# ELK Stack
> Elasticsearch, Logstash, & Kibana

This is just a little write-up on my research in deploying the ELK stack.

## Prerequisites
```shell
sudo apt-get install -y gpg apt-transport-https`
wget -qO - https://artifacts.elastic.co/GPG-KEY-elasticsearch | sudo gpg --dearmor -o /usr/share/keyrings/elasticsearch-keyring.gpg
echo "deb [signed-by=/usr/share/keyrings/elasticsearch-keyring.gpg] https://artifacts.elastic.co/packages/8.x/apt stable main" | sudo tee /etc/apt/sources.list.d/elastic-8.x.list
sudo apt-get update && sudo apt-get install elasticsearch kibana logstash
sudo certbot certonly --standalone --preferred-challenges http -d elastic.domain.org
```

## Setup Elasticsearch
* Copy your certificates to `/etc/elasticsearch/certs`:
```shell
mkdir -p /etc/elasticsearch/certs/
sudo cp /etc/letsencrypt/live/elastic.domain.org/fullchain.pem /etc/elasticsearch/certs/fullchain.pem
sudo cp /etc/letsencrypt/live/elastic.domain.org/privkey.pem   /etc/elasticsearch/certs/privkey.pem
sudo chmod -R 777 /etc/elasticsearch/certs/
```

* Edit your `/etc/elasticsearch/elasticsearch.yml` and change the follow options:
```yaml
cluster.name: BeeHive
node.name: gibson
network.host: 0.0.0.0    
bootstrap.memory_lock: true
xpack.security.audit.enabled: true
xpack.security.http.ssl:
  enabled: true
  key: /etc/elasticsearch/ssl/privkey.pem
  certificate: /etc/elasticsearch/ssl/fullchain.pem
```

* System changes:
```shell
sudo su  
	ulimit -n 65535
	ulimit -u 4096

echo "elasticsearch  -  nofile  65535" > /etc/security/limits.conf
mkdir -p /etc/systemd/system/elasticsearch.service.d/
echo "[Service]\nLimitMEMLOCK=infinity" > /etc/systemd/system/elasticsearch.service.d/override.conf
sudo swapoff -a
sudo sysctl -w vm.swappiness=1         # Add these
sudo sysctl -w vm.max_map_count=262144 # to /etc/systctl.conf
sudo sysctl -w net.ipv4.tcp_retries2=5 # 
```

* Set the password for Kibana:
`./usr/share/elasticsearch/bin/elasticsearch-reset-password -u kibana_system`
`./usr/share/elasticsearch/bin/elasticsearch-create-enrollment-token --scope kibana # Save this for when we access Kibana the first time`
`./usr/share/elasticsearch/bin/elasticsearch-create-enrollment-token -s node # enrollment token for a new node`

## Setup Kibana
* Copy your certificates to `/etc/kibana/certs`:
```shell
mkdir -p /etc/kibana/certs/
sudo cp /etc/letsencrypt/live/elastic.domain.org/fullchain.pem /etc/kibana/certs/fullchain.pem
sudo cp /etc/letsencrypt/live/elastic.domain.org/privkey.pem   /etc/kibana/certs/privkey.pem
```

* Edit your `/etc/kibana/kibana.yml` and change the follow options:
```yaml
server.host: "0.0.0.0"
server.publicBaseUrl: "https://elastic.domain.org"
server.ssl.enabled: true 
server.ssl.certificate: /etc/kibana/certs/fullchain.pem
server.ssl.key: /etc/kibana/certs/privkey.pem
elasticsearch.hosts: ["https://elastic.domain.org:9200"]
elasticsearch.username: "kibana_system"
elasticsearch.password: "changeme" # Use the password from the reset command we did earlier
```

## Setup Logstash
* Copy your certificates to `/etc/logstash/certs`:
```shell
mkdir -p /etc/logstash/certs/
sudo cp /etc/letsencrypt/live/elastic.domain.org/fullchain.pem /etc/logstash/certs/cacert.pem
```

* Edit your `/etc/logstash/logstash.yml` and change the follow options:
```yaml
input {
  beats {
    port => 5044
  }
}
output {
  elasticsearch {
    hosts => ["https://elastic.domain.org:9200"]
    index => "%{[@metadata][beat]}-%{[@metadata][version]}-%{+YYYY.MM.dd}"
    user => "elastic"
    password => "changeme"
    cacert => "/etc/logstash/cacert.pem"
  }
}
```

* `logstash-plugin install logstash-input-irc`

## Start the ELK stack:
```shell
sudo systemctl daemon-reload
sudo systemctl enable elasticsearch.service && sudo systemctl start elasticsearch.service
sudo systemctl enable kibana.service        && sudo systemctl start kibana.service
sudo systemctl enable logstash.service      && sudo systemctl start logstash.service
```