Web Management Guide-R04
Table Of Contents
- How to Use This Guide
- Contents
- Figures
- Tables
- Getting Started
- Web Configuration
- Using the Web Interface
- Basic Management Tasks
- Displaying System Information
- Displaying Hardware/Software Versions
- Configuring Support for Jumbo Frames
- Displaying Bridge Extension Capabilities
- Managing System Files
- Setting the System Clock
- Configuring the Console Port
- Configuring Telnet Settings
- Displaying CPU Utilization
- Configuring CPU Guard
- Displaying Memory Utilization
- Resetting the System
- Interface Configuration
- VLAN Configuration
- Address Table Settings
- Spanning Tree Algorithm
- Congestion Control
- Class of Service
- Layer 2 Queue Settings
- Layer 3/4 Priority Settings
- Setting Priority Processing to IP Precedence/DSCP or CoS
- Mapping Ingress DSCP Values to Internal DSCP Values
- Mapping CoS Priorities to Internal DSCP Values
- Mapping Internal DSCP Values to Egress CoS Values
- Mapping IP Precedence Values to Internal DSCP Values
- Mapping IP Port Priority to Internal DSCP Values
- Quality of Service
- VoIP Traffic Configuration
- Security Measures
- AAA Authentication, Authorization and Accounting
- Configuring User Accounts
- Web Authentication
- Network Access (MAC Address Authentication)
- Configuring HTTPS
- Configuring the Secure Shell
- Access Control Lists
- Filtering IP Addresses for Management Access
- Configuring Port Security
- Configuring 802.1X Port Authentication
- DoS Protection
- DHCPv4 Snooping
- DHCPv6 Snooping
- IPv4 Source Guard
- IPv6 Source Guard
- ARP Inspection
- Application Filter
- Basic Administration Protocols
- Configuring Event Logging
- Link Layer Discovery Protocol
- Simple Network Management Protocol
- Configuring Global Settings for SNMP
- Setting Community Access Strings
- Setting the Local Engine ID
- Specifying a Remote Engine ID
- Setting SNMPv3 Views
- Configuring SNMPv3 Groups
- Configuring Local SNMPv3 Users
- Configuring Remote SNMPv3 Users
- Specifying Trap Managers
- Creating SNMP Notification Logs
- Showing SNMP Statistics
- Remote Monitoring
- Switch Clustering
- Setting a Time Range
- Ethernet Ring Protection Switching
- OAM Configuration
- Connectivity Fault Management
- Configuring Global Settings for CFM
- Configuring Interfaces for CFM
- Configuring CFM Maintenance Domains
- Configuring CFM Maintenance Associations
- Configuring Maintenance End Points
- Configuring Remote Maintenance End Points
- Transmitting Link Trace Messages
- Transmitting Loop Back Messages
- Transmitting Delay-Measure Requests
- Displaying Local MEPs
- Displaying Details for Local MEPs
- Displaying Local MIPs
- Displaying Remote MEPs
- Displaying Details for Remote MEPs
- Displaying the Link Trace Cache
- Displaying Fault Notification Settings
- Displaying Continuity Check Errors
- OAM Configuration
- UDLD Configuration
- LBD Configuration
- Smart Pair Configuration
- Multicast Filtering
- Overview
- Layer 2 IGMP (Snooping and Query for IPv4)
- Configuring IGMP Snooping and Query Parameters
- Specifying Static Interfaces for a Multicast Router
- Assigning Interfaces to Multicast Services
- Setting IGMP Snooping Status per Interface
- Filtering IGMP Query Packets and Multicast Data
- Displaying Multicast Groups Discovered by IGMP Snooping
- Displaying IGMP Snooping Statistics
- Filtering and Throttling IGMP Groups
- MLD Snooping (Snooping and Query for IPv6)
- Multicast VLAN Registration for IPv4
- Multicast VLAN Registration for IPv6
- Basic IP Functions
- IP Configuration
- General IP Routing
- IP Services
- Appendices
- Glossary
Chapter 12
| Security Measures
DHCPv4 Snooping
– 369 –
messages received on an untrusted interface from a device not listed in the
DHCP snooping table will be dropped.
◆ Table entries are only learned for trusted interfaces. An entry is added or
removed dynamically to the DHCP snooping table when a client receives or
releases an IP address from a DHCP server. Each entry includes a MAC address,
IP address, lease time, VLAN identifier, and port identifier.
◆ The rate limit for the number of DHCP messages that can be processed by the
switch is 100 packets per second. Any DHCP packets in excess of this limit are
dropped.
◆ When DHCP snooping is enabled, DHCP messages entering an untrusted
interface are filtered based upon dynamic entries learned via DHCP snooping.
◆ Filtering rules are implemented as follows:
■
If the global DHCP snooping is disabled, all DHCP packets are forwarded.
■
If DHCP snooping is enabled globally, and also enabled on the VLAN where
the DHCP packet is received, all DHCP packets are forwarded for a trusted
port. If the received packet is a DHCP ACK message, a dynamic DHCP
snooping entry is also added to the binding table.
■
If DHCP snooping is enabled globally, and also enabled on the VLAN where
the DHCP packet is received, but the port is not trusted, it is processed as
follows:
■
If the DHCP packet is a reply packet from a DHCP server (including
OFFER, ACK or NAK messages), the packet is dropped.
■
If the DHCP packet is from a client, such as a DECLINE or RELEASE
message, the switch forwards the packet only if the corresponding
entry is found in the binding table.
■
If the DHCP packet is from a client, such as a DISCOVER, REQUEST,
INFORM, DECLINE or RELEASE message, the packet is forwarded if MAC
address verification is disabled. However, if MAC address verification is
enabled, then the packet will only be forwarded if the client’s hardware
address stored in the DHCP packet is the same as the source MAC
address in the Ethernet header.
■
If the DHCP packet is not a recognizable type, it is dropped.
■
If a DHCP packet from a client passes the filtering criteria above, it will only
be forwarded to trusted ports in the same VLAN.
■
If a DHCP packet is from server is received on a trusted port, it will be
forwarded to both trusted and untrusted ports in the same VLAN.
■
If the DHCP snooping is globally disabled, all dynamic bindings are
removed from the binding table.