Uses UDP port 500 (and UDP port 4500 when crossing NAT) Negotiates a tunnel’s private keys, authentication, and encryption One lPsec SA is used per traffic direction. Phases: Phase1 Phase2
IKE
ESP
AH
Phase 1 negotiation modes
main mode aggresive mode
main mode quick mode
Phase 2 negotiation mode
aggresive mode
quick mode
takes place when each endpoint of the tunnel—the initiator and the responder—connects and begins to set up the VPN.
Phase 1
Phase 2
❌ Negotiate one bidirectional SA (called IKE SA) *ln IKE v1, two possible ways: -Main mode: six packets exchanged -Aggressive mode: three packets exchanged *Not the same as final SAs later *Encrypted tunnel for Diffie-Hellman (DH)
❌ Authenticate peers *Pre—shared key or digital signature *Extended authentication (XAuth)
❌ DH exchange for secret keys
Key agreement method: Independently calculate a private key using only public keys
Each FortiGate uses a shared secret key plus a nonce to calculate keys for the following: Symmetric encryption algorithms (such as 3DES, AES) Symmetric authentication (HMACs)
Diffie-Hellman
ESP can´t support NAT because it has no port numbers.
Negotiates two unidirectional SAs for ESP (called lPsec SAS) Protected by phase IKE SA When SAs are about to expire, it renegotiates Optionally, if Perfect Forward Secrecy is set to Enabled, FortiGate uses Diffie-Hellman to generate new keys each time phase 2 expires. Each phase 1 can have multiple phase 2s. High security subnets can have stronger ESP.
Also, if you set ____________ to Enable, each time phase 2 expires, FortiGate will use Diffie-Hellman to recalculate new secret keys. In this way, new keys are not derived from older keys, making it much harder for an attacker to crack the tunnel.
Perfect Forward Secrecy
NAT-Transversal
Split tunneling
If multiple phase 2 exist, FortiGate directs traffic to the correct phase 2. Allows granular security settings for each LAN. If traffic does not match an lPsec SA selector, it is dropped. ln point-to-pointVPNs, selectors must match. - The source on one FortiGate is the destination setting on the other.
Select which SA to apply using: Destination and source IP subnet(s) Protocol number Source port and destination port
Quick mode selectors
Agressive mode
During phase 2, you must configure a pair of settings called quick mode selectors. They identify and direct traffic to the appropriate phase 2. In other words, they allow granular SAs.
In aggressive mode, how many packets are exchanged to establish phase 1 of the lPsec tunnel?
A. Six
B. Three
Which statement about quick mode selectors is true?
A. Only phase 2 has quick mode selectors.
B. Only phase 1 has quick mode selectors.
Settings need in Dialup VPN between two fortigates
A phase 1 At least one phase 2 Firewall policies Static routes or a dynamic routing protocol
A phase 1 At least one phase 2 Firewall policies Static routes or a dynamic routing protocol IPsec interface
Dialup IPsec is also known as
A. point-to-point
B. point-to—multipoint
IKE mode configuration automatically configures network settings?
A. client
B. server
