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Network Security Key concepts

Switch Security Features

Cisco SAFE Framework

  • Cisco SAFE is a security architectural framework designed to protect against evolving threats like phishing, malware, and ransomware. It ensures comprehensive security across the network in various "places in the network" (PINs).

Next-Generation Intrusion Prevention System (NGIPS)

  • NGIPS is an advanced system for detecting and preventing intrusion attacks. It can log, analyze, and block malicious activities. NGIPS is available in physical appliances, virtual machines, or integrated with other Cisco systems like ISR.
    • Firepower appliances provide dedicated hardware for intrusion prevention.
    • NGIPS Virtual (NGIPSv) is available for virtualization environments.

Technical Tip: NGIPS should be strategically deployed in areas with high traffic, such as edge devices or data centers, to monitor for anomalies effectively.

Next-Generation Firewall (NGFW)

  • NGFW provides stateful inspection by monitoring network traffic and applying security policies based on packet contents. It combines traditional firewall capabilities with advanced filtering for applications and deep packet inspection.

Cisco Identity Services Engine (ISE)

  • Cisco ISE provides Network Access Control (NAC) by identifying users and devices connected to the network. It supports advanced policies like:
    • 802.1x authentication
    • MAC Authentication Bypass (MAB)
    • Web Authentication (WebAuth)
    • Enhanced Flexible Authentication (FlexAuth): Allows concurrent use of multiple authentication methods, reducing delays in endpoint authentication.

Technical Tip: Configure ISE with Enhanced FlexAuth to reduce delays for non-802.1x devices by enabling concurrent MAB and WebAuth alongside 802.1x.

Cisco TrustSec

  • Cisco TrustSec is a scalable network access control solution using Security Group Tags (SGT) for policy enforcement. TrustSec reduces the need for maintaining numerous ACLs by tagging traffic at the ingress, and applying access control based on SGT tags at egress points.

Technical Tip: TrustSec tags can be integrated with Cisco's Software-Defined Access (SD-Access) solution for scalable access control across multiple sites or devices.

VACL, PACL

  • Port ACLs (PACLs): Applied to Layer 2 interfaces to control incoming traffic. They filter IP and non-IP traffic based on source and destination MAC addresses.
  • VLAN ACLs (VACLs): Used to filter traffic within a VLAN. VACLs are directionless and applied globally to VLANs.
    • VLAN maps: Used to apply VACLs with matching conditions and actions.

Technical Tip: PACLs take precedence over VACLs and Router ACLs (RACLs). They are applied first on incoming traffic.

Example Configuration:

ip access-list extended TELNET

 permit tcp any any eq 23

exit

vlan access-map VACL_20 10

 match ip address TELNET

 action drop log

Storm Control

  • Storm control mitigates traffic flooding on LANs from broadcast, multicast, or unicast storms.
  • Measured by:
    • Bandwidth percentage
    • Packet rate (pps)

Technical Tip: Storm control should be enabled on interfaces facing user devices to avoid disruption during traffic floods.

Example Configuration:

storm-control broadcast level 20

DHCP Snooping & Option 82

  • DHCP Snooping: Protects against rogue DHCP servers. It classifies ports as trusted (allowed to forward DHCP traffic) or untrusted (blocked).
  • Option 82: Provides additional information (circuit IDs) about the source of DHCP requests.

Technical Tip: Only configure trusted ports on interfaces connected to the DHCP server.

Example Configuration:

ip dhcp snooping vlan 10

ip dhcp snooping information option

IP Source Guard (IPSG)

  • IPSG: Prevents IP spoofing by filtering traffic based on the DHCP snooping database. It only allows traffic from valid IP-to-MAC bindings.

Technical Tip: Enable IPSG on all access ports to block IP spoofing attempts from rogue devices.

Example Configuration:

ip verify source port-security

Dynamic ARP Inspection (DAI)

  • DAI: Prevents man-in-the-middle attacks by validating ARP packets against the DHCP snooping database.
  • Trusted interfaces forward ARP traffic without inspection, while untrusted interfaces are inspected.

Technical Tip: Set ARP rate limits on untrusted interfaces to prevent excessive ARP packets from overwhelming the switch.

Example Configuration:

ip arp inspection vlan 10

ip arp inspection limit rate 15

Port Security

  • Port Security: Limits the number of MAC addresses on a port, preventing unauthorized devices from accessing the network.
  • Violation Modes:
    • Protect: Drops packets with unknown MAC addresses without notification.
    • Restrict: Drops and logs violations.
    • Shutdown: Disables the port on a violation.

Technical Tip: Use sticky MAC to learn and bind secure MAC addresses dynamically.

Example Configuration:

switchport port-security mac-address sticky

Private VLANs

  • Private VLANs (PVLANs): Partition a single VLAN into isolated sub-VLANs for enhanced security.
    • Promiscuous Ports: Can communicate with all secondary VLANs.
    • Isolated Ports: Cannot communicate with each other but can communicate with promiscuous ports.
    • Community Ports: Can communicate within the same community VLAN but not with other communities.

Technical Tip: Use VTPv3 to manage Private VLANs across multiple switches, ensuring proper VLAN propagation.

Example Configuration:

vlan 20

private-vlan primary

private-vlan association 501-503

Router Security Features

IPv6 Traffic Filters

  • IPv6 ACLs can be applied to interfaces to filter incoming and outgoing IPv6 traffic.

IPv4 Access Control Lists (ACLs)

  • Standard ACLs: Match on source IP addresses.
  • Extended ACLs: Match on source, destination, and protocol.

Technical Tip: Use Named ACLs for easier management, as they allow editing and resequencing of individual ACEs.

Example Configuration:

ip access-list extended WEB_FILTER

 deny tcp any any eq 80

Unicast Reverse Path Forwarding (uRPF)

  • uRPF: Prevents IP spoofing by verifying that the source address of incoming packets has a valid path in the routing table.

IPv6 Infrastructure Security

  • RA Guard: Protects against rogue router advertisements in IPv6 networks.
  • DHCP Guard: Blocks DHCP server responses from unauthorized interfaces.
  • ND Inspection: Validates Neighbor Discovery packets for IPv6.

Technical Tip: Always enable IPv6 security features to mitigate IPv6-specific vulnerabilities like rogue RA attacks.

IEEE 802.1X Port-Based Authentication

Device Roles and Port States

  • 802.1X: Ensures devices authenticate before accessing the network.

Authentication Process

  • MAC Authentication Bypass (MAB): A fallback for non-802.1X devices, using the MAC address for authentication.

Technical Tip: Use MAB with restricted access policies and downloadable ACLs to prevent unauthorized access.

Example Configuration:

authentication order mab dot1x

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