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https://issues.apache.org/jira/browse/FLINK-15174?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17010030#comment-17010030
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Bhagavan commented on FLINK-15174:
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The proposed setup is as you have noted.
* KeyStore = specific certificate (shared secret)
* TrustStore = internal CA
* Certificate fingerprint = ensuring only that single specific certificate is
accepted
However, for internal communication one could use the same Keystore file as
TrustStore
Re: "it really not possible to set up a TrustStore with only a non-self-signed
certificate" - correct. Tried that as the first step. JDK does not like this
setup. Code throws NPE while validating as the issuer is null.
So, It is not possible to have only the actual specific certificate in the
TrustStore (and not have the CA in there).
> FLINK security using PKI mutual auth needs certificate pinning or Private CA
> ----------------------------------------------------------------------------
>
> Key: FLINK-15174
> URL: https://issues.apache.org/jira/browse/FLINK-15174
> Project: Flink
> Issue Type: Improvement
> Components: Runtime / Configuration, Runtime / REST
> Affects Versions: 1.9.0, 1.9.1, 1.10.0
> Reporter: Bhagavan
> Assignee: Bhagavan
> Priority: Critical
> Labels: pull-request-available
> Fix For: 1.9.2, 1.10.0
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> The current design for Flink security for internal/REST relies on PKI mutual
> authentication. However, the design is not robust if CA used for generating
> certificates are public CA or Firwide internal CA. This is due to how the
> chain of trust works whilst validating the client certificate. i.e. Any
> certificate signed by same CA would be able to make a connection to internal
> Flink network.
> Proposed improvement.
> An environment where operators are constrained to use firmwide Internal
> public CA, Allow the operator to specify the certificate fingerprint to
> further protect the cluster allowing only specific certificate.
> This change should be a backward compatible change where one can use just
> certificate with private CA.
> Changes are easy to implement as all network communications are done using
> netty and netty provides FingerprintTrustManagerFactory.
> Happy to send PR if we agree on the change.
> Document corrections.
> From security documentation.
> [https://ci.apache.org/projects/flink/flink-docs-stable/ops/security-ssl.html]
> _"All internal connections are SSL authenticated and encrypted. The
> connections use *mutual authentication*, meaning both server and client-side
> of each connection need to present the certificate to each other. The
> certificate acts effectively as a shared secret."_
> _-_ This not exactly true. Any party who obtains the client certificate from
> CA would be able to form the connection even though the certificate
> public/private keys are different. So it's not *a* shared secret ( merely a
> common signature)
> _Further doc says - "A common setup is to generate a dedicated certificate
> (maybe self-signed) for a Flink deployment._
> - I think this is the only way to make the cluster secure. i.e. create
> private CA just for the cluster.
>
>
>
>
>
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