Dell C1048P Port Extender Networking Configuration Guide for the C9000 Series - Page 384

Invalid ARP Replies : 0 Dell# Bypassing the ARP Inspection You can configure a port to skip ARP inspection by defining the interface as trusted, which is useful in multi-switch environments. ARPs received on trusted ports bypass validation against the binding table. All ports are untrusted by default. To bypass the ARP inspection, use the following command. • Specify an interface as trusted so that ARPs are not validated against the binding table. INTERFACE mode arp inspection-trust DAI is supported on Layer 2 and Layer 3. Source Address Validation Using the DHCP binding table, Dell Networking OS can perform three types of source address validation (SAV). Table 26. Three Types of Source Address Validation Source Address Validation Description IP Source Address Validation Prevents IP spoofing by forwarding only IP packets that have been validated against the DHCP binding table. DHCP MAC Source Address Validation Verifies a DHCP packet's source hardware address matches the client hardware address field (CHADDR) in the payload. IP+MAC Source Address Validation Verifies that the IP source address and MAC source address are a legitimate pair. Enabling IP Source Address Validation IP source address validation (SAV) prevents IP spoofing by forwarding only IP packets that have been validated against the DHCP binding table. A spoofed IP packet is one in which the IP source address is strategically chosen to disguise the attacker. For example, using ARP spoofing, an attacker can assume a legitimate client's identity and receive traffic addressed to it. Then the attacker can spoof the client's IP address to interact with other clients. The DHCP binding table associates addresses the DHCP servers assign with the port or the port channel interface on which the requesting client is attached and the VLAN the client belongs to. When you enable IP source address validation on a port, the system verifies that the source IP address is one that is associated with the incoming port and optionally that the client belongs to the permissible VLAN. If an attacker is impostering as a legitimate client, the source address appears on the wrong ingress port and the system drops the packet. If the IP address is fake, the address is not on the list of permissible addresses for the port and the packet is dropped. Similarly, if the IP address does not belong to the permissible VLAN, the packet is dropped. To enable IP source address validation, use the following command. 384 Dynamic Host Configuration Protocol (DHCP)