Netband Project - IP Source Guard

<accesscontrol>NetBand</accesscontrol> This page is part of the Netband Project

IP source guard 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. You can use IP source guard to prevent traffic attacks caused when a host tries to use the IP address of its neighbor.
IP source guard is supported only on Layer 2 ports, including access and trunk ports
An ACL is applied to the interface, which allows only IP traffic with a source IP address in the IP source binding table and denies all other traffic.
Filtering options
- Source IP address
  - The switch forwards IP traffic when the source IP address matches an entry in the DHCP snooping binding database or a binding in the IP source binding table.
- Source IP and MAC Address
  - The switch forwards traffic only when the source IP and MAC addresses match an entry in the IP source binding table.
  - Filters both ip and non-ip traffic
  - Port security is used to filter source MAC addresses
  - Is not supported on pvlan

Configuration

DHCP snooping must be configured correctly, for IP source guard to work properly

Source IP -and Mac address filtering

interface FastEthernet0/10
 ip verify source port-security

Source IP address filtering

interface FastEthernet0/10
 ip verify source

Statically assigned IP -and Mac address entry

ip source binding 0003.47C9.A1D8 vlan 3 10.1.1.11 interface Fa0/1

Verification

HQSW1#sh ip source binding
MacAddress          IpAddress        Lease(sec)  Type           VLAN  Interface
------------------  ---------------  ----------  -------------  ----  --------------------
00:03:47:C9:A1:D8   10.1.1.11        infinite    static         3     FastEthernet0/1
00:1B:2A:79:5F:53   10.1.2.52        185         dhcp-snooping  5     FastEthernet0/13
00:03:47:C9:9F:AC   10.1.1.10        233         dhcp-snooping  3     FastEthernet0/2
00:21:5A:F7:F1:01   10.1.2.50        228         dhcp-snooping  5     FastEthernet0/11
Total number of bindings: 4