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ProSafe Wireless-N 8-Port Gigabit VPN Firewall FVS318N
LAN Security Checks
Block UDP flood Select the Block UDP flood check box (which is the default setting) to prevent the
wireless VPN firewall from accepting more than 20 simultaneous, active User
Datagram Protocol (UDP) connections from a single device on the LAN.
A UDP flood is a form of denial of service attack that can be initiated when one
device sends a large number of UDP packets to random ports on a remote host. As a
result, the distant host does the following:
1. Checks for the application listening at that port.
2. Sees that no application is listening at that port.
3. 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 wireless
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 you have a specific reason to
prevent the wireless VPN firewall from responding to a ping on a LAN port.
VPN Pass through
IPSec
PPTP
L2TP
When the wireless 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
wireless VPN firewall wants to connect to another VPN endpoint on the WAN side
(placing the wireless VPN firewall between two VPN endpoints), encrypted packets
are sent to the wireless VPN firewall. Because the wireless 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. Di
sables NAT filtering for PPTP tunnels.
• L2
TP. Disables NAT filtering for L2TP tunnels.
By default, all three check boxes are selected.
Multicast Pass through
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.
Table 35. Attack Checks screen settings for IPv4 (continued)
Setting Description