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ip dhcp snooping trust, Parameters, Default, Command Mode, Command Default Level, Usage Guideline

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DGS-1510 Series Gigabit Ethernet SmartPro Switch CLI Reference Guide 18-8 ip dhcp snooping trust This command is used to configure a port as a trusted interface for DHCP snooping. Use the no form of this command to return to the default setting. ip dhcp snooping trust no ip dhcp snooping trust Parameters None. Default By default, this option is disabled. Command Mode Interface Configuration Mode. Command Default Level Level: 12. Usage Guideline This command is available for physical port and port-channel interface configuration. Ports connected to the DHCP server or to other switches should be configured as trusted interfaces. The ports connected to DHCP clients should be configured as untrusted interfaces. DHCP snooping acts as a firewall between untrusted interfaces and DHCP servers. When a port is configured as a untrusted interface, the DHCP message arrives at the port on a VLAN that is enabled for DHCP snooping. The Switch forwards the DHCP packet unless any of the following conditions occur (in which case the packet is dropped): • The Switch port receives a packet (such as a DHCPOFFER, DHCPACK, or DHCPNAK packet) from a DHCP server outside the firewall. • If ip dhcp snooping verify mac-address is enabled, the source MAC in the Ethernet header must be the same as the DHCP client hardware address to pass the validation. • The untrusted interface receives a DHCP packet that includes a relay agent IP address that is not 0.0.0.0 or the relay agent forward a packet that includes Option 82 to an untrusted interface. • The router receives a DHCPRELEASE or DHCPDECLINE message from an untrusted host with an entry in the DHCP snooping binding table, and the interface information in the binding table does not match the interface on which the message was received. In addition to doing the validation, DHCP snooping also create a binding entry based on the IP address assigned to client by the server in DHCP snooping binding database. The binding entry contains information including MAC address, IP address, the VLAN ID and port ID where the client is located, and the expiry of the lease time. Example This example shows how to enable DHCP snooping trust for port 3/0/3. Switch# configure terminal Switch(config)# interface eth3/0/3 Switch(config-if)# ip dhcp snooping trust Switch(config-if)# 182

Section	Page
Table of Contents	2
1. Introduction	4
Audience	4
Other Documentation	4
Conventions	4
Notes, Notices, and Cautions	4
Command Descriptions	5
Command Modes	5
User EXEC Mode at Basic User Level	7
Privileged EXEC Mode at Operator Level	7
Privileged EXEC Mode at Administrator Level	7
Global Configuration Mode	7
Interface Configuration Mode	7
VLAN Interface Configuration Mode	7
Creating a User Account	8
Interface Notation	9
Error Messages	9
Editing Features	10
Display Result Output Modifiers	10
2. Basic CLI Commands	13
2-1 help	13
Parameters	13
Default	13
Command Mode	13
Command Default Level	13
Usage Guideline	13
Example	13
2-2 enable	14
Parameters	14
Default	14
Command Mode	15
Command Default Level	15
Usage Guideline	15
Example	15
2-3 disable	15
Parameters	15
Default	15
Command Mode	15
Command Default Level	15
Usage Guideline	15
Example	15
2-4 configure terminal	16
Parameters	16
Default	16
Command Mode	16
Command Default Level	16
Usage Guideline	16
Example	16
2-5 login (EXEC)	16
Parameters	16
Default	16
Command Mode	16
Command Default Level	16
Usage Guideline	16
Example	17
2-6 login (Line)	17
Parameters	17
Default	17
Command Mode	17
Command Default Level	17
Usage Guideline	17
Example	18
2-7 logout	18
Parameters	19
Default	19
Command Mode	19
Command Default Level	19
Usage Guideline	19
Example	19
2-8 end	19
Parameters	19
Default	19
Command Mode	19
Command Default Level	19
Usage Guideline	19
Example	19
2-9 exit	20
Parameters	20
Default	20
Command Mode	20
Command Default Level	20
Usage Guideline	20
Example	20
2-10 show history	20
Parameters	20
Default	20
Command Mode	21
Command Default Level	21
Usage Guideline	21
Example	21
2-11 show environment	21
Parameters	21
Default	21
Command Mode	21
Command Default Level	21
Usage Guideline	21
Example	22
Display Parameters	22
2-12 show unit	22
Parameters	22
Default	22
Command Mode	22
Command Default Level	22
Usage Guideline	22
Example	23
2-13 show cpu utilization	23
Parameters	23
Default	23
Command Mode	23
Command Default Level	23
Usage Guideline	23
Example	23
2-14 show version	24
Parameters	24
Default	24
Command Mode	24
Command Default Level	24
Usage Guideline	24
Example	24
2-15 snmp-server enable traps environment	24
Parameters	25
Default	25
Command Mode	25
Command Default Level	25
Usage Guideline	25
Example	25
2-16 environment temperature threshold	25
Parameters	25
Default	26
Command Mode	26
Command Default Level	26
Usage Guideline	26
Example	26
3. 802.1X Commands	27
3-1 clear dot1x counters	27
Parameters	27
Default	27
Command Mode	27
Command Default Level	27
Usage Guideline	27
Example	27
3-2 dot1x control-direction	27
Parameters	27
Default	28
Command Mode	28
Command Default Level	28
Usage Guideline	28
Example	28
3-3 dot1x default	28
Parameters	28
Default	28
Command Mode	29
Command Default Level	29
Usage Guideline	29
Example	29
3-4 dot1x port-control	29
Parameters	29
Default	29
Command Mode	29
Command Default Level	29
Usage Guideline	29
Example	29
3-5 dot1x forward-pdu	30
Parameters	30
Default	30
Command Mode	30
Command Default Level	30
Usage Guideline	30
Example	30
3-6 dot1x initialize	30
Parameters	30
Default	31
Command Mode	31
Command Default Level	31
Usage Guideline	31
Example	31
3-7 dot1x max-req	31
Parameters	31
Default	31
Command Mode	31
Command Default Level	31
Usage Guideline	32
Example	32
3-8 dot1x pae authenticator	32
Parameters	32
Default	32
Command Mode	32
Command Default Level	32
Usage Guideline	32
Example	32
3-9 dot1x re-authenticate	33
Parameters	33
Default	33
Command Mode	33
Command Default Level	33
Usage Guideline	33
Example	33
3-10 dot1x system-auth-control	33
Parameters	34
Default	34
Command Mode	34
Command Default Level	34
Usage Guideline	34
Example	34
3-11 dot1x timeout	34
Parameters	34
Default	34
Command Mode	34
Command Default Level	35
Usage Guideline	35
Example	35
3-12 show dot1x	35
Parameters	35
Default	35
Command Mode	35
Command Default Level	35
Usage Guideline	35
Example	35
3-13 show dot1x diagnostics	36
Parameters	36
Default	36
Command Mode	36
Command Default Level	36
Usage Guideline	36
Example	37
3-14 show dot1x statistics	37
Parameters	37
Default	37
Command Mode	38
Command Default Level	38
Usage Guideline	38
Example	38
3-15 show dot1x session-statistics	38
Parameters	38
Default	38
Command Mode	39
Command Default Level	39
Usage Guideline	39
Example	39
3-16 snmp-server enable traps dot1x	39
Parameters	39
Default	39
Command Mode	39
Command Default Level	39
Usage Guideline	39
Example	40
4. Access Control List (ACL) Commands	41
4-1 access-list resequence	41
Parameters	41
Default	41
Command Mode	41
Command Default Level	41
Usage Guideline	41
Example	41
4-2 acl-hardware-counter	42
Parameters	42
Default	42
Command Mode	42
Command Default Level	42
Usage Guideline	43
Example	43
4-3 action	43
Parameters	43
Default	43
Command Mode	43
Command Default Level	43
Usage Guideline	43
Example	43
4-4 clear acl-hardware-counter	44
Parameters	44
Default	44
Command Mode	44
Command Default Level	44
Usage Guideline	44
Example	44
4-5 expert access-group	45
Parameters	45
Default	45
Command Mode	45
Command Default Level	45
Usage Guideline	45
Example	45
4-6 expert access-list	45
Parameters	46
Default	46
Command Mode	46
Command Default Level	46
Usage Guideline	46
Example	46
4-7 ip access-group	46
Parameters	46
Default	47
Command Mode	47
Command Default Level	47
Usage Guideline	47
Example	47
4-8 ip access-list	47
Parameters	47
Default	47
Command Mode	48
Command Default Level	48
Usage Guideline	48
Example	48
4-9 ipv6 access-group	48
Parameters	48
Default	48
Command Mode	48
Command Default Level	48
Usage Guideline	48
Example	49
4-10 ipv6 access-list	49
Parameters	49
Default	49
Command Mode	49
Command Default Level	49
Usage Guideline	49
Example	49
4-11 list-remark	50
Parameters	50
Default	50
Command Mode	50
Command Default Level	50
Usage Guideline	50
Example	50
4-12 mac access-group	51
Parameters	51
Default	51
Command Mode	51
Command Default Level	51
Usage Guideline	51
Example	51
4-13 mac access-list	51
Parameters	52
Default	52
Command Mode	52
Command Default Level	52
Usage Guideline	52
Example	52
4-14 match ip address	52
Parameters	52
Default	52
Command Mode	52
Command Default Level	52
Usage Guideline	53
Example	53
4-15 match ipv6 address	53
Parameters	53
Default	53
Command Mode	53
Command Default Level	53
Usage Guideline	53
Example	53
4-16 match mac address	54
Parameters	54
Default	54
Command Mode	54
Command Default Level	54
Usage Guideline	54
Example	54
4-17 permit \| deny (expert access-list)	55
Parameters	55
Default	57
Command Mode	57
Command Default Level	57
Usage Guideline	57
Example	57
4-18 permit \| deny (ip access-list)	57
Parameters	58
Default	59
Command Mode	59
Command Default Level	59
Usage Guideline	59
Example	60
4-19 permit \| deny (ipv6 access-list)	60
Parameters	61
Default	62
Command Mode	62
Command Default Level	62
Usage Guideline	62
Example	62
4-20 permit \| deny (mac access-list)	63
Parameters	63
Default	63
Command Mode	63
Command Default Level	63
Usage Guideline	63
Example	64
4-21 show access-group	64
Parameters	64
Default	64
Command Mode	64
Command Default Level	64
Usage Guideline	64
Example	64
4-22 show access-list	65
Parameters	65
Default	65
Command Mode	65
Command Default Level	65
Usage Guideline	65
Example	65
4-23 show vlan access-map	66
Parameters	66
Default	67
Command Mode	67
Command Default Level	67
Usage Guideline	67
Example	67
4-24 show vlan filter	67
Parameters	68
Default	68
Command Mode	68
Command Default Level	68
Usage Guideline	68
Example	68
4-25 vlan access-map	68
Parameters	68
Default	69
Command Mode	69
Command Default Level	69
Usage Guideline	69
Example	69
4-26 vlan filter	69
Parameters	69
Default	69
Command Mode	69
Command Default Level	69
Usage Guideline	70
Example	70
5. Access Management Commands	71
5-1 access class	71
Parameters	71
Default	71
Command Mode	71
Command Default Level	71
Usage Guideline	71
Example	71
5-2 prompt	71
Parameters	72
Default	72
Command Mode	72
Command Default Level	72
Usage Guideline	72
Example	72
5-3 enable password	72
Parameters	72
Default	73
Command Mode	73
Command Default Level	73
Usage Guideline	73
Example	73
5-4 ip http server	73
Parameters	73
Default	73
Command Mode	73
Command Default Level	74
Usage Guideline	74
Example	74
5-5 ip http secure-server	74
Parameters	74
Default	74
Command Mode	74
Command Default Level	74
Usage Guideline	74
Example	74
5-6 ip http access-class	75
Parameters	75
Default	75
Command Mode	75
Command Default Level	75
Usage Guideline	75
Example	75
5-7 ip http service-port	75
Parameters	75
Default	76
Command Mode	76
Command Default Level	76
Usage Guideline	76
Example	76
5-8 ip http timeout-policy idle	76
Parameters	76
Default	76
Command Mode	76
Command Default Level	76
Usage Guideline	76
Example	76
5-9 ip telnet server	77
Parameters	77
Default	77
Command Mode	77
Command Default Level	77
Usage Guideline	77
Example	77
5-10 ip telnet service port	77
Parameters	77
Default	77
Command Mode	77
Command Default Level	77
Usage Guideline	78
Example	78

Match case Limit results 1 per page

DGS-1510 Series Gigabit Ethernet SmartPro Switch CLI Reference Guide

182

18-8 ip dhcp snooping trust

This command is used to configure a port as a trusted interface for DHCP snooping. Use the

form of

this command to return to the default setting.

ip dhcp snooping trust

no ip dhcp snooping trust

Parameters

None.

Default

By default, this option is disabled.

Command Mode

Interface Configuration Mode.

Command Default Level

Level: 12.

Usage Guideline

This command is available for physical port and port-channel interface configuration.

Ports connected to the DHCP server or to other switches should be configured as trusted interfaces. The

ports connected to DHCP clients should be configured as untrusted interfaces. DHCP snooping acts as a

firewall between untrusted interfaces and DHCP servers.

When a port is configured as a untrusted interface, the DHCP message arrives at the port on a VLAN that

is enabled for DHCP snooping. The Switch forwards the DHCP packet unless any of the following

conditions occur (in which case the packet is dropped):

•

The Switch port receives a packet (such as a DHCPOFFER, DHCPACK, or DHCPNAK packet)

from a DHCP server outside the firewall.

•

ip dhcp snooping verify mac-address

is enabled, the source MAC in the Ethernet header

must be the same as the DHCP client hardware address to pass the validation.

•

The untrusted interface receives a DHCP packet that includes a relay agent IP address that is not

0.0.0.0 or the relay agent forward a packet that includes Option 82 to an untrusted interface.

•

The router receives a DHCPRELEASE or DHCPDECLINE message from an untrusted host with

an entry in the DHCP snooping binding table, and the interface information in the binding table

does not match the interface on which the message was received.

In addition to doing the validation, DHCP snooping also create a binding entry based on the IP address

assigned to client by the server in DHCP snooping binding database. The binding entry contains

information including MAC address, IP address, the VLAN ID and port ID where the client is located, and

the expiry of the lease time.

Example

This example shows how to enable DHCP snooping trust for port 3/0/3.

Switch# configure terminal

Switch(config)# interface eth3/0/3

Switch(config-if)# ip dhcp snooping trust

Switch(config-if)#