Trusted replicas (advanced)

This information applies to advanced deployments.

By default, all directory servers in a replication topology trust all replicas. If a replica allows an update, then other servers relay and replay the update without further verification. This simplifies deployments where you control all the replicas.

In deployments where you do not control all the replicas, you can configure replication servers to accept updates only from trusted replicas. The trust depends on the certificate that a replica presents to the replication server when connecting. Specifically, replication servers can verify trust when:

Trusted certificates have the OID 1.3.6.1.4.1.36733.2.1.10.1 in their extended key usage certificate extension.

Use this policy when you control the CA signing the replicas' certificates, and can enforce that only authorized replicas have certificates with this setting.
They store fingerprints for all trusted certificates in their configurations.

Use this policy when you do not control the CA.

You choose the policy by setting the replication server advanced property, allow-updates-policy. It takes the following values:

all: (Default) Trust all replicas.
verify-certificate-key-usage: Only trust updates from replicas whose certificates' ExtendedKeyUsage includes 1.3.6.1.4.1.36733.2.1.10.1.
verify-certificate-fingerprint: Only trust updates from replicas with certificate fingerprints in the advanced property, allow-updates-server-fingerprints.

If a replication server does not trust an update, it logs an error message explaining why. The update is not replicated, and therefore may cause replication to diverge on the untrusted replica. Configure the untrusted replicas you control to be read-only, as described in Read-only replicas.

Trust extended key usage

For each trusted DS server, get the certificate for replication signed with the appropriate extended key usage.

The following example demonstrates a certificate signing request with the appropriate extended key usage:
```
$ keytool \
 -certreq \
 -ext ExtendedKeyUsage:critical=clientAuth,serverAuth,1.3.6.1.4.1.36733.2.1.10.1 \
 -alias ssl-key-pair \
 -keystore /path/to/opendj/config/keystore \
 -storepass:file /path/to/opendj/config/keystore.pin \
 -file ssl-key-pair.csr
```
The full process for each server involves generating a certificate signing request, signing the certificate in the request with the CA signing certificate, and importing the CA-signed certificate on the server.

For each replication server, update the configuration to trust certificates with the appropriate extended key usage:

$ dsconfig \
 set-replication-server-prop \
 --provider-name "Multimaster Synchronization" \
 --set allow-updates-policy:verify-certificate-key-usage \
 --hostname localhost \
 --port 4444 \
 --bindDN uid=admin \
 --bindPassword password \
 --usePkcs12TrustStore /path/to/opendj/config/keystore \
 --trustStorePassword:file /path/to/opendj/config/keystore.pin \
 --no-prompt

At this point, the replication server can trust the other server’s updates.

Trust fingerprints

For each trusted DS server, get the certificate fingerprint:

$ keytool \
 -list \
 -alias ssl-key-pair \
 -keystore /path/to/opendj/config/keystore \
 -storepass:file /path/to/opendj/config/keystore.pin \
ssl-key-pair, <date>, PrivateKeyEntry,
Certificate fingerprint (SHA-256): 05:55:BD:A5:E1:4C:35:A6:A5:4E:78:DD:3E:FD:EA:5A:66:5D:E0:DC:9C:C5:18:7E:E9:CA:A9:1E:CD:87:4B:78

For each replication server, update the configuration to trust replicas by their certificate fingerprints:

$ dsconfig \
 set-replication-server-prop \
 --provider-name "Multimaster Synchronization" \
 --set allow-updates-policy:verify-certificate-fingerprint \
 --hostname localhost \
 --port 4444 \
 --bindDN uid=admin \
 --bindPassword password \
 --usePkcs12TrustStore /path/to/opendj/config/keystore \
 --trustStorePassword:file /path/to/opendj/config/keystore.pin \
 --no-prompt

For each replication server, update the configuration to recognize each certificate fingerprint.

The following example demonstrates adding a trusted certificate fingerprint:

$ dsconfig \
 set-replication-server-prop \
 --provider-name "Multimaster Synchronization" \
 --add allow-updates-server-fingerprints:\
"{SHA-256}05:55:BD:A5:E1:4C:35:A6:A5:4E:78:DD:3E:FD:EA:5A:66:5D:E0:DC:9C:C5:18:7E:E9:CA:A9:1E:CD:87:4B:78" \
 --hostname localhost \
 --port 4444 \
 --bindDN uid=admin \
 --bindPassword password \
 --usePkcs12TrustStore /path/to/opendj/config/keystore \
 --trustStorePassword:file /path/to/opendj/config/keystore.pin \
 --no-prompt

At this point, the replication server can trust the other server’s updates.

Repeat the relevant steps each time a trusted certificate changes.

DS 7.3.4

Trusted replicas (advanced)

Trust extended key usage

Trust fingerprints