[HADOOP-7198] Hadoop defaults for web UI ports often fall smack in the middle of Linux ephemeral port range

• Type: Wish
• Status: Resolved
• Priority: Trivial
• Resolution: Duplicate
• Assignee: Unassigned
• Reporter: Philip Martin
• Created: 17/Mar/11 23:44
• Updated: 13/Sep/16 22:33
• Resolved: 13/Sep/16 22:33

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.

Issue Links

• is duplicated by: HDFS-9427 HDFS should not default to ephemeral ports