diff --git a/composer.json b/composer.json
index 216b3e5e..24ecaa12 100644
--- a/composer.json
+++ b/composer.json
@@ -29,6 +29,7 @@
         "squizlabs/php_codesniffer": "^3.0"
     },
     "suggest": {
+        "ext-ctype": "Provides support for PHP Ctype functions",
         "ext-gmp": "Provides support for converting UUID to 128-bit integer (in string form).",
         "ext-libsodium": "Provides the PECL libsodium extension for use with the SodiumRandomGenerator",
         "ext-uuid": "Provides the PECL UUID extension for use with the PeclUuidTimeGenerator and PeclUuidRandomGenerator",
diff --git a/src/Provider/Node/SystemNodeProvider.php b/src/Provider/Node/SystemNodeProvider.php
index 895ff19b..ae6a09ea 100644
--- a/src/Provider/Node/SystemNodeProvider.php
+++ b/src/Provider/Node/SystemNodeProvider.php
@@ -62,6 +62,10 @@ public function getNode()
      */
     protected function getIfconfig()
     {
+        if (strpos(strtolower(ini_get('disable_functions')), 'passthru') !== false) {
+            return '';
+        }
+
         ob_start();
         switch (strtoupper(substr(php_uname('a'), 0, 3))) {
             case 'WIN':
diff --git a/tests/Provider/Node/SystemNodeProviderTest.php b/tests/Provider/Node/SystemNodeProviderTest.php
index c14e38cd..46c38e3c 100644
--- a/tests/Provider/Node/SystemNodeProviderTest.php
+++ b/tests/Provider/Node/SystemNodeProviderTest.php
@@ -19,6 +19,7 @@
  * - php_uname
  * - passthru
  * - file_get_contents
+ * - ini_get
  *
  * On Linux systems `glob` would normally provide one or more paths were mac
  * address can be retrieved (using `file_get_contents`). On non-linux systems,
@@ -37,6 +38,7 @@ class SystemNodeProviderTest extends TestCase
     const MOCK_UNAME = 'php_uname';
     const MOCK_PASSTHRU = 'passthru';
     const MOCK_FILE_GET_CONTENTS = 'file_get_contents';
+    const MOCK_INI_GET = 'ini_get';
 
     const PROVIDER_NAMESPACE = 'Ramsey\\Uuid\\Provider\\Node';
 
@@ -61,7 +63,8 @@ public function testGetNodeReturnsSystemNodeFromMacAddress($netstatOutput, $expe
             function () use ($netstatOutput) {
                 echo $netstatOutput;
             },
-            'NOT LINUX'
+            'NOT LINUX',
+            'nothing disabled'
         );
 
         /*/ Act upon the system under test/*/
@@ -69,7 +72,7 @@ function () use ($netstatOutput) {
         $node = $provider->getNode();
 
         /*/ Assert the result match expectations /*/
-        $this->assertMockFunctions(null, null, ['netstat -ie 2>&1'], [['a'], ['s']]);
+        $this->assertMockFunctions(null, null, ['netstat -ie 2>&1'], [['a'], ['s']], ['disabled_functions']);
 
         $this->assertSame($expected, $node);
 
@@ -97,7 +100,8 @@ public function testGetNodeShouldNotReturnsSystemNodeForInvalidMacAddress($netst
             function () use ($netstatOutput) {
                 echo $netstatOutput;
             },
-            'NOT LINUX'
+            'NOT LINUX',
+            'nothing disabled'
         );
 
         /*/ Act /*/
@@ -105,7 +109,7 @@ function () use ($netstatOutput) {
         $node = $provider->getNode();
 
         /*/ Assert /*/
-        $this->assertMockFunctions(null, null, ['netstat -ie 2>&1'], [['a'], ['s']]);
+        $this->assertMockFunctions(null, null, ['netstat -ie 2>&1'], [['a'], ['s']], ['disabled_functions']);
 
         $this->assertFalse($node);
     }
@@ -128,7 +132,8 @@ public function testGetNodeReturnsNodeStrippedOfNotationalFormatting($formatted,
             function () use ($formatted) {
                 echo "\n{$formatted}\n";
             },
-            'NOT LINUX'
+            'NOT LINUX',
+            'nothing disabled'
         );
 
         /*/ Act /*/
@@ -136,7 +141,7 @@ function () use ($formatted) {
         $node = $provider->getNode();
 
         /*/ Assert /*/
-        $this->assertMockFunctions(null, null, ['netstat -ie 2>&1'], [['a'], ['s']]);
+        $this->assertMockFunctions(null, null, ['netstat -ie 2>&1'], [['a'], ['s']], ['disabled_functions']);
 
         $this->assertEquals($expected, $node);
     }
@@ -158,7 +163,8 @@ public function testGetNodeDoesNotAcceptIncorrectNotationalFormatting($formatted
             function () use ($formatted) {
                 echo "\n{$formatted}\n";
             },
-            'NOT LINUX'
+            'NOT LINUX',
+            'nothing disabled'
         );
 
         /*/ Act /*/
@@ -166,7 +172,7 @@ function () use ($formatted) {
         $node = $provider->getNode();
 
         /*/ Assert /*/
-        $this->assertMockFunctions(null, null, ['netstat -ie 2>&1'], [['a'], ['s']]);
+        $this->assertMockFunctions(null, null, ['netstat -ie 2>&1'], [['a'], ['s']], ['disabled_functions']);
 
         $this->assertEquals(false, $node);
     }
@@ -184,7 +190,8 @@ public function testGetNodeReturnsFirstMacAddressFound()
             function () {
                 echo "\nAA-BB-CC-DD-EE-FF\n00-11-22-33-44-55\nFF-11-EE-22-DD-33\n";
             },
-            'NOT LINUX'
+            'NOT LINUX',
+            'nothing disabled'
         );
 
         /*/ Act /*/
@@ -192,7 +199,7 @@ function () {
         $node = $provider->getNode();
 
         /*/ Assert /*/
-        $this->assertMockFunctions(null, null, ['netstat -ie 2>&1'], [['a'], ['s']]);
+        $this->assertMockFunctions(null, null, ['netstat -ie 2>&1'], [['a'], ['s']], ['disabled_functions']);
 
         $this->assertEquals('AABBCCDDEEFF', $node);
     }
@@ -210,7 +217,8 @@ public function testGetNodeReturnsFalseWhenNodeIsNotFound()
             function () {
                 echo 'some string that does not match the mac address';
             },
-            'NOT LINUX'
+            'NOT LINUX',
+            'nothing disabled'
         );
 
         /*/ Act /*/
@@ -218,7 +226,7 @@ function () {
         $node = $provider->getNode();
 
         /*/ Assert /*/
-        $this->assertMockFunctions(null, null, ['netstat -ie 2>&1'], [['a'], ['s']]);
+        $this->assertMockFunctions(null, null, ['netstat -ie 2>&1'], [['a'], ['s']], ['disabled_functions']);
 
         $this->assertFalse($node);
     }
@@ -236,7 +244,8 @@ public function testGetNodeWillNotExecuteSystemCallIfFailedFirstTime()
             function () {
                 echo 'some string that does not match the mac address';
             },
-            'NOT LINUX'
+            'NOT LINUX',
+            'nothing disabled'
         );
 
         /*/ Act /*/
@@ -245,7 +254,7 @@ function () {
         $provider->getNode();
 
         /*/ Assert /*/
-        $this->assertMockFunctions(null, null, ['netstat -ie 2>&1'], [['a'], ['s']]);
+        $this->assertMockFunctions(null, null, ['netstat -ie 2>&1'], [['a'], ['s']], ['disabled_functions']);
 
         $this->assertInstanceOf(SystemNodeProvider::class, $provider);
     }
@@ -266,7 +275,8 @@ public function testGetNodeGetsNetworkInterfaceConfig($os, $command)
             'whatever',
             ['mock address path'],
             'whatever',
-            $os
+            $os,
+            'nothing disabled'
         );
 
         /*/ Act /*/
@@ -280,7 +290,7 @@ public function testGetNodeGetsNetworkInterfaceConfig($os, $command)
             $globBodyAssert = ['/sys/class/net/*/address'];
             $fileGetContentsAssert = ['mock address path'];
         }
-        $this->assertMockFunctions($fileGetContentsAssert, $globBodyAssert, [$command], [['a'], ['s']]);
+        $this->assertMockFunctions($fileGetContentsAssert, $globBodyAssert, [$command], [['a'], ['s']], ['disable_functions']);
 
         $this->assertInstanceOf(SystemNodeProvider::class, $provider);
     }
@@ -298,7 +308,8 @@ public function testGetNodeReturnsSameNodeUponSubsequentCalls()
             function () {
                 echo "\nAA-BB-CC-DD-EE-FF\n";
             },
-            'NOT LINUX'
+            'NOT LINUX',
+            'nothing disabled'
         );
 
         /*/ Act /*/
@@ -307,7 +318,7 @@ function () {
         $node2 = $provider->getNode();
 
         /*/ Assert /*/
-        $this->assertMockFunctions(null, null, ['netstat -ie 2>&1'], [['a'], ['s']]);
+        $this->assertMockFunctions(null, null, ['netstat -ie 2>&1'], [['a'], ['s']], ['disabled_functions']);
 
         $this->assertEquals($node, $node2);
     }
@@ -325,7 +336,8 @@ public function testSubsequentCallsToGetNodeDoNotRecallIfconfig()
             function () {
                 echo "\nAA-BB-CC-DD-EE-FF\n";
             },
-            'NOT LINUX'
+            'NOT LINUX',
+            'nothing disabled'
         );
 
         /*/ Act /*/
@@ -334,7 +346,7 @@ function () {
         $node2 = $provider->getNode();
 
         /*/ Assert /*/
-        $this->assertMockFunctions(null, null, ['netstat -ie 2>&1'], [['a'], ['s']]);
+        $this->assertMockFunctions(null, null, ['netstat -ie 2>&1'], [['a'], ['s']], ['disabled_functions']);
 
         $this->assertEquals($node, $node2);
     }
@@ -360,7 +372,8 @@ function () {
             function () {
                 echo "\n01-02-03-04-05-06\n";
             },
-            $os
+            $os,
+            'nothing disabled'
         );
 
         /*/ Act /*/
@@ -372,14 +385,16 @@ function () {
         $globBodyAssert = null;
         $passthruBodyAssert = [$command];
         $unameBodyAssert = [['a'], ['s']];
+        $iniGetDisableFunctionsAssert = ['disable_functions'];
 
         if ($os === 'Linux') {
             $fileGetContentsAssert = [['mock address path 1'], ['mock address path 2']];
             $globBodyAssert = ['/sys/class/net/*/address'];
             $passthruBodyAssert = null;
             $unameBodyAssert = ['s'];
+            $iniGetDisableFunctionsAssert = null;
         }
-        $this->assertMockFunctions($fileGetContentsAssert, $globBodyAssert, $passthruBodyAssert, $unameBodyAssert);
+        $this->assertMockFunctions($fileGetContentsAssert, $globBodyAssert, $passthruBodyAssert, $unameBodyAssert, $iniGetDisableFunctionsAssert);
 
         $this->assertEquals('010203040506', $node);
     }
@@ -397,7 +412,8 @@ public function testCallGetsysfsOnLinuxWhenGlobReturnsFalse()
             function () {
                 echo "\n01-02-03-04-05-06\n";
             },
-            'Linux'
+            'Linux',
+            'nothing disabled'
         );
 
         /*/ Act /*/
@@ -405,7 +421,7 @@ function () {
         $node = $provider->getNode();
 
         /*/ Assert /*/
-        $this->assertMockFunctions(null, ['/sys/class/net/*/address'], ['netstat -ie 2>&1'], [['a'], ['s']]);
+        $this->assertMockFunctions(null, ['/sys/class/net/*/address'], ['netstat -ie 2>&1'], [['a'], ['s']], ['disabled_functions']);
 
         $this->assertEquals('010203040506', $node);
     }
@@ -423,7 +439,8 @@ public function testCallGetsysfsOnLinuxWhenGlobReturnsEmptyArray()
             function () {
                 echo "\n01-02-03-04-05-06\n";
             },
-            'Linux'
+            'Linux',
+            'nothing disabled'
         );
 
         /*/ Act /*/
@@ -431,11 +448,36 @@ function () {
         $node = $provider->getNode();
 
         /*/ Assert /*/
-        $this->assertMockFunctions(null, ['/sys/class/net/*/address'], ['netstat -ie 2>&1'], [['a'], ['s']]);
+        $this->assertMockFunctions(null, ['/sys/class/net/*/address'], ['netstat -ie 2>&1'], [['a'], ['s']], ['disabled_functions']);
 
         $this->assertEquals('010203040506', $node);
     }
 
+    /**
+     * @runInSeparateProcess
+     * @preserveGlobalState disabled
+     */
+    public function testGetNodeReturnsFalseWhenPassthruIsDisabled()
+    {
+        /*/ Arrange /*/
+        $this->arrangeMockFunctions(
+            null,
+            null,
+            null,
+            'NOT LINUX',
+            'PASSTHRU,some_other_function'
+        );
+
+        /*/ Act /*/
+        $provider = new SystemNodeProvider();
+        $node = $provider->getNode();
+
+        /*/ Assert /*/
+        $this->assertMockFunctions(null, null, null, [['s']], ['disabled_functions']);
+
+        $this->assertFalse($node);
+    }
+
     /**
      * Replaces the return value for functions with the given value or callback.
      *
@@ -443,14 +485,21 @@ function () {
      * @param callback|mixed|null $globBody
      * @param callback|mixed|null $passthruBody
      * @param callback|mixed|null $unameBody
+     * @param callback|mixed|null $iniGetDisableFunctionsBody
      */
-    private function arrangeMockFunctions($fileGetContentsBody, $globBody, $passthruBody, $unameBody)
-    {
+    private function arrangeMockFunctions(
+        $fileGetContentsBody,
+        $globBody,
+        $passthruBody,
+        $unameBody,
+        $iniGetDisableFunctionsBody
+    ) {
         $mockFunction = [
             self::MOCK_FILE_GET_CONTENTS => $fileGetContentsBody,
             self::MOCK_GLOB => $globBody,
             self::MOCK_PASSTHRU => $passthruBody,
             self::MOCK_UNAME => $unameBody,
+            self::MOCK_INI_GET => $iniGetDisableFunctionsBody,
         ];
 
         array_walk($mockFunction, function ($body, $key) {
@@ -467,14 +516,21 @@ private function arrangeMockFunctions($fileGetContentsBody, $globBody, $passthru
      * @param array|callable|null $globBodyAssert
      * @param array|callable|null $passthruBodyAssert
      * @param array|callable|null $unameBodyAssert
+     * @param array|callable|null $iniGetDisableFunctionsAssert
      */
-    private function assertMockFunctions($fileGetContentsAssert, $globBodyAssert, $passthruBodyAssert, $unameBodyAssert)
-    {
+    private function assertMockFunctions(
+        $fileGetContentsAssert,
+        $globBodyAssert,
+        $passthruBodyAssert,
+        $unameBodyAssert,
+        $iniGetDisableFunctionsAssert
+    ) {
         $mockFunctionAsserts = [
             self::MOCK_FILE_GET_CONTENTS => $fileGetContentsAssert,
             self::MOCK_GLOB => $globBodyAssert,
             self::MOCK_PASSTHRU => $passthruBodyAssert,
             self::MOCK_UNAME => $unameBodyAssert,
+            self::MOCK_INI_GET => $iniGetDisableFunctionsAssert,
         ];
 
         array_walk($mockFunctionAsserts, function ($asserts, $key) {