composer require "laravelcollective/html":"^5.3.0"

I tried other posts related to my issue but they didn't work. My computer has proxy, XAMPP and Composer. When I tried to type:

composer require "laravelcollective/html":"^5.3.0"

It shows the following message:

[Composer\Downloader\TransportException]
The "https://packagist.org/packages.json" file could not be downloaded: php_network_getaddresses: getaddrinfo faile d: No such host is known.
failed to open stream: php_network_getaddresses: getaddrinfo failed: No such host is known.

I set a variable for proxy but it didn't work either, according to post (Composer cannot download files)

HTTP_PROXY="http://mcd-server/mcd/proxy.pac" composer require "laravelcollective/html":"^5.4.0

JSON File:

{
"name": "laravel/laravel",
"description": "The Laravel Framework.",
"keywords": ["framework", "laravel"],
"license": "MIT",
"type": "project",
"require": {
    "php": ">=5.6.4",
    "laravel/framework": "5.4.*",
    "laravel/tinker": "~1.0",
    "laravelcollective/html": "5.4.*"
},
"require-dev": {
    "fzaninotto/faker": "~1.4",
    "mockery/mockery": "0.9.*",
    "phpunit/phpunit": "~5.7"
},
"autoload": {
    "classmap": [
        "database"
    ],
    "psr-4": {
        "App\\": "app/"
    }
},
"autoload-dev": {
    "psr-4": {
        "Tests\\": "tests/"
    }
},
"scripts": {
    "post-root-package-install": [
        "php -r \"file_exists('.env') || copy('.env.example', '.env');\""
    ],
    "post-create-project-cmd": [
        "php artisan key:generate"
    ],
    "post-install-cmd": [
        "Illuminate\\Foundation\\ComposerScripts::postInstall",
        "php artisan optimize"
    ],
    "post-update-cmd": [
        "Illuminate\\Foundation\\ComposerScripts::postUpdate",
        "php artisan optimize"
    ]
},
"config": {
    "preferred-install": "dist",
    "sort-packages": true,
    "optimize-autoloader": true
}

}

What else I can do?

via Chebli Mohamed