Netgear FVS336G FVS336G Reference Manual - Page 82

ProSafe Dual WAN Gigabit Firewall with SSL & IPsec VPN FVS336G Reference Manual - Block UDP flood-A UDP flood is a form of denial of service attack in which the attacking machine sends a large number of UDP packets to random ports to the victim host. As a result, the victim host will check for the application listening at that port, see that no application is listening at that port, and reply 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 may also spoof the IP address of the UDP packets, ensuring that the excessive ICMP return packets do not reach him, making the attacker's network location anonymous. If flood checking is enabled, the VPN firewall will not accept more than 20 simultaneous, active UDP connections from a single computer on the LAN. - Disable Ping Reply on LAN Ports. To prevent the VPN firewall from responding to Ping requests from the LAN, click this checkbox. - Disable DNS Proxy. Whether DNS Proxy is enabled or disabled in the DHCP server configuration (see "Configuring the LAN Setup Options" on page 3-2), the VPN firewall will service DNS requests sent to its own LAN IP address. To disable this service, check this checkbox. • VPN Pass through-When the FVS336G is in NAT mode, all packets going to the Remote VPN Gateway are first filtered through NAT and then encrypted per the VPN policy. If a VPN client or gateway on the LAN side of the VPN firewall wants to connect to another VPN endpoint on the WAN, with the FVS336G between the two VPN end points, all encrypted packets will be sent to the FVS336G. Since the FVS336G filters the encrypted packets through NAT, the packets become invalid. IPSec, PPTP, and L2TP represent different types of VPN tunnels that can pass through the FVS336G. To allow the VPN traffic to pass through without filtering, enable those options for the type of tunnel(s) that will pass through the FVS336G. Blocking Internet Sites (Content Filtering) To restrict internal LAN users from access to certain sites on the Internet, you can use the VPN firewall's Content Filtering and Web Components filtering. By default, these features are disabled; all requested traffic from any Web site is allowed. If you enable one or more of these features and users try to access a blocked site, they will see a "Blocked by NETGEAR" message. Several types of blocking are available: 4-20 Firewall Protection and Content Filtering v1.2, June 2008