diff --git a/lib/child_utils.js b/lib/child_utils.js
new file mode 100644
index 0000000..1237c4e
--- /dev/null
+++ b/lib/child_utils.js
@@ -0,0 +1,61 @@
+var processQueue = require('process-queue');
+
+var default_queue = processQueue.createQueue({concurrency:1});
+
+exports.exec = function (line, opts, cb) {
+  var stdout, stdout_length, stderr, stderr_length;
+
+  // avoid allocation
+  if (cb) {
+    stdout = [];
+    stdout_length = 0;
+    stderr = [];
+    stderr_length = 0;
+  }
+
+  var child;
+  var queue = opts.queue || default_queue;
+  if (cb) {
+    queue = queue.wrap({
+      child: function (spawned_child, next) {
+        child = spawned_child;
+        if (cb) {
+          child.stdout.on('data', function (data) {
+            if (!Buffer.isBuffer(data)) data = new Buffer(data);
+            stdout_length += data.length;
+            stdout.push(data);
+          });
+          child.stderr.on('data', function (data) {
+            if (!Buffer.isBuffer(data)) data = new Buffer(data);
+            stderr_length += data.length;
+            stderr.push(data);
+          });
+        }
+        next(null, child);
+      }
+    });
+  }
+  var cmd = {
+    spawnOptions: ['sh', ['-c', 'exec ' + line]]
+  };
+  function onFinish(err) {
+    if (!cb) return;
+    if (!child) {
+      cb(new Error('there was a problem spawning the child process'));
+      return;
+    }
+    if (err) {
+      err.killed = child.killed;
+      err.code = child.exitCode;
+      err.signal = child.signalCode;
+    } 
+    cb(err,
+       stdout_length ? String(Buffer.concat(stdout, stdout_length)) : '',
+       stderr_length ? String(Buffer.concat(stderr, stderr_length)) : ''
+    );
+  }
+  queue.push(cmd, onFinish);
+
+  // cleanup for gc
+  cmd = null;
+}
diff --git a/lib/ipset/add.js b/lib/ipset/add.js
index 2c53f52..fd36502 100644
--- a/lib/ipset/add.js
+++ b/lib/ipset/add.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 /**
  * Add a given entry to the set.
@@ -46,7 +46,7 @@ module.exports = function (options, cb) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
@@ -58,4 +58,4 @@ module.exports = function (options, cb) {
       cb(null);
     }
   });
-};
\ No newline at end of file
+};
diff --git a/lib/ipset/create.js b/lib/ipset/create.js
index ca9fc7b..a6bed4c 100644
--- a/lib/ipset/create.js
+++ b/lib/ipset/create.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 /**
  * Create a set identified with setsetname and specified type.
@@ -46,7 +46,7 @@ module.exports = function (options, cb) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
@@ -58,4 +58,4 @@ module.exports = function (options, cb) {
       cb(null);
     }
   });
-};
\ No newline at end of file
+};
diff --git a/lib/ipset/del.js b/lib/ipset/del.js
index f1bfa39..3188fba 100644
--- a/lib/ipset/del.js
+++ b/lib/ipset/del.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 /**
  * Delete an entry from a set.
@@ -46,7 +46,7 @@ module.exports = function (options, cb) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
@@ -58,4 +58,4 @@ module.exports = function (options, cb) {
       cb(null);
     }
   });
-};
\ No newline at end of file
+};
diff --git a/lib/ipset/destroy.js b/lib/ipset/destroy.js
index 6e34d29..683a342 100644
--- a/lib/ipset/destroy.js
+++ b/lib/ipset/destroy.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 /**
  * Destroy the specified set or all the sets if none is given.
@@ -44,7 +44,7 @@ module.exports = function (/* options?, cb */) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
@@ -56,4 +56,4 @@ module.exports = function (/* options?, cb */) {
       cb(null);
     }
   });
-};
\ No newline at end of file
+};
diff --git a/lib/ipset/flush.js b/lib/ipset/flush.js
index b9121a3..b5f1d00 100644
--- a/lib/ipset/flush.js
+++ b/lib/ipset/flush.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 /**
  * Flush all entries from the specified set or flush all sets if none is given.
@@ -44,7 +44,7 @@ module.exports = function (/* options?, cb */) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
@@ -56,4 +56,4 @@ module.exports = function (/* options?, cb */) {
       cb(null);
     }
   });
-};
\ No newline at end of file
+};
diff --git a/lib/ipset/rename.js b/lib/ipset/rename.js
index 8baaab7..974b011 100644
--- a/lib/ipset/rename.js
+++ b/lib/ipset/rename.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 /**
  * Rename a set.
@@ -35,7 +35,7 @@ module.exports = function (options, cb) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
@@ -47,4 +47,4 @@ module.exports = function (options, cb) {
       cb(null);
     }
   });
-};
\ No newline at end of file
+};
diff --git a/lib/ipset/swap.js b/lib/ipset/swap.js
index 28b6db5..9897164 100644
--- a/lib/ipset/swap.js
+++ b/lib/ipset/swap.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 /**
  * Swap the content of two sets.
@@ -35,7 +35,7 @@ module.exports = function (options, cb) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
@@ -47,4 +47,4 @@ module.exports = function (options, cb) {
       cb(null);
     }
   });
-};
\ No newline at end of file
+};
diff --git a/lib/ipset/test.js b/lib/ipset/test.js
index f31f9ba..3f4f289 100644
--- a/lib/ipset/test.js
+++ b/lib/ipset/test.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 /**
  * Test wether an entry is in a set or not.
@@ -46,7 +46,7 @@ module.exports = function (options, cb) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
@@ -58,4 +58,4 @@ module.exports = function (options, cb) {
       cb(null, 0);
     }
   });
-};
\ No newline at end of file
+};
diff --git a/lib/ipset/version.js b/lib/ipset/version.js
index 3627916..50fc45c 100644
--- a/lib/ipset/version.js
+++ b/lib/ipset/version.js
@@ -1,12 +1,16 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 /**
  * Print program version.
  *
  * @param cb
  */
-module.exports = function (cb) {
-  if (typeof arguments[0] != 'function') {
+module.exports = function (options, cb) {
+  if (typeof options === 'function') {
+    cb = options;
+    options = {};
+  }
+  if (typeof cb != 'function') {
     throw new Error('Invalid arguments. Signature: (callback)');
   }
 
@@ -22,7 +26,7 @@ module.exports = function (cb) {
   /*
    * Execute command.
    */
-  exec(cmd.join(' '), function (error, stdout, stderror) {
+  exec(cmd.join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
@@ -34,4 +38,4 @@ module.exports = function (cb) {
       cb(null, stdout.split('\n')[0]);
     }
   });
-};
\ No newline at end of file
+};
diff --git a/lib/iptables/append.js b/lib/iptables/append.js
index 9f0204a..c445bdc 100644
--- a/lib/iptables/append.js
+++ b/lib/iptables/append.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 var tables = require('./utils').tables;
 var processCommonRuleSpecs = require('./utils').processCommonRuleSpecs;
@@ -46,7 +46,7 @@ module.exports = function (options, cb) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
@@ -58,4 +58,4 @@ module.exports = function (options, cb) {
       cb(null);
     }
   });
-};
\ No newline at end of file
+};
diff --git a/lib/iptables/check.js b/lib/iptables/check.js
index 707266c..4bcbf99 100644
--- a/lib/iptables/check.js
+++ b/lib/iptables/check.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 var tables = require('./utils').tables;
 var processCommonRuleSpecs = require('./utils').processCommonRuleSpecs;
@@ -51,7 +51,7 @@ module.exports = function (options, cb) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
diff --git a/lib/iptables/delete.js b/lib/iptables/delete.js
index 1dfb4c2..cfa3b19 100644
--- a/lib/iptables/delete.js
+++ b/lib/iptables/delete.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 var tables = require('./utils').tables;
 var processCommonRuleSpecs = require('./utils').processCommonRuleSpecs;
@@ -51,7 +51,7 @@ module.exports = function (options, cb) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
@@ -63,4 +63,4 @@ module.exports = function (options, cb) {
       cb(null);
     }
   });
-};
\ No newline at end of file
+};
diff --git a/lib/iptables/delete_chain.js b/lib/iptables/delete_chain.js
index f187da3..049f051 100644
--- a/lib/iptables/delete_chain.js
+++ b/lib/iptables/delete_chain.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 var tables = require('./utils').tables;
 
@@ -54,7 +54,7 @@ module.exports = function (/* options?, cb */) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
@@ -66,4 +66,4 @@ module.exports = function (/* options?, cb */) {
       cb(null);
     }
   });
-};
\ No newline at end of file
+};
diff --git a/lib/iptables/dump.js b/lib/iptables/dump.js
index e2b9eb1..e81a976 100644
--- a/lib/iptables/dump.js
+++ b/lib/iptables/dump.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 var shell_quote = require('shell-quote');
 
 var tables = require('./utils').tables;
@@ -117,7 +117,7 @@ module.exports = function (options, cb) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
diff --git a/lib/iptables/flush.js b/lib/iptables/flush.js
index 6147cfc..0af81a9 100644
--- a/lib/iptables/flush.js
+++ b/lib/iptables/flush.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 var tables = require('./utils').tables;
 
@@ -54,7 +54,7 @@ module.exports = function (/* options?, cb */) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
@@ -66,4 +66,4 @@ module.exports = function (/* options?, cb */) {
       cb(null);
     }
   });
-};
\ No newline at end of file
+};
diff --git a/lib/iptables/insert.js b/lib/iptables/insert.js
index e95fabd..608547c 100644
--- a/lib/iptables/insert.js
+++ b/lib/iptables/insert.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 var tables = require('./utils').tables;
 var processCommonRuleSpecs = require('./utils').processCommonRuleSpecs;
@@ -51,7 +51,7 @@ module.exports = function (options, cb) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
@@ -63,4 +63,4 @@ module.exports = function (options, cb) {
       cb(null);
     }
   });
-};
\ No newline at end of file
+};
diff --git a/lib/iptables/new.js b/lib/iptables/new.js
index f598f4c..8e6a32d 100644
--- a/lib/iptables/new.js
+++ b/lib/iptables/new.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 var tables = require('./utils').tables;
 
@@ -41,7 +41,7 @@ module.exports = function (options, cb) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
@@ -53,4 +53,4 @@ module.exports = function (options, cb) {
       cb(null);
     }
   });
-};
\ No newline at end of file
+};
diff --git a/lib/iptables/policy.js b/lib/iptables/policy.js
index 558fbcd..ff9a659 100644
--- a/lib/iptables/policy.js
+++ b/lib/iptables/policy.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 var tables = require('./utils').tables;
 
@@ -45,7 +45,7 @@ module.exports = function (options, cb) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
@@ -57,4 +57,4 @@ module.exports = function (options, cb) {
       cb(null);
     }
   });
-};
\ No newline at end of file
+};
diff --git a/lib/iptables/rename.js b/lib/iptables/rename.js
index fdcb5ff..e0f1025 100644
--- a/lib/iptables/rename.js
+++ b/lib/iptables/rename.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 var tables = require('./utils').tables;
 
@@ -45,7 +45,7 @@ module.exports = function (options, cb) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue:options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
@@ -57,4 +57,4 @@ module.exports = function (options, cb) {
       cb(null);
     }
   });
-};
\ No newline at end of file
+};
diff --git a/lib/iptables/replace.js b/lib/iptables/replace.js
index 7bac661..7092bf6 100644
--- a/lib/iptables/replace.js
+++ b/lib/iptables/replace.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 var tables = require('./utils').tables;
 var processCommonRuleSpecs = require('./utils').processCommonRuleSpecs;
@@ -51,7 +51,7 @@ module.exports = function (options, cb) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
@@ -63,4 +63,4 @@ module.exports = function (options, cb) {
       cb(null);
     }
   });
-};
\ No newline at end of file
+};
diff --git a/lib/iptables/zero.js b/lib/iptables/zero.js
index 8d49d3f..64d8d23 100644
--- a/lib/iptables/zero.js
+++ b/lib/iptables/zero.js
@@ -1,4 +1,4 @@
-var exec = require('child_process').exec;
+var exec = require('../child_utils').exec;
 
 var tables = require('./utils').tables;
 
@@ -58,7 +58,7 @@ module.exports = function (/* options?, cb */) {
   /*
    * Execute command.
    */
-  exec(cmd.concat(args).join(' '), function (error, stdout, stderror) {
+  exec(cmd.concat(args).join(' '), {queue: options.cmdQueue}, function (error, stdout, stderror) {
     if (error && cb) {
       var err = new Error(stderror.split('\n')[0]);
       err.cmd = cmd.concat(args).join(' ');
@@ -70,4 +70,4 @@ module.exports = function (/* options?, cb */) {
       cb(null);
     }
   });
-};
\ No newline at end of file
+};
diff --git a/package.json b/package.json
index f0d700d..a49cf78 100644
--- a/package.json
+++ b/package.json
@@ -28,7 +28,9 @@
     "set"
   ],
   "dependencies": {
-    "async": "*",
+    "async": "~0.9.0",
+    "offspring": "~1.0.0",
+    "process-queue": "^1.0.1",
     "shell-quote": "^1.4.2"
   },
   "engines": {
@@ -46,5 +48,8 @@
   "repository": {
     "type": "git",
     "url": "https://github.com/diosney/node-netfilter.git"
+  },
+  "scripts": {
+    "test": "node test/*.js"
   }
 }