Looking for GSSAPI config [was: Looking for NTLM config example]
Mark Foley
mfoley at ohprs.org
Wed Jun 29 03:32:37 UTC 2016
Aki - partial success! I rebuilt my dovecot with ./config --with-gssapi, and restarted. Now I
don't get that "Unknown authentication mechanism 'gssapi'" message in maillog, and mail is
delivered successfully to the other domain users having PLAIN authentication. That's a big
step. In examining my original config.log output I apparently did not have --with-gssapi enabled.
HOWEVER - the Thunderbird client configured for 'Kerberos / GSSAPI' still cannot correctly
authenticate and retrieve mail. Here is the dovecot log for that host:
Jun 28 22:44:05 imap-login: Debug: SSL: elliptic curve secp384r1 will be used for ECDH and ECDHE key exchanges
Jun 28 22:44:05 imap-login: Debug: SSL: elliptic curve secp384r1 will be used for ECDH and ECDHE key exchanges
Jun 28 22:44:05 auth: Debug: Loading modules from directory: /usr/local/lib/dovecot/auth
Jun 28 22:44:05 auth: Debug: Read auth token secret from /usr/local/var/run/dovecot/auth-token-secret.dat
Jun 28 22:44:05 auth: Debug: auth client connected (pid=24076)
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x10, ret=1: before/accept initialization [192.168.0.58]
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x2001, ret=1: before/accept initialization [192.168.0.58]
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x2002, ret=-1: SSLv2/v3 read client hello A [192.168.0.58]
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x2001, ret=1: SSLv3 read client hello A [192.168.0.58]
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x2001, ret=1: SSLv3 write server hello A [192.168.0.58]
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x2001, ret=1: SSLv3 write certificate A [192.168.0.58]
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x2001, ret=1: SSLv3 write key exchange A [192.168.0.58]
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x2001, ret=1: SSLv3 write server done A [192.168.0.58]
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x2001, ret=1: SSLv3 flush data [192.168.0.58]
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x2002, ret=-1: SSLv3 read client certificate A [192.168.0.58]
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x2002, ret=-1: SSLv3 read client certificate A [192.168.0.58]
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x2001, ret=1: SSLv3 read client key exchange A [192.168.0.58]
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x2001, ret=1: SSLv3 read certificate verify A [192.168.0.58]
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x2001, ret=1: SSLv3 read finished A [192.168.0.58]
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x2001, ret=1: SSLv3 write session ticket A [192.168.0.58]
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x2001, ret=1: SSLv3 write change cipher spec A [192.168.0.58]
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x2001, ret=1: SSLv3 write finished A [192.168.0.58]
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x2001, ret=1: SSLv3 flush data [192.168.0.58]
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x20, ret=1: SSL negotiation finished successfully [192.168.0.58]
Jun 28 22:44:06 imap-login: Debug: SSL: where=0x2002, ret=1: SSL negotiation finished successfully [192.168.0.58]
Jun 28 22:44:11 imap-login: Debug: SSL alert: close notify [192.168.0.58]
Jun 28 22:44:11 imap-login: Debug: SSL alert: close notify [192.168.0.58]
Jun 28 22:44:11 imap-login: Info: Disconnected (no auth attempts in 6 secs): user=<>, rip=192.168.0.58, lip=98.102.63.107, TLS, session=<WeZyumE25wDAqAA6>
Does this tell you anything? `doveconf -n` and krb5.conf are configured as shown in previous
messages below.
Closer! --Mark
-----Original Message-----
From: Mark Foley <mfoley at ohprs.org>
Date: Tue, 28 Jun 2016 22:04:42 -0400
To: dovecot at dovecot.org
Subject: Re: Looking for GSSAPI config [was: Looking for NTLM config example]
Aki, you wrote:
> Doh. Seems your dovecot isn't compiled with gssapi support? Can you compile it yourself?
>
> I'll try to check status of NTLM this week.
I'm OK with continuing to try gssapi, esp. if NTLM is restricted to v1.
I do have the Dovecot sources and will peruse the possible options after I send this. I am on
version 2.2.15 and I see that the current downloadable version is 2.2.24. Should I upgrade? Do
you think that would help? (a perusal of the changes since 2.2.15 shows nothing obvious
realated to gssapi)
--Mark
-----Original Message-----
> Date: Tue, 28 Jun 2016 18:06:10 +0300 (EEST)
> From: aki.tuomi at dovecot.fi
> To: dovecot at dovecot.org
> Subject: Re: Looking for GSSAPI config [was: Looking for NTLM config example]
>
> > On June 28, 2016 at 5:17 PM Mark Foley <mfoley at ohprs.org> wrote:
> >
> >
> > Aki - made your suggested changes, but no joy :(
> >
> > My /etc/krb5.conf:
> >
> > ------SNIP--------
> > [libdefaults]
> > default_realm = HPRS.LOCAL
> > dns_lookup_realm = false
> > dns_lookup_kdc = true
> >
> > [libdefaults]
> > default_realm = HPRS.LOCAL
> > dns_lookup_kdc = true
> > kdc_timesync = 1
> > ccache_type = 4
> > forwardable = true
> > proxiable = true
> > fcc-mit-ticketflags = true
> >
> > [realms]
> > HPRS.LOCAL = {
> > default_domain = hprs.local
> > auth_to_local_names = {
> > Administrator = root
> > }
> > }
> >
> > [domain_realm]
> > hprs.local = HPRS.LOCAL
> > # this is not a mistake
> > .hprs.local = HPRS.LOCAL
> > ------PINS-----------
> >
> > you wrote:
> > > You can remove the krb4_ stuff
> >
> > I've remove krb4_ stuff from the [libdefaults] and eliminated the [login] section altogether.
> > Question on [realms]Administrator: should that really be root or should it be my AD Administrator?
> >
> > my doveconf -n is exactly the same as posted below, but in particular:
> >
> > auth_krb5_keytab = /etc/krb5.keytab
> > auth_mechanisms = plain login gssapi
> >
> > When I reloaded dovecot no mail was delivered to anyone (even though everyone was still using
> > plain/ssl, no one yet configured for gssapi).
> >
> > In /var/log/maillog I got (repeatedly):
> >
> > Jun 28 09:43:36 mail dovecot: imap-login: Warning: Auth process not responding, delayed sending initial response (greeting): user=<>, rip=192.168.0.54, lip=192.168.0.2, session=<Jy/e0lY2WADAqAA2>
> > Jun 28 09:43:37 mail dovecot: auth: Fatal: Unknown authentication mechanism 'gssapi'
> > Jun 28 09:43:37 mail dovecot: master: Error: service(auth): command startup failed, throttling for 60 secs
> > Jun 28 09:43:37 mail dovecot: imap-login: Warning: Auth process not responding, delayed sending initial response (greeting): user=<>, rip=166.170.27.161, lip=98.102.63.107, TLS, session=</GXn0lY22wCmqhuh>
> >
> > This looks pretty bad right off. Why "Unknown authentication mechanism 'gssapi'"?
> >
> > Do you have any idea from the configs I've posted? I'm rather depressed about this. I thought I'd
> > finally able to get AD authentication going for Dovecot. Not ready to give up though!
> >
> > Suggestions?
> >
> > THX -- Mark
> >
> > -----original Message-----
> > > Subject: Re: Looking for GSSAPI config [was: Looking for NTLM config example]
> > > To: dovecot at dovecot.org
> > > From: Aki Tuomi <aki.tuomi at dovecot.fi>
> > > Date: Tue, 28 Jun 2016 15:13:11 +0300
> > >
> > > On 28.06.2016 09:27, Mark Foley wrote:
> > > > Aki,
> > > >
> > > > To review your 5 points:
> > > >
> > > > On Mon, 27 Jun 2016 09:18:54 +0300 Aki Tuomi <aki.tuomi at dovecot.fi> wrote:
> > > >
> > > >> 1. Functional AD or Kerberos environment
> > > >> 2. Time synced against your KDC (which is your Domain Controller on Windows)
> > > >> 3. /etc/krb5.conf configured
> > > >> 4. Both forward / reverse DNS names correct for clients and servers.
> > > >> Reverse is only mandatory for servers, but having them right will work
> > > >> wonders. Most kerberos problems are about DNS problems.
> > > >> 5. You need a keytab. This keytab needs to hold entries like
> > > >> IMAP/your.host.name at REALM and IMAP/$HOSTNAME at REALM. You can generate
> > > >> these on any Windows DC server (at least).
> > > > I believe I am good on 1,2 and 4. I downloaded and installed kerberos and tested it with kinit
> > > > and klist according to the instructions at
> > > > https://wiki.samba.org/index.php/Setup_a_Samba_Active_Directory_Domain_Controller#Configure_Kerberos
> > > >
> > > > As to the the keytab (#5) I did the following:
> > > >
> > > > $ samba-tool domain exportkeytab /etc/krb5.keytab
> > > >
> > > > which created the file. I made this owned and readable by group dovecot, per instructions at
> > > > http://wiki2.dovecot.org/Authentication/Kerberos. Running `klist -k /etc/krb5.keytab` shows me
> > > > configuration listing all the users and computers in the domain, mostly in triplicate. A
> > > > partial list:
> > > >
> > > > Keytab name: FILE:/etc/krb5.keytab
> > > > KVNO Principal
> > > > ---- --------------------------------------------------------------------------
> > > > 18 COMMON$@HPRS.LOCAL
> > > > 18 COMMON$@HPRS.LOCAL
> > > > 18 COMMON$@HPRS.LOCAL
> > > > 1 MAIL$@HPRS.LOCAL
> > > > 1 MAIL$@HPRS.LOCAL
> > > > 1 MAIL$@HPRS.LOCAL
> > > > 1 charmaine at HPRS.LOCAL
> > > > 1 charmaine at HPRS.LOCAL
> > > > 1 charmaine at HPRS.LOCAL
> > > >
> > > > where COMMON and MAIL are hosts and charmaine is a user. I don't really understand the listing,
> > > > but am assuming it is OK.
> > >
> > > Strange that you do not have any host/ entries. Maybe it works without.
> > >
> > > >> setspn -q is helpful here, also setspn command in general.
> > > > I have no such command in my system. Is that a Windows thing?
> > > >
> > >
> > > Yes, but you can do those kind of things in Samba too.
> > >
> > > > As to the /etc/krb5.conf, the default one generated by samba is:
> > > >
> > > > [libdefaults]
> > > > default_realm = HPRS.LOCAL
> > > > dns_lookup_realm = false
> > > > dns_lookup_kdc = true
> > > >
> > > > I'd like to modify that to your suggestions, but I need more help. You have (with my questions):
> > > >
> > > >> Here is a *SAMPLE* configuration:
> > > >>
> > > >> [libdefaults]
> > > >> default_realm = YOUR.REALM
> > > >> dns_lookup_kdc = true
> > > >> krb4_config = /etc/krb.conf
> > > >> krb4_realms = /etc/krb.realms
> > > > Here, you have krb4_*. Do you mean that? My config file is krb5.conf. Should I rather have:
> > >
> > > You can remove the krb4_ stuff
> > >
> > > > krb5_config = /etc/krb5.conf
> > > >
> > > > Also, I have no /etc/krb*.realms file. Do I need this? If so, what should be in there?
> > > You don't necessarely require that.
> > >
> > > >> kdc_timesync = 1
> > > >> ccache_type = 4
> > > >> forwardable = true
> > > >> proxiable = true
> > > >> fcc-mit-ticketflags = true
> > > >>
> > > >> [realms]
> > > >> YOUR.REALM = {
> > > >> default_domain = your.domain.name
> > > >> auth_to_local_names = {
> > > >> Administrator = root
> > > >> }
> > > >> }
> > > > I suppose my "YOUR.REALM" is HPRS.LOCAL, right? Is my "your.domain.name" my FQDN for my AD
> > > > server: mail.hprs.local, or is it just hprs.local? (or something else!)
> > >
> > > HPRS.LOCAL is your REALM, hprs.local is your domain name.
> > > >
> > > >> [domain_realm]
> > > >> your.domain.name = YOUR.REALM
> > > >> # this is not a mistake
> > > >> .your.domain.name = YOUR.REALM
> > > >> [login]
> > > >> krb4_convert = true
> > > >> krb4_get_tickets = false
> > > > Likewise here a question on the whole krb4 versus krb5 thing.
> > > >
> > > > Your closing comment:
> > > >
> > > >> Also, note that kerberos can only act as AUTHENTICATION system. It
> > > >> cannot act as USER DATABASE. For that you need to configure LDAP or
> > > >> something else. With Active Directory LDAP is probably a damn good idea.
> > > > I have the following doveconf -n:
> > > >
> > > > # 2.2.15: /usr/local/etc/dovecot/dovecot.conf
> > > > # OS: Linux 3.10.17 x86_64 Slackware 14.1
> > > > auth_debug_passwords = yes
> > > > auth_krb5_keytab = /etc/krb5.keytab
> > > > auth_mechanisms = plain login gssapi
> > > > auth_verbose = yes
> > > > auth_verbose_passwords = plain
> > > > disable_plaintext_auth = no
> > > > info_log_path = /var/log/dovecot_info
> > > > mail_location = maildir:~/Maildir
> > > > passdb {
> > > > driver = shadow
> > > > }
> > > > protocols = imap
> > > > ssl_cert = </etc/ssl/certs/OHPRS/GoDaddy/Apache/2015-08-14/57aa6ed6ae98b4c7.crt
> > > > ssl_key = </etc/ssl/certs/OHPRS/GoDaddy/mail.ohprs.org.key
> > > > userdb {
> > > > driver = passwd
> > > > }
> > > > verbose_ssl = yes
> > > >
> > > > I assume the passwd driver for the userdb is OK? Seems to me it should work with gssapi, but in
> > > > any case I still have all but this test workstation NOT using gssapi, so I still need to
> > > > accomodate them.
> > > >
> > > > Thanks, --Mark
> > > passwd driver is fine, yes, if you ensure that users can be found.
> > >
> > > Aki
> > >
>
> Doh. Seems your dovecot isn't compiled with gssapi support? Can you compile it yourself?
>
> I'll try to check status of NTLM this week.
>
> Aki
>
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