Anecdotes from a Linux Systems Administrator. /root

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January 20, 2013

Certificate validation issue during Spacewalk install

by Alpha01


For some really annoying reason Spacewalk failed to populate the database during the initial setup.

[root@spacewalk ~]# spacewalk-setup --disconnected --external-db
** Database: Setting up database connection for PostgreSQL backend.
Hostname (leave empty for local)? 
Database? dbnamehere
Username? usernamehere
** Database: Populating database.
The Database has schema.  Would you like to clear the database [Y]? Y
** Database: Clearing database.
** Database: Shutting down spacewalk services that may be using DB.
** Database: Services stopped.  Clearing DB.
** Database: Re-populating database.
*** Progress: ##################################
* Setting up users and groups.
** GPG: Initializing GPG and importing key.
* Performing initial configuration.
* Activating Spacewalk.
** Loading Spacewalk Certificate.
** Verifying certificate locally.
** Activating Spacewalk.
There was a problem validating the satellite certificate: 1


Make sure your user’s database password does not have special characters!

Tags: [ centos ]
January 13, 2013

OpenBSD: PF firewall for the paranoid

by Alpha01

Block all traffic except for ssh.


tcp_services = "{ 22 }"
block all
pass out on em0 proto tcp to any port $tcp_services keep state
pass in on em0 proto tcp to any port $tcp_services keep state

Enabling rules:

pfctl -e ; pfctl -f /etc/pf.conf 
pfctl: pf already enabled
Tags: [ pf ]
January 2, 2013

Writing custom Nagios plugins: check_public-ip

by Alpha01

Now that I think Nagios is the greatest thing since slice bread, I’m slowly but surely re-writing all my custom monitoring scripts to Nagios plugins.

The following is a Nagios plugin ready script that I used to replace my old public IP monitoring (See



ip=`curl -connect-timeout 30 -s`

if [ "$current_ip" != "$ip" ] || [ -z "$ip" ]
        if [[ "$ip" =~ "Service Unavailable" ]] || [[ "$ip" =~ "html" ]]
                echo "IP service monitoring is unavailable."
                exit $STATE_WARNING
        elif [[ "$ip"  =~ [0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3} ]]
                echo "ALERT: Public IP has changed. NEW IP: $ip"
                exit $STATE_CRITICAL
                echo "Unknown state detected."
                exit $STATE_UNKNOWN

        echo "Public OK: $ip"
        exit $STATE_OK
Tags: [ bash nagios ]
January 2, 2013

Installing Nagios Remote Plugin Executor in FreeBSD 9.1

by Alpha01

This also installs the Nagios plugins in addition of nrpe. Follow the text-based menu install options. The installer will create and configure the nagios user account, and will install the naios and nrpe plugins in /usr/local/libexec/nagios.

cd /usr/ports/net-mgmt/nrpe2
make install clean

Update permissions.

chown -R nagios:nagios /usr/local/libexec/nagios

Create nrpe config file.

cd /usr/local/etc
cp nrpe.cfg-sample nrpe.cfg

Add the following entry to /etc/rc.conf.


Edit nrpe.cfg (Example: is my nagios server)


Start the nrpe daemon.

/usr/local/etc/rc.d/nrpe2 start
Tags: [ nagios freebsd ]
January 2, 2013

Cron monitoring plugin for Nagios

by Alpha01


CRON_CHECK=`ps aux | grep cron|grep -v grep|awk '{print $NF}'|grep -E -e '^(/usr/sbin/cron|crond)$'|wc -l`

case "${CRON_CHECK}" in
        0)  echo "Crond is not running."; exit ${STATE_CRITICAL}
        1)  echo "Crond is running."; exit ${STATE_OK}
        *)  echo "More than one crond process detected / crond is in an unknown state."; exit ${STATE_WARNING}
Tags: [ bash nagios ]