|The Cisco switch must uniquely identify and authenticate all network-connected endpoint devices before establishing any connection.
|Controlling LAN access via 802.1x authentication can assist in preventing a malicious user from connecting an unauthorized PC to a switch port to inject or receive data from the network without detection.
|The Cisco switch must have all disabled switch ports assigned to an unused VLAN.
|It is possible that a disabled port that is assigned to a user or management VLAN becomes enabled by accident or by an attacker and as a result gains access to that VLAN as a member.
|The Cisco switch must have all trunk links enabled statically.
|When trunk negotiation is enabled via Dynamic Trunk Protocol (DTP), considerable time can be spent negotiating trunk settings (802.1q or ISL) when a node or interface is restored. While this...
|The Cisco switch must enable Unidirectional Link Detection (UDLD) to protect against one-way connections.
|In topologies where fiber optic interconnections are used, physical misconnections can occur that allow a link to appear to be up when there is a mismatched set of transmit/receive pairs. When...
|The Cisco switch must implement Rapid STP where VLANs span multiple switches with redundant links.
|Spanning Tree Protocol (STP) is implemented on bridges and switches to prevent layer 2 loops when a broadcast domain spans multiple bridges and switches and when redundant links are provisioned to...
|The Cisco switch must have Dynamic Address Resolution Protocol (ARP) Inspection (DAI) enabled on all user VLANs.
|DAI intercepts Address Resolution Protocol (ARP) requests and verifies that each of these packets has a valid IP-to-MAC address binding before updating the local ARP cache and before forwarding...
|The Cisco switch must have IP Source Guard enabled on all user-facing or untrusted access switch ports.
|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...
|The Cisco switch must have the default VLAN pruned from all trunk ports that do not require it.
|The default VLAN (i.e., VLAN 1) is a special VLAN used for control plane traffic such as Spanning-Tree Protocol (STP), Dynamic Trunking Protocol (DTP), VLAN Trunking Protocol (VTP), and Port...
|The Cisco switch must not have the default VLAN assigned to any host-facing switch ports.
|In a VLAN-based network, switches use the default VLAN (i.e., VLAN 1) for in-band management and to communicate with other networking devices using Spanning-Tree Protocol (STP), Dynamic Trunking...
|The Cisco switch must have Unknown Unicast Flood Blocking (UUFB) enabled.
|Access layer switches use the Content Addressable Memory (CAM) table to direct traffic to specific ports based on the VLAN number and the destination MAC address of the frame. When a router has an...
|The Cisco switch must have DHCP snooping for all user VLANs to validate DHCP messages from untrusted sources.
|In an enterprise network, devices under administrative control are trusted sources. These devices include the switches, routers, and servers in the network. Host ports and unknown DHCP servers are...
|The Cisco switch must authenticate all VLAN Trunk Protocol (VTP) messages with a hash function using the most secured cryptographic algorithm available.
|VLAN Trunk Protocol (VTP) provides central management of VLAN domains, thus reducing administration in a switched network. When configuring a new VLAN on a VTP server, the VLAN is distributed...
|The Cisco switch must manage excess bandwidth to limit the effects of packet flooding types of denial of service (DoS) attacks.
|Denial of service is a condition when a resource is not available for legitimate users. Packet flooding DDoS attacks are referred to as volumetric attacks and have the objective of overloading a...
|The Cisco switch must have BPDU Guard enabled on all user-facing or untrusted access switch ports.
|If a rogue switch is introduced into the topology and transmits a Bridge Protocol Data Unit (BPDU) with a lower bridge priority than the existing root bridge, it will become the new root bridge...
|The Cisco switch must have STP Loop Guard enabled.
|The Spanning Tree Protocol (STP) loop guard feature provides additional protection against STP loops. An STP loop is created when an STP blocking port in a redundant topology erroneously...
|The Cisco switch must not use the default VLAN for management traffic.
|Switches use the default VLAN (i.e., VLAN 1) for in-band management and to communicate with directly connected switches using Spanning-Tree Protocol (STP), Dynamic Trunking Protocol (DTP), VLAN...
|The Cisco switch must have all user-facing or untrusted ports configured as access switch ports.
|Double encapsulation can be initiated by an attacker who has access to a switch port belonging to the native VLAN of the trunk port. Knowing the victim's MAC address and with the victim attached...
|The Cisco switch must have the native VLAN assigned to an ID other than the default VLAN for all 802.1q trunk links.
|VLAN hopping can be initiated by an attacker who has access to a switch port belonging to the same VLAN as the native VLAN of the trunk link connecting to another switch that the victim is...
|The Cisco switch must have IGMP or MLD Snooping configured on all VLANs.
|IGMP and MLD snooping provides a way to constrain multicast traffic at Layer 2. By monitoring the IGMP or MLD membership reports sent by hosts within a VLAN, the snooping application can set up...
|The Cisco switch must have Storm Control configured on all host-facing switchports.
|A traffic storm occurs when packets flood a LAN, creating excessive traffic and degrading network performance. Traffic storm control prevents network disruption by suppressing ingress traffic when...
|The Cisco switch must have Root Guard enabled on all switch ports connecting to access layer switches.
|Spanning Tree Protocol (STP) does not provide any means for the network administrator to securely enforce the topology of the switched network. Any switch can be the root bridge in a network....
|The Cisco switch must not have any switchports assigned to the native VLAN.
|Double encapsulation can be initiated by an attacker who has access to a switch port belonging to the native VLAN of the trunk port. Knowing the victim’s MAC address and with the victim attached...