Elastic has their own guide to install elasticsearch with Debian packages. you can find it on their website.

https://www.elastic.co/guide/en/elasticsearch/reference/current/deb.html

I used this one and now everything works like a charm.

Elasticsearch requires Java 8 or later:

$ sudo apt-get install openjdk-8-jdk
$ java -version
openjdk version "1.8.0_111"

Install Elasticsearch

$ wget -qO - https://artifacts.elastic.co/GPG-KEY-elasticsearch | sudo apt-key add -
$ sudo apt-get install apt-transport-https
$ echo "deb https://artifacts.elastic.co/packages/5.x/apt stable main" | sudo tee -a /etc/apt/sources.list.d/elastic-5.x.list
$ sudo apt-get update && sudo apt-get install elasticsearch

some remarks (from elastic website):

• Do not use add-apt-repository as it will add a deb-src entry as well, but we do not provide a source package. If you have added the deb-src entry, you will see an error like the following:

Unable to find expected entry 'main/source/Sources' in Release file
Wrong sources.list entry or malformed file)

=> Delete the deb-src entry from the /etc/apt/sources.list file and the installation should work as expected.

• If two entries exist for the same Elasticsearch repository, you will see an error like this during apt-get update:

Duplicate sources.list entry https://artifacts.elastic.co/packages/5.x/apt/ ...`

=> Examine /etc/apt/sources.list.d/elasticsearch-5.x.list for the duplicate entry or locate the duplicate entry amongst the files in /etc/apt/sources.list.d/ and the /etc/apt/sources.list file

For very basic installation of ElasticSearch 1.x or 2.x on Ubuntu 16.04

(the same goes for Ubuntu 14.04) do the next few steps on fresh install Ubuntu:

1. sudo apt-get update

2. sudo apt-get upgrade

3. sudo add-apt-repository ppa:webupd8team/java

4. sudo apt-get update

5. sudo apt-get install oracle-java8-installer

6. java -version

//For 2.x; elasticsearch 2.4.0

1. wget https://download.elastic.co/elasticsearch/release/org/elasticsearch/distribution/deb/elasticsearch/2.4.0/elasticsearch-2.4.0.deb

2. sudo dpkg -i elasticsearch-2.4.0.deb

3. service elasticsearch status

4. sudo apt-get install -y curl lynx links

5. lynx http : // localhost : 9200

OR

5. curl -X GET 'http : // localhost:9200'

Installing ElasticSearch 6.8.6 on Ubuntu 16

The latest version at the time of writing was 7 but we needed version 6 for compatibility reasons so using the typical apt-get package manager wouldn't work. Instead we opted to install the package directly.

1. Download and install the debian package for version 6.8.6:

   wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-6.8.6.deb
   wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-6.8.6.deb.sha512
   shasum -a 512 -c elasticsearch-6.8.6.deb.sha512 
   sudo dpkg -i elasticsearch-6.8.6.deb
   

2. Setup elasticsearch to start automatically on boot.

   sudo /bin/systemctl daemon-reload
   sudo /bin/systemctl enable elasticsearch.service
   

3. Start the elasticsearch service.

   bash
   sudo systemctl start elasticsearch.service
   

4. Confirm elasticsearch is running:

   $ curl -X GET "localhost:9200/?pretty"
   {
     "name" : "dfdnndd",
     "cluster_name" : "elasticsearch",
     "cluster_uuid" : "abcdadsf123234234",
     "version" : {
       "number" : "6.8.6",
       "build_flavor" : "default",
       "build_type" : "deb",
       "build_hash" : "3d9f765",
       "build_date" : "2019-12-13T17:11:52.013738Z",
       "build_snapshot" : false,
       "lucene_version" : "7.7.2",
       "minimum_wire_compatibility_version" : "5.6.0",
       "minimum_index_compatibility_version" : "5.0.0"
     },
     "tagline" : "You Know, for Search"
   } 
   

   NOTE: Sometimes it takes a few seconds to spin up.

5. Configure as necessary:

   vi /etc/elasticsearch/elasticsearch.yml
   

   For example, uncomment this line, #network.host: localhost, and replace localhost with your server's IP address so it looks someting like this: network.host: 123.123.123.123.

Elasticsearch 7.x installation on Ubuntu 20.04

• Installing openjdk 11 (8th version also have been used without issues):

    sudo apt install openjdk-11-jre-headless
  

• Elasticsearch installation

    curl -fsSL https://artifacts.elastic.co/GPG-KEY-elasticsearch | sudo apt-key add -
    echo "deb https://artifacts.elastic.co/packages/7.x/apt stable main" | sudo tee -a /etc/apt/sources.list.d/elastic-7.x.list
    sudo apt update
    sudo apt install elasticsearch
  

• Configure elasticsearch configuration file /etc/elasticsearch/elasticsearch.yml

    cluster.name: myclaster
    node.name: mynode1
    network.host: 192.168.0.5
  

  Uncomment the above option and specify your IP address or just localhost if you do not desire to give access to it through your local network.

• If you desire to allow access to it from your local network, then specify only IP addresses of specific machine you want to grant access from:

    sudo ufw allow from 192.168.0.55 to any port 9200
  

  Do not allow access from any host, because of it does not have restrictions.

• Start elasticsearch service:

    sudo systemctl start elasticsearch
  

• Test if your elasticsearch service is running using telnet from both machines (192.168.0.5 and 192.168.0.55):

    telnet 192.168.0.5 9200
  

  You'll get the next

    Trying 192.168.0.5...
    telnet: Unable to connect to remote host: Connection refused
  

  if elasticsearch service is not running

  You'll get the next if it is running but blocked by firewall:

    Trying 192.168.0.5...
    telnet: Unable to connect to remote host: Connection timed out
  

  You'll get the next output if the service is running and it is allowed in firewall:

    Trying 192.168.0.5...
    Connected to 192.168.0.5.
    Escape character is '^]'.
  

• Test elasticsearch configuration by:

    curl -X GET 'http://192.168.0.5:9200'
  

More details here