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https://issues.apache.org/jira/browse/AMQ-5468?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14236684#comment-14236684
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Nguyen Hong Phu commented on AMQ-5468:
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Hi @Timothy Bish, thanks for your quick reply,
I have been configured max connections on a transport connector and real number
of clients (wireless devices) is 2000, but connections count when invoke
operator in JMX and losf (command linux) more than 65000 TCP opened.
The fact that, at a time only one a socket is opened. But connection not
release when client disconnect not properly, client MQTT is removed on broker,
but TCP socket don't.
You can use telnet client to double check:
Example: Please try three simple steps:
1/ telnet <broker ip>:port
2/ view on Jconsole for JMX connector: image bellow
Socket tcp appear in folder remoteAddress
!http://s3.postimg.org/xbplh535f/amq.png!
3/ Close telnet client, waiting a long time (could be 1 hour, 1 day,...),
socket tcp not release, so a humman could be attack by open many sockets :(
In real-production, my clients could be disconnect not properly and many tcp
not release and cause max-openfiles error.
Sorry my English!
> AMQ MQTT doesn't reject remote connection after a long time
> ------------------------------------------------------------
>
> Key: AMQ-5468
> URL: https://issues.apache.org/jira/browse/AMQ-5468
> Project: ActiveMQ
> Issue Type: Bug
> Components: Connector, MQTT
> Affects Versions: 5.9.0, 5.9.1, 5.10.0
> Environment: Linux
> Reporter: Nguyen Hong Phu
>
> Test steps:
> - Using jConsole to explore JMX MBean clientConnectors (MQTT+NIO connector).
> - Using telnet client connect to MQTT+NIO port
> - On jConsole: clientConnectors/mqtt+nio/remoteAddess appear a new connection
> with IP and local port which connect to.
> - Close telnet program
> - Waiting a long time (could be more than a day) and view remoteAddess again
> on jConsole but Remote IP (telnet) does not remove.
> Imagine that if a human open a thousand or million connections to server, AMQ
> not release connections after short time, then AMQ could be throws the ERROR
> "To many open files" and it doesn't access new connection.
> In production server (ulimit max-open-files 65000), i'm using 2 thousand
> clients but after 2 days, many ERROR "To many open files" in activemq.log to
> be throws.
> On jConsole, number of clientId is equals with clients, but RemoteIP contains
> more than 65000 IPs.
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