ZyXEL Communications GS1920v2 Series - Technical Reference

Chapter 64 ARP Inspection
GS1920v2 Series User’s Guide
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The following table describes the labels in this screen.
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 Example: Man-in-the-middle Attack
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:
Table 231 SECURITY > IPv4 Source Guard > ARP Inspection > ARP Insp. VLAN Setup
LABEL DESCRIPTION
Search VLAN by
VID
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”.
Search Click this to display the specified range of VLANs in the section below.
The Number of
VLANs
This display the number of ARP inspection VLAN search results.
VID 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.
Enabled Select Yes to enable ARP inspection on the VLAN. Select No to disable ARP inspection on the
VLAN.
Log 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.
Apply 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.
Cancel Click this to reset the values in this screen to their last-saved values.