9 Specify the IKE Settings.[IKE Mode]The mode used for the key exchange protocol is displayed. The machine supports the main mode, not theaggressive mode.[Authentication Method]Select [Pre-Shared Key Method] or [Digital Signature Method] for the method used when authenticating themachine. You need to enable TLS for the Remote UI before selecting [Pre-Shared Key Method] ( EnablingTLS Encrypted Communication for the Remote UI(P. 570) ). You need to generate or install a key pairbefore selecting [Digital Signature Method] ( Configuring Settings for Key Pairs and DigitalCertificates(P. 588) ).[Valid for]Specify how long a session lasts for IKE SA (ISAKMP SA). Enter the time in minutes.[Authentication]/[Encryption]/[DH Group]Select an algorithm from the drop-down list. Each algorithm is used in the key exchange.[Authentication] Select the hash algorithm.[Encryption] Select the encryption algorithm.[DH Group] Select the Diffie-Hellman group, which determines the key strength.Using a pre-shared key for authentication1 Click the [Pre-Shared Key Method] radio button for [Authentication Method] and then click [Shared KeySettings].2 Enter up to 24 alphanumeric characters for the pre-shared key and click [OK].Security579