Which UDP ports are commonly used for IKE negotiation messages in IPsec-based VPNs?

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Multiple Choice

Which UDP ports are commonly used for IKE negotiation messages in IPsec-based VPNs?

Explanation:
IKE negotiation for IPsec VPNs relies on UDP to traverse network devices. The standard ports involved are UDP 500 for the initial ISAKMP/IKE exchanges that establish security associations, and UDP 4500 for NAT traversal when devices are behind NAT. NAT-T encapsulates ESP (and related IKE traffic) so it can pass through NAT devices reliably, which is why 4500 is used alongside 500 in typical deployments. The other ports listed map to different services—DNS (UDP 53), OpenVPN’s common port (UDP 1194), and SSH (UDP 22)—and are not used for IKE negotiation in IPsec.

IKE negotiation for IPsec VPNs relies on UDP to traverse network devices. The standard ports involved are UDP 500 for the initial ISAKMP/IKE exchanges that establish security associations, and UDP 4500 for NAT traversal when devices are behind NAT. NAT-T encapsulates ESP (and related IKE traffic) so it can pass through NAT devices reliably, which is why 4500 is used alongside 500 in typical deployments.

The other ports listed map to different services—DNS (UDP 53), OpenVPN’s common port (UDP 1194), and SSH (UDP 22)—and are not used for IKE negotiation in IPsec.

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