- Preface
- Using the Command-Line Interface
- Using the Web Graphical User Interface
-
- Configuring the Switch for Access Point Discovery
- Configuring Data Encryption
- Configuring Retransmission Interval and Retry Count
- Configuring Adaptive Wireless Intrusion Prevention System
- Configuring Authentication for Access Points
- Converting Autonomous Access Points to Lightweight Mode
- Using Cisco Workgroup Bridges
- Configuring Probe Request Forwarding
- Optimizing RFID Tracking
- Configuring Country Codes
- Configuring Link Latency
- Configuring Power over Ethernet
-
- Preventing Unauthorized Access
- Controlling Switch Access with Passwords and Privilege Levels
- Configuring TACACS+
- Configuring RADIUS
- Configuring Kerberos
- Configuring Local Authentication and Authorization
- Configuring Secure Shell (SSH)
- Configuring Secure Socket Layer HTTP
- Configuring IPv4 ACLs
- Configuring IPv6 ACLs
- Configuring DHCP
- Configuring IP Source Guard
- Configuring Dynamic ARP Inspection
- Configuring IEEE 802.1x Port-Based Authentication
- Configuring Web-Based Authentication
- Configuring Port-Based Traffic Control
- Configuring IPv6 First Hop Security
- Configuring Cisco TrustSec
- Configuring Wireless Guest Access
- Managing Rogue Devices
- Classifying Rogue Access Points
- Configuring wIPS
- Configuring Intrusion Detection System
-
- Administering the System
- Performing Switch Setup Configuration
- Configuring Right-To-Use Licenses
- Configuring Administrator Usernames and Passwords
- Configuring 802.11 parameters and Band Selection
- Configuring Aggressive Load Balancing
- Configuring Client Roaming
- Configuring Application Visibility and Control
- Configuring Voice and Video Parameters
- Configuring RFID Tag Tracking
- Configuring Location Settings
- Monitoring Flow Control
- Configuring SDM Templates
- Configuring System Message Logs
- Configuring Online Diagnostics
- Managing Configuration Files
- Configuration Replace and Configuration Rollback
- Working with the Flash File System
- Working with Cisco IOS XE Software Bundles
- Troubleshooting the Software Configuration
- Index
Configuring IP Source Guard
IP Source Guard (IPSG) is a security feature that restricts IP traffic on nonrouted, Layer 2 interfaces by filtering traffic based on the DHCP snooping binding database and on manually configured IP source bindings.
This chapter contains the following topics:
- Finding Feature Information
- Information About IP Source Guard
- How to Configure IP Source Guard
- Monitoring IP Source Guard
- Additional References
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Information About IP Source Guard
IP Source Guard
You can use IP source guard to prevent traffic attacks if a host tries to use the IP address of its neighbor and you can enable IP source guard when DHCP snooping is enabled on an untrusted interface.
After IPSG is enabled on an interface, the switch blocks all IP traffic received on the interface except for DHCP packets allowed by DHCP snooping.
The switch uses a source IP lookup table in hardware to bind IP addresses to ports. For IP and MAC filtering, a combination of source IP and source MAC lookups are used. IP traffic with a source IP address is the binding table is allowed, all other traffic is denied.
The IP source binding table has bindings that are learned by DHCP snooping or are manually configured (static IP source bindings). An entry in this table has an IP address, its associated MAC address, and its associated VLAN number. The switch uses the IP source binding table only when IP source guard is enabled.
IPSG is supported only on Layer 2 ports, including access and trunk ports. You can configure IPSG with source IP address filtering or with source IP and MAC address filtering.
IP Source Guard for Static Hosts
 Note | Do not use IPSG (IP source guard) for static hosts on uplink ports or trunk ports. |
IPSG for static hosts extends the IPSG capability to non-DHCP and static environments. The previous IPSG used the entries created by DHCP snooping to validate the hosts connected to a switch. Any traffic received from a host without a valid DHCP binding entry is dropped. This security feature restricts IP traffic on nonrouted Layer 2 interfaces. It filters traffic based on the DHCP snooping binding database and on manually configured IP source bindings. The previous version of IPSG required a DHCP environment for IPSG to work.
IPSG for static hosts allows IPSG to work without DHCP. IPSG for static hosts relies on IP device tracking-table entries to install port ACLs. The switch creates static entries based on ARP requests or other IP packets to maintain the list of valid hosts for a given port. You can also specify the number of hosts allowed to send traffic to a given port. This is equivalent to port security at Layer 3.
IPSG for static hosts also supports dynamic hosts. If a dynamic host receives a DHCP-assigned IP address that is available in the IP DHCP snooping table, the same entry is learned by the IP device tracking table. In a stacked environment, when the master failover occurs, the IP source guard entries for static hosts attached to member ports are retained. When you enter the show ip device tracking all EXEC command, the IP device tracking table displays the entries as ACTIVE.
Note | Some IP hosts with multiple network interfaces can inject some invalid packets into a network interface. The invalid packets contain the IP or MAC address for another network interface of the host as the source address. The invalid packets can cause IPSG for static hosts to connect to the host, to learn the invalid IP or MAC address bindings, and to reject the valid bindings. Consult the vender of the corresponding operating system and the network interface to prevent the host from injecting invalid packets. |
IPSG for static hosts initially learns IP or MAC bindings dynamically through an ACL-based snooping mechanism. IP or MAC bindings are learned from static hosts by ARP and IP packets. They are stored in the device tracking database. When the number of IP addresses that have been dynamically learned or statically configured on a given port reaches a maximum, the hardware drops any packet with a new IP address. To resolve hosts that have moved or gone away for any reason, IPSG for static hosts leverages IP device tracking to age out dynamically learned IP address bindings. This feature can be used with DHCP snooping. Multiple bindings are established on a port that is connected to both DHCP and static hosts. For example, bindings are stored in both the device tracking database as well as in the DHCP snooping binding database.
IP Source Guard Configuration Guidelines
-
You can configure static IP bindings only on nonrouted ports. If you enter the ip source binding mac-address vlan vlan-id ip-address interface interface-id global configuration command on a routed interface, this error message appears:
Static IP source binding can only be configured on switch port.
-
When IP source guard with source IP filtering is enabled on an interface, DHCP snooping must be enabled on the access VLAN for that interface.
-
If you are enabling IP source guard on a trunk interface with multiple VLANs and DHCP snooping is enabled on all the VLANs, the source IP address filter is applied on all the VLANs.
Note
If IP source guard is enabled and you enable or disable DHCP snooping on a VLAN on the trunk interface, the switch might not properly filter traffic.
-
You can enable this feature when 802.1x port-based authentication is enabled.
How to Configure IP Source Guard
Enabling IP Source Guard
2.
interface
interface-id
3.
ip verify source
[mac-check
]
4.
exit
5.
ip source binding
mac-address
vlan
vlan-id ip-address
interface
interface-id
DETAILED STEPS
Enabling IP source guard with source IP and MAC filtering on VLANs 10 and 11
Switch# configure terminal Enter configuration commands, one per line. End with CNTL/Z. Switch(config)# interface gigabitethernet 1/0/1 Switch(config-if)# ip verify source Switch(config-if)# exit Switch(config)# ip source binding 0100.0022.0010 vlan 10 10.0.0.2 interface gigabitethernet 1/0/1 Switch(config)# ip source binding 0100.0230.0002 vlan 11 10.0.0.4 interface gigabitethernet 1/0/1 Switch(config)# end
Configuring IP Source Guard for Static Hosts on a Layer 2 Access Port
You must configure the ip device tracking maximum limit-number interface configuration command globally for IPSG for static hosts to work. If you only configure this command on a port without enabling IP device tracking globally or by setting an IP device tracking maximum on that interface, IPSG with static hosts rejects all the IP traffic from that interface.
2.
ip device tracking
3.
interface
interface-id
4.
switchport mode access
5.
switchport access vlan
vlan-id
6.
ip verify source[tracking] [mac-check ]
7.
ip device tracking maximum
number
DETAILED STEPS
Eight Examples
This example shows how to stop IPSG with static hosts on an interface.
Switch(config-if)# no ip verify source Switch(config-if)# no ip device tracking max
This example shows how to enable IPSG with static hosts on a port.
Switch(config)# ip device tracking Switch(config-if)# ip device tracking maximum 10 Switch(config-if)# ip verify source tracking
This example shows how to enable IPSG for static hosts with IP filters on a Layer 2 access port and to verify the valid IP bindings on the interface Gi1/0/3:
Switch# configure terminal Enter configuration commands, one per line. End with CNTL/Z. Switch(config)# ip device tracking Switch(config)# interface gigabitethernet1/0/3 Switch(config-if)# switchport mode access Switch(config-if)# switchport access vlan 10 Switch(config-if)# ip device tracking maximum 5 Switch(config-if)# ip verify source tracking Switch(config-if)# end Switch# show ip verify source Interface Filter-type Filter-mode IP-address Mac-address Vlan --------- ----------- ----------- --------------- ----------------- ---- Gi1/0/3 ip trk active 40.1.1.24 10 Gi1/0/3 ip trk active 40.1.1.20 10 Gi1/0/3 ip trk active 40.1.1.21 10
This example shows how to enable IPSG for static hosts with IP-MAC filters on a Layer 2 access port, to verify the valid IP-MAC bindings on the interface Gi1/0/3, and to verify that the number of bindings on this interface has reached the maximum:
Switch# configure terminal Enter configuration commands, one per line. End with CNTL/Z. Switch(config)# ip device tracking Switch(config)# interface gigabitethernet1/0/3 Switch(config-if)# switchport mode access Switch(config-if)# switchport access vlan 1 Switch(config-if)# ip device tracking maximum 5 Switch(config-if)# ip verify source tracking Switch(config-if)# end Switch# show ip verify source Interface Filter-type Filter-mode IP-address Mac-address Vlan --------- ----------- ----------- --------------- ----------------- ---- Gi1/0/3 ip trk active deny-all 1
This example displays all IP or MAC binding entries for all interfaces. The CLI displays all active as well as inactive entries. When a host is learned on a interface, the new entry is marked as active. When the same host is disconnected from that interface and connected to a different interface, a new IP or MAC binding entry displays as active as soon as the host is detected. The old entry for this host on the previous interface is marked as INACTIVE.
Switch# show ip device tracking all
IP Device Tracking for wireless clients = Enabled
Global IP Device Tracking for wired clients = Enabled
Global IP Device Tracking Probe Count = 3
Global IP Device Tracking Probe Interval = 30
-----------------------------------------------------------------------------------------------
IP Address MAC Address Vlan Interface Probe-Timeout STATE
-----------------------------------------------------------------------------------------------
200.1.1.8 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
200.1.1.9 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
200.1.1.10 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
200.1.1.1 0001.0600.0000 9 GigabitEthernet1/0/2 ACTIVE
200.1.1.1 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
200.1.1.2 0001.0600.0000 9 GigabitEthernet1/0/2 ACTIVE
200.1.1.2 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
200.1.1.3 0001.0600.0000 9 GigabitEthernet1/0/2 ACTIVE
200.1.1.3 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
200.1.1.4 0001.0600.0000 9 GigabitEthernet1/0/2 ACTIVE
200.1.1.4 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
200.1.1.5 0001.0600.0000 9 GigabitEthernet1/0/2 ACTIVE
200.1.1.5 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
200.1.1.6 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
200.1.1.7 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
This example displays all active IP or MAC binding entries for all interfaces:
Switch# show ip device tracking all active
IP Device Tracking for wireless clients = Enabled
Global IP Device Tracking for wired clients = Enabled
Global IP Device Tracking Probe Count = 3
Global IP Device Tracking Probe Interval = 30
-----------------------------------------------------------------------------------------------
IP Address MAC Address Vlan Interface Probe-Timeout STATE
-----------------------------------------------------------------------------------------------
200.1.1.1 0001.0600.0000 9 GigabitEthernet1/0/1 ACTIVE
200.1.1.2 0001.0600.0000 9 GigabitEthernet1/0/1 ACTIVE
200.1.1.3 0001.0600.0000 9 GigabitEthernet1/0/1 ACTIVE
200.1.1.4 0001.0600.0000 9 GigabitEthernet1/0/1 ACTIVE
200.1.1.5 0001.0600.0000 9 GigabitEthernet1/0/1 ACTIVE
This example displays all inactive IP or MAC binding entries for all interfaces. The host was first learned on GigabitEthernet 1/0/1 and then moved to GigabitEthernet 0/2. the IP or MAC binding entries learned on GigabitEthernet1/ 0/1 are marked as inactive.
Switch# show ip device tracking all inactive
IP Device Tracking for wireless clients = Enabled
Global IP Device Tracking for wired clients= Enabled
Global IP Device Tracking Probe Count = 3
Global IP Device Tracking Probe Interval = 30
-----------------------------------------------------------------------------------------------
IP Address MAC Address Vlan Interface Probe-Timeout STATE
-----------------------------------------------------------------------------------------------
200.1.1.8 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
200.1.1.9 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
200.1.1.10 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
200.1.1.1 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
200.1.1.2 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
200.1.1.3 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
200.1.1.4 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
200.1.1.5 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
200.1.1.6 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
200.1.1.7 0001.0600.0000 8 GigabitEthernet1/0/1 INACTIVE
This example displays the count of all IP device tracking host entries for all interfaces:
Switch# show ip device tracking all count
Total IP Device Tracking Host entries: 5
---------------------------------------------------------------------
Interface Maximum Limit Number of Entries
---------------------------------------------------------------------
Gi1/0/3 5
Monitoring IP Source Guard
|
Command |
Purpose |
|---|---|
|
Displays the IP source guard configuration on the switch or on a specific interface. |
|
|
show ip device tracking { all | interface interface-id | ip ip-address | mac imac-address} |
Displays information about the entries in the IP device tracking table. |
|
Command |
Purpose |
|---|---|
|
Verifies the data source. |
For detailed information about the fields in these displays, see the command reference for this release.
Additional References
Error Message Decoder
| Description | Link |
|---|---|
|
To help you research and resolve system error messages in this release, use the Error Message Decoder tool. |
https://www.cisco.com/cgi-bin/Support/Errordecoder/index.cgi |
MIBs
| MIB | MIBs Link |
|---|---|
|
All supported MIBs for this release. |
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: |
Technical Assistance
| Description | Link |
|---|---|
|
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password. |
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