Mac IKEv2 profile: set both SA dictionaries, then test
IKE parameters are inherited by the Child SA when that dictionary is missing. Fill both, translate the names, and check what the peers actually negotiated.
Connecting successfully proves only that both ends found a set of values they accept. A managed Mac IKEv2 profile carries two security-association dictionaries, the gateway has its own proposal list, and the connection succeeds on whatever intersection both sides allow. Work the checks below in order, and stop where the two ends disagree rather than adding another cipher to see if it helps. Each step rules out a different layer of the profile.
Check both dictionaries before you edit a value
Inside the VPN payload's IKEv2 settings, IKESecurityAssociationParameters describes the IKE association and ChildSecurityAssociationParameters describes the Child SA. Apple's schema states that the IKE parameters also apply to the Child SA when the second dictionary is absent. That inheritance is convenient, and it is also how a profile ends up with values nobody consciously chose.
<key>IKESecurityAssociationParameters</key>
<dict>
<key>EncryptionAlgorithm</key><string>AES-256</string>
<key>IntegrityAlgorithm</key><string>SHA-256</string>
<key>DiffieHellmanGroup</key><integer>14</integer>
<key>LifeTimeInMinutes</key><integer>1440</integer>
</dict>Write both rows into the deployment record even when the values match. A reviewer can then see that the Child SA was considered rather than inherited by accident, and a later change to one row does not silently alter the other.
Check what each key means before copying a string
The four keys are not interchangeable with a proposal string from another product. The algorithm names are implementation-specific, so translate the chosen suite through each side's documented syntax instead of pasting a strongSwan proposal into an Apple field.
| Key | Holds | Common mistake |
|---|---|---|
| EncryptionAlgorithm | Cipher for that association | Assuming an AEAD name also sets integrity |
| IntegrityAlgorithm | Integrity for the chosen suite | Leaving it set for an AEAD suite that does not use one |
| DiffieHellmanGroup | Numeric group identifier | Reading the number as key size in bits |
| LifeTimeInMinutes | Association lifetime | Setting it shorter than the gateway's renewal margin |
"Use the largest group number" is not a selection method. Group identifiers name different constructions, and a higher number does not simply mean a stronger version of the same thing. Have the owner of the gateway approve the complete combination, because a suite is valid or invalid as a whole. An approved cipher with an unapproved group is an unapproved proposal, and it will either fail or silently fall back to something neither side documented.
Check the version limits that retire old algorithms
The Apple payload schema restricts DES, 3DES, SHA1-96, SHA1-160 and Diffie-Hellman groups 1, 2 and 5 to macOS versions before 26. A profile carried forward from an older deployment may still contain one of those values and still connect to an old gateway, which is exactly the case where a working configuration hides a retirement date.
Obtain the supported Mac versions and the gateway's maintained proposal policy before you build the profile. Then choose the intersection and record why the remaining options were excluded. A note that says "gateway still offers group 2 for legacy clients" is worth more than a cipher list with no history. Without that note, the next reviewer cannot tell a deliberate exception from an oversight.
Check authentication on its own line
Agreement on a proposal does not repair a wrong server identity. Gateway identity, certificate trust and the user or device credentials are separate decisions, and each can fail while the algorithms are perfectly aligned. Changing a certificate's signature algorithm is not the same act as selecting the IKE encryption algorithm, even though both appear in the same review.
Keep the expected server identity next to the proposal in the record. When a connection fails after a certificate change, that pairing tells the next person whether the negotiation or the trust decision moved first.
Deploy one revision and inspect what was negotiated
Use the organisation's supported distribution workflow and record the profile identifier, the revision, the target Mac versions, and the matching gateway policy. Give devices that cannot connect a documented recovery path, and avoid creating a second identically named profile whose ownership nobody can establish.
During acceptance, inspect the installed configuration and the negotiated IKE and Child associations through approved diagnostics. Then force a controlled renewal, because the first connection only proves that the initial negotiation worked; a lifetime mismatch usually appears at the first rekey, long after the deployment was signed off.
Keep the accepted suite with the revision record. The next macOS update or gateway change then has a baseline to compare against instead of a profile that merely happens to connect today.