14.9.11 Packet Tracer - Layer 2 Vlan Security Direct

Instead of using VLAN 1 (the default native VLAN), change it to, for example, VLAN 999.

interface g0/1 switchport trunk native vlan 999 Then, ensure VLAN 999 exists but is used nowhere else. No user devices, no DHCP, no routing.

The four techniques in form the backbone of the Cisco Cyber Threat Defense model: 14.9.11 packet tracer - layer 2 vlan security

In the world of networking, we often talk about firewalls, ACLs, and encryption. But what happens if an attacker simply unplugs a legitimate user’s laptop and plugs in a rogue device? What if they spoof a VLAN or launch a MAC flood?

ip dhcp snooping ip dhcp snooping vlan 10,20 interface g0/1 ip dhcp snooping trust interface range fa0/1-24 ip dhcp snooping limit rate 10 no ip dhcp snooping trust Now, only the uplink port can send DHCP Offer/ACK messages. Any rogue server on an access port will be ignored. Instead of using VLAN 1 (the default native

DHCP Snooping.

Layer 2 security is invisible when done right. But when it's missing, the whole network crumbles. What other Layer 2 attacks worry you most—CDP/LLDP recon, STP manipulation, or ARP poisoning? Drop a comment below. The four techniques in form the backbone of

That’s where comes in. It’s the often-overlooked foundation of network defense.

Disable DTP and set trunking manually.

Never use VLAN 1 for anything. Not for native VLAN, not for management, not for users. VLAN 1 is the universal key to many Layer 2 attacks. Step 4: DHCP Snooping – Stopping the Rogue Server The Threat: An attacker plugs in a laptop running a rogue DHCP server. When legitimate clients broadcast for an IP, the rogue server replies first, giving them a malicious gateway (the attacker) or a bogus DNS server (phishing).

On the access ports connecting to end devices (Fa0/1, Fa0/2, etc.), you need to lock down the MAC addresses.