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From "Daryn Sharp (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-4457) WebHDFS obtains/sets delegation token service hostname using wrong config leading to issues when NN is configured with 0.0.0.0 RPC IP
Date Fri, 01 Feb 2013 22:42:13 GMT

    [ https://issues.apache.org/jira/browse/HDFS-4457?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13569183#comment-13569183
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Daryn Sharp commented on HDFS-4457:
-----------------------------------

Ignoring the issue of the client relying on the server to set the service - which is what
I don't approve of since it's a big step backwards - you still have the problem if a proxy
is between the client and the webhdfs server.  The token will contain the hostname that the
proxy used to contact the server, not the hostname the client used to contact the proxy. 
The proxy, or even some form of NAT may be redirecting the port.  The server doesn't know
this, only the client knows what port it thinks it contacted.

The remote server also doesn't have the ability to know if the client has use_ip enabled or
disabled.  

Basically, only the client that requested the token knows the exact host:port authority it
used to request the token.  When it attempts to re-contact that service, it needs to match
the service with the authority.

My second concern is that you must be assuming the key to store the token in the credentials.
 It currently happens to be the token's service, but it's a private implementation detail.
 If the key format changes, and the passed-along token is added to the credentials with the
old format, then job submission will attempt to reacquire the token and fail.  Fetchdt solves
this by allowing you to acquire tokens and opaquely pass them along in binary form.

What error are you encountering with fetchdt?  It's working for me on a production cluster:
{noformat}
$ hdfs fetchdt -fs webhdfs://host /tmp/tokens
Fetched token for host:50070 into file:/tmp/tokens
{noformat}
                
> WebHDFS obtains/sets delegation token service hostname using wrong config leading to
issues when NN is configured with 0.0.0.0 RPC IP
> -------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-4457
>                 URL: https://issues.apache.org/jira/browse/HDFS-4457
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: webhdfs
>    Affects Versions: 1.1.1, 2.0.2-alpha
>            Reporter: Alejandro Abdelnur
>            Assignee: Alejandro Abdelnur
>            Priority: Critical
>         Attachments: HDFS_4457.patch, HDFS_4457.patch
>
>
> If the NameNode RPC address is configured with an wildcard IP 0.0.0.0, then delegationotkens
are configured with 0.0.0.0 as service and this breaks clients trying to use those tokens.
> Looking at NamenodeWebHdfsMethods#generateDelegationToken() the problem is SecurityUtil.setTokenService(t,
namenode.getHttpAddress());, tracing back what is being used to resolve getHttpAddress() the
NameNodeHttpServer is resolving the httpAddress doing a httpAddress = new InetSocketAddress(bindAddress.getAddress(),
httpServer.getPort());
> , and if using "0.0.0.0" in the configuration, you get 0.0.0.0 from bindAddress.getAddress().
> Normally (non webhdfs) this is not an issue because it is the responsibility of the client,
but in the case of WebHDFS, WebHDFS does it before returning the string version of the token
(it must be this way because the client may not be a java client at all and cannot manipulate
the DelegationToken as such).
> The solution (thanks to Eric Sammer for helping figure this out) is for WebHDFS to use
the exacty hostname that came in the HTTP request as the service to set in the delegation
tokens.

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