Netgear FVS318Gv2 – ProSAFE VPN Firewall Series Manual De Referência

Block UDP flood

Select the Block UDP flood check box to prevent the VPN firewall from accepting 
more than a specified number of simultaneous, active User Datagram Protocol 
(UDP) connections from a single device on the LAN. 
In the field, enter the number of connections per second that define a UDP flood. You 
can enter a number from 25 to 999. The default value is 25. The VPN firewall drops 
UDP packets that exceed the specified number of connections per second.
By default, the Block UDP flood check box is cleared so that the number of 
simultaneous, active UDP connections from a single device on the LAN is not 
restricted.
A UDP flood is a form of denial of service attack that can be initiated when one 
device sends many UDP packets to random ports on a remote host. As a result, the 
distant host does the following:

Checks for the application listening at that port.

Sees that no application is listening at that port.

Replies with an ICMP Destination Unreachable packet. 

When the victimized system is flooded, it is forced to send many ICMP packets, 
eventually making it unreachable by other clients. The attacker might also spoof the 
IP address of the UDP packets, ensuring that the excessive ICMP return packets do 
not reach the attacker, thus making the attacker’s network location anonymous.

Disable Ping Reply 
on LAN Ports

Select the Disable Ping Reply on LAN Ports check box to prevent the VPN firewall 
from responding to a ping on a LAN port. A ping can be used as a diagnostic tool. 
Keep this check box cleared unless a specific reason exists to prevent the VPN 
firewall from responding to a ping on a LAN port.

IPSec
PPTP
L2TP

When the VPN firewall functions in NAT mode, all packets going to the remote VPN 
gateway are first filtered through NAT and then encrypted according to the VPN 
policy. For example, if a VPN client or gateway on the LAN side of the VPN firewall 
wants to connect to another VPN endpoint on the WAN side (placing the VPN firewall 
between two VPN endpoints), encrypted packets are sent to the VPN firewall. 
Because the VPN firewall filters the encrypted packets through NAT, the packets 
become invalid unless you enable the VPN Pass through feature.
To enable the VPN tunnel to pass the VPN traffic without any filtering, select any or 
all of the following check boxes:

IPSec.  Disables  NAT  filtering  for  IPSec  tunnels.

PPTP.  Disables  NAT  filtering  for  PPTP  tunnels.

L2TP.  Disables  NAT  filtering  for  L2TP  tunnels.

By default, all three check boxes are selected.

Enable IGMP

IP multicast pass-through allows multicast packets that originate in the WAN, such 
as packets from a media streaming or gaming application, to be forwarded to the 
LAN subnet. Internet Group Management Protocol (IGMP) is used to support 
multicast between IP hosts and their adjacent neighbors.
Select the Enable IGMP check box to enable IP multicast pass-through. By default, 
IP multicast pass-through is disabled.