Rule ID
SV-273682r1111010_rule
Version
V1R1
CCIs
IP Source Guard provides source IP address filtering on a layer 2 port to prevent a malicious host from impersonating a legitimate host by assuming the legitimate host's IP address. The feature uses dynamic DHCP snooping and static IP source binding to match IP addresses to hosts on untrusted layer 2 access ports. Initially, all IP traffic on the protected port is blocked except for DHCP packets. After a client receives an IP address from the DHCP server, or after static IP source binding is configured by the administrator, all traffic with that IP source address is permitted from that client. Traffic from other hosts is denied. This filtering limits a host's ability to attack the network by claiming a neighbor host's IP address.
Review the configuration for source-guard enabled on user-facing or untrusted ports. interface ethernet 1/1/47 port-name FlexAuth_port authentication source-guard-protection enable ! interface ethernet 1/1/48 source-guard enable ! If all user-facing or untrusted switch ports are not configured for IP Source Guard, this is a finding.
Configure the switch to have source-guard enabled on all user-facing or untrusted access switch ports. 1. Interface only: device# configure terminal device(config)# interface ethernet 1/1/4 device(config-if-e10000-1/1/4)# source-guard enable Optional Step 2: Apply to range of interfaces: device# configure terminal device(config)# interface ethernet 1/1/1 device(config-if-e10000-1/1/1)# interface ethernet 1/1/21 to 1/1/25 device(config-mif-1/1/21-1/1/25)# source-guard enable Optional Step 2: Apply to VLAN single port: device# configure terminal device(config)# vlan 12 device(config-vlan-12)# untagged ethernet 1/1/5 to 1/1/8 device(config-vlan-12)# tagged ethernet 1/1/23 to 1/1/24 device(config-vlan-12)# source-guard enable ethernet 1/1/23 Optional Step 2: Apply to VLAN all ports: device# configure terminal device(config)# vlan 12 device(config-vlan-12)# untagged ethernet 1/1/5 to 1/1/8 device(config-vlan-12)# tagged ethernet 1/1/23 to 1/1/24 device(config-vlan-12)# source-guard enable Optional Step 2: Apply to VLAN LAG port: device# configure terminal device(config)# vlan 12 device(config-vlan-12)# tagged lag 9 device(config-vlan-12)# source-guard enable lag 9 Note: Ports with FlexAuth (802.1X/MAC Auth) will require the keyword "authentication source-guard-protection enable" to apply this feature.