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I am trying to configure Kerberos for GSSAPI Currently I have two nodes One the KDC server (windows server 2016) and the the other is Postgres-server(Ubuntu). I have created Active directory on in kdc-server and create user with the name of postgres and selected the option "password will never expire".

Then I have installed a kerbrose client of MIT. here is krb5.ini on kdc server.

[libdefaults]
    default_realm = HIGHGO.CA

# The following krb5.conf variables are only for MIT Kerberos.
    kdc_timesync = 1
    ccache_type = 4
    forwardable = true
    proxiable = true

# The following encryption type specification will be used by MIT Kerberos
# if uncommented.  In general, the defaults in the MIT Kerberos code are
# correct and overriding these specifications only serves to disable new
# encryption types as they are added, creating interoperability problems.
#
# The only time when you might need to uncomment these lines and change
# the enctypes is if you have local software that will break on ticket
# caches containing ticket encryption types it doesn't know about (such as
# old versions of Sun Java).

#   default_tgs_enctypes = des3-hmac-sha1
#   default_tkt_enctypes = des3-hmac-sha1
#   permitted_enctypes = des3-hmac-sha1

# The following libdefaults parameters are only for Heimdal Kerberos.
    fcc-mit-ticketflags = true

[realms]
    HIGHGO.CA = {
        kdc = kdc.highgo.ca
        admin_server = kdc.highgo.ca
    }
    ATHENA.MIT.EDU = {
        kdc = kerberos.mit.edu
        kdc = kerberos-1.mit.edu
        kdc = kerberos-2.mit.edu:88
        admin_server = kerberos.mit.edu
        default_domain = mit.edu
    }
    ZONE.MIT.EDU = {
        kdc = casio.mit.edu
        kdc = seiko.mit.edu
        admin_server = casio.mit.edu
    }
    CSAIL.MIT.EDU = {
        admin_server = kerberos.csail.mit.edu
        default_domain = csail.mit.edu
    }
    IHTFP.ORG = {
        kdc = kerberos.ihtfp.org
        admin_server = kerberos.ihtfp.org
    }
    1TS.ORG = {
        kdc = kerberos.1ts.org
        admin_server = kerberos.1ts.org
    }
    ANDREW.CMU.EDU = {
        admin_server = kerberos.andrew.cmu.edu
        default_domain = andrew.cmu.edu
    }
        CS.CMU.EDU = {
                kdc = kerberos-1.srv.cs.cmu.edu
                kdc = kerberos-2.srv.cs.cmu.edu
                kdc = kerberos-3.srv.cs.cmu.edu
                admin_server = kerberos.cs.cmu.edu
        }
    DEMENTIA.ORG = {
        kdc = kerberos.dementix.org
        kdc = kerberos2.dementix.org
        admin_server = kerberos.dementix.org
    }
    stanford.edu = {
        kdc = krb5auth1.stanford.edu
        kdc = krb5auth2.stanford.edu
        kdc = krb5auth3.stanford.edu
        master_kdc = krb5auth1.stanford.edu
        admin_server = krb5-admin.stanford.edu
        default_domain = stanford.edu
    }
        UTORONTO.CA = {
                kdc = kerberos1.utoronto.ca
                kdc = kerberos2.utoronto.ca
                kdc = kerberos3.utoronto.ca
                admin_server = kerberos1.utoronto.ca
                default_domain = utoronto.ca
    }

[domain_realm]
    .mit.edu = ATHENA.MIT.EDU
    mit.edu = ATHENA.MIT.EDU
    .media.mit.edu = MEDIA-LAB.MIT.EDU
    media.mit.edu = MEDIA-LAB.MIT.EDU
    .csail.mit.edu = CSAIL.MIT.EDU
    csail.mit.edu = CSAIL.MIT.EDU
    .whoi.edu = ATHENA.MIT.EDU
    whoi.edu = ATHENA.MIT.EDU
    .stanford.edu = stanford.edu
    .slac.stanford.edu = SLAC.STANFORD.EDU
        .toronto.edu = UTORONTO.CA
        .utoronto.ca = UTORONTO.CA

created principle

setspn -A postgres/pg.highgo.ca@HIGHGO.CA postgres

after creating principle I have tested it with the following command

c:\Users\administrator\Desktop>kinit postgres
Password for postgres@HIGHGO.CA:

which is working fine.

that's how I have created key tab

ktpass -out pgkt.keytab -princ postgres/pg.highgo.ca@HIGHGI.CA
-mapUser enterprisedb -pass Casper@12 -crypto all -ptype KRB5_NT_PRINCIPAL

and cpoy this file in postgres server and replace it with the file /etc/krb5.keytab with following permission.

chmod 600 /etc/krb5.keytab

and here is my /etc/host entries on linux and windows.

192.168.100.112 pg.highgo.ca
192.168.100.114 kdc.highgo.ca

and I have put an entery in postgress.conf.

krb_server_keyfile = '/etc/krb5.keytab'

and here is pg_hba.conf entries.

 host     all             all              0.0.0.0/0               gss include_realm=0

after that I have tried to access postgress server with the following command .

psql -U postgres -d postgress -h 192.168.100.114

in responce I got the following error on windows.

psql: error: could not connect to server: SSPI continuation error: The specified target is unknown or unreachable
 (80090303)

and seen the logs on posgtes.

2020-08-18 05:49:36.534 PDT [5086] [unknown]@[unknown] LOG:  connection failed during start up processing: user= database=
2020-08-18 05:49:36.541 PDT [5087] postgres@postgres FATAL:  GSSAPI authentication failed for user "postgress"
2020-08-18 05:49:36.541 PDT [5087] postgres@postgres DETAIL:  Connection matched pg_hba.conf line 97: "host     all             all              0.0.0.0/0               gss include_realm=0 "

I have checked the lots of tutorials but did not get a chance to resolve it.

(Note : same commands works fine with MD5 authentication )

thanks advance.

shanjay
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  • would you mind editing your post for accuracy? I see some instances where you spell `postgres` as `postgress`, and I'm not sure if the database is complaining about your spelling or actually failing to authenticate. I also see `HIGHGO` spelled as `HIGHGI` – richyen Aug 18 '20 at 21:59
  • I have edit the post thanks. – shanjay Aug 18 '20 at 22:51

2 Answers2

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This is a common issue experienced in earlier releases of Postgres and EDB Postgres v. 12, since GSSAPI encryption has been added, but a bug existed. The bug has been fixed in commit 79e594cf04754d55196d2ce54fc869ccad5fa9c3, released in v. 12.3. If you can upgrade to v. 12.3, you may be able to work around this issue.

If you require use of an older client for some reason, please be sure to set gssencmode=disable in your connection string or set PGGSSAPIENCMODE=disable in your environment.

richyen
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  • you are talking about the Postgres 12.3 or EDB Postgres 12.3, I am asking it because I am already using EDB Postgres 12.3 in my Linux VM. – shanjay Aug 18 '20 at 20:49
  • And also there one more thing, I have tried authentication with GSSAPI while my KDC server was linux (Ubuntu 18.xx) in that case I got connected successfully. But I am not able to auth with the GSSAPI in case of Active Directory KDC. and also the version of the EDB Postgres is same 12.xx. – shanjay Aug 18 '20 at 21:25
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I have resolve it with the help of my Colleagues this is done on the fresh environment. Steps:

(Note : there no need of kerbrose client on the PG-Server machien (mine is Ubuntu 18.xx))

  1. Active Directory is setup on Windows 2016 MYDOMAIN.CA and EPAS Server 11 or 12 is installed on both machines. Active Directory Setup Link
  2. Make sure time zone and time on both machines are the same.

  • /etc/hosts

  • IP of Windows machine is 192.168.100.19 and that of Linux is 192.168.100.17.

    Also assuming that Windows machine name is “client” so its full name is “client.mydomain.ca”.

    Enter the following in /etc/hosts on linux (Comment out other entries)

192.168.100.19 client.mydomain.ca client
192.168.100.17 pg.mydomain.ca  pg
  • Enter the following in c:\Windows\System32\Drivers\etc\hosts on Windows
192.168.100.19 client.mydomain.ca
192.168.100.17 pg.mydomain.ca

Verify the host are communicating with the ping.

Create User in Active Directory (Windows Machine)

  • Assuming you are logged in as Administrator, In “Server Manager” click “Tools” and select “Active Directory Users and Computers”

  • Under your domain “MYDOMAIN.CA” select users to show all users

    Right Click Administrator and select “Copy”

  • Enter “pguser” in “First Name” and “User logon name” fields. Click Next. Domain “MYDOMAIN.CA” should be shown in combo box against “User logon name”

  • Enter password for user and uncheck “Password never expires” checkbox. -> Click Next -> Click Finish. User account is created.

  • Double click this user in Users list OR right click this user and select Properties.

  • In Account Tab, under Account options check “This account supports kerberos AES 256 bit encryption” checkbox and click OK.

  • Log off Windows and login using “pguser” user.

Create Keytab

  • Windows Machine: Open Command Prompt as Administrator and enter the following command to create Keytab.
  ktpass -out krb5.keytab -mapUser pguser@MYDOMAIN.CA +rndPass -mapOp set +DumpSalt -crypto AES256-SHA1 -ptype KRB5_NT_PRINCIPAL -princ POSTGRES/pg.mydomain.ca@MYDOMAIN.CA

  • Note that this command should not give any error or warning. If you see an error or warning and the keytab is generated, this keytab will not work.

  • If the keytab is created successfully, you can check by opening pguser user properties, Account tab that “user logon name” is changed to postgres/pg.mydomain.ca.

  • Now you have created keytab file “krb5.keytab”.

  • Linux Machine: Copy this file to Linux machine as “/etc/krb5.keytab”.

//Suppose file is on Desktop of user edb on Linux machine. su to become root.

cd /etc/

cp /home/edb/Desktop/krb5.keytab .

chown enterprisedb:enterprisedb krb5.keytab

chmod 600 krb5.keytab

  • Open postgresql.conf file and set krb_server_keyfile to “/etc/krb5.keytab” (uncomment this line as it is commented out by default)

krb_server_keyfile = '/etc/krb5.keytab'

  • Open pg_hba.conf file and add the following line (Comment out all other lines except “local all enterprisedb trust/md5” so any remote user can only connect using gss)

local all enterprisedb trust

host all all 0.0.0.0/0 gss

  • Restart server.
  • Create user “pguser@MYDOMAIN.CA”.

CREATE USER "pg1postgres@HIGHGO.CA" SUPERUSER CREATEDB CREATEROLE;

PSQL command from Windows

Issue this command to connect to D on Linux

psql -U pgUSER@MYDOMAIN.CA -d edb -h pg.mydomain.ca

Regards,

shanjay
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