Technical Reference; Arp Inspection Overview - ZyXEL Communications GS1920v2 Series User Manual

The following table describes the labels in this screen.
Table 231 SECURITY > IPv4 Source Guard > ARP Inspection > ARP Insp. VLAN Setup
LABEL
Search VLAN by
VID
Search
The Number of
VLANs
VID
Enabled
Log
Apply
Cancel

64.7 Technical Reference

This section provides technical background information on the topics discussed in this chapter.

64.7.1 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 297
In this example, computer B tries to establish a connection with computer A. Computer X is in the same
broadcast domain as computer A and intercepts the ARP request for computer A. Then, computer X
does the following things:
Chapter 64 ARP Inspection
DESCRIPTION
Specify the VLANs you want to manage in the section below. Use a comma (,) to separate
individual VLANs or a hyphen (-) to indicates a range of VLANs. For example, "3,4" or "3-9".
Click this to display the specified range of VLANs in the section below.
This display the number of ARP inspection VLAN search results.
This field displays the VLAN ID of each VLAN in the range specified above. If you configure the
* VLAN, the settings are applied to all VLANs.
Select Yes to enable ARP inspection on the VLAN. Select No to disable ARP inspection on the
VLAN.
Specify when the Switch generates log messages for receiving ARP packets from the VLAN.
None: The Switch does not generate any log messages when it receives an ARP packet from
the VLAN.
Deny: The Switch generates log messages when it discards an ARP packet from the VLAN.
Permit: The Switch generates log messages when it forwards an ARP packet from the VLAN.
All: The Switch generates log messages every time it receives an ARP packet from the VLAN.
Click Apply to save your changes to the Switch's run-time memory. The Switch loses these
changes if it is turned off or loses power, so use the Save link on the top navigation panel to
save your changes to the non-volatile memory when you are done configuring.
Click this to reset the values in this screen to their last-saved values.
Example: Man-in-the-middle Attack
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