NETGEAR C3000 User Manual page 24

Attack, UDP Flood, ARP Attack, Spoofing ICMP, Null Scan, and many others. This setting
should be disabled only in special circumstances.
• Default DMZ Server. This feature is sometimes helpful when you are playing online
games or videoconferencing. Be careful when using this feature, it makes the firewall
security less effective. The default DMZ server feature is helpful when you are using
some online games and videoconferencing applications that are incompatible with
Network Address Translation (NAT). The gateway is programmed to recognize some of
these applications and to work correctly with them, but some applications do not function
well. In some cases, one local computer can run the application correctly if the IP address
of that computer is entered as the default DMZ server.
• Respond to Ping on Internet Port. If you want the modem router to respond to a ping
from the Internet, select this check box. Use this feature only as a diagnostic tool because
it also allows your modem router to be discovered. Do not select this check box unless
you have a specific reason.
• MTU Size (in bytes). The normal MTU (maximum transmit unit) value for most Ethernet
networks is 1500 bytes, or 1492 bytes for PPPoE connections. For some ISPs, you might
need to reduce the MTU. Reduce the MTU only if you are sure that it is necessary for
your ISP connection.
• Disable SIP/ALG. The Session Initiation Protocol (SIP) Application Level Gateway (ALG)
is disabled by default which is useful when running certain applications. To enable
SIP/ALG and optimize VoIP phone calls that use the SIP, uncheck the check box.
The default DMZ server feature is helpful when you are using some online games and
videoconferencing applications that are incompatible with Network Address Translation
(NAT). The modem router is programmed to recognize some of these applications and to
work correctly with them, but some applications do not function well. In some cases, one local
computer can run the application correctly if the IP address of that computer is entered as the
default DMZ server.
WARNING:
DMZ servers pose a security risk. A computer that is designated
as the default DMZ server loses much of the protection of the
firewall and is exposed to exploits from the Internet. If
compromised, the DMZ server computer can be used to attack
other computers on your network.
The modem router discards incoming traffic from the Internet unless the traffic is a response
to one of your local computers or a service that you have configured in the Port
Forwarding/Port Triggering screen. Instead of discarding this traffic, you can have it
forwarded to one computer on your network. This computer is called the default DMZ server.

To set up a default DMZ server:
1. On the WAN Setup screen, select the Default DMZ Server check box.
2. Type the IP address.
C3000 WiFi Cable Modem Router
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