How do you secure VLANs against attacks such as VLAN hopping and spoofing?

Port Security Settings 802.1X Authentication VLAN Segmentation Detection and Prevention of VLAN Hopping Attacks MAC Address Filtering Security Policies and Education Network Monitoring and Logging Up-to-date Software and Firmware Usage Physical Security Measures Continuous Improvement and Evaluation

Do NOT use vlan 1 as the native vlan. Ideally, create a new VLAN, disable it and configure it as native on every trunk and also on every access port that is not used.

In a past project, we identified a VLAN hopping attack where an attacker gained access to another VLAN by sending double-tagged frames. This allowed unauthorized access to sensitive traffic. To fix the issue, we disabled Dynamic Trunking Protocol (DTP) on unused ports, restricted trunk links to necessary VLANs, and assigned the native VLAN to an unused ID. We also detected MAC spoofing attempts, so we enabled port security, DHCP snooping, and Dynamic ARP Inspection (DAI) to block further attacks. This incident reinforced the importance of VLAN security to prevent unauthorized access and maintain network integrity.

Follow a standard set of basic configuration items on all user facing switchports. Set them to not dynamically negotiate trunks, and use other features such as STP security features to prevent users from connecting devices that may promote VLAN hopping.

Following good security practices is crucial and should be given the highest priority to minimize the risk of VLAN hopping. Turn off any ports that are not being used on your network. This helps reduce the chances of someone getting unauthorized access through those unused ports. Limit the use of VLANs on trunk ports to only those instances where necessary. Opt for manual configuration of access ports using the switchport mode access command to enhance control and security. Effective switch configuration plays a pivotal role in mitigating the risks. To mitigate switch spoofing, deactivate the autotrunking feature on switches not requiring trunking. Designate ports that shouldn't function as trunks to be configured explicitly as access ports

To prevent VLAN hopping, follow these key steps: 1. Disable Dynamic Trunking Protocol (DTP):Disable trunking on all ports that don’t require it by setting the ports to access mode to prevent attackers from negotiating a trunk link. 2. Manually Configure Trunks: Only enable trunking on ports that connect to other switches. Avoid auto-negotiation, and configure trunks manually. 3. Limit VLANs on Trunks: Use the `switchport trunk allowed vlan` command to specify which VLANs are allowed on each trunk port, restricting access to only necessary VLANs. 4. Avoid Default and Native VLANs: Don’t use VLAN 1 or the native VLAN for data traffic, as they are more prone to VLAN hopping. Assign an unused VLAN as the native VLAN

During a large office network deployment, we encountered a situation where users reported frequent connection drops.we discovered an attacker was spoofing MAC addresses, overwhelming the network with rogue devices, and causing disruptions. To address this, we enabled dynamic port security on all access ports, allowing the switches to limit the number of allowed MAC addresses per port. This immediately stopped the attack by restricting unauthorized MAC addresses. Any attempt to spoof resulted in the port shutting down temporarily, alerting us to the intrusion. Additionally, to prevent IP spoofing, we implemented DHCP snooping. This allowed the switches to monitor DHCP messages and ensure only trusted DHCP servers could allocate ip Address.

L’usurpation d’identité VLAN est une menace sérieuse pour la sécurité des réseaux. Voici quelques mesures que vous pouvez prendre pour prévenir l’usurpation d’identité VLAN : Utilisez le protocole de sécurité VLAN (VLAN Security Protocol) Désactivez les ports inutilisés Utilisez l’authentification 802.1X Mettez en place une politique de sécurité stricte Mettez régulièrement à jour votre logiciel de sécurité Mettez régulièrement à jour votre logiciel de sécurité Formez vos employés

La surveillance et le dépannage des VLAN (Virtual Local Area Network) sont des tâches essentielles pour maintenir la santé et la sécurité de votre réseau quelques étapes que vous pouvez suivre : 1-Comprendre les VLAN 2-Utiliser des outils de gestion de réseau 3-Surveiller la table CAM Enfin, il est important de surveiller régulièrement votre réseau pour détecter toute activité suspecte. Si vous soupçonnez un problème avec un VLAN, il est important d’agir rapidement pour minimiser les dommages.

Be purposeful with your VLAN configuration. Ensure that segmentation is occurring in a way that makes it easy to control access in the future.

quelques-unes des meilleures pratiques pour la configuration et la gestion des VLAN : 1-Comprendre les numéros de VLAN et les ID de VLAN 2-Configuration des interfaces VLAN 3-Communication inter-VLAN 4-Sécurisation des VLAN avec des listes de contrôle d’accès 5-Optimisation des performances VLAN 6-Utilisation de VLANs dynamiques pour une meilleure flexibilité 7-Mise en place de politiques de sécurité strictes pour chaque VLAN 8-Régulière mise à jour et surveillance des configurations de VLAN

Use a method higher in the stack other than VLANS to act as a secondary enforcement for security policies. Most vendors have solutions like Cisco's Trust Sec to harden the network as a whole where even if a VLAN is hopped, the traffic will still be confined to the tag the user authenticated with.