[
https://issues.apache.org/jira/browse/HDFS-3618?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15816250#comment-15816250
]
Kihwal Lee commented on HDFS-3618:
----------------------------------
The "-z" option is supported by the plain old BSD implementation of netcat. It
looks like newer distros are moving to NMAP's netcat replacement, which does
not support "-z".
Someone suggested an equivalent of "-z" for nmap-ncat.
http://unix.stackexchange.com/questions/296023/whats-the-gnu-netcats-z-equivalent-option-in-nmap-ncat
A lazy way out is simply making the entire command configurable. One could
also make it detect which variant is available. {{nc -z 127.0.0.1 1234}} will
return 2 if the host has nmap-ncat and 0 or 1 if bsd nc.
> SSH fencing option may incorrectly succeed if nc (netcat) command not present
> -----------------------------------------------------------------------------
>
> Key: HDFS-3618
> URL: https://issues.apache.org/jira/browse/HDFS-3618
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: auto-failover
> Affects Versions: 2.0.0-alpha
> Reporter: Brahma Reddy Battula
> Assignee: Vinayakumar B
> Labels: BB2015-05-TBR
> Attachments: HDFS-3618-04.patch, HDFS-3618.patch, HDFS-3618.patch,
> HDFS-3618.patch, zkfc.txt, zkfc_threaddump.out
>
>
> Started NN's and zkfc's in Suse11.
> Suse11 will have netcat installation and netcat -z will work(but nc -z wn't
> work)..
> While executing following command, got command not found hence rc will be
> other than zero and assuming that server was down..Here we are ending up
> without checking whether service is down or not..
> {code}
> LOG.info(
> "Indeterminate response from trying to kill service. " +
> "Verifying whether it is running using nc...");
> rc = execCommand(session, "nc -z " + serviceAddr.getHostName() +
> " " + serviceAddr.getPort());
> if (rc == 0) {
> // the service is still listening - we are unable to fence
> LOG.warn("Unable to fence - it is running but we cannot kill it");
> return false;
> } else {
> LOG.info("Verified that the service is down.");
> return true;
> }
> {code}
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
---------------------------------------------------------------------
To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org
For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org
