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20050615: Getting LDM on plane to receive via UCAR RAS and PPP

>From:  Janet Scannell <address@hidden>
>Organization:  UCAR
>Keywords:  200506151705.j5FH5nZu025238 LDM IDD Fedora Core 3

Hi Janet,

I wanted to chime in with an additional comment on why logging may not
be working on cirque (everything that Steve said was correct; this
is in addition):

Under Fedora Core 3+, there is a facility called SELINUX which can
either be enabled or disabled depending on how the OS was installed
(enabling/disabling is an option during installation).  When it is
enabled, it will limit syslogd logging (among other things) in exactly
the manner you are seeing.  To get around this, you will need to do the

<as 'ldm'>
ldmadmin stop

<as 'root'>
cd /etc/selinux
-- edit 'config' and make sure that you do _not_ have a line like:
   If you do, change the line to:


Tom Yoksas

>>Date: Wed, 15 Jun 2005 10:13:11 -0600
>>From: Janet Scannell <address@hidden>
>>Organization: UCAR
>>To: address@hidden
>>Subject: LDM questions
>The above message contained the following:
>> I took your LDM class last November and I have some questions.  I am 
>> trying to get the LDM to work between the aircraft and the ground.  I am 
>> running LDM version 6.3.0 on a Fedora Core 3 machine (cirque) on the 
>> aircraft which is the downstream LDM.  I am running LDM version 6.1.0 on 
>> a Fedora Core 2 machine (linus) on the ground which is the upstream 
>> LDM.  When the aircraft computer is attached to the internal network, 
>> the LDM works correctly.  When I put files in the queue on linus, they 
>> do appear on cirque.  When I connect cirque to RAS over a ppp link, I do 
>> not get any files on cirque from linus when I insert new files into the 
>> data queue on linus.  In the ldmadmin-pl.conf file, I did not put in a 
>> specific ip address, so the LDM should listen on all networks.  Does the 
>> LDM listen on ppp network links?
>It's irrelevant what interface (i.e., IP address) the LDM on Cirque
>listens because it's only receiving data: no other LDM-s connect to it.
>The LDM on Linus will listen on all interfaces and doesn't really know 
>or care that Cirque might be using PPP.
>> What machine name do I put in the 
>> ldmd.conf file on linus?  When I connect to RAS, cirque gets a name such 
>> as ras34.ucar.edu (  This name can change every time I 
>> make a connection to RAS.  Cirque also has the name cirque.p3.public.net 
>> (  I did put both of these names in the ldmd.conf file 
>> on linus, but cirque didn't get any new data from linus. 
>The ALLOW entries for Cirque should cover all RAS names and also
>Cirque's standard name.  For example:
>    ALLOW      ANY     ^cirque\.p3\.public\.net$
>    ALLOW      ANY     ^ras[0-9]*\.ucar\.edu$
>There's actually a "public.net" domain?
>> Another question:
>> I can't get any information to show up in the log file on cirque.  Here 
>> are the relevant parts of the /etc/syslog.conf file on cirque:
>> # Log anything (except mail) of level info or higher.
>> # Don't log private authentication messages!
>> *.info;mail.none;news.none;authpriv.none;cron.none;local0.none  
>> /var/log/messages
>> # Save LDM messages to ldm log
>> local0.debug                                            
>> /jnet/local/ldm/logs/ldmd.log
>The above entries aren't in the right format: there are newlines before
>the destination fields.  They should look like this:
>    # Log anything (except mail) of level info or higher.
>    # Don't log private authentication messages!
>    *.info;mail.none;news.none;authpriv.none;cron.none;local0.none     /var/lo
> g/messages
>    # Save LDM messages to ldm log
>    local0.debug                               /jnet/local/ldm/logs/ldmd.log
>I assume the breaks are due to your user-mail-agent.
>Otherwise, the entries look good.  You might try, however, replacing
>"local0.debug" with "local0.*" -- although it shouldn't make any
>difference.  Also, ensure that the separators between the fields are tabs
>and not spaces (although, again, it shouldn't matter).
>In order for the "syslog.conf" entries to take effect, the system
>logging daemon, syslogd(8), must be sent a SIGHUP.  In order for ldm
>system to do that, the program "bin/hupsyslog" must be owned by "root"
>and setuid.  Is it?
>syslogd(8) also won't write to a non-existent file.  The file
>"/jnet/local/ldm/logs/ldmd.log" should have been created by the
>ldmadmin(1) script if it didn't exist.  Does it exist?
>You can use the logger(1) utility to test the logging mechanism.  For
>    logger -p local0.notice "This is a test at level NOTICE"
>> I get information in the log on linus and I compared the syslog.conf 
>> files on both machines and they had the same information in them for the 
>> ldm logging.  syslogd is running on cirque and cirque has been rebooted 
>> after I changed the syslog.conf file and the log messages still don't 
>> appear.  I tried the logger command that I found in 19990222 in the 
>> mailing list archive on Unidata web site and that didn't work either.
>Hmm...  Ensure that the logging file exists on Cirque and that the 
>hupsyslog utility is owned by root and setuid and try the "shouldn't
>matter" suggestions -- then get back to me.
>> Thanks for your help,
>> Janet
>> x1093
>Steve Emmerson
>LDM Developer


>From address@hidden  Wed Jun 15 16:46:00 2005

re: procedure to disable SELINUX

>><as 'root'>
>>cd /etc/selinux
>>-- edit 'config' and make sure that you do _not_ have a line like:
>>   SELINUX=enforcing
>>   If you do, change the line to:
>>   SELINUX=disabled

>This solved the problem I was having with the logging not working.


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