GSSAPI authentication
Hello all
We are running Postgres 14 on Ubuntu. Our Windows users connect passwordless using GSSAPI. This works great.
Now we want users on Linux client to also connect passwordless using GSSAPI. Users on Linux log on using their Active Directory credentials, as the Linux host (Ubuntu 22.04) is joined to the domain. Logon to Linux works fine, access to Windows cifs shares works fine authentication with Kerberos.
But psql won't connect using GSSAPI. It does hit the right pg_hba.conf line and the username is translated via pg_ident.conf, just fine. But psql says
psql: error: connection to server at "srvpostgres4.xxx.local" (172.30.33.30), port 1609 failed: could not initiate GSSAPI security context: Unspecified GSS failure. Minor code may provide more information: Server not found in Kerberos database connection to server at "srvpostgres4.xxx.local" (172.30.33.30), port 1609 failed: GSSAPI continuation error: Unspecified GSS failure. Minor code may provide more information: Server not found in Kerberos database
Server log is like this
2022-06-06 08:14:01.176 CEST,"yyy","db1",474094,"172.30.32.213:33556",627e83c9.73bee,2,"authentication",2022-06-06 08:14:01 CEST,2/14544,0,FATAL,28000,"GSSAPI authentication failed for user ""yyy""","Connection matched pg_hba.conf line 15: ""host all all 172.0.0.0/8 gss map=xxxlocal include_realm=0 krb_realm=""XXX.LOCAL""""",,,,,,,,"","client backend",,-3382135431624836920
We are a bit lost here. What are we missing?
Regards Niels Jespersen
This sounds like your PG service was unable to authenticate itself to AD.
There's probably a trick to that somewhere - AD doesn't really want to be a
Kerberos server, it just happens to use it 😉
On Mon, 6 June 2022, 10:05 pm Niels Jespersen, <NJN@dst.dk> wrote:
Show quoted text
Hello all
We are running Postgres 14 on Ubuntu. Our Windows users connect
passwordless using GSSAPI. This works great.Now we want users on Linux client to also connect passwordless using
GSSAPI. Users on Linux log on using their Active Directory credentials, as
the Linux host (Ubuntu 22.04) is joined to the domain. Logon to Linux works
fine, access to Windows cifs shares works fine authentication with
Kerberos.But psql won't connect using GSSAPI. It does hit the right pg_hba.conf
line and the username is translated via pg_ident.conf, just fine. But psql
sayspsql: error: connection to server at "srvpostgres4.xxx.local"
(172.30.33.30), port 1609 failed: could not initiate GSSAPI security
context: Unspecified GSS failure. Minor code may provide more information:
Server not found in Kerberos database connection to server at
"srvpostgres4.xxx.local" (172.30.33.30), port 1609 failed: GSSAPI
continuation error: Unspecified GSS failure. Minor code may provide more
information: Server not found in Kerberos databaseServer log is like this
2022-06-06 08:14:01.176 CEST,"yyy","db1",474094,"172.30.32.213:33556",627e83c9.73bee,2,"authentication",2022-06-06
08:14:01 CEST,2/14544,0,FATAL,28000,"GSSAPI authentication failed for user
""yyy""","Connection matched pg_hba.conf line 15: ""host all
all 172.0.0.0/8 gss map=xxxlocal include_realm=0
krb_realm=""XXX.LOCAL""""",,,,,,,,"","client backend",,-3382135431624836920We are a bit lost here. What are we missing?
Regards Niels Jespersen
Looking closely at a configuration guide for MSSQL with Kerberos
authentication, I see this part:
https://docs.microsoft.com/en-us/sql/database-engine/configure-windows/register-a-service-principal-name-for-kerberos-connections?view=sql-server-ver16#Manual.
It looks like it might be adapted to your question.
--Michael
On Mon, Jun 6, 2022 at 10:26 PM Michael van der Kolff <
mvanderkolff@gmail.com> wrote:
Show quoted text
This sounds like your PG service was unable to authenticate itself to AD.
There's probably a trick to that somewhere - AD doesn't really want to be
a Kerberos server, it just happens to use it 😉On Mon, 6 June 2022, 10:05 pm Niels Jespersen, <NJN@dst.dk> wrote:
Hello all
We are running Postgres 14 on Ubuntu. Our Windows users connect
passwordless using GSSAPI. This works great.Now we want users on Linux client to also connect passwordless using
GSSAPI. Users on Linux log on using their Active Directory credentials, as
the Linux host (Ubuntu 22.04) is joined to the domain. Logon to Linux works
fine, access to Windows cifs shares works fine authentication with
Kerberos.But psql won't connect using GSSAPI. It does hit the right pg_hba.conf
line and the username is translated via pg_ident.conf, just fine. But psql
sayspsql: error: connection to server at "srvpostgres4.xxx.local"
(172.30.33.30), port 1609 failed: could not initiate GSSAPI security
context: Unspecified GSS failure. Minor code may provide more information:
Server not found in Kerberos database connection to server at
"srvpostgres4.xxx.local" (172.30.33.30), port 1609 failed: GSSAPI
continuation error: Unspecified GSS failure. Minor code may provide more
information: Server not found in Kerberos databaseServer log is like this
2022-06-06 08:14:01.176 CEST,"yyy","db1",474094,"172.30.32.213:33556",627e83c9.73bee,2,"authentication",2022-06-06
08:14:01 CEST,2/14544,0,FATAL,28000,"GSSAPI authentication failed for user
""yyy""","Connection matched pg_hba.conf line 15: ""host all
all 172.0.0.0/8 gss map=xxxlocal include_realm=0
krb_realm=""XXX.LOCAL""""",,,,,,,,"","client backend",,-3382135431624836920We are a bit lost here. What are we missing?
Regards Niels Jespersen
Fra: Michael van der Kolff <mvanderkolff@gmail.com>
Sendt: 6. juni 2022 14:26
Til: Niels Jespersen <NJN@dst.dk>
Cc: pgsql-general list <pgsql-general@lists.postgresql.org>
Emne: Re: GSSAPI authentication
This sounds like your PG service was unable to authenticate itself to AD.
There's probably a trick to that somewhere - AD doesn't really want to be a Kerberos server, it just happens to use it 😉
But it works fine when the same AD-user connects from Windows to the same postgres (Linux) server. Auth fails when the user initiates login from a Linux box (that otherwise uses Kerberized ressources just fine).
Niels
The part that you're missing, I think, is that Kerberized services require
a service account.
The SPN (service principal name) is the name that is used in Kerberos
contexts for that service account. PostgreSQL uses
postgres/${hostname}@${realm}
by default - see https://www.postgresql.org/docs/14/gssapi-auth.html.
The important part to note here is that $hostname must match what is
registered in the SPN for the user that you're using as the service account
in AD. It might (I don't know) have to match what AD believes about the
host from its PTR records for that domain as well.
--Michael
On Mon, Jun 6, 2022 at 11:33 PM Niels Jespersen <NJN@dst.dk> wrote:
Show quoted text
*Fra:* Michael van der Kolff <mvanderkolff@gmail.com>
*Sendt:* 6. juni 2022 14:26
*Til:* Niels Jespersen <NJN@dst.dk>
*Cc:* pgsql-general list <pgsql-general@lists.postgresql.org>
*Emne:* Re: GSSAPI authenticationThis sounds like your PG service was unable to authenticate itself to AD.
There's probably a trick to that somewhere - AD doesn't really want to be
a Kerberos server, it just happens to use it 😉
But it works fine when the same AD-user connects from Windows to the same
postgres (Linux) server. Auth fails when the user initiates login from a
Linux box (that otherwise uses Kerberized ressources just fine).Niels
Oh wait, I see.
On Mon, Jun 6, 2022 at 11:41 PM Michael van der Kolff <
mvanderkolff@gmail.com> wrote:
Show quoted text
The part that you're missing, I think, is that Kerberized services require
a service account.The SPN (service principal name) is the name that is used in Kerberos
contexts for that service account. PostgreSQL uses postgres/${hostname}@${realm}
by default - see https://www.postgresql.org/docs/14/gssapi-auth.html.The important part to note here is that $hostname must match what is
registered in the SPN for the user that you're using as the service account
in AD. It might (I don't know) have to match what AD believes about the
host from its PTR records for that domain as well.--Michael
On Mon, Jun 6, 2022 at 11:33 PM Niels Jespersen <NJN@dst.dk> wrote:
*Fra:* Michael van der Kolff <mvanderkolff@gmail.com>
*Sendt:* 6. juni 2022 14:26
*Til:* Niels Jespersen <NJN@dst.dk>
*Cc:* pgsql-general list <pgsql-general@lists.postgresql.org>
*Emne:* Re: GSSAPI authenticationThis sounds like your PG service was unable to authenticate itself to AD.
There's probably a trick to that somewhere - AD doesn't really want to
be a Kerberos server, it just happens to use it 😉
But it works fine when the same AD-user connects from Windows to the same
postgres (Linux) server. Auth fails when the user initiates login from a
Linux box (that otherwise uses Kerberized ressources just fine).Niels
From the tiny bit I know about this, and a bit of googling, I arrived at
https://stackoverflow.com/questions/13850252/cannot-get-kerberos-service-ticket-krbexception-server-not-found-in-kerberos-d
.
It seems to suggest that either the KDC or your service account might have
bad PTR records, and you might want to capture DNS traffic on the two
hosts. Of course, I have no idea whether that is actually the issue.
I remember reading these docs ages ago - best of luck!
--Michael
On Mon, Jun 6, 2022 at 11:42 PM Michael van der Kolff <
mvanderkolff@gmail.com> wrote:
Show quoted text
Oh wait, I see.
On Mon, Jun 6, 2022 at 11:41 PM Michael van der Kolff <
mvanderkolff@gmail.com> wrote:The part that you're missing, I think, is that Kerberized services
require a service account.The SPN (service principal name) is the name that is used in Kerberos
contexts for that service account. PostgreSQL uses postgres/${hostname}@${realm}
by default - see https://www.postgresql.org/docs/14/gssapi-auth.html.The important part to note here is that $hostname must match what is
registered in the SPN for the user that you're using as the service account
in AD. It might (I don't know) have to match what AD believes about the
host from its PTR records for that domain as well.--Michael
On Mon, Jun 6, 2022 at 11:33 PM Niels Jespersen <NJN@dst.dk> wrote:
*Fra:* Michael van der Kolff <mvanderkolff@gmail.com>
*Sendt:* 6. juni 2022 14:26
*Til:* Niels Jespersen <NJN@dst.dk>
*Cc:* pgsql-general list <pgsql-general@lists.postgresql.org>
*Emne:* Re: GSSAPI authenticationThis sounds like your PG service was unable to authenticate itself to
AD.
There's probably a trick to that somewhere - AD doesn't really want to
be a Kerberos server, it just happens to use it 😉
But it works fine when the same AD-user connects from Windows to the
same postgres (Linux) server. Auth fails when the user initiates login from
a Linux box (that otherwise uses Kerberized ressources just fine).Niels
Thank you for your suggestion. I arrived at the same suspicion. And that was it. Reverse DNS was not set up correctly.
Fra: Michael van der Kolff <mvanderkolff@gmail.com>
Sendt: 6. juni 2022 15:50
Til: Niels Jespersen <NJN@dst.dk>
Cc: pgsql-general list <pgsql-general@lists.postgresql.org>
Emne: Re: GSSAPI authentication
From the tiny bit I know about this, and a bit of googling, I arrived at https://stackoverflow.com/questions/13850252/cannot-get-kerberos-service-ticket-krbexception-server-not-found-in-kerberos-d.
It seems to suggest that either the KDC or your service account might have bad PTR records, and you might want to capture DNS traffic on the two hosts. Of course, I have no idea whether that is actually the issue.
I remember reading these docs ages ago - best of luck!
--Michael
On Mon, Jun 6, 2022 at 11:42 PM Michael van der Kolff <mvanderkolff@gmail.com<mailto:mvanderkolff@gmail.com>> wrote:
Oh wait, I see.
On Mon, Jun 6, 2022 at 11:41 PM Michael van der Kolff <mvanderkolff@gmail.com<mailto:mvanderkolff@gmail.com>> wrote:
The part that you're missing, I think, is that Kerberized services require a service account.
The SPN (service principal name) is the name that is used in Kerberos contexts for that service account. PostgreSQL uses postgres/${hostname}@${realm} by default - see https://www.postgresql.org/docs/14/gssapi-auth.html.
The important part to note here is that $hostname must match what is registered in the SPN for the user that you're using as the service account in AD. It might (I don't know) have to match what AD believes about the host from its PTR records for that domain as well.
--Michael
On Mon, Jun 6, 2022 at 11:33 PM Niels Jespersen <NJN@dst.dk<mailto:NJN@dst.dk>> wrote:
Fra: Michael van der Kolff <mvanderkolff@gmail.com<mailto:mvanderkolff@gmail.com>>
Sendt: 6. juni 2022 14:26
Til: Niels Jespersen <NJN@dst.dk<mailto:NJN@dst.dk>>
Cc: pgsql-general list <pgsql-general@lists.postgresql.org<mailto:pgsql-general@lists.postgresql.org>>
Emne: Re: GSSAPI authentication
This sounds like your PG service was unable to authenticate itself to AD.
There's probably a trick to that somewhere - AD doesn't really want to be a Kerberos server, it just happens to use it 😉
But it works fine when the same AD-user connects from Windows to the same postgres (Linux) server. Auth fails when the user initiates login from a Linux box (that otherwise uses Kerberized ressources just fine).
Niels