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https://issues.apache.org/jira/browse/ACCUMULO-3513?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14305797#comment-14305797
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Josh Elser commented on ACCUMULO-3513:
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I haven't really read up about DIGEST-MD5. I'll have to look into that and see
if there's anything better we can use with SASL.
bq The individual MapReduce nodes do not have Kerberos principals at all? How
do they authenticate to the job controller?
Delegation tokens.
bq. you have to talk to the TServer which issued it
This would require us have clients hold onto N delegation tokens though. That'd
make the client implementation much more difficult than a singular delegation
token that any node in the instance can verify.
bq. If you use a single shared key, you really don't need leader election
(because they all have the secret and perform the same function)
You need the coordination to roll new secret keys. Using the same secret key
for months (assuming average uptime of a cluster) is just asking for attacks.
bq. I'm very curious precisely how you are generating these delegation tokens,
though. I could be on a completely separate page regarding that and your
suggestion for leader elections.
Code will speak better than I can:
https://github.com/joshelser/accumulo/tree/delegation-tokens/server/base/src/main/java/org/apache/accumulo/server/security/delegation.
I just finished this up, I think. Each Master and Tserver has a SecretManager
implementation. The Master (or more generally, whoever is creating the secret
keys), also runs the KeyManager which generates a new secret key every
$timelength. That process also uses the KeyDistributor to add secret keys to ZK
(for all of the "followers"). The "followers" (tservers) use the KeyWatcher to
see changes made by the KeyDistributor and update their SecretManager.
In general, the SecretManager is a local cache off of ZooKeeper which can
generate/verify the passwords in delegation tokens. No mechanisms yet exist to
ensure that all followers/tservers have seen a new secret key.
> Ensure MapReduce functionality with Kerberos enabled
> ----------------------------------------------------
>
> Key: ACCUMULO-3513
> URL: https://issues.apache.org/jira/browse/ACCUMULO-3513
> Project: Accumulo
> Issue Type: Bug
> Components: client
> Reporter: Josh Elser
> Assignee: Josh Elser
> Priority: Blocker
> Fix For: 1.7.0
>
> Attachments: ACCUMULO-3513-design.pdf
>
>
> I talked to [~devaraj] today about MapReduce support running on secure Hadoop
> to help get a picture about what extra might be needed to make this work.
> Generally, in Hadoop and HBase, the client must have valid credentials to
> submit a job, then the notion of delegation tokens is used by for further
> communication since the servers do not have access to the client's sensitive
> information. A centralized service manages creation of a delegation token
> which is a record which contains certain information (such as the submitting
> user name) necessary to securely identify the holder of the delegation token.
> The general idea is that we would need to build support into the master to
> manage delegation tokens to node managers to acquire and use to run jobs.
> Hadoop and HBase both contain code which implements this general idea, but we
> will need to apply them Accumulo and verify that it is M/R jobs still work on
> a kerberized environment.
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