense setup by
using the web configurator. There are a total 8 kinds of defense function for the
DoS Defense Setup. By default, the DoS Defense functionality is disabled. Further,
once the DoS Defense functionality is enabled, the default values for the
threshold and timeout values existing in some functions are set to 300 packets per
second and 10 seconds, respectively. A brief description for each item in the DoS
defense function is shown below.
4.2 SYN Flooding
Check or uncheck this option to enable or disable protection against SYN Flood
attacks. This attack involves sending connection requests to a server, but never
fully completing the connections. This will cause some computers to get into a
“suck state” where they cannot accept connections from legitimate users. (“SYN”
is short for SYN chronize”; this is the first step in opening an Internet connection).
You can select this box if you wish to protect the network from TCP SYN flooding.
4.3 WinNuke
Check or un-check this option to enable or disable protection against WinNuke
attacks. Some older versions of the Microsoft Windows OS are vulnerable to this
attack. If the computers in the LAN are not updated with recent versions/patches,
you are advised to enable this protection by checking this check box.
4.4 MIME Flood
Check or un-check this option to enable or disable protection against MIME
attacks. You can select this box to protect the mail server in your network against
MIME flooding.
4.5 FTP Bounce
Check or un-check this option to enable or disable protection against FTP bounce
attack. In its simplest terms, the attack is based on the misuse of the PORT
command in the FTP protocol. An attacker can establish a connection between
the FTP server machine and an arbitrary port on another system. This connection
may be used to bypass access controls that would otherwise apply.
4.6 IP Unaligned Time-Stamp
Check or un-check this option to enable or disable protection against unaligned IP
time stamp attack. Certain operating systems will crash if they receive a frame
with the IP timestamp option that isn’t aligned on a 32-bit boundary.