Stuck on NRPE for OS X Server

Andrew Davis nccomp at gmail.com
Thu Mar 19 15:57:13 CET 2009


One person suggested my openssl version might be too new (0.9.8). I just 
removed it and installed 0.9.7i, older enough version to be safe and one 
that I know another user has in a working configuration. After compiling 
it, I then recompiled NRPE against it and copied the files in place. It 
still fails with the same error.

/var/log/system.log shows:

    Mar 19 10:45:17 seth xinetd[26057]: Started working: 1 available service
    Mar 19 10:45:25 seth nrpe[26064]: Error: NRPE daemon cannot be run
    as user/group root!

I had it set to run as nobody:nobody, but that wasn't working. I even 
tried setting to run as daemon:wheel, but the same results. Finally, I 
created a nagios user and configured /etc/xinetd.d/nrpe to run as 
nagios:nagios and updated /etc/nagios/nrpe.cfg to use the same. However, 
all remote tests still result in the following:

 From the server:

    [nagios at nagios ~]$ /usr/local/nagios/libexec/check_nrpe -H seth
    CHECK_NRPE: Error - Could not complete SSL handshake.

 From the client:

    Mar 19 10:45:17 seth xinetd[26057]: Started working: 1 available service
    Mar 19 10:45:25 seth nrpe[26064]: Error: NRPE daemon cannot be run
    as user/group root!

Scouring Google shows that the "cannot be run as ... root" error is in 
the nrpe.c code. What I can't figure out is why its trying to run as 
root instead of the configured user...

Anyone running NRPE with xinetd for Mac's? I'm frustrated enough that I 
almost just want to use check_by_ssh, but I'd prefer to get this working 
and keep things consistent (ie: with NRPE). My /etc/nagios/nrpe.cfg and 
/etc/xinetd.d/nrpe are below:

    seth:/etc/xinetd.d root# pwd
    /etc/xinetd.d
    seth:/etc/xinetd.d root# cat nrpe
    # /etc/xinetd.d/nrpe
    # description: NRPE
    # default: on
    service nrpe
    {
            flags           = REUSE
            socket_type     = stream
            port        = 5666
            wait            = no
            user            = nagios
            group           = nagios
            server          = /usr/local/sbin/nrpe
            server_args     = -c /etc/nagios/nrpe.cfg --inetd
            log_on_failure  += USERID
            disable         = no
            only_from       = 127.0.0.1 10.1.1.170
    }

---------------------------

    seth:/etc/nagios root# pwd
    /etc/nagios
    seth:/etc/nagios root# cat nrpe.cfg
    #############################################################################
    # Sample NRPE Config File
    # Written by: Ethan Galstad (nagios at nagios.org)
    #
    # Last Modified: 11-23-2007
    #
    # NOTES:
    # This is a sample configuration file for the NRPE daemon.  It needs
    to be
    # located on the remote host that is running the NRPE daemon, not
    the host
    # from which the check_nrpe client is being executed.
    #############################################################################
    # LOG FACILITY
    # The syslog facility that should be used for logging purposes.

    log_facility=daemon

    # PID FILE
    # The name of the file in which the NRPE daemon should write it's
    process ID
    # number.  The file is only written if the NRPE daemon is started by
    the root
    # user and is running in standalone mode.

    pid_file=/var/run/nrpe.pid

    # PORT NUMBER
    # Port number we should wait for connections on.
    # NOTE: This must be a non-priviledged port (i.e. > 1024).
    # NOTE: This option is ignored if NRPE is running under either inetd
    or xinetd

    server_port=5666

    # SERVER ADDRESS
    # Address that nrpe should bind to in case there are more than one
    interface
    # and you do not want nrpe to bind on all interfaces.
    # NOTE: This option is ignored if NRPE is running under either inetd
    or xinetd

    #server_address=127.0.0.1

    # NRPE USER
    # This determines the effective user that the NRPE daemon should run
    as. 
    # You can either supply a username or a UID.
    #
    # NOTE: This option is ignored if NRPE is running under either inetd
    or xinetd

    nrpe_user=nagios

    # NRPE GROUP
    # This determines the effective group that the NRPE daemon should
    run as. 
    # You can either supply a group name or a GID.
    #
    # NOTE: This option is ignored if NRPE is running under either inetd
    or xinetd

    nrpe_group=nagios

    # ALLOWED HOST ADDRESSES
    # This is an optional comma-delimited list of IP address or hostnames
    # that are allowed to talk to the NRPE daemon.
    #
    # Note: The daemon only does rudimentary checking of the client's IP
    # address.  I would highly recommend adding entries in your
    /etc/hosts.allow
    # file to allow only the specified host to connect to the port
    # you are running this daemon on.
    #
    # NOTE: This option is ignored if NRPE is running under either inetd
    or xinetd

    allowed_hosts=127.0.0.1

    # COMMAND ARGUMENT PROCESSING
    # This option determines whether or not the NRPE daemon will allow
    clients
    # to specify arguments to commands that are executed.  This option
    only works
    # if the daemon was configured with the --enable-command-args
    configure script
    # option. 
    #
    # *** ENABLING THIS OPTION IS A SECURITY RISK! ***
    # Read the SECURITY file for information on some of the security
    implications
    # of enabling this variable.
    #
    # Values: 0=do not allow arguments, 1=allow command arguments

    dont_blame_nrpe=0



    # COMMAND PREFIX
    # This option allows you to prefix all commands with a user-defined
    string.
    # A space is automatically added between the specified prefix string
    and the
    # command line from the command definition.
    #
    # *** THIS EXAMPLE MAY POSE A POTENTIAL SECURITY RISK, SO USE WITH
    CAUTION! ***
    # Usage scenario:
    # Execute restricted commmands using sudo.  For this to work, you
    need to add
    # the nagios user to your /etc/sudoers.  An example entry for alllowing
    # execution of the plugins from might be:
    #
    # nagios          ALL=(ALL) NOPASSWD: /usr/lib/nagios/plugins/
    #
    # This lets the nagios user run all commands in that directory (and
    only them)
    # without asking for a password.  If you do this, make sure you
    don't give
    # random users write access to that directory or its contents!

    # command_prefix=/usr/bin/sudo



    # DEBUGGING OPTION
    # This option determines whether or not debugging messages are
    logged to the
    # syslog facility.
    # Values: 0=debugging off, 1=debugging on

    debug=0



    # COMMAND TIMEOUT
    # This specifies the maximum number of seconds that the NRPE daemon will
    # allow plugins to finish executing before killing them off.

    command_timeout=60



    # CONNECTION TIMEOUT
    # This specifies the maximum number of seconds that the NRPE daemon will
    # wait for a connection to be established before exiting. This is
    sometimes
    # seen where a network problem stops the SSL being established even
    though
    # all network sessions are connected. This causes the nrpe daemons to
    # accumulate, eating system resources. Do not set this too low.

    connection_timeout=300



    # WEEK RANDOM SEED OPTION
    # This directive allows you to use SSL even if your system does not have
    # a /dev/random or /dev/urandom (on purpose or because the necessary
    patches
    # were not applied). The random number generator will be seeded from
    a file
    # which is either a file pointed to by the environment valiable
    $RANDFILE
    # or $HOME/.rnd. If neither exists, the pseudo random number
    generator will
    # be initialized and a warning will be issued.
    # Values: 0=only seed from /dev/[u]random, 1=also seed from weak
    randomness

    #allow_weak_random_seed=1



    # INCLUDE CONFIG FILE
    # This directive allows you to include definitions from an external
    config file.

    #include=<somefile.cfg>



    # INCLUDE CONFIG DIRECTORY
    # This directive allows you to include definitions from config files
    (with a
    # .cfg extension) in one or more directories (with recursion).

    #include_dir=<somedirectory>
    #include_dir=<someotherdirectory>



    # COMMAND DEFINITIONS
    # Command definitions that this daemon will run.  Definitions
    # are in the following format:
    #
    # command[<command_name>]=<command_line>
    #
    # When the daemon receives a request to return the results of
    <command_name>
    # it will execute the command specified by the <command_line> argument.
    #
    # Unlike Nagios, the command line cannot contain macros - it must be
    # typed exactly as it should be executed.
    #
    # Note: Any plugins that are used in the command lines must reside
    # on the machine that this daemon is running on!  The examples below
    # assume that you have plugins installed in a /usr/local/nagios/libexec
    # directory.  Also note that you will have to modify the definitions
    below
    # to match the argument format the plugins expect.  Remember, these are
    # examples only!

    # The following examples use hardcoded command arguments...

    command[check_disks]=/usr/local/nagios/libexec/check_disk -m -e -w
    10% -c 5%
    command[check_load]=/usr/local/nagios/libexec/check_load -r -w 5.0
    -c 10.0
    command[check_memory]=/usr/local/nagios/libexec/check_memory.pl -w
    10% -c 5%
    command[check_swap]=/usr/local/nagios/libexec/check_swap -a -w 50%
    -c 20%
    command[check_ntp]=/usr/local/nagios/libexec/check_ntp_time -H
    10.1.1.14 -w 1.0 -c 1.5
    command[check_zombie_procs]=/usr/local/nagios/libexec/check_procs -w
    5 -c 10 -s Z
    command[check_total_procs]=/usr/local/nagios/libexec/check_procs -w
    150 -c 200
    command[check_users]=/usr/local/nagios/libexec/check_users -w 25 -c 50


  A. Davis
  Email:     nccomp at gmail.com

  "There is no limit to what a man can accomplish
   if he doesn't care who gets the credit." - Ronald Reagan



Andrew Davis wrote:
> My /etc/xinetd.d/nrpe is below:
>
> # /etc/xinetd.d/nrpe
> # description: NRPE
> # default: on
> service nrpe
> {
>         flags           = REUSE
>         socket_type     = stream
>         port            = 5666
>         wait            = no
> #        user            = nobody
>         user            = daemon
> #        group           = nobody
>         group           = wheel
>         server          = /usr/local/sbin/nrpe
>         server_args     = -c /etc/nagios/nrpe.cfg --inetd
>         log_on_failure  += USERID
>         disable         = no
>         only_from       = 127.0.0.1 10.1.1.170
> }
>
> Originally, it was set to nobody:nobody. As a test, I set it to 
> daemon:wheel. In all cases, it gives the "cannot run as root" error. I 
> guess I can try making a Nagios user & group and testing with that.
>   A. Davis
>   Email:     nccomp at gmail.com
>
>   "There is no limit to what a man can accomplish
>    if he doesn't care who gets the credit." - Ronald Reagan
>   
>
>
> Allan Clark wrote:
>> Reply is bottom-posted.
>>
>> On Wed, Mar 18, 2009 at 16:57, Andrew Davis <nccomp at gmail.com 
>> <mailto:nccomp at gmail.com>> wrote:
>>
>>     If I'm reading this correctly, the line about "NRPE daemon cannot
>>     be run as user/group root!" is directly from the source code of
>>     NRPE. Its not an xinetd thing. I've confirmed that xinetd is
>>     running and listening on port 5666. I tried changing the
>>     owner/group from nobody:nobody to another unprivileged user, but
>>     it didn't work. Same results. It appears that despite my
>>     configuring the /etc/nagios/nrpe.cfg and the /etc/xinetd.d/nrpe
>>     files to use a user other than root, it still tries to start it
>>     as the root user and thus when an incoming connection comes in,
>>     it gives the "NRPE daemon cannot be run as user/group root!"
>>     error. Any thoughts on how to rectify this? Since NRPE is working
>>     fine on Linux, is this just a Mac OS X thing? Any help would be
>>     immensely appreciated.
>>
>>     AD
>>
>>
>>     Andrew Davis wrote:
>>>     FYI: /var/log/system.log on the client shows:
>>>
>>>     Mar 18 16:08:07 shu xinetd[29066]: START: nrpe pid=557
>>>     from=10.1.1.170
>>>     Mar 18 16:08:07 shu nrpe[557]: Error: NRPE daemon cannot be run
>>>     as user/group root!
>>>
>>>     whether I do the default test (with SSL) or use the -n flag to
>>>     test w/o SSL. The odd thing is that the nrpe config in
>>>     /etc/xinetd.d is set to run as nobody:nobody and
>>>     /etc/nagios/nrpe.cfg is owned by nobody:nobody. Only
>>>     /usr/local/sbin/nrpe is owned by root (as it should be), but is
>>>     also set to 755 perms. I've compared to a Linux box I have with
>>>     NRPE and xinetd working properly and the permissions are identical.
>>>
>>>     I'm stumped...
>>>
>>>     Andrew Davis wrote:
>>>>     I have two Mac OS X servers, one running 10.3, the other
>>>>     running 10.4. Neither can be upgraded to 10.5 due to third
>>>>     party s/w constraints. Both are PPC based XServe's.
>>>>
>>>>     Trying to compile nrpe with:
>>>>
>>>>         ./configure --sysconfdir=/etc/nagios --enable-ssl
>>>>
>>>>     Initially, I got the "cannot find ssl libraries" error:
>>>>
>>>>         ~
>>>>         checking for SSL headers... SSL headers found in /usr/local/ssl
>>>>         checking for SSL libraries... configure: error: Cannot find
>>>>         ssl libraries
>>>>
>>>>     I downloaded the latest openssl and built it with:
>>>>
>>>>         ./config --prefix=/usr/local shared
>>>>         --openssldir=/usr/local/openssl
>>>>         make
>>>>         make test
>>>>         make install
>>>>
>>>>     I then had to edit ~/src/nrpe/configure and change the
>>>>     reference from libssl.so to libssl.dylib
>>>>
>>>>     After that, nrpe compiled cleanly and I was able to move
>>>>     ~src/nrpe/src/nrpe to /usr/local/sbin and start xinetd up. I've
>>>>     confirmed that port 5666 is open and xinetd is running:
>>>>
>>>>         /usr/local/src/nrpe-2.12/src root# ps waux|grep xinet|grep
>>>>         -v greproot   29066   0.0 -0.0    27484    308  ??  Ss   
>>>>         3:53PM   0:00.02 /usr/sbin/xinetd -pidfile
>>>>         /var/run/xinetd.pid -stayalive
>>>>         /usr/local/src/nrpe-2.12/src root# netstat -an|grep
>>>>         5666tcp4       0      0  *.5666                
>>>>         *.*                    LISTEN
>>>>
>>>>     However, when connecting from the remote server, I get:
>>>>
>>>>         /usr/local/nagios/libexec/check_nrpe -H host.mydomain.org
>>>>         <http://host.mydomain.org>
>>>>         CHECK_NRPE: Error - Could not complete SSL handshake.
>>>>
>>>>     The same test but w/o SSL gives yields:
>>>>
>>>>         [nagios at nephilim src]$ /usr/local/nagios/libexec/check_nrpe
>>>>         -n -H host.mydomain.org <http://host.mydomain.org>
>>>>         CHECK_NRPE: Received 0 bytes from daemon.  Check the remote
>>>>         server logs for error messages.
>>>>
>>>>     So two questions:
>>>>
>>>>     1) I'm a UNIX guy, but obviously Mac's are A) different and B)
>>>>     a tad different being BSD-based. So what's the proper way to
>>>>     stop/restart the xinetd daemon?
>>>>     2) Any thoughts on SSL handshake error? I've googled it, but
>>>>     I'm not getting very far.
>>>>
>>>>     Anyone have a step-by-step for compiling nagios plugins and
>>>>     NRPE from source on OS X 10.x (specifically 10.3 and 10.4)? I'm
>>>>     using NRPE for all other internal hosts, so I prefer to use it
>>>>     for the Mac's too. I know I could do it via check_by_ssh and
>>>>     get around this, but I prefer to use NRPE if I can.
>>>>     -- 
>>>>             
>>
>>
>> On a Mac, your xinetd is a bolt-on over the launchd that's there by 
>> default; you've obviously got it running.  Since you're in 
>> /etc/xinetd.d/<something>, you need to cnfigure a different username 
>> via xinetd's config.  Look for a /etc/xinetd.d/nrpe file, or similar, 
>> containing the config for your nrpe service.  I tend to grep for the 
>> port number in order to find the file.  Remember to check /local/*
>>
>> The time service has an example with juicy comments:
>>
>>
>> service time
>> {
>> # This is for quick on or off of the service
>>         disable         = yes
>> ...
>> ...
>> # External services must fill out the following
>> #       user            =
>> #       group           =
>> ...
>> ...
>> }
>>
>>
>> Take a look there, see if you can choose a better username and/or 
>> group and if your port of xinetd honours it.  I don't know if you 
>> have a nrpe user, or run it as nobody.
>>
>> A better option would be a proper launchd config, allowing you to 
>> shutdown xinetd if you're installing it there for this purpose only, 
>> but then it's a Mac-only thing, and would be more difficult to 
>> maintain for non-Mac people.
>>
>> Allan
>>
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