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This article introduces how emq monitors ports below 1024. The content is very detailed. Interested friends can use it for reference. I hope it will be helpful to you.

The application listens for ports below 1024

Our own application listens for the port number of the service. Ordinary users can only access ports above 1024. When you need to use port numbers of 1024 or less, you need the application to obtain root user rights as follows (assuming that the name of the application we wrote is myproc):

Chown root:root myprocchmod Utility myproc

Change systemctl to emqx so that root user startup is invalid

Vim / usr/lib/systemd/system/ emqx.service[Unit] Description=emqx daemonAfter= network.target[Service] User=emqxGroup=emqxType=forkingEnvironment=HOME=/var/lib/emqxExecStart=/bin/sh / usr/bin/emqx startLimitNOFILE=1048576ExecStop=/bin/sh / usr/bin/emqx stop[Install] WantedBy=multi-user.target

Later, it is found that emqx is a script file, not a binary file, and the startup user has been specified in the file, so if you change the startup user, you need to change the script file vim / usr/bin/emqx.

Emq is run as an emqx user by default, and the following error is reported in the log after the command line starts emqx start

The following has no effect after modifying the emqx permissions (because emqx is a file, as mentioned earlier)

Chown root:root emqxchmod Utility emqx

After looking at the process after emqx starts normally, it is found that the startup file is this / usr/lib/emqx/erts-10.3.5.1/bin/beam.smp

Chmod Utility beam.smp

After modification, the permissions are as follows, which can be started normally.

Reference: https://blog.csdn.net/weixin_43050332/article/details/89420007

This is enough about how emq monitors the ports below 1024. I hope the above content can be helpful to you and learn more knowledge. If you think the article is good, you can share it for more people to see.

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