ZyXEL ES-2108PWR User Guide - Page 165

IP Source Guard

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CHAPTER 21 IP Source Guard Use IP source guard to filter unauthorized ARP packets in your network. 21.1 IP Source Guard Overview IP source guard uses a binding table to distinguish between authorized and unauthorized ARP packets in your network. A binding contains these key attributes: • MAC address • VLAN ID • IP address • Port number When the Switch receives an ARP packet, it looks up the appropriate MAC address, VLAN ID, IP address, and port number in the binding table. If there is a binding, the Switch forwards the packet. If there is not a binding, the Switch discards the packet. The Switch builds from information provided manually by administrators (static bindings). IP source guard consists of the following features: • Static bindings. Use this to create static bindings in the binding table. • ARP inspection. Use this to filter unauthorized ARP packets on the network. 21.1.1 ARP Inspection Overview Use ARP inspection to filter unauthorized ARP packets on the network. This can prevent many kinds of man-in-the-middle attacks, such as the one in the following example. Figure 90 Example: Man-in-the-middle Attack A B X ES-2108 Series User's Guide 165

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ES-2108 Series User’s Guide
165
C
HAPTER
21
IP Source Guard
Use IP source guard to filter unauthorized ARP packets in your network.
21.1
IP Source Guard Overview
IP source guard uses a binding table to distinguish between authorized and unauthorized ARP
packets in your network. A binding contains these key attributes:
MAC address
VLAN ID
IP address
Port number
When the Switch receives an ARP packet, it looks up the appropriate MAC address, VLAN
ID, IP address, and port number in the binding table. If there is a binding, the Switch forwards
the packet. If there is not a binding, the Switch discards the packet.
The Switch builds from information provided manually by administrators (static bindings).
IP source guard consists of the following features:
Static bindings. Use this to create static bindings in the binding table.
ARP inspection. Use this to filter unauthorized ARP packets on the network.
21.1.1
ARP Inspection Overview
Use ARP inspection to filter unauthorized ARP packets on the network. This can prevent
many kinds of man-in-the-middle attacks, such as the one in the following example.
Figure 90
Example: Man-in-the-middle Attack
A
X
B