SMC Networks SMC Tiger 10/100 SMC6128PL2 - Manual (Page 630)

Command Line Interface
4-322
4
DHCP Snooping Commands
DHCP snooping allows a switch to protect a network from rogue DHCP servers or
other devices which send port-related information to a DHCP server. This
information can be useful in tracking an IP address back to a physical port. This
section describes commands used to configure DHCP snooping.
ip dhcp snooping
This command enables DHCP snooping globally. Use the no form to restore the
default setting.
Syntax
[no] ip dhcp snooping
Default Setting
Disabled
Command Mode
Global Configuration
Command Usage
• Network traffic may be disrupted when malicious DHCP messages are
received from an outside source. DHCP snooping is used to filter DHCP
messages received on an unsecure interface from outside the network or
firewall. When DHCP snooping is enabled globally by this command, and
enabled on a VLAN interface by the ip dhcp snooping vlan command
(page 4-324), DHCP messages received on an untrusted interface (as
specified by the no ip dhcp snooping trust command, page 4-325) from a
device not listed in the DHCP snooping table will be dropped.
Table 4-88 DHCP Snooping Commands
Command Function Mode Page
ip dhcp snooping Enables DHCP snooping globally GC 4-322
ip dhcp snooping vlan Enables DHCP snooping on the specified VLAN GC 4-324
ip dhcp snooping trust Configures the specified interface as trusted IC 4-325
ip dhcp snooping verify
mac-address
Verifies the client’s hardware address stored in the DHCP
packet against the source MAC address in the Ethernet header
GC 4-325
ip dhcp snooping
information option
Enables or disables DHCP Option 82 information relay GC 4-326
ip dhcp snooping
information policy
Sets the information option policy for DHCP client packets that
include Option 82 information
GC 4-327
ip dhcp snooping
database flash
Writes all dynamically learned snooping entries to flash
memory
GC 4-327
show ip dhcp snooping Shows the DHCP snooping configuration settings PE 4-328
show ip dhcp snooping
binding
Shows the DHCP snooping binding table entries PE 4-328