Source Address Validation; Enabling Ip Source Address Validation - Dell C9000 Series Networking Configuration Manual

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Table of Contents

Valid ARP Replies

Invalid ARP Requests

Invalid ARP Replies

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

Table 26. Three Types of Source Address Validation

Source Address Validation

IP Source Address Validation

DHCP MAC Source Address Validation

IP+MAC 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

Prevents IP spoofing by forwarding only IP packets

that have been validated against the DHCP binding

Verifies a DHCP packet's source hardware address

matches the client hardware address field (CHADDR)

in the payload.

Verifies that the IP source address and MAC source

address are a legitimate pair.

Dynamic Host Configuration Protocol (DHCP)