Supported IPSec Parameters

This topic lists the supported phase 1 (ISAKMP) and phase 2 (IPSec) configuration parameters for Site-to-Site VPN. Oracle chose these values to maximize security and to cover a wide range of CPE devices. If your CPE device is not on the list of verified devices, use the information here to configure your device.

You can also use the CPE Configuration Helper to gather information that a network engineer uses when configuring the CPE device.

Important

Oracle uses asymmetric routing across the multiple tunnels that make up the IPSec connection. Even if you configure one tunnel as primary and another as backup, traffic from your VCN to your on-premises network can use any tunnel that is "up" on your device. Configure your firewalls accordingly. Otherwise, ping tests or application traffic across the connection will not reliably work.

Supported Encryption Domain or Proxy ID

The values for the encryption domain (also known as a proxy ID, security parameter index (SPI), or traffic selector) depend on whether your CPE supports route-based tunnels or policy-based tunnels. For more information about the correct encryption domain values to use, see Supported Encryption Domain or Proxy ID.

Custom IKE and IPSec Parameters

When using custom internet key exchange (IKE) or IPSec parameters, if you select custom phase 1 proposals the CPE must be configured to accept the exact proposal. A mismatch prevents IKE from setting up the IPSec tunnel phase one security association.

For custom phase 2 IPSec proposals, expect the following behavior:

  • When Oracle initiates a new phase 2 IPSec security association, IKE only proposes the custom values.
  • When the CPE initiates a new phase 2 IPSec security association, the phase 2 security association is established as long as Oracle supports the parameters.

Oracle IKE Initiation and IP Fragments

The default set of Oracle IKE parameter proposals is too large to fit into a single UDP packet, so the Oracle end of the IPSec connection fragments the initiation request. To successfully initiate a new IKE security association, any firewall or security list between the Oracle VPN Public IP and the CPE must allow IP fragments.

Supported Parameters for the Commercial Cloud

This section lists the supported parameters if your Site-to-Site VPN is for the commercial cloud. For a list of the commercial cloud regions, see Regions and Availability Domains.

For some parameters, Oracle supports multiple values, and the recommended one is noted.

Oracle supports the following parameters for IKEv1 or IKEv2. Check the documentation for your particular CPE to confirm which parameters the CPE supports for IKEv1 or IKEv2.

Phase 1 (ISAKMP)

Parameter Options
ISAKMP Protocol

Version 1

Exchange type

Main mode

Authentication method

Pre-shared keys *

Encryption algorithm

AES-256-CBC (recommended)

AES-192-CBC

AES-128-CBC

Authentication algorithm

SHA-2 384 (recommended)

SHA-2 256

SHA-1 (also called SHA or SHA1-96) **

Diffie-Hellman group

group 2 (MODP 1024-bit)

group 5 (MODP 1536-bit)

group 14 (MODP 2048-bit)

group 19 (ECP 256-bit random)

group 20 (ECP 384-bit random) (recommended)

IKE session key lifetime

28800 seconds (8 hours)

* Only numbers, letters, and spaces are allowed characters in pre-shared keys.

** Oracle strongly recommends against the use of SHA-1. NIST formally deprecated use of SHA-1 in 2011 and disallowed its use for digital signatures in 2013.

Phase 2 (IPSec)

Parameter Options
IPSec Protocol

ESP, tunnel mode

Encryption algorithm

AES-256-GCM (recommended)

AES-192-GCM

AES-128-GCM

AES-256-CBC

AES-192-CBC

AES-128-CBC

Authentication algorithm

If using GCM, no authentication algorithm is required because authentication is included with GCM encryption.

If not using GCM, the following options are supported:

HMAC-SHA-256-128 (recommended)

HMAC-SHA1-128 *

IPSec session key lifetime

3600 seconds (1 hour)

Perfect Forward Secrecy (PFS)

Enabled, group 5 (default, recommended)

Supports disabled as well as enabled for group 2, 5, 14, 19, 20, 24.

* Oracle strongly recommends against the use of SHA-1. NIST formally deprecated use of SHA-1 in 2011 and disallowed its use for digital signatures in 2013.

Supported Parameters for the Government Cloud

This section lists the supported parameters if your Site-to-Site VPN is for the Government Cloud. For more information, see For All US Government Cloud Customers.

For some parameters, Oracle supports multiple values, and the recommended one is highlighted in bold text.

Oracle supports the following parameters for IKEv1 or IKEv2. Check the documentation for your particular CPE to confirm which parameters the CPE supports for IKEv1 or IKEv2.

Phase 1 (ISAKMP)

Parameter Options
ISAKMP protocol

Version 1

Exchange type

Main mode

Authentication method

Pre-shared keys *

Encryption algorithm

AES-256-CBC (recommended)

AES-192-CBC

AES-128-CBC

Authentication algorithm

SHA-2 384 (recommended)

SHA-2 256

SHA-1 (also called SHA or SHA1-96)

Diffie-Hellman group

group 14 (MODP 2048)

group 19 (ECP 256)

group 20 (ECP 384) (recommended)

IKE session key lifetime

28800 seconds (8 hours)

* Only numbers, letters, and spaces are allowed characters in pre-shared keys.

Phase 2 (IPSec)

Parameter Options
IPSec protocol

ESP, tunnel mode

Encryption algorithm

AES-256-GCM (recommended)

AES-192-GCM

AES-128-GCM

AES-256-CBC

AES-192-CBC

AES-128-CBC

Authentication algorithm

If using GCM (Galois/Counter Mode), no authentication algorithm is required because authentication is included with GCM encryption.

If not using GCM, use HMAC-SHA-256-128.

IPSec session key lifetime

3600 seconds (1 hour)

Perfect Forward Secrecy (PFS)

Enabled, group 14 (default, recommended)

Supports disabled as well as enabled for group 2, 5, 14, 19, 20, 24.

References

If you're not already familiar with the parameters mentioned previously, Links to relevant standards are provided in the following tables.

Option Relevant Standard
Advanced Encryption Standard (AES) FIPS PUB 197 standard
Cipher Block Chaining (CBC) SP 800-38A standard
Secure Hash Algorithm (SHA) FIPS PUB 180-4 standard
Diffie-Hellman (DH) groups

RFC 2631: Diffie-Hellman Key Agreement Method

RFC 3526: More Modular Exponential (MODP) Diffie-Hellman groups for Internet Key Exchange (IKE)

RFC 4306: Internet Key Exchange (IKEv2) Protocol

DH group type: Modular Exponential (MODP) or Elliptic Curve Prime (ECP)

MODP RFC 3526: More Modular Exponential (MODP) Diffie-Hellman groups for Internet Key Exchange (IKE)

ECP RFC 5114: Additional Diffie-Hellman Groups for Use with IETF Standards

Galois Counter Mode (GCM) RFC 5288: AES Galois Counter Mode (GCM) Cipher Suites for TLS
Perfect Forward Secrecy (PFS) RFC 2412: The OAKLEY Key Determination Protocol