IP Source Guard
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Web – Click DHCP Snooping, DHCP Snooping Binding Information.
Figure 3-118 DHCP Snooping Binding Information
CLI – This example shows how to display the DHCP Snooping binding table entries.
IP Source Guard
IP Source Guard is a security feature that filters IP traffic on network interfaces
based on manually configured entries in the IP Source Guard table, or static and
dynamic entries in the DHCP Snooping table when enabled (see “DHCP Snooping”
on page 3-186). IP source guard can be used to prevent traffic attacks caused when
a host tries to use the IP address of a neighbor to access the network. This section
describes commands used to configure IP Source Guard.
Note:
Due to a chip limitation, IP source guard and Quality of Service (only for IP related
QoS function) cannot be enabled at the same time. Thus, if the user has already
enabled the IP source guard function, it needs to be disabled first in order for the
QoS function to work and vice versa.
IP Source Guard Port Configuration
IP Source Guard is used to filter traffic on an unsecure port which receives
messages from outside the network or firewall, and therefore may be subject to
traffic attacks caused by a host trying to use the IP address of a neighbor.
When enabled, traffic is filtered based upon dynamic entries learned via DHCP
snooping or static addresses configured in the source guard binding table. An
inbound packet’s IP address (sip option) or both its IP address and corresponding
MAC address (sip-mac option) are checked against the binding table. If no matching
entry is found, the packet is dropped.
Console#show ip dhcp snooping binding 4-237
MacAddress IpAddress Lease(sec) Type VLAN
Interface
----------------- --------------- ---------- -------------------- ---- --
11-22-33-44-55-66 192.168.0.99 0 Dynamic 1 Eth
1/5
Console#
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