Siemens RUGGEDCOM ROX II User Manual page 304

Chapter 7
IP Address Assignment
Section 7.3.18
Managing Option 82 Classes for Address Pools
Option 82, or the DHCP relay agent information option, helps protect the DHCP server from IP address spoofing
and DHCP IP starvation attacks by providing information about the network source of IP address requests. When
a DHCP client issues an IP address request, a DHCP relay agent adds Option 82 information to the packet header
for the request. The relay agent then forwards the request to the DHCP server for consideration. If the DHCP server
determines the request came from an untrusted source, the request is rejected.
The DHCP server must be configured to accept Option 82 information if it is to determine the trustworthiness of
the network interface used by a DHCP client. This can be done at the global level or for individual subnets.
IMPORTANT!
For more information about enabling the DHCP server to accept Option 82 information, refer to either
Section 7.3.4, "Configuring DHCP Server Options"
Once Option 82 is enabled, sub-option components (or classes) must be defined for each address pool that
includes DHCP clients that will send Option 82 information. This section describes how to manage the sub-option
components for address pools.
CONTENTS
• Section 7.3.18.1, "Viewing a List of Option 82 Classes for Address Pools"
• Section 7.3.18.2, "Adding an Option 82 Class to an Address Pool"
• Section 7.3.18.3, "Deleting an Option 82 Class From an Address Pool"
Section 7.3.18.1
Viewing a List of Option 82 Classes for Address Pools
To view a list of Option 82 classes configured for an address pool, type:
show running-config services dhcpserver subnet-name name options ippool description option82
Where:
• name is the name of the subnet
• description is the name of the address pool
If classes have been configured, a table or list similar to the following example appears:
ruggedcom# show running-config services dhcpserver subnet Local options ippool pool1 option82
services
dhcpserver
subnet Local
options
ippool pool1
option82 class1
remote-id
circuit-id 00:00:00:01:01:01
!
!
!
!
!
!
258
00:00:00:01:03:01
or Section 7.3.8.3, "Configuring Subnet
Managing Option 82 Classes for Address Pools
RUGGEDCOM ROX II
CLI User Guide
Options".