Chapter 26 IP Source Guard
GS1920v2 Series User’s Guide
257
• It pretends to be computer
B
and sends a message to computer
A
.
As a result, all the communication between computer
A
and computer
B
passes through computer
X
.
Computer
X
can read and alter the information passed between them.
26.11.2.1 ARP Inspe c tio n a nd MAC Addre ss Filte rs
When the Switch identifies an unauthorized ARP packet, it automatically creates a MAC address filter to
block traffic from the source MAC address and source VLAN ID of the unauthorized ARP packet. You
can configure how long the MAC address filter remains in the Switch.
These MAC address filters are different than regular MAC address filters (
Chapter 12 on page 133
).
• They are stored only in volatile memory.
• They do not use the same space in memory that regular MAC address filters use.
• They appear only in the
ARP Inspe c tio n
screens and commands, not in the
MAC Addre ss Filte r
screens
and commands.
26.11.2.2 Truste d vs. Untruste d Po rts
Every port is either a trusted port or an untrusted port for ARP inspection. This setting is independent of
the trusted/untrusted setting for DHCP snooping. You can also specify the maximum rate at which the
Switch receives ARP packets on untrusted ports.
The Switch does not discard ARP packets on trusted ports for any reason.
The Switch discards ARP packets on untrusted ports in the following situations:
• The sender’s information in the ARP packet does not match any of the current bindings.
• The rate at which ARP packets arrive is too high.
26.11.2.3 Syslo g
The Switch can send syslog messages to the specified syslog server (
Chapter 43 on page 372
) when it
forwards or discards ARP packets. The Switch can consolidate log messages and send log messages in
batches to make this mechanism more efficient.
26.11.2.4 C o nfig uring ARP Inspe c tio n
Follow these steps to configure ARP inspection on the Switch.
1
Configure DHCP snooping. See
Section 26.11.1.4 on page 256
.
Note: It is recommended you enable DHCP snooping at least one day before you enable
ARP inspection so that the Switch has enough time to build the binding table.
2
Enable ARP inspection on each VLAN.
3
Configure trusted and untrusted ports, and specify the maximum number of ARP packets that each port
can receive per second.
Содержание GS1920-48HPv2
Страница 19: ...19 PA RT I Use r s Guide...
Страница 43: ...43 PA RT II T e c hnic al Re fe re nc e...
Страница 124: ...Chapter 9 VLAN GS1920v2 Series User s Guide 124 Figure 97 Advanced Application VLAN Port Based VLAN Setup Port Isolation...
Страница 155: ...Chapter 13 Spanning Tree Protocol GS1920v2 Series User s Guide 155 Figure 118 MSTP and Legacy RSTP Network Example...
Страница 193: ...GS1920v2 Series User s Guide 193 Figure 140 Classifier Example...
Страница 224: ...Chapter 24 Multicast GS1920v2 Series User s Guide 224 Figure 162 MVR Group Configuration Example 2 EXAMPLE...
Страница 367: ...Chapter 40 Access Control GS1920v2 Series User s Guide 367 Figure 271 Example Lock Denoting a Secure Connection EXAMPLE...
Страница 388: ...Chapter 48 Configure Clone GS1920v2 Series User s Guide 388 Figure 284 Management Configure Clone...