
C
HAPTER
25
| General Security Measures
DHCP Snooping
– 744 –
R
ELATED
C
OMMANDS
ip dhcp snooping
trust
This command configures the specified interface as trusted. Use the
no
form to restore the default setting.
S
YNTAX
[
no
]
ip dhcp snooping trust
D
EFAULT
S
ETTING
All interfaces are untrusted
C
OMMAND
M
ODE
Interface Configuration (Ethernet, Port Channel)
C
OMMAND
U
SAGE
A trusted interface is an interface that is configured to receive only
messages from within the network. An untrusted interface is an
interface that is configured to receive messages from outside the
network or fire wall.
Set all ports connected to DHCP servers within the local network or fire
wall to trusted, and all other ports outside the local network or fire wall
to untrusted.
When DHCP snooping ia enabled globally using the
command, and enabled on a VLAN with
command, DHCP packet filtering will be performed on any untrusted
ports within the VLAN according to the default status, or as specifically
configured for an interface with the
no ip dhcp snooping trust
command.
When an untrusted port is changed to a trusted port, all the dynamic
DHCP snooping bindings associated with this port are removed.
Additional considerations when the switch itself is a DHCP client
– The
port(s) through which it submits a client request to the DHCP server
must be configured as trusted.
E
XAMPLE
This example sets port 5 to untrusted.
Console(config)#interface ethernet 1/5
Console(config-if)#no ip dhcp snooping trust
Console(config-if)#
R
ELATED
C
OMMANDS
Summary of Contents for DG-FS4526E
Page 4: ...ABOUT THIS GUIDE 4...
Page 34: ...CONTENTS 34...
Page 50: ...TABLES 50...
Page 52: ...SECTION I Getting Started 52...
Page 62: ...CHAPTER 1 Introduction System Defaults 62...
Page 80: ...CHAPTER 2 Initial Switch Configuration Managing System Files 80...
Page 82: ...SECTION II Web Configuration 82...
Page 100: ...CHAPTER 3 Using the Web Interface Navigating the Web Browser Interface 100...
Page 128: ...CHAPTER 4 Basic Management Tasks Resetting the System 128...
Page 166: ...CHAPTER 5 Interface Configuration VLAN Trunking 166...
Page 198: ...CHAPTER 6 VLAN Configuration Configuring VLAN Mirroring 198...
Page 516: ...CHAPTER 17 IP Services Displaying the DNS Cache 516...
Page 562: ...CHAPTER 19 Using the Command Line Interface CLI Command Groups 562...
Page 652: ...CHAPTER 22 SNMP Commands 652...
Page 660: ...CHAPTER 23 Remote Monitoring Commands 660...
Page 714: ...CHAPTER 24 Authentication Commands Management IP Filter 714...
Page 802: ...CHAPTER 27 Interface Commands 802...
Page 824: ...CHAPTER 29 Port Mirroring Commands RSPAN Mirroring Commands 824...
Page 846: ...CHAPTER 32 Address Table Commands 846...
Page 874: ...CHAPTER 33 Spanning Tree Commands 874...
Page 886: ...CHAPTER 34 ERPS Commands 886...
Page 928: ...CHAPTER 35 VLAN Commands Configuring Voice VLANs 928...
Page 942: ...CHAPTER 36 Class of Service Commands Priority Commands Layer 3 and 4 942...
Page 998: ...CHAPTER 38 Multicast Filtering Commands Multicast VLAN Registration 998...
Page 1022: ...CHAPTER 39 LLDP Commands 1022...
Page 1064: ...CHAPTER 40 CFM Commands 1064...
Page 1084: ...CHAPTER 42 Domain Name Service Commands 1084...
Page 1090: ...CHAPTER 43 DHCP Commands DHCP Client 1090...
Page 1122: ...CHAPTER 44 IP Interface Commands IPv6 Interface 1122...
Page 1124: ...SECTION IV Appendices 1124...
Page 1130: ...APPENDIX A Software Specifications Management Information Bases 1130...
Page 1152: ...COMMAND LIST 1152...
Page 1161: ......
Page 1162: ...DG FS4526E 042012 HW R01...