Archives April 2017

Installing OpenLDAP 2.4 and Configuring Apache DS – Part 3

This web series is brought to you by: dOpenSource and Flyball Labs

This post is PART 3 of a series that details how to install Apache Directory Studio and OpenLDAP server and connect the two seamlessly. In the last post we went adding users, groups and organizations to your OpenLDAP server. We also went over modifying existing users and groups in your LDAP tree as well and how to query your LDAP database.

We have been using “.ldif” files and a terminal to manage our OpenLDAP tree thus far, but this method (although necessary to start) doesn’t provide a very nice “User Experience” or UX as we call it on the dev side of the house. So lets change that and put a nice Graphical User Interface (GUI) on top of our OpenLDAP system to manage our LDAP tree entries.

A quick note: there is a ton of information on querying your OpenLDAP tree structure that we have not yet touched on. Learning these methods will be vital to managing your users quickly and efficiently. Just to give you a glimpse forward, there are many advanced methods for searching and filtering LDAP queries such as: specifying search base, binding to a DN, specifying scope or search, advanced regular expression matching and filter output fileds, to name a few. We will go over ways to effectively get your data from your OpenLDAP server in a later post.

If you haven’t read PART 1 you can find it here: Installing OpenLDAP

If you haven’t read PART 2 you can find it here: Configuring OpenLDAP

We will now walthrough the installation of Apache Direcotry Studio and how to connect it to your existing OpenLDAP server. The examples below assume that the domain is dopensource.com but, you MUST REPLACE this with your own domain. Lets get started!

Requirements

This guide assumes you have either a Debian-based or cent-os / red-hat based linux distro.
This guide also assumes that you have root access on the server to install the software.
This guide assumes you have followed the steps in PART 1 and PART 2 of the series and have an OpenLDAP server configured with some test users and groups added to your tree.

Installing Apache Directory Studio


Switch to root user and enter your root users pw

Either using sudo:

sudo -i

Or if you prefer using su:

su

Install Oracle Java

Prior to installing Apache Directory Studio (Apache DS) we need to install Oracle Java version 8 or higher. The easiest way to do this is through a well a maintained repository / ppa.

Unistall all old versions of openjdk and oracle jdk:

On a debian based system the cmd would be:

apt-get -y remove --purge $(apt list | grep -ioP '.*open(jre|jdk).*' 'oracle-java.*' '^java([0-9]{1}|-{1}).*' '^ibm-java.*')

On a centos based system the cmd would be:

yum -y erase $(yum list | grep -ioP '(.*open(jre|jdk).*|oracle-java.*|^java([0-9]{1}|-{1}).*|^ibm-java.*)'
Remove old Java environment variables

We also need to cleanup any old java environment variables that may cause issues when we install the new version.

Check your environment for any java variables using this cmd:

env | grep "java"

If there are no matches then you can move on to the next section. Otherwise you need to manually remove those variables from your environment.

Check each one of the following files to see if there are any vars we need to remove. If you get a match remove the line that contains that variable entry (most likely an export statement):

cat /etc/environment 2> /dev/null | grep "java"
cat /etc/profile 2> /dev/null | grep "java"
cat ~/.bash_profile 2> /dev/null | grep "java"
cat ~/.bash_login 2> /dev/null | grep "java"
cat ~/.profile 2> /dev/null | grep "java"
cat ~/.bashrc 2> /dev/null | grep "java"

To remove the line just use your favorite text editor and source that file. For example if .bashrc what the culprit:

vim ~/.bashrc
... remove stuff ...
source ~/.bashrc

Now you are ready to install a recent release of Oracle Java.

Download and install Oracle JDK

For debian based systems there is a group of developers that package the latest versions of Oracle Java and provide it as a ppa repository. This is very convenient for updating Java versions. For centos based systems you will have to download the tar file of the latest release from Oracle’s website and install it manually.

For debian based systems we will add the ppa, update our packages and install the latest release of Oracle JDK.

cat << EOF > /etc/apt/sources.list.d/oracle-java.list
deb http://ppa.launchpad.net/webupd8team/java/ubuntu trusty main
deb-src http://ppa.launchpad.net/webupd8team/java/ubuntu trusty main
EOF

apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys EEA14886
apt-get -y update && apt-get -y install oracle-java8-installer
apt-get install oracle-java8-set-default

For centos based systems go to Oracle’s website here click on accept license agreement and copy the link of the linux .rpm file corresponding to your OS architecture. If you don’t know what architecture your machine is run the following command to find out:

uname -m

Now dowload and install the rpm using the following cmds:

JAVA_URL='the link that you copied'
JAVA_RPM=${JAVA_URL##*/}

cd /usr/local/
wget -c --no-cookies --no-check-certificate \
--header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" \
"$JAVA_URL"

rpm -ivh "$JAVA_RPM"
rm -f "$JAVA_RPM"

unset JAVA_URL && 
unset JAVA_RPM

At this point you should have Oracle Java JDK installed on your machine. Verify with the following cmds:

java -version
javac -version

You should see output similar to the following:

[root@box ~]# java -version
java version "1.8.0_131"
Java(TM) SE Runtime Environment (build 1.8.0_131-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.131-b11, mixed mode)

[root@box ~]# javac -version
javac 1.8.0_131

If you get an error here you may need to uninstall any dependencies on your system that are linked to the old java version and redo the process. One example may be libreoffice (often installed by default and depends on default java installation) which we could remove with following:

Debian based systems:

apt-get -y remove --purge '.*libreoffice.*'

Centos based systems:

yum -y remove '.*libreoffice.*'

For those with errors; after removing any packages that depended on the old versions of java, go back through the installation steps outlines above and you should be able to print out your java version.

Set Java environment vars for new version

First we will set our environment variables using a script we will make here: /etc/profile.d/jdk.sh

cat << 'EOF' > /etc/profile.d/jdk.sh
#!/bin/sh
#
# Dynamic loading of java environment variables
# We also set class path to include the following:
# if already set the current path is included,
# the current directory, the jdk and jre lib dirs,
# and the shared java library dir.
#

export JAVA_HOME=$(readlink -f /usr/bin/javac 2> /dev/null | sed 's:/bin/javac::' 2> /dev/null)
export JRE_HOME=$(readlink -f /usr/bin/java 2> /dev/null | sed 's:/bin/java::' 2> /dev/null)
export J2SDKDIR=J2REDIR=$JAVA_HOME
export DERBY_HOME=$JAVA_HOME/db

export PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin:$DERBY_HOME/bin
export CLASSPATH=$CLASSPATH:.:$JAVA_HOME/lib:$JRE_HOME/lib:/usr/share/java
EOF

After our script is created make it executable, and then source the main profile.

chmod +x /etc/profile.d/jdk.sh
source /etc/profile

You should now see the environment variables we added above when running this cmd:

env | grep -oP '.*(JAVA_HOME|JRE_HOME|J2SDKDIR|J2REDIR|DERBY_HOME|CLASSPATH).*'

Lastly we are going to enable the Java client for our web browsers:

Close all instances of firefox and chrome:

kill all firefox
kill all chrome

Grab the plugin from your Oracle Java install and link it:

JAVA_PLUGIN=$(find ${JRE_HOME}/ -name 'libnpjp2.so')

mkdir -p /usr/lib/firefox-addons/plugins && cd /usr/lib/firefox-addons/plugins
ln -s ${JAVA_PLUGIN}

mkdir -p /opt/google/chrome/plugins && cd /opt/google/chrome/plugins
ln -s ${JAVA_PLUGIN}

unset JAVA_PLUGIN
cd ~

Install the Apache Directory Studio suite

Download either the 32bit or 64bit (depending on you OS) version of Apache DS with the following:

APACHE_DSx64_URL="http://www-eu.apache.org/dist/directory/studio/2.0.0.v20161101-M12/ApacheDirectoryStudio-2.0.0.v20161101-M12-linux.gtk.x86_64.tar.gz"

APACHE_DSx32_URL="http://www-eu.apache.org/dist/directory/studio/2.0.0.v20161101-M12/ApacheDirectoryStudio-2.0.0.v20161101-M12-linux.gtk.x86.tar.gz"

APACHE_DS_URL="the url for your os architecture"
APACHE_DS_TAR=${APACHE_DS_URL##*/}

cd /usr/local/
wget --no-cookies --no-check-certificate "$APACHE_DS_URL"
tar -xzf "$APACHE_DS_TAR" && rm -f "$APACHE_DS_TAR" && cd ApacheDirectoryStudio

Now you can start the gui with the following cmd:

./ApacheDirectoryStudio

If you are configuring this on a remote server (like I was) you will need to set the ssh configs properly to forward X-applications (GUI / display) over to your local machine. If you are configuring the server locally and have a display you can skip this step.

Enable X11 forwarding over ssh on the remote server:

sed -ie '0,/.*X11Forwarding.*/{s/.*X11Forwarding.*/X11Forwarding yes/}; 0,/.*X11UseLocalhost.*/{s/.*X11UseLocalhost.*/X11UseLocalhost yes/}' /etc/ssh/sshd_config

Now disconnect and allow your local machine’s ssh client to receive the forwarded display:

sed -ie '0,/.*ForwardX11.*/{s/.*ForwardX11.*/ForwardX11 yes/}; 0,/.*ForwardX11Trusted.*/{s/.*ForwardX11Trusted.*/ForwardX11Trusted yes/}' /etc/ssh/ssh_config

Then establish a an ssh connection with remote X11 forwarding enabled and run it:

ssh -Y -C -4 -c blowfish-cbc,arcfour 'your remote user@your remote server ip'
cd /usr/local/ApacheDirectoryStudio
./ApacheDirectoryStudio

You should now see the GUI appear. Lets connect to our OpenLDAP server.

Click on the buttons File –> New –> LDAP Browser –> LDAP Connection>

Enter a name for your connection and enter the hostname of the LDAP server (you can find it using the **hostname** cmd)

Make sure to check your connection to the server by pressing the “Check Network Parameter” button before moving on. If you get an error, verify connectivity to the OpenLDAP server and port that your entered and try again.

Enter the LDAP admin’s Bind DN and password. From our example in the first blog post it would look something like this:

Bind DN or user: cn=Manager,dc=dopensource,dc=com

Bind Password: ‘ldap admin password’

Make sure to click the “Check Authentication” button and verifiy your credentials before moving on.

Enter your Base DN, for our example this was: **dc=dopensource,dc=com**

Check the feature box “Fetch Operational attributes while browsing”

You can now click “finish” and your connection to your OpenLDAP server through Apache DS is complete.

To view your DN and to manage the entries we made earlier:

click the LDAP icon on the left and it will bring up the sidbar for LDAP

Alternatively you can navigate to your LDAP tree by clicking window –> show view –> ldap browser

Congratulations you have set up your Apache DS front-end application to access your OpenLDAP server!

For More Information


For more information, or for any questions visit us at:

dOpenSource

Flyball Labs

For Professional services and Ldap configurations see:

dOpenSource OpenLDAP

dOpenSource OpenLDAP Services

If you have any suggestions for topics you would like us to cover in our next blog post please leave them in the comments ūüôā

Written By:

DevOpSec
Software Engineer
Flyball Labs

— Keep Calm and Code On —

Installing OpenLDAP-2.4 and Configuring Apache DS – Part 2

This web series is brought to you by: dOpenSource and Flyball Labs

This post is PART 2 of a series that details how to install Apache Directory Studio and OpenLDAP server and connect the two seamlessly. In the last post we went over installing OpenLDAP server and you should now have an operating OpenLDAP server on either a Debian based or Cent-OS based machine.

If you haven’t read PART 1 you can find it here: Installing OpenLDAP

We will now go over adding users, groups and organizations to your nice and shiny OpenLDAP server. These are all LDAP entries that will go in your OpenLDAP tree. The examples below assume that the domain is dopensource.com but, you MUST REPLACE this with your own domain. Lets get started!

Requirements

This guide assumes you have either a Debian-based or cent-os / red-hat based linux distro.
This guide also assumes that you have root access on the server to install the software.
This guide assumes you have followed the steps in PART 1 of the series and have an OpenLDAP server configured and running already.

Adding LDAP entries to your OpenLDAP tree


Switch to root user and enter your root users pw

Either using sudo:

sudo -i

Or if you prefer using su:

su

Adding an Organization Unit (OU)

Lets add an OU to our tree called ‘users’ that will hold all of our companies users.

We will modify our tree the same we did before, using tmp .ldif files and loading into ldap.

cat << EOF > /tmp/users.ldif
dn: ou=Users,dc=dopensource,dc=com
objectClass: organizationalUnit
ou: Users
EOF

Then add it to the tree using the following cmd:

ldapadd -f /tmp/users.ldif -D cn=Manager,dc=dopensource,dc=com -w < ldap admin pw >

And of course we clean up after ourselves:

rm -f /tmp/users.ldif

Lets check out our new and shiny organization in ldap:

ldapsearch -x -L -b dc=dopensource,dc=com

Adding Users to the OU

Next lets add some of our employess to the users OU:

cat << EOF > /tmp/fred.ldif
dn: cn=Fred Flintstone,ou=Users,dc=dopensource,dc=com
cn: Fred Flintstone
sn: Flintstone
objectClass: inetOrgPerson
userPassword: < user password >
uid: fflintstone
EOF

cat << EOF > /tmp/wilma.ldif
dn: cn=Wilma Flintstone,ou=Users,dc=dopensource,dc=com
cn: Wilma Flintstone
sn: Flintstone
objectClass: inetOrgPerson
userPassword: < user password >
uid: wflintstone
EOF

Like before we need to add the entry to our tree:

ldapadd -f fred.ldif -D cn=Manager,dc=dopensource,dc=com -w < ldap admin pw >
ldapadd -f wilma.ldif -D cn=Manager,dc=dopensource,dc=com -w < ldap admin pw >

And then cleanup for a nice and clean system:

rm -f /tmp/fred.ldif
rm -f /tmp/wilma.ldif

Lets make sure we didn’t miss any employees in our long list of users:

ldapsearch -x -L -b ou=Users,dc=dopensource,dc=com

Adding a Group to the OU

We have to seperate our employees because the Engineers don’t play nice with the Salesperson’s:

cat << EOF > /tmp/engineering.ldif
dn: cn=Engineering,ou=Users,dc=dopensource,dc=com
cn: Engineering
objectClass: groupOfNames
member: cn=Fred Flintstone,ou=Users,dc=dopensource,dc=com
EOF

cat << EOF > /tmp/sales.ldif
dn: cn=Sales,ou=Users,dc=dopensource,dc=com
cn: Sales
objectClass: groupOfNames
member: cn=Wilma Flintstone,ou=Users,dc=dopensource,dc=com
EOF

Lets add it to the good ‘ol christmass tree of ldap:

ldapadd -f /tmp/engineering.ldif -D cn=Manager,dc=dopensource,dc=com -w < ldap admin pw >
ldapadd -f /tmp/sales.ldif -D cn=Manager,dc=dopensource,dc=com -w < ldap admin pw >

And we have to cleanup after the holiday party:

rm -f /tmp/engineering.ldif
rm -f /tmp/sales.ldif

Lets check our groups and make sure they mingle well together:

ldapsearch -x -L -b ou=Users,dc=dopensource,dc=com cn=Engineering
ldapsearch -x -L -b ou=Users,dc=dopensource,dc=com cn=Sales

We can narrow it down even further, if we only want to see what groups exist:

ldapsearch -x -LLL -b "ou=Users,dc=dopensource,dc=com" "(&(objectclass=groupOfNames))" *

Adding an Existing User to an Existing Group

So Fred is sick and tired of R&D and wants to sell stuff, lets transfer him over to sales:

cat << EOF > /tmp/addtogroup.ldif
dn: cn=Sales,ou=Users,dc=dopensource,dc=com
changetype: modify
add: member
member: cn=Fred Flintstone,ou=Users,dc=dopensource,dc=com
EOF

Get him on the sales floor by adding into Sales group:

ldapadd -f /tmp/addtogroup.ldif -D cn=Manager,dc=dopensource,dc=com -w < ldap admin pw >

Gotta cleanup his desk before we go visit:

rm -f /tmp/addtogroup.ldif

Lets check out Fred’s new office:

ldapsearch -x -LLL -b "ou=Users,dc=dopensource,dc=com" "(&(cn=Engineering))" member

Looks like he’s right next to Wilma, hopefully they work well together ūüôā

For More Information


For more information, the next post in the series or for any questions visit us at:

dOpenSource
Flyball Labs

For Professional services and Ldap configurations see:

dOpenSource OepnLDAP
dOpenSource OpenLDAP Services

Written By:

DevOpSec
Software Engineer
Flyball Labs

Installing OpenLDAP 2.4 and Configuring Apache DS – Part 1

This web series is brought to you by: dOpenSource and Flyball Labs

This post is PART 1 of a series that details how to install Apache Directory Studio and OpenLDAP server and connect the two seamlessly. OpenLDAP is what’s referred to as an “Lightweight Directory Access Protocol” or LDAP for short, and is based on X.500 standards.

OpenLDAP can be used to manage user and groups in an organization and authenticate them on your systems, through certificate validation. APache DS is the front-end GUI we will be using to interface with our OpenLDAP server to manage our users and groups.

A quick note before we begin; in this post we use angle brackets to denote that you either need to input information there, or that there will be information output there. Great, lets get started!

Requirements

This guide assumes you have either a Debian-based or cent-os / red-hat based linux distro.
This guide also assumes that you have root access on the server to install the software.

Installing OpenLDAP Server


Switch to root user and enter your root users pw

Either using sudo:

sudo -i

Or if you prefer using su:

su

Install OpenLDAP dependencies using you package manager

On Debian based systems would be:

apt-get update -q -y
apt-get install -q -y dpkg slapd ldap-utils ldapscripts

On cent-os / rhel systems:

yum -y -q update
yum -y -q install openldap compat-openldap openldap-clients \
        openldap-servers openldap-servers-sql openldap-devel

The debian package may ask you for the admin ldap password now, no worries. We are going to write over this in the next step so put the same password that you will use throughout the tutorial.

Create a password for the admin ldap user

slappasswd
<enter secret pw here>
<re-enter secret pw here>
<you will see hash of pw here>

Copy the hash that is output from this cmd to your clipboard.

Update the ldap conf file with the new password

We are going to move to the dir where our ldap configs are:

For centos / rhel that is here: /etc/openldap/slapd.d/cn\=config
For debian / ubuntu that is here: /etc/ldap/slapd.d/cn\=config

Then we need to add the root pw hash we copied from last step.

cd /etc/*ldap/slapd.d/cn\=config
echo "olcRootPW: {SSHA}<pw hash goes here>" >> olcDatabase\=\{2\}bdb.ldif

Modify the distinguished name or (DN) for short; of the olcSuffix. This can be done using sed:

You should set the suffix to your DNS domain name. This will be appended to the DN in your tree.
For example, for dopensource.com would be:

sed -i "s/olcSuffix:.*/olcSuffix: dc=dopensource,dc=com/" olcDatabase\=\{2\}bdb.ldif
sed -i "s/olcRootDN:.*/olcRootDN: cn=Manager,dc=dopensource,dc=com/" olcDatabase\=\{2\}bdb.ldif

You would replace dopensource && com with your own domain.

Now change the monitor.ldif file to match tholcRootDN we changed earlier in bdb/ldif:

sed -i 's/olcAccess:.*/olcAccess: {0}to *  by dn.base="gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth" read  by dn.base="cn=Manager,dc=dopensource,dc=com" read  by * none/' olcDatabase={1}monitor.ldif
sed -ie '7d;' olcDatabase={1}monitor.ldif

Restrict users from viewing other users’ password hashes:

echo 'olcAccess: {0}to attrs=userPassword by self write by dn.base="cn=Manager,dc=dopensource,dc=com" write by anonymous auth by * none' >> olcDatabase\=\{2\}bdb.ldif
echo 'olcAccess: {1}to * by dn.base="cn=Manager,dc=dopensource,dc=com" write by self write by * read' >> olcDatabase\=\{2\}bdb.ldif

Set OpenLDAP service to start on boot

chkconfig slapd on
service slapd start

If you get any echecksum errors, such as:

5900f369 ldif_read_file: checksum error on "/etc/openldap/slapd.d/cn=config/olcDatabase={0}config.ldif"
5900f369 ldif_read_file: checksum error on "/etc/openldap/slapd.d/cn=config/olcDatabase={1}monitor.ldif"
5900f369 ldif_read_file: checksum error on "/etc/openldap/slapd.d/cn=config/olcDatabase={2}bdb.ldif"

Then you must run the following commands to fix your checksums before adding any entries.

Fixing checksum errors in config files

Copy the file(s) shown to have bad checksums when starting slapd to /tmp

mkdir -p /tmp/fixes &&
/bin/cp -rf /etc/openldap/slapd.d/cn=config/{olcDatabase={0}config.ldif,olcDatabase={1}monitor.ldif,olcDatabase={2}bdb.ldif} /tmp/fixes &&
cd /tmp/fixes

Remove the first 2 lines containing the old checksums:

for file in /tmp/fixes/*; do
    sed -i '1,2d' "${file}"
done

Install the zlib dev package and perl archive utils if not installed

For centos based systems:

yum -y -q install zlib-dev perl-Archive-Zip

For debian based sytems:

apt-get -y -q install zlib1g-dev libarchive-zip-perl

Now we can go ahead and calculate the new checksums:

for file in /tmp/fixes/*; do
CRC=$(crc32 "$file")

read -r -d '' INSERT_LINES << EOF
# AUTO-GENERATED FILE - DO NOT EDIT!! Use ldapmodify.
# CRC32 ${CRC}
EOF

cat << EOF > "${file}"
${INSERT_LINES}
$(cat ${file})
EOF
done

Then copy back the fixed files over the originals & delete tmp folder:

/bin/cp -rf /tmp/fixes/* /etc/openldap/slapd.d/cn=config/
cd /tmp && rm -Rf fixes

Create the root entry in our ldap tree.

The root entry is going to be configured as a special entry called a domain controller. To do this we will add the same domain name we have been using to the domain controller root entry.

Create the root entry in a temp file, should be named after your domain:

cat << EOF > /tmp/dopensource.ldif
dn: dc=dopensource,dc=com
objectClass: dcObject
objectClass: organization
dc: dopensource
o : dopensource
EOF

Add the contents of the file to your tree (pw is the amdmin ldap user):

ldapadd -f /tmp/dopensource.ldif -D cn=Manager,dc=dopensource,dc=com -w <your ldap admin pw>

Verify it was added (you should see the same info you added displayed):

ldapsearch -x -LLL -b dc=dopensource,dc=com

If you got back the same entry you put in, then delete the temp file:

rm -f /tmp/dopensource.ldif

We add in a symlink for better portable here:

ln -s /etc/openldap /etc/ldap

Allow access to the ldap server in your firewall rules:

iptables -A INPUT -p tcp --dport 389 -j ACCEPT
/sbin/service iptables save
iptables -F
service iptables restart

To ensure your iptables rule persisted you can check with:

iptables -L

To verify ldap is up check on port 389:

netstat -antup | grep -i 389 --color=auto
<terminal output here>

You should see LISTEN in your output, something like this:

tcp        0      0 0.0.0.0:389                 0.0.0.0:*                   LISTEN      22905/slapd
tcp        0      0 :::389                      :::*                        LISTEN      22905/slapd

For More Information


For more information, the next post in the series or for any questions visit us at:

dOpenSource
Flyball Labs

For Professional services and Ldap configurations see:

dOpenSource OepnLDAP
dOpenSource OpenLDAP Services

Written By:

DevOpSec
Software Engineer
Flyball Labs

Creating Custom OCF Resource Agents

A Simple Guide for Creating OCF Resource Agents with Pacemaker and Corosync


HA Clustering Explained

For those not familiar with High Availability resources & services or Cluster Computing, in this section we will go over a brief summary and explanation of OCF RA’s before we dive in to creating our own. In cluster networking multiple servers are inter-connected together on a network to provide improved delivery of services such as with HA.

The servers (referred to as nodes) are all managed by a Cluster Resource Manager (CRM), which as you may have guessed, manages cluster resources. High Availability (HA) refers to the ability to provide a resource or service with minimal to zero downtime. In layman’s terms, whatever client wants, client gets, and the store is open 24/7/365. In our case we will be using Pacemaker as our CRM.

Now each node has to have a way to communicate with other nodes in cluster for this to work, when a resource fails, or a node goes down, the CRM needs to be notified to make other resources available. This is where Corosync steps in. Corosync the communication layer that provides Pacemaker with the status of resources and nodes on the cluster. The information that Pacemaker receives can communicate many complex situations and scenarios that Pacemaker can deal with in a variety of ways.

OCF Resource Agents

Where do the Resource Agents fit into this picture you say? Glad you asked, the RA’s are deployed by pacemaker to interface with each resource that needs managed, using Corosync’s communication layer. The protocol used by the RA’s is known as the Open Cluster Framework (OCF) and defines how RA’s should be implemented and requirements to create one. Most of the time they are implemented in a shell script, but they can be written in any programming language needed. More info on HA cluster computing and OCF protocol implementation can be found at Cluster Labs and if you have any further questions feel free to email us at Flyball Labs That is it for the lecture today, on with the chlorophyll!


How to Create Your Own OCF RA


Prerequisites

This guide assumes that you have Corosync and Pacemaker setup on muli-node cluster (atleast 2).

You must also have access to the remote nodes via ssh / scp to transfer the completed files. Note that every node will need a copy of the RA script.

Design

We will be creating a simple Resource Agent that runs a supplied script to perform a health check. Our health check will simply check if the node has any hard drives that are 95% used or more. If the health check does not pass, then we must shut the node down and perform a failover to another node (including our RA).

Instructions

  1. First we are going to grab a template OCF script. You will need to install git cmd line package if you haven’t installed already. Change dir into that directory.
    
        git clone https://github.com/russki/cluster-agents.git &&
        cd cluster-agents
    
  2. Make a copy and rename the RA something pertinent like “HealthAgent”.
        cp generic-script health-agent
    
  3. Make sure to mae the copy executable.
        chmod +x HealthAgent
    
  4. Change names in the agent script to the one we renamed it to.
        sed -i 's/generic_script/health_agent/g' health-agent
        sed -i 's/generic-script/health-agent/g' health-agent
        sed -i 's/Generic Script/Health Agent/'  health-agent
    

    We now have a Resource Agent that can run and manage a shell script. Arguments will be passed through the agent to the calling script that we supply it. Now we need to copy it over to each of the cluster nodes, install and test it.

  5. We can accomplish this fairly simple with a bash script such as the one below. Note I just whipped this up so may need tweaked.

        #!/bin/bash
        #
        # Assuming user is the same on each node
        #
    
        USAGE() {
            echo "./rlogin.sh    ..."
        }
    
        if [ "$#" -eq 0 ]; then
            USAGE
            exit 1
        fi
    
        read -p "Username: " user
    
        for server in "$@"
        do
          scp health-agent "$user"@"$server":/usr/lib/ocf/resource.d/heartbeat
        done
    
        exit 0
    
  6. Create a shell script for the resource manager to run, which will check the HDD status on the node.
    Here is a sample script that I use across my cluster nodes, that checks the HDD capacity, and returns status.

    
        #!/bin/bash
        # Check if physical hard drives are full
        # Return 1 if any drive is over tolerance (percent)
        # Return 0 if all drives are under tolerance (percent)
    
        TOLERANCE=5 #default to 1)print $0}')
        TEST="$((100 - $TOLERANCE))"
    
        while read -r line; do
            if [[ "$line" -gt "$TEST" ]]; then
                echo "drive is over tolerance"
                exit 1
            fi
        done <<< "$USED"
    
        echo "all drives passed"
        exit 0
    

    Save the bash script, make it executable, then SCP it over to all the servers. Then connect to each node, perform tests, and add resource if everything checks out.

  7. Test your agent using ocf-tester to catch any mistakes (on remote nodes). We want to do this on all nodes to ensure they are configured / have correct dependencies to run our script. Node: provide it with full path to script.

        ocf-tester -n /usr/lib/ocf/resource.d/heartbeat/health-agent
    
  8. Try executing agent in a shell and make sure it executes w/o any major errors. Again like previous example we should check each of the nodes.
        export OCF_ROOT=/usr/lib/ocf; bash -x /usr/lib/ocf/resource.d/heartbeat/health-agent start
    
  9. Add the resource to Pacemaker using pcs.
    This should be done on all nodes in cluster you want that resource agent to monitor on.

        pcs resource create health-agent ocf:heartbeat:health-agent script="full/path/to/script/to/run" state="/dev/shm" alwaysrun="yes" op monitor interval=60s
    
  10. To see status of cluster:
        pcs status
    

    Which should show your newly added resource agent and some additional status information that can be helpful in debugging.

    To show detailed information about only the health-agent resource run the following:

        pcs resource show health-agent
    

    You can also run resource agent action cmds with the same cmd. This can be useful to test if a certain action isn’t working properly.

        pcs resource debug-start health-agent
        pcs resource debug-stop health-agent
        pcs resource debug-monitor health-agent
    

Summary

I hope that helped clear up a few gotchas about cluster resource management. The OCF protocol is not very intuitive and small changes can completely ruin your previously working agents. Make sure to test, test, and test again. There is also a more sophisticated testing framework for OCF resource agents called: ocft which allows for testing environments, creating test cases, and much more. You can find that tool at Linux HA Hope you enjoyed this post, more awesomeness to follow!


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Written By:

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Software Engineer
Flyball Labs

Enabling Secure WebSockets: FreePBX 12 and sipML5

Assumptions:

  • Using chan_sip
  • Using Chrome as your WebRTC client
  • Asterisk 11.x
  • Using FreePBX 12.0.x
  • CentOS 6.x

Download sipML 5

sipML is the WebRTC Client that we are going to use. We need to download the repository

yum install git
cd /var/www/html/
git clone https://github.com/DoubangoTelecom/sipml5.git
chown -R asterisk:asterisk sipml5/

Enable SSL on Built-in HTTP Server of Asterisk

vim /etc/asterisk/http_custom.conf

tlsenable=yes
tlsbindaddr=0.0.0.0:8089
tlscertfile=/etc/pki/tls/certs/localhost.crt
tlsprivatekey=/etc/pki/tls/private/localhost.key

We also need to give asterisk permissions to read the tls certs

chown asterisk:asterisk /etc/pki/tls/certs/localhost.crt
chown asterisk:asterisk /etc/pki/tls/private/localhost.key

Enable Extension for Secure Web Sockets (WSS)

In older version of freepbx, they do not support wss transports, so this will need to be manually configured in /etc/asterisk/sip_custom.conf replacing SOME_EXTENSION and SOMESECRET. The important line is the transport=wss,udp,tcp,tls, which will have wss as the first entry. dtlscertfile and dtlsprivatekey will need to be pointed at the same key cert and key setup in http_custom.conf

[SOME_EXTENSION]
deny=0.0.0.0/0.0.0.0
secret=1234pccw
dtmfmode=rfc2833
canreinvite=no
context=from-internal
host=dynamic
trustrpid=yes
mediaencryption=yes
sendrpid=pai
type=friend
nat=force_rport,comedia
port=5060
qualify=yes
qualifyfreq=60
transport=wss,udp,tcp,tls
avpf=yes
force_avp=no
icesupport=yes
encryption=yes
callgroup=
pickupgroup=
dial=SIP/1103
permit=0.0.0.0/0.0.0.0
callerid=SOME_EXTENSION
callcounter=yes
faxdetect=no
cc_monitor_policy=generic
dtlsenable=yes
dltsverify=no
dtlscertfile=/etc/pki/tls/certs/localhost.crt
dtlsprivatekey=/etc/pki/tls/private/localhost.key

Configure sipML5 expert mode

Browse to https://<server-name>/sipml5. Make sure you include the https and click on the demo button. You should now be at a registration screen. Enter in the extension you would like to register as in the display name and private identity. The public identity will follow the following format:

sip:<Extensions>@<ip-address>

The password will be the secret set for your extensions and the realm will be the ip address or domain name of your server.

We also need to configure expert mode to set the wss address and stun settings.

Under expert mode, the WebSocket Server URL follows the following syntax:

wss://<ip-of-server>:8089/ws

Then set the ice server to the following google address:

[{stun.l.google.com:19302}]

Finally select Enable RTCWeb Breaker and hit save.

You should now be able to register to your extension. To troubleshoot, you can bring up the console in chrome by right clicking and selecting inspect. Additionally, make sure you have opened the necessary wss and rtp ports in your firewall (8089/tcp, 10000-20000/udp)

Start up two instances of Chrome and test

To make a call between two webrtc phones, you will need to install chromium, an open source version of the Google Chrome browser. You can alternatively use two computers with chrome installed. You can add a second extension in /etc/asterisk/sip_custom.conf following the same syntax as the previous extension. After an asterisk restart, you should be able to register to the new extension using the same methods and place a call between the two browsers.

Site-to-Site VPN Options Using AWS

We recently worked with a customer that had a requirement that their application needed to connect via Site-to-Site VPN to there clients application.  They had a few choices, but they decided to move there application to Amazon Web Services  (AWS) and connect to there clients datacenter from there.  Therefore we setup a Virtual Private Cloud (VPC) within Amazon and started down the path of setting up a Site-to-Site Virtual Private Network (VPN) connection.

There are multiple ways of implementing a VPN within Amazon as discussed here. ¬†In most cases, it’s going to come down to using a AWS Hardware VPN or a Software VPN. ¬†The AWS Hardware VPN can be configured within a couple clicks and it gives you the option to generate the configuration for multiple well known firewalls, which ¬†you can use to configure your firewall or you can provide to your firewall administrator. ¬†The Software VPN consists of running an EC2 instance that has software that implements VPN functionality.

The main factor in deciding AWS Hardware VPN versus Software VPN should be based on who’s initiating the traffic. ¬†In our case, the customers application needed to initiate the request. ¬†This means that we had to leverage the Software VPN approach because the AWS Hardware VPN can not initiate traffic. ¬†It can only accept request. ¬†So, it’s great for a company that wants to migrate systems from there datacenter to Amazon and then have there user access the systems. Hence, their users are the initiators of the traffic.

The installation and setup of a Software VPN isn’t really that difficult, but you have to have some basic understanding of how AWS networking works. ¬†There are a few Software VPN implementations, but we selected OpenSWAN. ¬†There’s a few good articles that we used.

One of the main gotcha’s in setting up OpenSwan are to ensure that the Access Control List (ACL) defined by the far end (the Router that you are establishing the VPN with) matches the Right side configuration parameter within the setup. ¬†Once you read thru the above articles you will know what I mean.

The average time to setup an AWS Hardware VPN is 5 hours.  This includes configuration, testing and turn-up with the far end.

The average time to setup a Software VPN is 10-20 hours.  It really depends on the complexity of the Amazon VPC and how you need traffic to be routed and represented.

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