[Freeipa-users] FreeIPA and FQDN requirements
Rich Megginson
rmeggins at redhat.com
Fri Aug 8 18:37:33 UTC 2014
On 08/08/2014 12:21 PM, brendan kearney wrote:
>
> Double check your example. -h means the hostname of the ldap server
> to connect to and issue your query to. Man page calls it ldaphost.
>
Yes.
> I have not run across a client that does cert validation using ldap.
> Is that IPA specific?
>
I'm not talking about cert validation using ldap. I'm talking about the
fact that, by default, the ldapsearch client will expect the hostname
you pass in to match the hostname in the ssl server cert subject DN.
> It seems that a lot of effort is being spent to justify a dependency
> on fully qualified hostnames, when there is no reason to require it.
> In fact, it may even break somethings or even violate some rfc.
>
If requiring fully qualified hostnames violates RFCs or other standards,
I'd like to hear about it.
> On Aug 8, 2014 1:43 PM, "Rich Megginson" <rmeggins at redhat.com
> <mailto:rmeggins at redhat.com>> wrote:
>
> On 08/08/2014 11:17 AM, brendan kearney wrote:
>>
>> The cert should have the fqdn, just like the kerberos instance,
>> but the hostname is not required to be fq'd. The lookup of a
>> short name, as well as and more specifically the IP, in dns will
>> result in the fqdn being returned by dns (the short name
>> resolution being affected by domain and search directives in
>> resolv.conf and the origin directive in dns if either of those
>> are absent).
>>
>> Back to the point, dns lookup for cert matching is not dependent
>> on hostnames. PTR lookups will always return fqdns, so a
>> dependency on fqdns as hostnames is artificial, no?
>>
>
> Most clients will also do the additional step of matching the
> hostname in the cert against the originally given hostname. For
> example, with ldapsearch:
>
> ldapsearch -xLLLZZ -h hostname ...
>
> This will fail if the server cert for hostname has
> "cn=hostname.domain.tld"
>
>> On Aug 8, 2014 1:03 PM, "Rich Megginson" <rmeggins at redhat.com
>> <mailto:rmeggins at redhat.com>> wrote:
>>
>> On 08/08/2014 10:56 AM, brendan kearney wrote:
>>>
>>> Arent all of those lookups done in dns?
>>>
>>
>> Yes.
>>
>>> Wouldnt that mean hostnames being fqdn's is irrelevant?
>>>
>>
>> Not sure what you mean.
>>
>> I guess if you issued your server certs with a subject DN of
>> "cn=hostname", instead of "cn=hostname.domain.tld", and you
>> had the DNS PTR lookups configured so that w.x.y.z returned
>> "hostname" instead of "hostname.domain.tld", then TLS/SSL
>> would work.
>>
>>> On Aug 8, 2014 12:11 PM, "Rich Megginson"
>>> <rmeggins at redhat.com <mailto:rmeggins at redhat.com>> wrote:
>>>
>>> On 08/08/2014 08:57 AM, brendan kearney wrote:
>>>>
>>>> Kerberos is dependent on A records in dns. The
>>>> instance (as in principal/instance at REALM) should match
>>>> the A record in dns.
>>>>
>>>> There is absolutely no Kerberos dependency on hostnames
>>>> being fully qualified. I have all my devices named
>>>> with short names and I have no issues with Kerberos
>>>> ticketing.
>>>>
>>>> This seems to be an artificial requirement in FreeIPA
>>>> that is wrong.
>>>>
>>>
>>> The other hostname requirement is for TLS/SSL, for MITM
>>> checking. By default, when an SSL server cert is
>>> issued, the subject DN contains cn=fqdn as the leftmost
>>> component. clients use this fqdn to verify the server.
>>> That is, client knows the IP address of the server -
>>> client does a reverse lookup (i.e. PTR) to see if the
>>> server returned by that lookup matches the cn=fqdn in
>>> the server cert. This requires reverse lookups are
>>> configured and that the fqdn is the first name/alias
>>> returned.
>>>
>>>> On Aug 8, 2014 8:54 AM, "Bruno Henrique Barbosa"
>>>> <bruno-barbosa at prodesan.com.br
>>>> <mailto:bruno-barbosa at prodesan.com.br>> wrote:
>>>>
>>>> Hello everyone,
>>>>
>>>> I'm running through an issue where an application
>>>> needs its server's hostname to be in short name
>>>> format, such as "server" and not
>>>> "server.example.com <http://server.example.com>".
>>>> When I started deploying FreeIPA in the very
>>>> beginning of this year, I remember I couldn't
>>>> install freeipa-client with a bare "ipa-client
>>>> install", because of this:
>>>>
>>>> ____________
>>>>
>>>> [root at server ~]# hostname
>>>> server
>>>> [root at server ~]# hostname -f
>>>> server.example.com <http://server.example.com>
>>>> [root at server ~]# ipa-client-install
>>>> Discovery was successful!
>>>> Hostname: server.example.com
>>>> <http://server.example.com>
>>>> Realm: EXAMPLE.COM <http://EXAMPLE.COM>
>>>> DNS Domain: example.com <http://example.com>
>>>> IPA Server: ipa01.example.com
>>>> <http://ipa01.example.com>
>>>> Base DN: dc=example,dc=com
>>>>
>>>> Continue to configure the system with these values?
>>>> [no] yes
>>>> User authorized to enroll computers: admin
>>>> Synchronizing time with KDC...
>>>> Unable to sync time with IPA NTP Server, assuming
>>>> the time is in sync. Please check that port 123 UDP
>>>> is opened.
>>>> Password for admin at EXAMPLE.COM
>>>> <mailto:admin at EXAMPLE.COM>:
>>>> Joining realm failed: The hostname must be
>>>> fully-qualified: server
>>>> Installation failed. Rolling back changes.
>>>> IPA client is not configured on this system.
>>>>
>>>> ________________
>>>>
>>>> So, using the short name as hostname didn't work
>>>> for install, I then make it like "ipa-client
>>>> install --hostname=`hostname -f` --mkhomedir -N",
>>>> and it installs and works like a charm, BUT it
>>>> updates the machine's hostname to FQDN.
>>>>
>>>> What I tested and, at first, worked: after
>>>> deploying and ipa-client installation with those
>>>> parameters which work, renaming the machine back to
>>>> a short name AT FIRST is not causing any problems.
>>>> I can login with my ssh rules perfectly, but I
>>>> don't find any IPA technical docs saying it
>>>> will/won't work if I change the hostname back to
>>>> short name and not FQDN.
>>>>
>>>> Searching for it, I found on RedHat guide: "The
>>>> hostname of a system is critical for the correct
>>>> operation of Kerberos and SSL. Both of these
>>>> security mechanisms rely on the hostname to ensure
>>>> that communication is occurring between the
>>>> specified hosts."
>>>> I've also found this message
>>>> http://osdir.com/ml/freeipa-users/2012-03/msg00006.html
>>>> which seems to be related to my case, but what I
>>>> need to know is: where does it state FQDN is a
>>>> mandatory requirement in order to FreeIPA to work
>>>> and/or is there anything else (a patch, update,
>>>> whatever) to solve this issue, so I don't need to
>>>> change my applications?
>>>>
>>>> Thank you and sorry for the wall of a text.
>>>>
>>>> PS: Enviroment is CentOS 6.5, in both IPA server
>>>> and client. DNS is not the same server as IPA (it
>>>> forwards to a Windows DC).
>>>>
>>>> RPMs:
>>>> libipa_hbac-1.9.2-129.el6_5.4.x86_64
>>>> libipa_hbac-python-1.9.2-129.el6_5.4.x86_64
>>>> python-iniparse-0.3.1-2.1.el6.noarch
>>>> ipa-pki-common-theme-9.0.3-7.el6.noarch
>>>> ipa-pki-ca-theme-9.0.3-7.el6.noarch
>>>> ipa-admintools-3.0.0-37.el6.x86_64
>>>> ipa-server-selinux-3.0.0-37.el6.x86_64
>>>> ipa-server-3.0.0-37.el6.x86_64
>>>> ipa-python-3.0.0-37.el6.x86_64
>>>> ipa-client-3.0.0-37.el6.x86_64
>>>>
>>>>
>>>>
>>>> --
>>>> Manage your subscription for the Freeipa-users
>>>> mailing list:
>>>> https://www.redhat.com/mailman/listinfo/freeipa-users
>>>> Go To http://freeipa.org for more info on the project
>>>>
>>>>
>>>>
>>>
>>>
>>> --
>>> Manage your subscription for the Freeipa-users mailing list:
>>> https://www.redhat.com/mailman/listinfo/freeipa-users
>>> Go To http://freeipa.org for more info on the project
>>>
>>
>
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