Enabling Dhcp Snooping; Dhcp Snooping - HP ProCurve 6120G/XG Manual

DHCP snooping accomplishes this by allowing you to distinguish between
trusted ports connected to a DHCP server or switch and untrusted ports
connected to end-users. DHCP packets are forwarded between trusted ports
without inspection. DHCP packets received on other switch ports are
inspected before being forwarded. Packets from untrusted sources are
dropped. Conditions for dropping packets are shown below.
Condition for Dropping a Packet
A packet from a DHCP server received on an untrusted port DHCPOFFER, DHCPACK,
If the switch is configured with a list of authorized DHCP
server addresses and a packet is received from a DHCP
server on a trusted port with a source IP address that is not
in the list of authorized DHCP server addresses.
Unless configured to not perform this check, a DHCP packet N/A
received on an untrusted port where the DHCP client
hardware address field does not match the source MAC
address in the packet
Unless configured to not perform this check, a DHCP packet N/A
containing DHCP relay information (option 82) received from
an untrusted port
A broadcast packet that has a MAC address in the DHCP
binding database, but the port in the DHCP binding database DHCPDECLINE
is different from the port on which the packet is received

Enabling DHCP Snooping

DHCP snooping is enabled globally by entering this command:
ProCurve(config)# dhcp-snooping
Use the no form of the command to disable DHCP snooping.
Syntax: [no] dhcp-snooping [authorized-server | database | option | trust | verify |
vlan]
authorized server: Enter the IP address of a trusted DHCP
server. If no authorized servers are configured, all DHCP
server addresses are considered valid.
Maximum: 20 authorized servers
database: To configure a location for the lease database,
enter a URL in the format tftp://ip-addr/ascii-string. The
maximum number of characters for the URL is 63.
Configuring Advanced Threat Protection

DHCP Snooping

Packet Types
DHCPNACK
DHCPOFFER, DHCPACK,
DHCPNACK
DHCPRELEASE,
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