diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index 534b647..2293aa9 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -559,10 +559,9 @@ function config_get_config_directory($type = CONFIG_ACTIVE_DIRECTORY) {
  * return the expected values.
  *
  * Most other parameters do not need to be passed in, but may be necessary in
- * some cases; for example, if Drupal::service('request')->getClientIP()
- * needs to return anything but the standard localhost value ('127.0.0.1'),
- * the command line script should pass in the desired value via the
- * 'REMOTE_ADDR' key.
+ * some cases; for example, if Drupal's ip_address() function needs to return
+ * anything but the standard localhost value ('127.0.0.1'), the command line
+ * script should pass in the desired value via the 'REMOTE_ADDR' key.
  *
  * @param $variables
  *   (optional) An associative array of variables within $_SERVER that should
@@ -573,7 +572,7 @@ function config_get_config_directory($type = CONFIG_ACTIVE_DIRECTORY) {
  *
  * @see conf_path()
  * @see request_uri()
- * @see \Symfony\Component\HttpFoundation\Request::getClientIP()
+ * @see ip_address()
  */
 function drupal_override_server_variables($variables = array()) {
   // Allow the provided URL to override any existing values in $_SERVER.
@@ -1791,7 +1790,7 @@ function watchdog($type, $message, array $variables = NULL, $severity = WATCHDOG
       'uid'         => $user_uid,
       'request_uri' => $base_root . request_uri(),
       'referer'     => isset($_SERVER['HTTP_REFERER']) ? $_SERVER['HTTP_REFERER'] : '',
-      'ip'          => Drupal::service('request')->getClientIP(),
+      'ip'          => ip_address(),
       // Request time isn't accurate for long processes, use time() instead.
       'timestamp'   => time(),
     );
@@ -2055,7 +2054,7 @@ function drupal_hash_base64($data) {
 function drupal_anonymous_user() {
   $values = array(
     'uid' => 0,
-    'hostname' => Drupal::service('request')->getClientIP(),
+    'hostname' => ip_address(),
     'roles' => array(
       DRUPAL_ANONYMOUS_RID => DRUPAL_ANONYMOUS_RID,
     ),
@@ -3105,6 +3104,17 @@ function arg($index = NULL, $path = NULL) {
 }
 
 /**
+ * Returns the IP address of the client machine.
+ *
+ * @return
+ *   IP address of client machine, adjusted for reverse proxy and/or cluster
+ *   environments.
+ */
+function ip_address() {
+  return Drupal::service('request')->getClientIp();
+}
+
+/**
  * Initializes and returns the class loader.
  *
  * The class loader is responsible for lazy-loading all PSR-0 compatible
diff --git a/core/includes/session.inc b/core/includes/session.inc
index 5c09535..31e67a6 100644
--- a/core/includes/session.inc
+++ b/core/includes/session.inc
@@ -173,7 +173,7 @@ function _drupal_session_write($sid, $value) {
       // Either ssid or sid or both will be added from $key below.
       $fields = array(
         'uid' => $user->uid,
-        'hostname' => Drupal::service('request')->getClientIP(),
+        'hostname' => ip_address(),
         'session' => $value,
         'timestamp' => REQUEST_TIME,
       );
diff --git a/core/modules/action/tests/action_loop_test/action_loop_test.module b/core/modules/action/tests/action_loop_test/action_loop_test.module
index dfc5226..0c04346 100644
--- a/core/modules/action/tests/action_loop_test/action_loop_test.module
+++ b/core/modules/action/tests/action_loop_test/action_loop_test.module
@@ -69,7 +69,7 @@ function watchdog_skip_semaphore($type, $message, $variables = array(), $severit
     'uid'         => isset($user->uid) ? $user->uid : 0,
     'request_uri' => $base_root . request_uri(),
     'referer'     => $_SERVER['HTTP_REFERER'],
-    'ip'          => Drupal::service('request')->getClientIP(),
+    'ip'          => '127.0.0.1',
     'timestamp'   => REQUEST_TIME,
   );
 
diff --git a/core/modules/ban/ban.admin.inc b/core/modules/ban/ban.admin.inc
index 6def75e..0ea23fc 100644
--- a/core/modules/ban/ban.admin.inc
+++ b/core/modules/ban/ban.admin.inc
@@ -85,7 +85,7 @@ function ban_ip_form_validate($form, &$form_state) {
   if (db_query("SELECT * FROM {ban_ip} WHERE ip = :ip", array(':ip' => $ip))->fetchField()) {
     form_set_error('ip', t('This IP address is already banned.'));
   }
-  elseif ($ip == Drupal::service('request')->getClientIP()) {
+  elseif ($ip == ip_address()) {
     form_set_error('ip', t('You may not ban your own IP address.'));
   }
   elseif (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_RES_RANGE) == FALSE) {
diff --git a/core/modules/ban/lib/Drupal/ban/EventSubscriber/BanSubscriber.php b/core/modules/ban/lib/Drupal/ban/EventSubscriber/BanSubscriber.php
index 8e24181..8d9f2ad 100644
--- a/core/modules/ban/lib/Drupal/ban/EventSubscriber/BanSubscriber.php
+++ b/core/modules/ban/lib/Drupal/ban/EventSubscriber/BanSubscriber.php
@@ -43,7 +43,6 @@ public function __construct(BanIpManager $manager) {
    *   The Event to process.
    */
   public function onKernelRequestBannedIpCheck(GetResponseEvent $event) {
-    // @todo convert this to Request::getClientIP().
     $ip = $event->getRequest()->getClientIp();
     if ($this->manager->isDenied($ip)) {
       $response = new Response('Sorry, ' . check_plain($ip) . ' has been banned.', 403);
diff --git a/core/modules/ban/lib/Drupal/ban/Tests/IpAddressBlockingTest.php b/core/modules/ban/lib/Drupal/ban/Tests/IpAddressBlockingTest.php
index b058f11..4b40572 100644
--- a/core/modules/ban/lib/Drupal/ban/Tests/IpAddressBlockingTest.php
+++ b/core/modules/ban/lib/Drupal/ban/Tests/IpAddressBlockingTest.php
@@ -78,7 +78,7 @@ function testIPAddressValidation() {
     // manually.
     // TODO: On some systems this test fails due to a bug/inconsistency in cURL.
     // $edit = array();
-    // $edit['ip'] = \Drupal::service('request')->getClientIP();
+    // $edit['ip'] = ip_address();
     // $this->drupalPost('admin/config/people/ban', $edit, t('Save'));
     // $this->assertText(t('You may not ban your own IP address.'));
   }
diff --git a/core/modules/comment/lib/Drupal/comment/CommentStorageController.php b/core/modules/comment/lib/Drupal/comment/CommentStorageController.php
index aa7df09..77e441f 100644
--- a/core/modules/comment/lib/Drupal/comment/CommentStorageController.php
+++ b/core/modules/comment/lib/Drupal/comment/CommentStorageController.php
@@ -153,7 +153,7 @@ protected function preSave(EntityInterface $comment) {
       }
       // Add the values which aren't passed into the function.
       $comment->thread->value = $thread;
-      $comment->hostname->value = \Drupal::service('request')->getClientIP();
+      $comment->hostname->value = ip_address();
     }
   }
 
diff --git a/core/modules/comment/lib/Drupal/comment/Tests/CommentLinksTest.php b/core/modules/comment/lib/Drupal/comment/Tests/CommentLinksTest.php
index 1edce50..5585650 100644
--- a/core/modules/comment/lib/Drupal/comment/Tests/CommentLinksTest.php
+++ b/core/modules/comment/lib/Drupal/comment/Tests/CommentLinksTest.php
@@ -145,7 +145,7 @@ function setEnvironment(array $info) {
           'uid' => 0,
           'status' => COMMENT_PUBLISHED,
           'subject' => $this->randomName(),
-          'hostname' => \Drupal::service('request')->getClientIP(),
+          'hostname' => '127.0.0.1',
           'langcode' => LANGUAGE_NOT_SPECIFIED,
           'comment_body' => array(LANGUAGE_NOT_SPECIFIED => array($this->randomName())),
         ));
diff --git a/core/modules/comment/lib/Drupal/comment/Tests/CommentNewIndicatorTest.php b/core/modules/comment/lib/Drupal/comment/Tests/CommentNewIndicatorTest.php
index 6d36525..818227e 100644
--- a/core/modules/comment/lib/Drupal/comment/Tests/CommentNewIndicatorTest.php
+++ b/core/modules/comment/lib/Drupal/comment/Tests/CommentNewIndicatorTest.php
@@ -52,7 +52,7 @@ public function testCommentNewCommentsIndicator() {
       'uid' => $this->loggedInUser->uid,
       'status' => COMMENT_PUBLISHED,
       'subject' => $this->randomName(),
-      'hostname' => \Drupal::service('request')->getClientIP(),
+      'hostname' => '127.0.0.1',
       'langcode' => LANGUAGE_NOT_SPECIFIED,
       'comment_body' => array(LANGUAGE_NOT_SPECIFIED => array($this->randomName())),
     ));
diff --git a/core/modules/dblog/lib/Drupal/dblog/Tests/DBLogTest.php b/core/modules/dblog/lib/Drupal/dblog/Tests/DBLogTest.php
index 17df6a1..9fcc1ee 100644
--- a/core/modules/dblog/lib/Drupal/dblog/Tests/DBLogTest.php
+++ b/core/modules/dblog/lib/Drupal/dblog/Tests/DBLogTest.php
@@ -137,7 +137,7 @@ private function generateLogEntries($count, $type = 'custom', $severity = WATCHD
       'uid'         => isset($this->big_user->uid) ? $this->big_user->uid : 0,
       'request_uri' => $base_root . request_uri(),
       'referer'     => $_SERVER['HTTP_REFERER'],
-      'ip'          => \Drupal::service('request')->getClientIP(),
+      'ip'          => '127.0.0.1',
       'timestamp'   => REQUEST_TIME,
       );
     $message = 'Log entry added to test the dblog row limit. Entry #';
@@ -424,7 +424,7 @@ protected function testDBLogAddAndClear() {
       'uid'         => isset($this->big_user->uid) ? $this->big_user->uid : 0,
       'request_uri' => $base_root . request_uri(),
       'referer'     => $_SERVER['HTTP_REFERER'],
-      'ip'          => \Drupal::service('request')->getClientIP(),
+      'ip'          => '127.0.0.1',
       'timestamp'   => REQUEST_TIME,
     );
     // Add a watchdog entry.
diff --git a/core/modules/openid/openid.module b/core/modules/openid/openid.module
index b23473b..6d31124 100644
--- a/core/modules/openid/openid.module
+++ b/core/modules/openid/openid.module
@@ -1066,7 +1066,7 @@ function openid_verify_assertion_nonce($service, $response) {
     return TRUE;
   }
   else {
-    watchdog('openid', 'Nonce replay attempt blocked from @ip, nonce: @nonce.', array('@ip' => Drupal::service('request')->getClientIP(), '@nonce' => $response['openid.response_nonce']), WATCHDOG_CRITICAL);
+    watchdog('openid', 'Nonce replay attempt blocked from @ip, nonce: @nonce.', array('@ip' => ip_address(), '@nonce' => $response['openid.response_nonce']), WATCHDOG_CRITICAL);
     return FALSE;
   }
 }
diff --git a/core/modules/user/user.module b/core/modules/user/user.module
index 200ac00..bdf5862 100644
--- a/core/modules/user/user.module
+++ b/core/modules/user/user.module
@@ -1324,7 +1324,7 @@ function user_login_authenticate_validate($form, &$form_state) {
         // The default identifier is a combination of uid and IP address. This
         // is less secure but more resistant to denial-of-service attacks that
         // could lock out all users with public user names.
-        $identifier = $account->uid . '-' . Drupal::service('request')->getClientIP();
+        $identifier = $account->uid . '-' . ip_address();
       }
       $form_state['flood_control_user_identifier'] = $identifier;