Netgear XCM8810 Chassis User Manual - Page 447
DHCP Snooping and Trusted DHCP Server,
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NETGEAR 8800 User Manual • Gratuitous ARP Protection on page 458 • ARP Validation on page 460 Figure 31 displays the dependencies of IP security. Any feature that appears directly above another feature depends on it. For example, to configure ARP validation, you must configure DHCP snooping and trusted DHCP server. Disable ARP learning DHCP secured ARP ARP validation Gratuitous ARP inspection-protect hosts and switch Source IP lockdown DHCP snooping and trusted DHCP server Gratuitous ARP inspection- protect only switch EX_178 Figure 31. IP Security Dependencies Note: IP security features are supported on link aggregation ports with the exception of DHCP snooping with the block-mac option and source IP lockdown. You can enable IP security on pre-existing trunks, but you cannot make IP security-enabled ports into trunks without first disabling IP security. DHCP Snooping and Trusted DHCP Server A fundamental requirement for most of the IP security features described in this section is to configure DHCP snooping and trusted DHCP server. DHCP snooping enhances security by filtering untrusted DHCP messages and by building and maintaining a DHCP bindings database. Trusted DHCP server also enhances security by forwarding DHCP packets from only configured trusted servers within your network. The DHCP bindings database contains the IP address, MAC Address, VLAN ID, and port number of the untrusted interface or client. If the switch receives a DHCP ACK message and the IP address does not exist in the DHCP bindings database, the switch creates an entry in the DHCP bindings database. If the switch receives a DHCP RELEASE, NAK or DECLINE message and the IP address exists in the DHCP bindings database, the switch removes the entry. You can enable DHCP snooping on a per port, per-VLAN basis and trusted DHCP server on a per-vlan basis. If configured for DHCP snooping, the switch snoops DHCP packets on the indicated ports and builds a DHCP bindings database of IP address and MAC address bindings from the received packets. If configured for trusted DHCP server, the switch forwards only DHCP packets from the trusted servers. The switch drops DHCP packets from other DHCP snooping-enabled ports. In addition, to prevent rogue DHCP servers from farming out IP addresses, you can optionally configure a specific port or set of ports as trusted ports. Trusted ports do not block traffic; rather, the switch forwards any DHCP server packets that appear on trusted ports. Chapter 17. Security | 447
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