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https://issues.apache.org/jira/browse/HDFS-7073?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14139816#comment-14139816
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Yi Liu commented on HDFS-7073:
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Thanks Chris.
{quote}
One of the big use cases motivating fallback is distcp between a secure cluster
and a non-secure cluster. In that scenario, setting
ipc.client.fallback-to-simple-auth-allowed could accidentally trigger fallback
during communication with the secured cluster, when we really only want it for
the unsecured cluster.
{quote}
Agree.
At least in this JIRA we can fix the checking for
{{dfs.data.transfer.protection}}, and for the fallback, we can continue in a
new JIRA?
{quote}
I'm going to explore an alternative implementation that detects if fallback
actually occurred during the corresponding NameNode interaction before the
DataTransferProtocol call. This would tell us unambiguously if the remote
DataNode was unsecured. Doing this would require some additional plumbing at
the RPC layer.
{quote}
> Allow falling back to a non-SASL connection on DataTransferProtocol in
> several edge cases.
> ------------------------------------------------------------------------------------------
>
> Key: HDFS-7073
> URL: https://issues.apache.org/jira/browse/HDFS-7073
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: datanode, hdfs-client, security
> Reporter: Chris Nauroth
> Assignee: Chris Nauroth
> Attachments: HDFS-7073.1.patch
>
>
> HDFS-2856 implemented general SASL support on DataTransferProtocol. Part of
> that work also included a fallback mode in case the remote cluster is running
> under a different configuration without SASL. I've discovered a few edge
> case configurations that this did not support:
> * Cluster is unsecured, but has block access tokens enabled. This is not
> something I've seen done in practice, but I've heard historically it has been
> allowed. The HDFS-2856 code relied on seeing an empty block access token to
> trigger fallback, and this doesn't work if the unsecured cluster actually is
> using block access tokens.
> * The DataNode has an unpublicized testing configuration property that could
> be used to skip the privileged port check. However, the HDFS-2856 code is
> still enforcing requirement of SASL when the ports are not privileged, so
> this would force existing configurations to make changes to activate SASL.
> This patch will restore the old behavior so that these edge case
> configurations will continue to work the same way.
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