ELK, the free alternative to Splunk

Installation of ELK is not too bad. There are a few guides online that walk through the processes but you will be hard pressed to find one to covers it all the way through. Some great links to help with this endeavor are:



Installing ELK (CentOS)

This is a short step-by-step guide on installing ElasticSearch LogStash and Kibana Stack on a CentOS environment to gather and analyze logs.

I. Install JDK

rpm -ivh https://dl.dropboxusercontent.com/u/5756075/jdk-7u45-linux-x64.rpm

II. Install & Configure ElasticSearch

Add repository

rpm --import http://packages.elasticsearch.org/GPG-KEY-elasticsearch
cat > /etc/yum.repos.d/elasticsearch.repo <<EOF
name=Elasticsearch repository for 1.3.x packages

Install ElasticSearch

yum -y install elasticsearch

Configure ElasticSearch

  1. Increase the openfile limits to elasticsearch by:

    echo 'elasticsearch soft nofile 32000' >> /etc/security/limits.conf
    echo 'elasticsearch hard nofile 32000' >> /etc/security/limits.conf
  2. Configure elasticsearch data storage path

    echo 'path.data: /data/es/logs' >> /etc/elasticsearch/elasticsearch.yml
    mkdir -p /data/es/logs
    chown -R elasticsearch:elasticsearch /data/es/logs
  3. Disallow elasticsearch process from swapping (try to lock the process address space into RAM)

    sed -i "s|^# bootstrap.mlockall:.*$|bootstrap.mlockall: true|" /etc/elasticsearch/elasticsearch.yml
  4. Change the JVM Size

    sed -i "s|^#ES_HEAP_SIZE=.*$|ES_HEAP_SIZE=4g|" /etc/sysconfig/elasticsearch

    NOTE: Make sure you have enough RAM on the machine before bumping up the value of the ElasticSearch Deamon’s JVM Heap Size and make changes accordingly.

  5. Start ElasticSearch

    service elasticsearch start

III. Install & Configure Kibana

  1. Download Kibana

    cd /opt
    wget https://download.elasticsearch.org/kibana/kibana/kibana-3.1.0.tar.gz
    tar xzf kibana-3.1.0.tar.gz
    ln -s kibana-3.1.0 kibana
  2. Install Nginx

    rpm -Uvh http://download.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm
    yum -y install nginx
  3. Configure Nginx to server kibana

    mkdir -p /usr/share/nginx/kibana3
    cp -R /opt/kibana/* /usr/share/nginx/kibana3/
  4. Download sample nginx config:

    cd ~; curl -OL https://raw.githubusercontent.com/elasticsearch/kibana/kibana3/sample/nginx.conf
    sed -i "s|kibana.myhost.org|$(hostname -f)|" nginx.conf
    sed -i "s|root.*/usr/share/kibana3;|root /usr/share/nginx/kibana3;|" nginx.conf
    cp ~/nginx.conf /etc/nginx/conf.d/default.conf

    NOTE: If you don’t find the sample nginx.conf try this: https://github.com/elasticsearch/kibana/blob/kibana3/sample/nginx.conf, it generally should be laying around in some other branch of kibana.

  5. Install apache2-utils to generate username and password pair

    yum -y install httpd-tools-2.2.15
    htpasswd -c /etc/nginx/conf.d/$(hostname -f).htpasswd admin
  6. Start nginx for serving kibana and to make sure that kibana is available after reboot’s

    service nginx start
    chkconfig nginx on

IV. Install & Configure LogStash

Add Repository

cat > /etc/yum.repos.d/logstash.repo <<EOF
name=logstash repository for 1.4.x packages

Install logstash

yum -y install logstash logstash-contrib

Generating SSL Certificates

Since we are going to use Logstash Forwarder to ship logs from our Servers to our Logstash Server, we need to create an SSL certificate and key pair. The certificate is used by the Logstash Forwarder to verify the identity of Logstash Server.

Generate the SSL certificate and private key, in the appropriate locations (/etc/pki/tls/…), with the following command:

cd /etc/pki/tls; sudo openssl req -x509 -batch -nodes -days 3650 -newkey rsa:2048 -keyout private/logstash-forwarder.key -out certs/logstash-forwarder.crt

The logstash-forwarder.crt file will be copied to all of the servers that will send logs to Logstash but we will do that a little later. Let’s complete our Logstash configuration.

Configure logstash

cat > /etc/logstash/conf.d/01-lumberjack-input.conf <<EOF
input {
  lumberjack {
    port => 5000
    type => "logs"
    ssl_certificate => "/etc/pki/tls/certs/logstash-forwarder.crt"
    ssl_key => "/etc/pki/tls/private/logstash-forwarder.key"

This specifies a lumberjack input that will listen on tcp port 5000, and it will use the SSL certificate and private key that we created earlier.

Now lets create another config file, where we will add a filter for syslog messages:

cat > /etc/logstash/conf.d/10-syslog.conf <<EOF
filter {
  if [type] == "syslog" {
    grok {
      match => { "message" => "%{SYSLOGTIMESTAMP:syslog_timestamp} %{SYSLOGHOST:syslog_hostname} %{DATA:syslog_program}(?:\[%{POSINT:syslog_pid}\])?: %{GREEDYDATA:syslog_message}" }
      add_field => [ "received_at", "%{@timestamp}" ]
      add_field => [ "received_from", "%{host}" ]
    syslog_pri { }
    date {
      match => [ "syslog_timestamp", "MMM  d HH:mm:ss", "MMM dd HH:mm:ss" ]

This filter looks for logs that are labeled as “syslog” type (by a Logstash Forwarder), and it will try to use “grok” to parse incoming syslog logs to make it structured and query-able.

Now lets create another config file to tell logstash to store logs in elasticsearch.

cat > /etc/logstash/conf.d/30-lumberjack-output.conf <<EOF
output {
  elasticsearch { host => localhost }
  stdout { codec => rubydebug }

Start logstash

service logstash start

V. Setup Logstash Forwarder

Note: Do these steps for each server that you want to send logs to your Logstash Server.

Copy SSL certificate to logstash forwarder agents from logstash server:

scp /etc/pki/tls/certs/logstash-forwarder.crt [user]@[server]:/tmp

NOTE: Replace [user] and [server] with the username you have access to ssh into the logstash agents and the server with hostname/ip-address of logstash agent

Install logstash forwarder

rpm -ivh http://packages.elasticsearch.org/logstashforwarder/centos/logstash-forwarder-0.3.1-1.x86_64.rpm

Install logstash forwarder init script

cd /etc/init.d/; sudo curl -o logstash-forwarder http://logstashbook.com/code/4/logstash_forwarder_redhat_init
chmod +x logstash-forwarder
cat > /etc/sysconfig/logstash-forwarder <<EOF
LOGSTASH_FORWARDER_OPTIONS="-config /etc/logstash-forwarder -spool-size 100"
cp /tmp/logstash-forwarder.crt /etc/pki/tls/certs

Configure logstash forwarder

cat > /etc/logstash-forwarder <<EOF
  "network": {
    "servers": [ "${LS_SERVER}:5000" ],
    "timeout": 15,
    "ssl ca": "/etc/pki/tls/certs/logstash-forwarder.crt"
  "files": [
      "paths": [
      "fields": { "type": "syslog" }

NOTE: Be sure to replace [LOGSTASH_SERVER_FQDN] with the FQDN of your logstash server

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For those who are inclined to install ELK in Windows, these sites are pretty useful.


Building up a logging server – OSS style!