I wrote up a short and dirty script in order to archive out all the Zoneminder events as mpeg files.   The script goes through and identifies all the events and creates a mpeg video file for each day of footage per camera (monitor).  I found this was the best way to keep the event organized and able to look up a particular day and monitor the easiest.  This is sort of a work in progress though, and for one of the awk statements, I had trouble incorporating the variable, so you may need to change it up slightly.

A prerequisite is that you will need to have FFMPEG installed on your system.  You may also have to change some of the parameters to match your systems, such as where the root directory for the event image files are as well as adjusting for the number of EVENT_IMAGE_DIGITS you are using in your zoneminder options/configuration.  I use 5 digits, but I believe the default is set to 3, which limits your events to 999 images.  Anyway, here it is.

archive_all script (zipped)

Maybe you can find this useful.

One site that I manage that has a lot of complex disease-related data that is given out for free to the public directly via the web site and also via an iOS app.  The entire site is dynamic and derived from multiple back end sources and subsequently causes a bit of a hit to render the information together.  We have often seen other entities (IPs originating from China & Germany recently) decide they want to “scrape” the entire site for all of the content without throttling their connections.  Due to our limited resources (only two front-end application servers), when someone hits us this way, this effectively creates a minor DoS for us.   The best place to try to control for these sort of scenarios would of course be at the load balancer device, but I don’t have control of configuration of them and so I have had to try to take matters into my own hands.

While there are quite a number of ways to cap someone’s impact on your server (mod_bw, mod_ratelimit, IP Tables, etc), most often, these are rendered fairly useless by the client’s IP being replaced by the IP of the LTM (traffic manager / load balancer).

Here’s how I effectively was able to limit other entities ability to hit our site beyond what it could handle.

Step 1:  Install mod_security (and mod_unique if not already loaded) – my mod_security was version 2.7 on CentOS

Step 2: Create a basic config for mod security
########## MOD SEC Basic Config File ###########
LoadModule unique_id_module modules/mod_unique_id.so
LoadModule security2_module modules/mod_security2.so
SecRuleEngine On
SecDataDir /tmp
SecTmpDir /tmp
SecDebugLog /var/log/httpd_logs/modsec_debug.log
SecDebugLogLevel 0

Step 3: Add the specific connection limiting configuration anywhere inside the VirtualHost directives of the site you are trying to protect:

####### SPECIFIC rate limiting for this site inside apache VirtualHost #########
<LocationMatch “^/(?!(?:jpe?g|png|bmp|gif|css|js|svg))(.*)”>
#counts everything but images and such
SecAction initcol:ip=%{X-Forwarded-For},pass,nolog,id:4444446
SecAction “phase:5,deprecatevar:ip.mysiteconncounter=1/1,pass,nolog,id:4444447”
SecRule IP:MYSITECONNCOUNTER “@gt 150” “id:4444448,phase:2,pause:300,deny,status:509,setenv:RATELIMITED,skip:1,nolog”
SecAction “id:4444449,phase:2,pass,setvar:ip.mysiteconncounter=+1,nolog”
Header always set Retry-After “15” env=RATELIMITED
ErrorDocument 509 “Rate Limit Exceeded”
############## End rate limit configuration for virtual host here ###########

Step 4: Restart apache!

Some additional notes:
* You can limit what portion of your site is watched in the LocationMatch (instead of the whole site like I did)
* With Mod Security 2.7, I guess you need to add unique rule ID’s to each rule.  For these numbers I chose arbitrarily 4444446 – 4444449
* Change the “@gt 150” to a lower number if you want to lower the threshold for number of connections (each second the number of connections decreases by 1 for each IP) or the speed to which it deprecates the IP connection stat (1/1)
* If you would like to protect multiple sites (additional VirtualHosts on the same server), use a different variable for collecting IPs. In my case above I used “mysiteconncounter” so make sure it is something different, otherwise they will stomp on each other.
* You could probably return a different error code rather than 509 as it is only really partially supported out there.


Here’s a short little test that I worked up many years ago specifically for using for Linux SysOps candidates and I thought I would share it for anyone who would like to use it.  It measures a few things.  Firstly, of course, it tests for basic familiarity with Linux but more importantly, how well a candidate can follow instructions.  This is probably the most important trait to have where critical systems are involved and most of the operator actions are pre-scripted.  I have found the last part of the test on page 3 will identify detail-oriented candidates for you quite effectively and weed out the rest.  I’ve put it in PDF format so you can print it easily.

Click on the thumbnail below to download it.

Link for Linux Sys Ops test download
Click to download the Linux Sys Ops test (PDF format)

I’m sure the last part also can easily be adapted for other non-linux oriented roles that require good traits for focus, memory and precision.

I can post up the answer key, but really if you don’t already know the answers, you probably shouldn’t be administering this test!

Here’s the steps I had to take in order to add an encrypted listener in addition to the standard listener on an old Oracle instance.  Hopefully it may save you some time.. I had to futz around with it a bit until I got it going and then was able to deploy to some other servers in the same fashion:

STEP1 – – Go to the directory right above your “TNS_ADMIN” location.. typically it would be something like this:

cd /u01/product/11.2.0/dbhome_1/network/

STEP2 – – Create a new “admin2” directory

mkdir /u01/product/11.2.0/dbhome_1/network/admin2

STEP3 – –  Create new listener.ora and sqlnet.ora files in the new admin2 directory, and customize for your particular instance.  I arbitrarily picked port 11521 because it would be easy to remember for me.

####### listener.ora ########



####### sqlnet.ora ########

SQLNET.CRYPTO_SEED = ‘SomeCrazyCryptoSeedWhateverYouWantHere’

STEP4 – – Next we will need to register the new listener to let the DB know about the regular one and the new encrypted one (or more if you’d like).  I’m doing this in the TNSNAMES.ORA file and calling it “ALL_LISTENERS”.

In my case this was located in the regular TNS_ADMIN home location: /u01/product/11.2.0/dbhome_1/network/admin/tnsnames.ora


Then in SQLPLUS as the SYSDBA you will need to run:

Note: You may have to stop everything and restart the DB at this point… but it may not be necessary.  I just did it to make sure everything was clean.

STEP5 – – Start up your standard listener first as usual:

lsnrctl start

Next follow this procedure in order to start the second encrypted listener:

cd /u01/product/11.2.0/dbhome_1/network/admin2
export TNS_ADMIN=`pwd`

After a minute or so you should be able to see that the listener status is READY, and has 1 handler(s) for this service by running the command:


Hopefully this is straight forward enough.  I hate reading Oracle docs and would rather just have an example cookbook approach, so if you are like me maybe you will appreciate this.


I have a data center that I don’t physically visit very often.  Recently I’d replaced some UPS units that conveniently had some external temperature sensors on them which I used to use to monitor the environmental temperature.  One of my HVAC units does report temperature, but because it isn’t too close to the main equipment rack, I really wanted to know what sort of temperature my servers were experiencing directly in the rack.  I finally came up with a way to do this with some of my HP ProLiant DL360 G7s.  I used to do this with Dell’s that had built-in temperature sensors, but we don’t have any of them around any more.   The hardest part of the process was figuring out all the necessary drivers and agents required to get the sensors monitored and able to be queried by snmp on the HPs.

First thing you need to do is download and install the HP Health command line utility and snmp agents on your server that needs to be monitored.  I located them by going to http://www.hp.com and then Support > Put in “DL360 G7” as model > Linux > choose “Software – System Management”  category > Download both the HP SNMP Agents for Linux as well as the HP Health command line utility.

Then I installed them and some standard RHEL packages:

# rpm -ivh ./hp-health-10.10-1710.30.rhel6.x86_64.rpm
# rpm -ivh ./hp-snmp-agents-10.10-2732.25.rhel6.x86_64.rpm
# yum install net-snmp net-snmp-utils lm_sensors

** Don’t forget to edit the /etc/snmp/snmpd.conf file to allow only appropriate access **
I’m not going to detail these steps in particular as this is more generic setup that you find in the man pages, etc. However, you WILL need to source the dlmod for the HP agent as follows in the snmpd.conf file as shown below:

dlmod cmaX /usr/lib64/libcmaX64.so

– – Or you can alternatively run:
# /sbin/hpsnmpconfig

(And then chose to use existing snmpd.conf, or create a new one.  However, I found it easier to  simply add in the dynamic module as I did above.)

** Also, I ran through the sensors-detect in order to see if there was anything else I could monitor of interest
# sensors-detect

…and chose to update the config file when prompted “Do you want to overwrite /etc/sysconfig/lm_sensors? (YES/no): YES”

Once all that was done I gave the new services a clean start if they weren’t already running and made sure they start at boot time:
# /etc/init.d/hp-snmp-agents restart
# /etc/init.d/snmpd restart
# chkconfig snmpd on

Now for the fun part!

I searched around online and figured out the at the Health / thermal MIB OIDS start at: -ish
and that temp Sensor locations by INTEGER can be identified as follows: (I was really only interested in the ambient “11” sensor for this project, but you could track whichever ones you really wanted)

Locations: other(1), unknown(2), system(3), systemBoard(4), ioBoard(5), cpu(6),
memory(7), storage(8), removableMedia(9), powerSupply(10), ambient(11),
chassis(12), bridgeCard(13)

So then, from using the SNMPWALK utility I was able to derive all the available sensor locations:
e.g.  snmpwalk -Of -c public -v 1 localhost

.iso.org.dod.internet.private.enterprises. = INTEGER: 11
.iso.org.dod.internet.private.enterprises. = INTEGER: 6
.iso.org.dod.internet.private.enterprises. = INTEGER: 7
.iso.org.dod.internet.private.enterprises. = INTEGER: 7
.iso.org.dod.internet.private.enterprises. = INTEGER: 7
.iso.org.dod.internet.private.enterprises. = INTEGER: 7
.iso.org.dod.internet.private.enterprises. = INTEGER: 7
.iso.org.dod.internet.private.enterprises. = INTEGER: 10
.iso.org.dod.internet.private.enterprises. = INTEGER: 10
.iso.org.dod.internet.private.enterprises. = INTEGER: 7
.iso.org.dod.internet.private.enterprises. = INTEGER: 6
.iso.org.dod.internet.private.enterprises. = INTEGER: 6
.iso.org.dod.internet.private.enterprises. = INTEGER: 7
.iso.org.dod.internet.private.enterprises. = INTEGER: 6
.iso.org.dod.internet.private.enterprises. = INTEGER: 3
.iso.org.dod.internet.private.enterprises. = INTEGER: 3
.iso.org.dod.internet.private.enterprises. = INTEGER: 3
.iso.org.dod.internet.private.enterprises. = INTEGER: 3
.iso.org.dod.internet.private.enterprises. = INTEGER: 3
.iso.org.dod.internet.private.enterprises. = INTEGER: 3
.iso.org.dod.internet.private.enterprises. = INTEGER: 3
.iso.org.dod.internet.private.enterprises. = INTEGER: 3
.iso.org.dod.internet.private.enterprises. = INTEGER: 8
.iso.org.dod.internet.private.enterprises. = INTEGER: 3

And what the current reading in Celsius of the sensor is:

.iso.org.dod.internet.private.enterprises. = INTEGER: 22
.iso.org.dod.internet.private.enterprises. = INTEGER: 40
.iso.org.dod.internet.private.enterprises. = INTEGER: 34
.iso.org.dod.internet.private.enterprises. = INTEGER: 33
.iso.org.dod.internet.private.enterprises. = INTEGER: 31
.iso.org.dod.internet.private.enterprises. = INTEGER: 32
.iso.org.dod.internet.private.enterprises. = INTEGER: 32
.iso.org.dod.internet.private.enterprises. = INTEGER: 34
.iso.org.dod.internet.private.enterprises. = INTEGER: 45
.iso.org.dod.internet.private.enterprises. = INTEGER: 29
.iso.org.dod.internet.private.enterprises. = INTEGER: 31
.iso.org.dod.internet.private.enterprises. = INTEGER: 31
.iso.org.dod.internet.private.enterprises. = INTEGER: 28
.iso.org.dod.internet.private.enterprises. = INTEGER: 40
.iso.org.dod.internet.private.enterprises. = INTEGER: 35
.iso.org.dod.internet.private.enterprises. = INTEGER: 37
.iso.org.dod.internet.private.enterprises. = INTEGER: 43
.iso.org.dod.internet.private.enterprises. = INTEGER: 45
.iso.org.dod.internet.private.enterprises. = INTEGER: 40
.iso.org.dod.internet.private.enterprises. = INTEGER: 48
.iso.org.dod.internet.private.enterprises. = INTEGER: 36
.iso.org.dod.internet.private.enterprises. = INTEGER: 48
.iso.org.dod.internet.private.enterprises. = INTEGER: 35
.iso.org.dod.internet.private.enterprises. = INTEGER: 72

So, e.g. specifically looking at the “Ambient Sensor” we see a reading of 22 degrees Celsius (~71 deg F)
# snmpwalk -Of -c public -v 1  localhost
.iso.org.dod.internet.private.enterprises. = INTEGER: 22

Then on my Nagios server, I defined the new service and all the other params and restarted Nagios.  Below are the config files and custom commands I set up for this (your set up may be slightly different, but pretty close):

** /etc/nagios/conf.d/service_templates.cfg

define service {
register                0
use                     default-service
name                    hp_check_ambienttemp
service_description     HP Ambient Temperature
servicegroups           hpenv
check_command           snmp_hpenv_ambienttemp!public

** /etc/nagios/servers/servername.cfg

define host {
host_name    someservername
address        someservername.fqdn
hostgroups    acceptance
alias        Some HP DL360 G7 Server
use        server

define service {
host_name    someservername
use        ping,lowpriority

define service {
host_name        someservername
use            hp_check_ambienttemp,graph,critical
notifications_enabled     0

** /etc/nagios/conf.d/commands.cfg  (Note how I set 25 degrees as the warning threshold and 26 degrees as critical)

# ‘snmp_hpenv_ambienttemp’ command definition
define command {
command_name    snmp_hpenv_ambienttemp
command_line    $USER1$/check_snmp -H $HOSTADDRESS$ -C $ARG1$ -o . -w 25 -c 26 -l ‘\Ambient Air Temp\’ -u ‘\Celcius\’

** /etc/nagios/conf.d/servicegroups.cfg

define servicegroup {
servicegroup_name       hpenv
alias                   HP Server Envir Monitors


Here’s what the result is in Nagios.. (also, graphing is a good idea, but that could be another post).


We ended up getting a new Challenger 3000 Liebert (Emerson Power) HVAC unit in our data center recently.  We typically monitor everything using the Nagios system for our servers and we were pleased to find that inside the Liebert toward the top was a component that they refer to as the “Unity” module.  After reading some online user guides I was able to bind an IP to it and start querying it via SNMP.  Hint: the default username and password to get in to the web interface were both “Liebert”.  After looking around for a bit, I realized there weren’t any stock commands in Nagios via the check_snmp plugin to handle this, so I added some of my own.  Using snmpwalk, I was able to determine which of the OIDs I was interested in and made some custom command definitions.

Here’s the command definitions:

# ‘snmp_lbenv_humidity’ command definition – consider anything under 21 percent critical
define command {
command_name    snmp_lbenv_humidity
command_line    $USER1$/check_snmp -H $HOSTADDRESS$ -C $ARG1$ -o . -l ‘\Return Humidity\’ -u ‘\%\’ -c @0:20.9 -w @21:35

# ‘snmp_lbenv_returnairtemp’ command definition – critical at 24 or more degrees Celcius
define command {
command_name    snmp_lbenv_returnairtemp
command_line    $USER1$/check_snmp -H $HOSTADDRESS$ -C $ARG1$ -o . -w 23 -c 24 -l ‘\Return Air Temp\’ -u ‘\Celcius\’

# ‘snmp_lbenv_hvacstatus’ command definition
define command {
command_name    snmp_lbenv_hvacstatus
command_line    $USER1$/check_snmp -H $HOSTADDRESS$ -C $ARG1$ -o . -l ‘\HVAC Status\’ -u ‘\Normal vs Abnormal\’ -s ‘”Normal Operation”‘


I also set up nagiograph plugin in order to give me a quick historical overview of the changes in temperature and humidity.


Pretty neat way to monitor the Liebert without having to set up anything additional!

I was stumped for a while trying to figure out how to provide a Git repo via HTTP(s) in order to allow a separate group of ldap authenticated users to have read-only access to each individual repos while another group in A/D has full read-write access.  Here’s what I finally came up and included in my apache’s conf file to make it work:

<Location /git/MyGitRepo>
Require ldap-group CN=MyGitRepoRO,OU=Git Security Groups,OU=Organizational Units,DC=ds,DC=dinkyuniversity,DC=edu

<LocationMatch “^/git/MyGitRepo/git-receive-pack$”>
Require ldap-group CN=MyGitRepoRW,OU=Git Security Groups,OU=Organizational Units,DC=ds,DC=dinkyuniversity,DC=edu

As you can see above, basically the trick I figured out was to limit access for the “git-receive-pack” command for a separate group of people needing the read-write access.  Users needing RW access must also exist in the RO group as well.

At some point in time late in March 2013, an update to my Mac broke the ldapsearch functionality.  I had a simple script written with a menu that would allow me to query the school’s directory for commonly needed info such as usernames, phone numbers, departments and so on.

Everything worked wonderfully until last month I started receiving this error:

ldap_sasl_bind(SIMPLE): Can’t contact LDAP server (-1)

After a lot of googlin’ most people receiving this error suggested adding either of these to my ldap.conf file

TLS_REQCERT    never
TLS_REQCERT     allow

Unfortunately, neither of these made any difference.  How frustrating.  After a while I came to the realization that the ldapsearch was not longer looking at the configuration file in the standard location /etc/openldap/ldap.conf

On the Mac, using the dtruss command (similar to strace), I was able to track down where it was looking for the file by a command similar to this:

sudo dtruss -a ldapsearch [rest of the query here] 2>&1 |grep conf

which gave me what I was looking for…
346/0x2f28:    247865   12423    152 open_nocancel(“/opt/local/etc/openldap/ldap.conf\0″, 0x0, 0x1B6)         = 3 0

No file existed there yet, so a simple symlink to my original configuation file fixed my ldapsearch!

sudo  ln -s /etc/openldap/ldap.conf /opt/local/etc/openldap/ldap.conf

My old wireless router had started having trouble and the wireless chipset was beginning to get flaky.  I’d been running DD-WRT on it for about a year and a half without any problems, but lately it started having issues only with wireless connections.  Being the cheapskate I am, I ordered a refurb E2500 Cisco from Amazon for under $40 and in a few days it showed up in the mail.  I had already looked up the router in the DD-WRT router database and pulled down the mini firmware in order to overwrite the stock firmware.  (Unfortunately, what I would later read in the forum posts is that the firmware version dd-wrt.v24-18625_NEWD-2_K2.6_mini-e2500.bin would basically brick the router.)  So do yourself a favor and use the 18710 version right off the bat  (dd-wrt.v24-18710_NEWD-2_K2.6_std_usb_nas-e2500.bin).

Even though I had properly followed the 30-30-30 power cycling procedure and updated the firmware with the one recommended in the router database, my router was caught in a continuous reboot cycle.  Every so often I could ping the router for a little while and if I timed it right, I could successfully TFTP up the original stock firmware, however after manually power cycling, it would go back to it’s constant reboot cycle on its own.  Believe me, I worked on it for quite a few hours and then gave up on it.  Then as luck would have it a few days later, I read a post that someone had left it unplugged for a day and the router no longer went through the automatic reboot and stayed solid, but they couldn’t get to the GUI DD-WRT interface.  I had the same results, and left the router unplugged for two days, and when I tired was able to telnet to the router and fix it using these steps:

Telnetting to the E2500 router
I had to set my laptop’s NIC card manually first to and then was able to telnet to the router at

Then, as you can see above, I performed an “erase linux” and “erase nvram” and then power cycled the router.   At this point I could get to the Management Mode Firmware Upgrade Utility by going to

Firmware upgrade management interface - cisco E2500
Thank goodness for the firmware upgrade management interface – cisco E2500

Now believe me, I really thought hard about loading up the stock firmware, but hey, I might as well try DD-WRT again.  Using the management interface I uploaded  newer fixed version of the DDWRT firmware (version 18625).

Of course waiting during the firmware upload is the worst part
Of course waiting during the firmware upload is the worst part for me. I’ve spent too many sleepless hours back in the day waiting around for hours while uploading images to old cisco routers over xmodem protocols to enjoy this sort of thing anymore.

Luckily this time the firmware took and after a single *yay* power-cycle, I was presented with the standard, change your password page for DD-WRT!

Yay!  The default change your user and password page for DD-WRT
Yay! The default change your user and password page for DD-WRT

Then all I had to do was go thought and put back in all my settings… and enjoy my new router with much better working wireless.

This is how you can perform authentication using RSA Secure ID authentication in your PHP environment. RSA does not provide a module or agent to directly work with PHP, so in order to make it work we will use a PAM PECL extension.  This tutorial assumes you already have a working RSA Manager installation and SecureID tokens, and a running apache/php install.

Step 1:

Install the PAM PECL extension.  You can find it at  http://pecl.php.net/package/PAM

Follow the instructions to install and enable this extension.  This may require some development packages if you’re using the vendor-supplied build of PHP.  So for instance, in the case of RHEL6, this will require assignment of the “RHEL Server Optional” channel.   You can then install the php-devel package.  If using a custom build of PHP, this step should not be necessary.

yum install php-devel
yum install pam-devel
Unzip, and run “phpize” in the directory
Then run “./configure”
Then “make”
Then “make install”

Edit your /etc/php.ini configuration file to include:


Step 2:

Install the linux RSA PAM agent following the instructions that are included with that agent.  Download from here: http://www.rsa.com/node.aspx?id=2844

Step 3:

Make sure to run acetest that is provided with the RSA pam authentication agent.  For 64-bit Red Hat, this utility will typically live in /opt/pam/bin/64bit/acetest .  This serves two purposes:  it creates files in /var/ace that we will need to change permissions on, and it also verifies that you are communicating with and properly authenticating against the RSA Manager/server.  If you are not able to verify with the acetest utility, make sure you have properly added the agent to your RSA Manager.

 Step 4:

Change the permissions on files in /var/ace:

Change the group of sdstatus.1 and securid to the web server group (for example, apache)

cd /var/ace
chgrp apache sdstatus.1
chgrp apache securid
chmod 664 sdstatus.1
chmod 440 securid

This is required so that the php process can read the securid file and update sdstatus.1 .  Default permissions only allow root to do this.

Step 5:

Create a PAM configuration file.  The default pam configuration name is “php” unless a different pam.servicename is specified in the php.ini.

As an example, on RHEL 6, you could create this as /etc/pam.d/php with the following entries:

auth         required        pam_securid.so debug
account       required        pam_permit.so

Note: debug is optional, this gives you some potentially useful logging information while you are fine tuning your authentication.  Once you have a working config, debug can certainly be removed.

Step 6:

Create an rsa_auth.php test page to verify if your php/pam/RSA configuration is working:

<head><title>RSA Test Page!</title></head>
$message = “”;
$err = “”;
if (isset($_POST[‘username’] ) && isset($_POST[‘passcode’])) {
if (pam_auth($_POST[‘username’], $_POST[‘passcode’], $err, false) === true) {
$message = “Authentication was Successfull”;
else {
$message = “Authentication Failed – $err”;
<font color=”red”><?php echo $message ?></font><br>
<form method=POST action=”<?php echo $_SERVER[‘PHP_SELF’]?>”>
username: <input type=”text” name=”username” /><br>
passcode: <input type=”password” name=”passcode” />
<input type=”submit” />

Step 7:
Restart apache and try it out!

Please remember to integrate your real PHP authentication page with the appropriate input filtering to better secure and sanitze the input to protect against exploits, etc.