diff --git a/docs/README-iptables.md b/docs/README-iptables.md
index a9a641b..104d426 100644
--- a/docs/README-iptables.md
+++ b/docs/README-iptables.md
@@ -222,4 +222,18 @@ The wrapper error codes matches (unsurprisingly) the same as iptables. They are:
 		if (error) {
 			console.log(error);
 		}
-	});
\ No newline at end of file
+	});
+
+#### Dump
+
+       iptables.dump({
+         table: 'nat', // default: null == all
+       }, function(err, dump) {
+         for (var table_name in dump) {
+           var table_dump = dump[table];
+           for (var chain_name in table_dump.chains) {
+             var chain_dump = table_dump.chains[chain_name];
+             console.log(table_name, chain_name, chain_dump);
+           }   
+         }
+       });
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
new file mode 100644
index 0000000..4bcbf99
--- /dev/null
+++ b/lib/iptables/check.js
@@ -0,0 +1,66 @@
+var exec = require('../child_utils').exec;
+
+var tables = require('./utils').tables;
+var processCommonRuleSpecs = require('./utils').processCommonRuleSpecs;
+
+
+/**
+ * Checks the existence one or more rules from the selected chain.
+ *
+ * @param options
+ * @param cb
+ */
+module.exports = function (options, cb) {
+  if (typeof arguments[0] != 'object') {
+    throw new Error('Invalid arguments. Signature: (options, callback?)');
+  }
+
+  var table = (typeof options.table != 'undefined')
+    ? options.table
+    : tables.filter;
+
+  var ipt_cmd = (options.sudo)
+    ? 'sudo '
+    : '';
+
+  ipt_cmd += (options.ipv6)
+    ? 'ip6tables'
+    : 'iptables';
+
+  /*
+   * Build cmd to execute.
+   */
+  var cmd = [ipt_cmd, '--table', table, '--check'];
+  var args = [];
+
+  /*
+   * Process options.
+   */
+  if (typeof options.chain != 'undefined') {
+    args = args.concat(options.chain);
+  }
+
+  if (typeof options.rulenum != 'undefined') {
+    args = args.concat(options.rulenum);
+  }
+  else {
+    var common_rule_specs = processCommonRuleSpecs(options);
+    args = args.concat(common_rule_specs);
+  }
+
+  /*
+   * Execute command.
+   */
+  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(' ');
+      err.code = error.code;
+
+      cb(err);
+    }
+    else if (cb) {
+      cb(null);
+    }
+  });
+};
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
new file mode 100644
index 0000000..e81a976
--- /dev/null
+++ b/lib/iptables/dump.js
@@ -0,0 +1,267 @@
+var exec = require('../child_utils').exec;
+var shell_quote = require('shell-quote');
+
+var tables = require('./utils').tables;
+
+
+/**
+ * Print out all the rules in iptables-save 
+ *
+ * @param options
+ * @param cb(err, {table:[rule,...]})
+ */
+var MAPPED_ARG = {
+  '-A': '--append',
+  '-D': '--delete',
+  '-I': '--insert',
+  '-R': '--replace',
+  '-L': '--list',
+  '-S': '--list-rules',
+  '-F': '--flush',
+  '-Z': '--zero',
+  '-N': '--new-chain',
+  '-X': '--delete-chain',
+  '-P': '--policy',
+  '-E': '--rename-chain',
+  '-d': '--destination',
+  '--dport': '--destination-port',
+  '--dports': '--destination-ports',
+  '-i': '--in-interface',
+  '-j': '--jump',
+  '-f': '--fragment',
+  '-g': '--goto',
+  '-m': '--match',
+  '-o': '--out-interface',
+  '-p': '--protocol',
+  '-s': '--source',
+  '-t': '--table',
+  '--sport': '--source-port',
+  '--sports': '--source-ports'
+};
+var MATCH_EXTENSIONS = [
+  'addrtype',
+  'ah',
+  'cluster',
+  'comment',
+  'connbytes',
+  'connlimit',
+  'connmark',
+  'conntrack',
+  'dccp',
+  'dscp',
+  'ecn',
+  'esp',
+  'hashlimit',
+  'helper',
+  'iprange',
+  'length',
+  'limit',
+  'mac',
+  'mark',
+  'multiport',
+  'owner',
+  'physdev',
+  'pkttype',
+  'policy',
+  'quota',
+  'rateest',
+  'realm',
+  'recent',
+  'sctp',
+  'set',
+  'socket',
+  'state',
+  'statistic',
+  'string',
+  'tcpmss',
+  'time',
+  'tos',
+  'ttl',
+  'u32',
+  'unclean' 
+];
+var COMMON_ARGS = [
+  'protocol',
+  'jump',
+  'goto',
+  'source',
+  'destination',
+  'in-interface',
+  'out-interface',
+  'fragment',
+]
+module.exports = function (options, cb) {
+  if (typeof arguments[0] != 'object') {
+    throw new Error('Invalid arguments. Signature: (options, callback?)');
+  }
+
+  var table = options.table;
+
+  var ipt_cmd = (options.sudo)
+    ? 'sudo '
+    : '';
+
+  ipt_cmd += (options.ipv6)
+    ? 'ip6tables-save'
+    : 'iptables-save';
+
+  /*
+   * Build cmd to execute.
+   */
+  var cmd = [ipt_cmd];
+  if (table) {
+    cmd.push('--table', table);
+  }
+  var args = [];
+
+  /*
+   * Execute command.
+   */
+  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(' ');
+      err.code = error.code;
+
+      cb(err);
+    }
+    else if (cb) {
+      var lines = String(stdout).split(/\n/g);
+      var tables = Object.create(null);
+      var chains = Object.create(null);
+      var table = '';
+      var chain = '';
+      var policy = '';
+      var rules = [];
+      function commit_chain() {
+        if (chain === '') return;
+        if (chains[chain]) {
+          chains[chain].rules = chains[chain].rules.concat(rules);
+        }
+        else {
+          chains[chain] = {
+            policy: policy,
+            rules: rules
+          }
+        }
+        chain = '';
+        policy = '';
+        rules = [];
+      }
+      lines.forEach(function (line) {
+        line = line.trim();
+        if (line === 'COMMIT') {
+          commit_chain();
+          tables[table] = {
+            chains: chains
+          };
+          table = '';
+          chains = Object.create(null);
+          return;
+        }
+        var c = line.charAt(0);
+        if (c === '#') return;
+        else if (c === '*') {
+          table = line.slice(1).trim();
+          return;
+        }
+        else if (c === ':') {
+          commit_chain();
+          var parts = /^:(\S+)\s+(\S+)/.exec(line);
+          chain = parts[1]; 
+          policy = parts[2];
+          return;
+        }
+        else {
+          var args = shell_quote.parse(line);
+          var rule = Object.create(null);
+          var negated = false;
+          var option = '';
+          var in_target = false; 
+          var match = null; 
+          var matches = Object.create(null);
+          var target_options = null; 
+          var had_match = false;
+          args.forEach(function (arg) {
+            if (option === '') {
+              arg = Object.prototype.hasOwnProperty.call(MAPPED_ARG, arg) ? MAPPED_ARG[arg] : arg;
+              if (arg.charAt(0) === '-') {
+                option = arg.replace(/^[\-]+/,'');
+		if ('random' === option) {
+		  rule.random = true;
+		  option = '';
+		}
+		else if ('ports' === option) {
+		  rule['source-ports'] = rule['source-ports'] || [];
+		  rule['destination-ports'] = rule['destination-ports'] || [];
+		}
+		else if ('--source-ports' === option) {
+		  rule['source-ports'] = rule['source-ports'] || [];
+		}
+		else if ('--destination-ports' === option) {
+		  rule['destination-ports'] = rule['destination-ports'] || [];
+		}
+              }
+	      else if (arg === '!') {
+		 negated = true;
+	      }
+            }
+            else {
+              if (option === 'jump') {
+                match = null;
+                in_target = true;
+              }
+              var configure_target = rule;
+              if (MATCH_EXTENSIONS.indexOf(option) !== -1) {
+                had_match = true;
+                matches[option] = match = Object.create(null); 
+                option = '';
+                negated = false;
+                return;
+              }
+              else if (COMMON_ARGS.indexOf(option) === -1) {
+                // little bit wonky to detect if target_options was used
+                if (in_target) configure_target = target_options || (target_options = Object.create(null));
+                else configure_target = match;
+              }
+              if (option === 'match' || option === 'protocol') {
+                had_match = true;
+                matches[arg] = match = matches[arg] || Object.create(null); 
+                option = '';
+                negated = false;
+              }
+              else if (option === 'append') {
+                if (arg != chain) commit_chain();
+                chain = arg;
+                option = '';
+                negated = false;
+              }
+              else if (option === 'ports') {
+                configure_target['source-ports'].push(arg);
+                configure_target['destination-ports'].push(arg);
+                option = '';
+                negated = false;
+              }
+              else {
+                var val = negated ? '!' + arg : arg;
+                if (Array.isArray(rule[option])) {
+                  configure_target[option].push(val);
+                }
+                else {
+                  configure_target[option] = val;
+                }
+                option = '';
+                negated = false;
+              }
+            }
+          });
+          if (had_match) rule.matches = matches;
+          if (target_options != null) rule.target_options = target_options;
+          rules.push(rule); 
+        }
+      });
+      cb(null, tables);
+    }
+  });
+};
+
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/index.js b/lib/iptables/index.js
index a03b69b..fd1259d 100644
--- a/lib/iptables/index.js
+++ b/lib/iptables/index.js
@@ -28,5 +28,11 @@ exports.insert = require('./insert');
 // Replace a rule in the selected chain.
 exports.replace = require('./replace');
 
+// Get the current chains and rules. 
+exports.dump = require('./dump');
+
+// Check for existence of a rule in a chain.
+exports.check = require('./check');
+
 // General utility functions and constants.
-exports.utils = require('./utils');
\ No newline at end of file
+exports.utils = require('./utils');
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/utils.js b/lib/iptables/utils.js
index c125d4b..e79944c 100644
--- a/lib/iptables/utils.js
+++ b/lib/iptables/utils.js
@@ -13,84 +13,60 @@ exports.tables = {
  * @param options
  * @returns {Array}
  */
-exports.processCommonRuleSpecs = function (options) {
-  var args = [];
-
-  if (typeof options.protocol != 'undefined') {
-    if (options.protocol.split('!').length > 1) {
-      args = args.concat('! --protocol', options.protocol.split('!')[1]);
-    }
-    else {
-      args = args.concat('--protocol', options.protocol);
-    }
-  }
-
-  if (typeof options.source != 'undefined') {
-    if (options.source.split('!').length > 1) {
-      args = args.concat('! --source', options.source.split('!')[1]);
-    }
-    else {
-      args = args.concat('--source', options.source);
-    }
-  }
-
-  if (typeof options.destination != 'undefined') {
-    if (options.destination.split('!').length > 1) {
-      args = args.concat('! --destination', options.destination.split('!')[1]);
+function manage_arg(property, flag, args) {
+  if (property != null) {
+    var val = String(property);
+    var index = val.indexOf('!'); 
+    if (index !== -1) {
+      args.push('!', flag, val.slice(index));
     }
     else {
-      args = args.concat('--destination', options.destination);
+      args.push(flag, val);
     }
   }
-
-  if (typeof options['in-interface'] != 'undefined') {
-    if (options['in-interface'].split('!').length > 1) {
-      args = args.concat('! --in-interface', options['in-interface'].split('!')[1]);
-    }
-    else {
-      args = args.concat('--in-interface', options['in-interface']);
-    }
+}
+function hasOwnProperty(obj, key) {
+  return Object.prototype.hasOwnProperty.call(obj, key);
+}
+exports.processCommonRuleSpecs = function (options) {
+  var args = [];
+  
+  if (options.comment != null) {
+    args.push('-m', 'comment', '--comment', String(options.comment).slice(0,255).replace(/[^A-Za-z_]/g,'\\$&'));
   }
 
-  if (typeof options['out-interface'] != 'undefined') {
-    if (options['out-interface'].split('!').length > 1) {
-      args = args.concat('! --out-interface', options['out-interface'].split('!')[1]);
-    }
-    else {
-      args = args.concat('--out-interface', options['out-interface']);
-    }
-  }
+  manage_arg(options.protocol, '--protocol', args);
+  manage_arg(options.source, '--source', args);
+  manage_arg(options['in-interface'], '--in-interface', args);
+  manage_arg(options['out-interface'], '--out-interface', args);
 
-  if (typeof options.fragment != 'undefined') {
-    if (options.fragment.split('!').length > 1) {
-      args = args.concat('! --fragment');
+  if (options.fragment != null) {
+    var val = String(options.fragment);
+    var index = val.indexOf('!'); 
+    if (index !== -1) {
+      args.push('!', '--fragment');
     }
     else {
-      args = args.concat('--fragment');
+      args.push('--fragment');
     }
   }
 
   /*
    * Matches processing.
    */
-  if (typeof options.matches != 'undefined') {
+  if (options.matches != null) {
     for (var match in options.matches) {
-      if (options.matches.hasOwnProperty(match)) {
+      if (hasOwnProperty(options.matches, match)) {
         // Initial match load.
-        args = args.concat('--match', match);
+        args.push('--match', match);
 
         // Specific match options.
         var this_match = options.matches[match];
 
-        for (var match_option in this_match) {
-          if (this_match.hasOwnProperty(match_option)) {
-            if (typeof this_match[match_option] == 'string'
-              && this_match[match_option].split('!').length > 1) {
-
-              args = args.concat('! --' + match_option, this_match[match_option].split('!')[1]);
-            }
-            else {
-              args = args.concat('--' + match_option, this_match[match_option]);
+        if (this_match != null && typeof this_match === 'object') {
+          for (var match_option in this_match) {
+            if (hasOwnProperty(this_match, match_option)) {
+              manage_arg(this_match[match_option], '--' + match_option, args); 
             }
           }
         }
@@ -98,22 +74,22 @@ exports.processCommonRuleSpecs = function (options) {
     }
   }
 
-  if (typeof options.goto != 'undefined') {
-    args = args.concat('--goto', options.goto);
+  if (options.goto != null) {
+    args.push('--goto', String(options.goto));
   }
 
-  if (typeof options.jump != 'undefined') {
-    args = args.concat('--jump', options.jump);
+  if (options.jump != null) {
+    args.push('--jump', String(options.jump));
 
     // Target extension options.
-    if (typeof options.target_options != 'undefined') {
+    if (options.target_options != null && typeof options.target_options === 'object') {
       for (var target_option in options.target_options) {
-        if (options.target_options.hasOwnProperty(target_option)) {
-          args = args.concat('--' + target_option, options.target_options[target_option]);
+        if (hasOwnProperty(options.target_options, target_option)) {
+          manage_arg(options.target_options[target_option], '--' + target_option, args);
         }
       }
     }
   }
 
   return args;
-};
\ 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 b16fc29..a49cf78 100644
--- a/package.json
+++ b/package.json
@@ -1,9 +1,9 @@
 {
-  "name"        : "netfilter",
-  "version"     : "0.2.3",
-  "description" : "Packet filtering framework. Wrapper to provide netfilter capabilities from Node.js",
-  "main"        : "index.js",
-  "keywords"    : [
+  "name": "netfilter",
+  "version": "0.2.3",
+  "description": "Packet filtering framework. Wrapper to provide netfilter capabilities from Node.js",
+  "main": "index.js",
+  "keywords": [
     "stateless",
     "stateful",
     "packet",
@@ -28,22 +28,28 @@
     "set"
   ],
   "dependencies": {
-    "async": "*"
+    "async": "~0.9.0",
+    "offspring": "~1.0.0",
+    "process-queue": "^1.0.1",
+    "shell-quote": "^1.4.2"
   },
-  "engines"     : {
+  "engines": {
     "node": ">=0.8.0"
   },
-  "homepage"    : "https://github.com/diosney/node-netfilter",
-  "bugs"        : {
+  "homepage": "https://github.com/diosney/node-netfilter",
+  "bugs": {
     "url": "https://github.com/diosney/node-netfilter/issues"
   },
-  "author"      : {
-    "name" : "Diosney Sarmiento",
+  "author": {
+    "name": "Diosney Sarmiento",
     "email": "diosney.s@gmail.com"
   },
-  "license"     : "MIT",
-  "repository"  : {
+  "license": "MIT",
+  "repository": {
     "type": "git",
-    "url" : "https://github.com/diosney/node-netfilter.git"
+    "url": "https://github.com/diosney/node-netfilter.git"
+  },
+  "scripts": {
+    "test": "node test/*.js"
   }
 }