diff --git a/lib/ansible/inventory/__init__.py b/lib/ansible/inventory/__init__.py
index 2eda3e6649d..657084c724d 100644
--- a/lib/ansible/inventory/__init__.py
+++ b/lib/ansible/inventory/__init__.py
@@ -33,6 +33,7 @@ from ansible.inventory.group import Group
 from ansible.inventory.host import Host
 from ansible.plugins import vars_loader
 from ansible.utils.vars import combine_vars
+from ansible.parsing.utils.addresses import parse_address
 
 try:
     from __main__ import display
@@ -83,27 +84,16 @@ class Inventory(object):
                 host_list = host_list.split(",")
                 host_list = [ h for h in host_list if h and h.strip() ]
 
+        self.parser = None
+
         if host_list is None:
-            self.parser = None
+            pass
         elif isinstance(host_list, list):
-            self.parser = None
             all = Group('all')
             self.groups = [ all ]
-            ipv6_re = re.compile('\[([a-f:A-F0-9]*[%[0-z]+]?)\](?::(\d+))?')
-            for x in host_list:
-                m = ipv6_re.match(x)
-                if m:
-                    all.add_host(Host(m.groups()[0], m.groups()[1]))
-                else:
-                    if ":" in x:
-                        tokens = x.rsplit(":", 1)
-                        # if there is ':' in the address, then this is an ipv6
-                        if ':' in tokens[0]:
-                            all.add_host(Host(x))
-                        else:
-                            all.add_host(Host(tokens[0], tokens[1]))
-                    else:
-                        all.add_host(Host(x))
+            for h in host_list:
+                (host, port) = parse_address(h, allow_ranges=False)
+                all.add_host(Host(host, port))
         elif self._loader.path_exists(host_list):
             #TODO: switch this to a plugin loader and a 'condition' per plugin on which it should be tried, restoring 'inventory pllugins'
             if self._loader.is_directory(host_list):
diff --git a/lib/ansible/inventory/expand_hosts.py b/lib/ansible/inventory/expand_hosts.py
index 0d63ba08bbc..7e1c127c27e 100644
--- a/lib/ansible/inventory/expand_hosts.py
+++ b/lib/ansible/inventory/expand_hosts.py
@@ -44,7 +44,7 @@ def detect_range(line = None):
 
     Returnes True if the given line contains a pattern, else False.
     '''
-    if 0 <= line.find("[") < line.find(":") < line.find("]"):
+    if '[' in line:
         return True
     else:
         return False
diff --git a/lib/ansible/inventory/ini.py b/lib/ansible/inventory/ini.py
index 36115c57975..30408048136 100644
--- a/lib/ansible/inventory/ini.py
+++ b/lib/ansible/inventory/ini.py
@@ -29,6 +29,7 @@ from ansible.inventory.host import Host
 from ansible.inventory.group import Group
 from ansible.inventory.expand_hosts import detect_range
 from ansible.inventory.expand_hosts import expand_hostname_range
+from ansible.parsing.utils.addresses import parse_address
 from ansible.utils.unicode import to_unicode, to_bytes
 
 class InventoryParser(object):
@@ -265,30 +266,20 @@ class InventoryParser(object):
         optional port number that applies to all of them.
         '''
 
-        # Is a port number specified?
-        #
-        # This may be a mandatory :NN suffix on any square-bracketed expression
-        # (IPv6 address, IPv4 address, host name, host pattern), or an optional
-        # :NN suffix on an IPv4 address, host name, or pattern. IPv6 addresses
-        # must be in square brackets if a port is specified.
+        # Can the given hostpattern be parsed as a host with an optional port
+        # specification?
 
-        port = None
+        (pattern, port) = parse_address(hostpattern, allow_ranges=True)
+        if not pattern:
+            self._raise_error("Can't parse '%s' as host[:port]" % hostpattern)
 
-        for type in ['bracketed_hostport', 'hostport']:
-            m = self.patterns[type].match(hostpattern)
-            if m:
-                (hostpattern, port) = m.groups()
-                continue
+        # Once we have separated the pattern, we expand it into list of one or
+        # more hostnames, depending on whether it contains any [x:y] ranges.
 
-        # Now we're left with just the pattern, which results in a list of one
-        # or more hostnames, depending on whether it contains any [x:y] ranges.
-        #
-        # FIXME: We could be more strict here about validation.
-
-        if detect_range(hostpattern):
-            hostnames = expand_hostname_range(hostpattern)
+        if detect_range(pattern):
+            hostnames = expand_hostname_range(pattern)
         else:
-            hostnames = [hostpattern]
+            hostnames = [pattern]
 
         return (hostnames, port)
 
@@ -374,29 +365,3 @@ class InventoryParser(object):
                 $                           # end of the line
             ''', re.X
         )
-
-        # The following patterns match the various ways in which a port number
-        # may be specified on an IPv6 address, IPv4 address, hostname, or host
-        # pattern. All of the above may be enclosed in square brackets with a
-        # mandatory :NN suffix; or all but the first may be given without any
-        # brackets but with an :NN suffix.
-
-        self.patterns['bracketed_hostport'] = re.compile(
-            r'''^
-                \[(.+)\]                    # [host identifier]
-                :([0-9]+)                   # :port number
-                $
-            ''', re.X
-        )
-
-        self.patterns['hostport'] = re.compile(
-            r'''^
-                ((?:                        # We want to match:
-                    [^:\[\]]                # (a non-range character
-                    |                       # ...or...
-                    \[[^\]]*\]              # a complete bracketed expression)
-                )*)                         # repeated as many times as possible
-                :([0-9]+)                   # followed by a port number
-                $
-            ''', re.X
-        )
diff --git a/lib/ansible/parsing/utils/addresses.py b/lib/ansible/parsing/utils/addresses.py
new file mode 100644
index 00000000000..71675769d27
--- /dev/null
+++ b/lib/ansible/parsing/utils/addresses.py
@@ -0,0 +1,208 @@
+# Copyright 2015 Abhijit Menon-Sen <ams@2ndQuadrant.com>
+#
+# This file is part of Ansible
+#
+# Ansible is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Ansible is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
+
+# Make coding more python3-ish
+from __future__ import (absolute_import, division, print_function)
+__metaclass__ = type
+
+import re
+
+# Components that match a numeric or alphanumeric begin:end or begin:end:step
+# range expression inside square brackets.
+
+numeric_range = r'''
+    \[
+        (?:[0-9]+:[0-9]+)               # numeric begin:end
+        (?::[0-9]+)?                    # numeric :step (optional)
+    \]
+'''
+
+alphanumeric_range = r'''
+    \[
+        (?:
+            [a-z]:[a-z]|                # one-char alphabetic range
+            [0-9]+:[0-9]+               # ...or a numeric one
+        )
+        (?::[0-9]+)?                    # numeric :step (optional)
+    \]
+'''
+
+# Components that match a 16-bit portion of an IPv6 address in hexadecimal
+# notation (0..ffff) or an 8-bit portion of an IPv4 address in decimal notation
+# (0..255) or an [x:y(:z)] numeric range.
+
+ipv6_component = r'''
+    (?:
+        [0-9a-f]{{1,4}}|                # 0..ffff
+        {range}                         # or a numeric range
+    )
+'''.format(range=numeric_range)
+
+ipv4_component = r'''
+    (?:
+        [01]?[0-9]{{1,2}}|              # 0..199
+        2[0-4][0-9]|                    # 200..249
+        25[0-5]|                        # 250..255
+        {range}                         # or a numeric range
+    )
+'''.format(range=numeric_range)
+
+# A hostname label, e.g. 'foo' in 'foo.example.com'. Consists of alphanumeric
+# characters plus dashes (and underscores) or valid ranges. The label may not
+# start or end with a hyphen or an underscore. This is interpolated into the
+# hostname pattern below. We don't try to enforce the 63-char length limit.
+
+label = r'''
+    (?:[\w]|{range})                    # Starts with an alphanumeric or a range
+    (?:[\w_-]|{range})*                 # Then zero or more of the same or [_-]
+    (?<![_-])                           # ...as long as it didn't end with [_-]
+'''.format(range=alphanumeric_range)
+
+patterns = {
+    # This matches a square-bracketed expression with a port specification. What
+    # is inside the square brackets is validated later.
+
+    'bracketed_hostport': re.compile(
+        r'''^
+            \[(.+)\]                    # [host identifier]
+            :([0-9]+)                   # :port number
+            $
+        ''', re.X
+    ),
+
+    # This matches a bare IPv4 address or hostname (or host pattern including
+    # [x:y(:z)] ranges) with a port specification.
+
+    'hostport': re.compile(
+        r'''^
+            ((?:                        # We want to match:
+                [^:\[\]]                # (a non-range character
+                |                       # ...or...
+                \[[^\]]*\]              # a complete bracketed expression)
+            )*)                         # repeated as many times as possible
+            :([0-9]+)                   # followed by a port number
+            $
+        ''', re.X
+    ),
+
+    # This matches an IPv4 address, but also permits range expressions.
+
+    'ipv4': re.compile(
+        r'''^
+            (?:{i4}\.){{3}}{i4}         # Three parts followed by dots plus one
+            $
+        '''.format(i4=ipv4_component), re.X|re.I
+    ),
+
+    # This matches an IPv6 address, but also permits range expressions.
+    #
+    # This expression looks complex, but it really only spells out the various
+    # combinations in which the basic unit of an IPv6 address (0..ffff) can be
+    # written, from :: to 1:2:3:4:5:6:7:8, plus the IPv4-in-IPv6 variants such
+    # as ::ffff:192.0.2.3.
+    #
+    # Note that we can't just use ipaddress.ip_address() because we also have to
+    # accept ranges in place of each component.
+
+    'ipv6': re.compile(
+        r'''^
+            (?:{0}:){{7}}{0}|           # uncompressed: 1:2:3:4:5:6:7:8
+            (?:{0}:){{1,6}}:|           # compressed variants, which are all
+            (?:{0}:)(?:{0}){{1,6}}|     # a::b for various lengths of a,b
+            (?:{0}:){{2}}(?::{0}){{1,5}}|
+            (?:{0}:){{3}}(?::{0}){{1,4}}|
+            (?:{0}:){{4}}(?::{0}){{1,3}}|
+            (?:{0}:){{5}}(?::{0}){{1,2}}|
+            (?:{0}:){{6}}(?::{0})|      # ...all with 2 <= a+b <= 7
+            :(?::{0}){{1,6}}|           # ::ffff(:ffff...)
+            {0}?::|                     # ffff::, ::
+                                        # ipv4-in-ipv6 variants
+            (?:0:){{6}}(?:{0}\.){{3}}{0}|
+            ::(?:ffff:)?(?:{0}\.){{3}}{0}|
+            (?:0:){{5}}ffff:(?:{0}\.){{3}}{0}
+            $
+        '''.format(ipv6_component), re.X|re.I
+    ),
+
+    # This matches a hostname or host pattern including [x:y(:z)] ranges.
+    #
+    # We roughly follow DNS rules here, but also allow ranges (and underscores).
+    # In the past, no systematic rules were enforced about inventory hostnames,
+    # but the parsing context (e.g. shlex.split(), fnmatch.fnmatch()) excluded
+    # various metacharacters anyway.
+    #
+    # We don't enforce DNS length restrictions here (63 characters per label,
+    # 253 characters total) or make any attempt to process IDNs.
+
+    'hostname': re.compile(
+        r'''^
+            {label}                     # We must have at least one label
+            (?:\.{label})*              # Followed by zero or more .labels
+            $
+        '''.format(label=label), re.X|re.I|re.UNICODE
+    ),
+}
+
+def parse_address(address, allow_ranges=False):
+    """
+    Takes a string and returns a (host, port) tuple. If the host is None, then
+    the string could not be parsed as a host identifier with an optional port
+    specification. If the port is None, then no port was specified.
+
+    The host identifier may be a hostname (qualified or not), an IPv4 address,
+    or an IPv6 address. If allow_ranges is True, then any of those may contain
+    [x:y] range specifications, e.g. foo[1:3] or foo[0:5]-bar[x-z].
+
+    The port number is an optional :NN suffix on an IPv4 address or host name,
+    or a mandatory :NN suffix on any square-bracketed expression: IPv6 address,
+    IPv4 address, or host name. (This means the only way to specify a port for
+    an IPv6 address is to enclose it in square brackets.)
+    """
+
+    # First, we extract the port number if one is specified.
+
+    port = None
+    for type in ['bracketed_hostport', 'hostport']:
+        m = patterns[type].match(address)
+        if m:
+            (address, port) = m.groups()
+            port = int(port)
+            continue
+
+    # What we're left with now must be an IPv4 or IPv6 address, possibly with
+    # numeric ranges, or a hostname with alphanumeric ranges.
+
+    host = None
+    for type in ['ipv4', 'ipv6', 'hostname']:
+        m = patterns[type].match(address)
+        if m:
+            host = address
+            continue
+
+    # If it isn't any of the above, we don't understand it.
+
+    if not host:
+        return (None, None)
+
+    # If we get to this point, we know that any included ranges are valid. If
+    # the caller is prepared to handle them, all is well. Otherwise we treat
+    # it as a parse failure.
+
+    if not allow_ranges and '[' in host:
+        return (None, None)
+
+    return (host, port)
diff --git a/lib/ansible/plugins/action/add_host.py b/lib/ansible/plugins/action/add_host.py
index cf2dab17373..0e7d3187e56 100644
--- a/lib/ansible/plugins/action/add_host.py
+++ b/lib/ansible/plugins/action/add_host.py
@@ -23,6 +23,8 @@ __metaclass__ = type
 import re
 
 from ansible.plugins.action import ActionBase
+from ansible.parsing.utils.addresses import parse_address
+from ansible.errors import AnsibleError, AnsibleParserError
 
 class ActionModule(ActionBase):
     ''' Create inventory hosts and groups in the memory inventory'''
@@ -40,9 +42,11 @@ class ActionModule(ActionBase):
         new_name = self._task.args.get('name', self._task.args.get('hostname', None))
         #vv("creating host via 'add_host': hostname=%s" % new_name)
 
-        new_name, new_port = _parse_ip_host_and_port(new_name)
-        if new_port:
-            self._task.args['ansible_ssh_port'] = new_port
+        name, port = parse_address(new_name, allow_ranges=False)
+        if not name:
+            raise AnsibleError("Invalid inventory hostname: %s" % new_name)
+        if port:
+            self._task.args['ansible_ssh_port'] = port
 
         groups = self._task.args.get('groupname', self._task.args.get('groups', self._task.args.get('group', ''))) 
         # add it to the group if that was specified
@@ -58,28 +62,4 @@ class ActionModule(ActionBase):
             if not k in [ 'name', 'hostname', 'groupname', 'groups' ]:
                 host_vars[k] = self._task.args[k] 
 
-        return dict(changed=True, add_host=dict(host_name=new_name, groups=new_groups, host_vars=host_vars))
-
-def _parse_ip_host_and_port(hostname):
-    """
-    Attempt to parse the hostname and port from a hostname, e.g.,
-
-    some-host-name
-    some-host-name:80
-    8.8.8.8
-    8.8.8.8:80
-    2001:db8:0:1
-    [2001:db8:0:1]:80
-    """
-    if hostname.count(':') > 1:
-        match = re.match(
-            '\[(?P<ip>[^\]]+)\](:(?P<port>[0-9]+))?',
-            hostname
-        )
-        if match:
-            return match.group('ip'), match.group('port')
-        else:
-            return hostname, None
-    elif ':' in hostname:
-        return hostname.rsplit(':', 1)
-    return hostname, None
+        return dict(changed=True, add_host=dict(host_name=name, groups=new_groups, host_vars=host_vars))
diff --git a/test/integration/unicode.yml b/test/integration/unicode.yml
index 1044c252705..6e8e073a79d 100644
--- a/test/integration/unicode.yml
+++ b/test/integration/unicode.yml
@@ -4,10 +4,9 @@
   connection: local
   vars:
     test_var: 'Ī ī Ĭ ĭ Į į İ ı IJ ij Ĵ ĵ Ķ ķ ĸ Ĺ ĺ Ļ ļ Ľ ľ Ŀ ŀ Ł ł Ń ń Ņ ņ Ň ň ʼn Ŋ ŋ Ō ō Ŏ ŏ Ő ő Œ'
-    num_hosts: 5
     hostnames:
-        - 'host-#ϬϭϮϯϰ'
-        - 'host-ͰͱͲͳʹ͵'
+        - 'host-ϬϭϮϯϰ'
+        - 'host-fóöbär'
         - 'host-ΙΚΛΜΝΞ'
         - 'host-στυφχψ'
         - 'host-ϬϭϮϯϰϱ'
@@ -29,11 +28,11 @@
         - 'ā Ă ă Ą ą Ć ć Ĉ ĉ Ċ ċ Č č Ď ď Đ đ Ē ē Ĕ ĕ Ė ė Ę ę Ě ě Ĝ ĝ Ğ ğ Ġ ġ Ģ ģ Ĥ ĥ Ħ ħ Ĩ ĩ'
 
     - add_host:
-        name: '{{hostnames}}.{{item}}'
+        name: '{{item}}'
         groups: 'ĪīĬĭ'
+        ansible_ssh_host: 127.0.0.1
         ansible_connection: local
-        host_id: '{{item}}'
-      with_sequence: start=1 end={{num_hosts}} format=%d
+      with_items: hostnames
 
     - name: 'A task with unicode extra vars'
       debug: var=extra_var
diff --git a/test/units/parsing/test_addresses.py b/test/units/parsing/test_addresses.py
new file mode 100644
index 00000000000..8f4fe3696e4
--- /dev/null
+++ b/test/units/parsing/test_addresses.py
@@ -0,0 +1,69 @@
+# -*- coding: utf-8 -*-
+
+import unittest
+
+from ansible.parsing.utils.addresses import parse_address
+
+class TestParseAddress(unittest.TestCase):
+
+    tests = {
+        # IPv4 addresses
+        '192.0.2.3': ['192.0.2.3', None],
+        '192.0.2.3:23': ['192.0.2.3', 23],
+
+        # IPv6 addresses
+        '::': ['::', None],
+        '::1': ['::1', None],
+        '[::1]:442': ['::1', 442],
+        'abcd:ef98:7654:3210:abcd:ef98:7654:3210': ['abcd:ef98:7654:3210:abcd:ef98:7654:3210', None],
+        '[abcd:ef98:7654:3210:abcd:ef98:7654:3210]:42': ['abcd:ef98:7654:3210:abcd:ef98:7654:3210', 42],
+
+        # Hostnames
+        'some-host': ['some-host', None],
+        'some-host:80': ['some-host', 80],
+        'some.host.com:492': ['some.host.com', 492],
+        '[some.host.com]:493': ['some.host.com', 493],
+        'a-b.3foo_bar.com:23': ['a-b.3foo_bar.com', 23],
+        u'fóöbär': [u'fóöbär', None],
+        u'fóöbär:32': [u'fóöbär', 32],
+        u'fóöbär.éxàmplê.com:632': [u'fóöbär.éxàmplê.com', 632],
+
+        # Various errors
+        '': [None, None],
+        'some..host': [None, None],
+        'some.': [None, None],
+        '[example.com]': [None, None],
+        'some-': [None, None],
+        'some-.foo.com': [None, None],
+        'some.-foo.com': [None, None],
+    }
+
+    range_tests = {
+        '192.0.2.[3:10]': ['192.0.2.[3:10]', None],
+        '192.0.2.[3:10]:23': ['192.0.2.[3:10]', 23],
+        'abcd:ef98::7654:[1:9]': ['abcd:ef98::7654:[1:9]', None],
+        '[abcd:ef98::7654:[6:32]]:2222': ['abcd:ef98::7654:[6:32]', 2222],
+        u'fóöb[a:c]r.éxàmplê.com:632': [u'fóöb[a:c]r.éxàmplê.com', 632],
+        '[a:b]foo.com': ['[a:b]foo.com', None],
+        'foo[a:b].com': ['foo[a:b].com', None],
+        'foo[a:b]:42': ['foo[a:b]', 42],
+        'foo[a-b]-.com': [None, None],
+        'foo[a-b]:32': [None, None],
+        'foo[x-y]': [None, None],
+    }
+
+    def test_without_ranges(self):
+        for t in self.tests:
+            test = self.tests[t]
+
+            (host, port) = parse_address(t)
+            assert host == test[0]
+            assert port == test[1]
+
+    def test_with_ranges(self):
+        for t in self.range_tests:
+            test = self.range_tests[t]
+
+            (host, port) = parse_address(t, allow_ranges=True)
+            assert host == test[0]
+            assert port == test[1]
diff --git a/test/units/plugins/action/test_add_host.py b/test/units/plugins/action/test_add_host.py
deleted file mode 100644
index c694d387a3a..00000000000
--- a/test/units/plugins/action/test_add_host.py
+++ /dev/null
@@ -1,47 +0,0 @@
-import unittest
-
-from ansible.plugins.action import add_host
-
-
-class TestAddHost(unittest.TestCase):
-
-    def test_hostname(self):
-        host, port = add_host._parse_ip_host_and_port('some-remote-host')
-        assert host == 'some-remote-host'
-        assert port is None
-
-    def test_hostname_with_port(self):
-        host, port = add_host._parse_ip_host_and_port('some-remote-host:80')
-        assert host == 'some-remote-host'
-        assert port == '80'
-
-    def test_parse_ip_host_and_port_v4(self):
-        host, port = add_host._parse_ip_host_and_port('8.8.8.8')
-        assert host == '8.8.8.8'
-        assert port is None
-
-    def test_parse_ip_host_and_port_v4_and_port(self):
-        host, port = add_host._parse_ip_host_and_port('8.8.8.8:80')
-        assert host == '8.8.8.8'
-        assert port == '80'
-
-    def test_parse_ip_host_and_port_v6(self):
-        host, port = add_host._parse_ip_host_and_port(
-            'dead:beef:dead:beef:dead:beef:dead:beef'
-        )
-        assert host == 'dead:beef:dead:beef:dead:beef:dead:beef'
-        assert port is None
-
-    def test_parse_ip_host_and_port_v6_with_brackets(self):
-        host, port = add_host._parse_ip_host_and_port(
-            '[dead:beef:dead:beef:dead:beef:dead:beef]'
-        )
-        assert host == 'dead:beef:dead:beef:dead:beef:dead:beef'
-        assert port is None
-
-    def test_parse_ip_host_and_port_v6_with_brackets_and_port(self):
-        host, port = add_host._parse_ip_host_and_port(
-            '[dead:beef:dead:beef:dead:beef:dead:beef]:80'
-        )
-        assert host == 'dead:beef:dead:beef:dead:beef:dead:beef'
-        assert port == '80'