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I am trying to set up the Check_MK agent with launchd on a Mac server, to return data over port 6556 when another machine connects to it.

(The agent itself is essentially just a shell script that outputs various information about the machine's status in a vaguely machine-readable format.)

I am able to connect to it from the machine itself, e.g. with curl localhost:6556, but if I try to connect externally, it just times out.

I have a .plist file set up like the one at de.mathias-kettner.check_mk.plist, stored in /Library/LaunchDaemon:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
        <key>EnvironmentVariables</key>
        <dict>
                <key>HOME</key>
                <string>/var/root</string>
                <key>PATH</key>
                <string>/sbin:/usr/sbin:/usr/local/sbin:/bin:/usr/bin:/usr/local/bin</string>
        </dict>
        <key>Label</key>
        <string>de.mathias-kettner.check_mk</string>
        <key>ProgramArguments</key>
        <array>
                <string>/usr/local/bin/check_mk_agent</string>
        </array>
        <key>Sockets</key>
        <dict>
                <key>Listeners</key>
                <dict>
                        <key>SockServiceName</key>
                        <string>6556</string>
                </dict>
        </dict>
        <key>inetdCompatibility</key>
        <dict>
                <key>Wait</key>
                <false/>
        </dict>
        <key>AbandonProcessGroup</key>
        <true/>
        <key>StandardErrorPath</key>
        <string>/var/log/check_mk.err</string>
        <key>WorkingDirectory</key>
        <string>/var/root</string>
</dict>
</plist>

(The only difference is that the check_mk_agent is /usr/local/bin instead of /usr/bin, because I couldn't create the file there.)

The check_mk_agent file itself can be found at: check_mk_agent.macosx

The strange thing is, if I point the .plist file to something like /bin/date, then it works externally as well.

The only thing I can conclude is that the task runs with different permissions depending on the IP or interface the connection comes from, but I don't know how to change the permissions it tries to run with.

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  • I have no problem to curl a remote machine and getting all details with check_mk_agent running there. The plist is root:wheel. The file check_mk_agent is also root:wheel and chmod +x. Check your error file at /var/log/check_mk.err! Additional: did you modify export MK_LIBDIR and export MK_CONFDIR in check_mk_agent.macosx and did you create the appropriate files & folders in the system?
    – klanomath
    Oct 31, 2017 at 16:28
  • Hi. Thanks for the suggestions. I have created the necessary folders, and checked the permissions. The error file is empty. But it still continues to only allow localhost connections.
    – mwfearnley
    Nov 3, 2017 at 12:20

1 Answer 1

Reset to default
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why you are not using ssh to request the data from the agent at the mac? https://mathias-kettner.de/checkmk_datasource_programs.html You need not the launchd.

regards, Oliver

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  • Thanks, this is potentially good advice. I wasn't the person to originally set it up, but I may consider switching to this method. I am still intrigued by the original problem though.
    – mwfearnley
    Nov 3, 2017 at 12:22
  • Note: at time of writing the above URL seems to have vanished, but mathias-kettner.com/checkmk_datasource_programs.html seems to work. Perhaps they are migrating to a new server.
    – mwfearnley
    Nov 3, 2017 at 12:23

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