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  1. Hadoop Common
  2. HADOOP-7198

Hadoop defaults for web UI ports often fall smack in the middle of Linux ephemeral port range

    Details

    • Type: Wish
    • Status: Resolved
    • Priority: Trivial
    • Resolution: Duplicate
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: None
    • Labels:
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      Description

      It turns out (see http://en.wikipedia.org/wiki/Ephemeral_port and /proc/sys/net/ipv4/ip_local_port_range) that when you bind to port 0, Linux chooses an ephemeral port. On my default-ridden Ubuntu Maverick box and on CentOS 5.5, that range is 32768-61000. So, when HBase binds to 60030 or when mapReduce binds to 50070, there's a small chance that you'll conflict with, say, an FTP session, or with some other Hadoop daemon that's had a listening address configured as :0.

      I don't know that there's a practical resolution here, since changing the defaults seems like an ill-fated effort, but if you have any ephemeral port use, you can run into this. We've now run into it once.

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              • Assignee:
                Unassigned
                Reporter:
                philip Philip Zeyliger
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                  Updated:
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