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Changes for page KerberosAndLDAP

Last modified by Sirius Rayner-Karlsson on 2024/05/09 10:54
From version 31.1
edited by Sirius Rayner-Karlsson
on 2024/05/09 05:52
Change comment: There is no comment for this version
To version 14.1
edited by Sirius Rayner-Karlsson
on 2024/05/01 17:15
Change comment: There is no comment for this version

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1 -(% data-xwiki-non-generated-content="java.util.List" %)
2 -(((
3 -" data-xwiki-parameter-name="title" class="xwiki-metadata-container">**Contents**
4 -)))
5 -
6 -(% data-xwiki-non-generated-content="java.util.List" %)
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8 -" class="xwiki-metadata-container">
9 -
10 -{{toc/}}
11 -)))
12 -
13 -{{box cssClass="floatinginfobox" title="**Contents**"}}
14 -{{toc/}}
15 -{{/box}}
16 -
17 17  = Debian =
18 18  
19 -The guide I followed was https://wiki.debian.org/LDAP/OpenLDAPSetup#Kerberos which while it worked required some minor tweaks. I obtained edit privileges for the Debian Wiki and updated the guide with the fixes that I found. I however have a Synology NAS and that can run an LDAP Server. So this guide differs from the upstream Debian Guide.
3 +The guide I followed was [[https:~~/~~/wiki.debian.org/LDAP/OpenLDAPSetup#Kerberos>>https://wiki.debian.org/LDAP/OpenLDAPSetup#Kerberos]] which while it worked required some minor tweaks. I obtained edit privileges for the Debian Wiki and updated the guide with the fixes that I found. I however have a Synology NAS and that can run an LDAP Server. So this guide differs a little from the upstream Debian Guide.
20 20  
21 -Assumption is that you have installed the LDAP Server package on your NAS and gone through initial configuration steps, so it has a domain, there is a DN you can bind as and so forth. It is also assumed you have a Debian system (12.5 or later, though this guide should work with 11.x and likely 10.x as well) that will become your KDC and KAdmin server.
22 22  
23 -Recommendation is that you create actual ##.ldif## files rather than use here-documents as used in this guide. It is far easier to make adjustments to things if you have a file to edit rather than having to type it all out again or paste it and then have to try and make edits to it without making mistakes.
6 +First, install the packages containing the LDAP-enabled Kerberos servers ([[krb5-kdc-ldap>>url:https://packages.debian.org/krb5-kdc-ldap]] and [[krb5-admin-server>>url:https://packages.debian.org/krb5-admin-server]]) and the [[schema2ldif>>url:https://packages.debian.org/schema2ldif]] tool:
24 24  
25 -**The guide is for illustration. Expectation is that you do not follow it verbatim but adapt it to your needs.**
26 -
27 -
28 -===== Install packages: =====
29 -
30 -(% class="wikigeneratedid" %)
31 -The packages you need are [[krb5-kdc-ldap>>url:https://packages.debian.org/krb5-kdc-ldap]], [[krb5-admin-server>>url:https://packages.debian.org/krb5-admin-server]] for the actual KDC and [[schema2ldif>>url:https://packages.debian.org/schema2ldif]]  plus [[slapd>>https://packages.debian.org/search?keywords=slapd]] for adding the schema and ##slappasswd##. They are to be installed on your designated Debian host.
32 -
33 -(% style="color:#400" %)
34 34  ##{{{$ sudo apt install krb5-kdc-ldap krb5-admin-server schema2ldif}}}##
35 35  
36 36  
37 -===== Load ##kerberos LDAP## schema: =====
11 +Then load the ##kerberos## schema:
38 38  
39 -Now you need to load the kerberos schema into the LDAP server on the Synology. And here you need to use the ##cn=config## DN.
13 +##{{{$ zcat /usr/share/doc/krb5-kdc-ldap/kerberos.openldap.ldif.gz | ldapadd -H ldap:~/~/nas.fqdn/ -D uid=root,cn=users,dc=example,dc=com}}}##
40 40  
41 -(% style="color:#400" %)
42 -##{{{$ zcat /usr/share/doc/krb5-kdc-ldap/kerberos.openldap.ldif.gz | ldapadd -H ldaps://nas.example.com/ -D cn=config -W}}}##
43 -##{{{Enter LDAP Password:}}}##
15 +##{{{Password:}}}##
16 +
44 44  ##{{{adding new entry "cn=kerberos,cn=schema,cn=config"}}}##
45 -##{{{$}}}##
46 46  
47 -
48 -===== Create Index on krbPrincipalName: =====
49 -
50 -Having an index on the ##krbPrincipalName## improves performance and also suppresses some log messages if ##slapd## is configured to log more than default for the database(s) where you intend to store Kerberos data. As this is OpenLDAP on the Synology, it does not use ##mdb## format, it uses ##bdb##. If you install ##slapd## on Debian, it uses ##mdb## format. It is different database format, but the principle is the same. Again, as you are modifying config, the DN is ##cn=config##. Interestingly, it is still the main password you set for the Synology LDAP server.
51 -
52 -(% style="color:#400" %)
53 -##{{{$ ldapmodify -H ldaps://nas.example.com/ -D cn=config -W <<EOF}}}##
54 -##{{{dn: olcDatabase={1}bdb,cn=config}}}##
55 -##{{{add: olcDbIndex}}}##
56 -##{{{olcDbIndex: krbPrincipalName eq,pres,sub}}}##
57 -##{{{EOF}}}##
58 -##{{{Enter LDAP Password:}}}##
59 -##{{{modifying entry "olcDatabase={1}bdb,cn=config"}}}##
60 60  ##{{{$}}}##
61 61  
62 62  
63 -===== Create principals kadmin and kdc: =====
22 +Having an index on the ##krbPrincipalName## improves performance and also suppresses some log messages if ##slapd## is configured to log more than default for the database(s) where you intend to store Kerberos data. As this is OpenLDAP on the Synology, it does not use mdb format, it uses bdb:
64 64  
65 -Next, you create and configure two entries which will be used by the Kerberos servers to connect to OpenLDAP. As you will not run the Kerberos KDC and Admin Server on the same host as OpenLDAP, these steps are required. In order to keep things nicely separated, everything will be created under a separate ##organizationalUnit##. I diverge from the official Debian guide here as I do not agree with the DN they use. I also had to make changes to the DNs of ##kdc## and ##kadmin## due to ##pwdPolicy## applied by Synology to their LDAP server. The official guide will have you use placeholder passwords and that does not work with the Synology LDAP server. You need to generate them upfront with ##slappasswd -h {SSHA}##.
66 -
67 -(% style="color:#400" %)
68 -##{{{$ ldapadd -H ldap://nas.example.com/ -D uid=root,cn=users,dc=example,dc=com -W <<EOF}}}##
69 -##{{{dn: ou=kerberos,dc=example,dc=com}}}##
70 -##{{{objectClass: organizationalUnit}}}##
71 -##{{{objectClass: top}}}##
72 -##{{{ou: kerberos}}}##
73 -
74 -(% style="color:#400" %)
75 -##{{{dn: cn=kdc,ou=kerberos,dc=example,dc=com}}}##
76 -##{{{cn: kdc}}}##
77 -##{{{sn: kdc}}}##
78 -##{{{objectClass: person}}}##
79 -##{{{objectClass: pwdPolicy}}}##
80 -##{{{pwdAttribute: userPassword}}}##
81 -##{{{pwdMinLength: 8}}}##
82 -##{{{pwdCheckQuality: 2}}}##
83 -##{{{pwdPolicySubentry: cn=kdc,ou=kerberos,dc=example,dc=com}}}##
84 -##{{{userPassword: {SSHA}<password-hash>}}}##
85 -##{{{description: Kerberos KDC Account}}}##
86 -
87 -(% style="color:#400" %)
88 -##{{{dn: cn=kadmin,ou=kerberos,dc=example,dc=com}}}##
89 -##{{{cn: kadmin}}}##
90 -##{{{sn: kadmin}}}##
91 -##{{{objectClass: person}}}##
92 -##{{{objectClass: pwdPolicy}}}##
93 -##{{{pwdAttribute: userPassword}}}##
94 -##{{{pwdMinLength: 8}}}##
95 -##{{{pwdCheckQuality: 2}}}##
96 -##{{{pwdPolicySubentry: cn=kadmin,ou=kerberos,dc=example,dc=com}}}##
97 -##{{{userPassword: {SSHA}<password-hash>}}}##
98 -##{{{description: Kerberos KDC Account}}}##
99 -##{{{EOF}}}##
100 -##{{{Enter LDAP Password:}}}##
101 -
102 -(% style="color:#400" %)
103 -##{{{adding new entry "ou=kerberos,dc=example,dc=com"}}}##
104 -
105 -(% style="color:#400" %)
106 -##{{{adding new entry "cn=kdc,ou=kerberos,dc=example,dc=com"}}}##
107 -
108 -(% style="color:#400" %)
109 -##{{{adding new entry "cn=kadmin,ou=kerberos,dc=example,dc=com"}}}##
110 -
111 -
112 -Synology LDAP server did not like adding users with placeholder passwords, because Synology puts in place password policies. Hence changing this to a ##cn## instead of a ##uid##. It seems to have worked out fine as my KDC is fully functioning.
113 -
114 -
115 -===== Grant kdc and kadmin permissions: =====
116 -
117 -This switches back to the ##cn=config## DN as you are changing the permissions.
118 -
119 -$ ldapmodify -H ldaps:~/~/ds723.trudheim.com -W -D cn=config <<EOF
120 -
24 +##{{{$ sudo ldapmodify -H ldap://nas.fqhn <<EOF
121 121  dn: olcDatabase={1}bdb,cn=config
122 -add: olcAccess
123 -olcAccess: {0}to attrs=krbPrincipalKey
124 - by anonymous auth
125 - by dn.exact="cn=kdc,ou=kerberos,dc=trudheim,dc=com" write
126 - by dn.exact="cn=kadmin,ou=kerberos,dc=trudheim,dc=com" write
127 - by self write
128 - by * none
129 --
130 -add: olcAccess
131 -olcAccess: {1}to dn.subtree="cn=krbContainer,ou=kerberos,dc=example,dc=com"
132 - by dn.exact="cn=kdc,ou=kerberos,dc=trudheim,dc=com" write
133 - by dn.exact="cn=kadmin,ou=kerberos,dc=trudheim,dc=com" write
134 - by * none
135 -
26 +add: olcDbIndex
27 +olcDbIndex: krbPrincipalName eq,pres,sub
136 136  EOF
29 +Password:
137 137  
138 -Enter LDAP Password:
139 139  modifying entry "olcDatabase={1}bdb,cn=config"
32 +$
33 +}}}##
140 140  
141 -$
142 142  
143 143  
144 -Note that we now reference our kdc and kadmin accounts and we grant them permission to the krbContainer which will house all our kerberos principals. Give both of them write access, because we do want to have the ability to track last login and lock accounts if there are login failures. We like security.
37 +Next, you need to create and configure two entries which will be used by the Kerberos servers to connect to OpenLDAP. If you are running Kerberos and OpenLDAP on the same system, these steps are optional, but recommended. In order to keep things nicely separated, everything will be created under a separate ##organizationalUnit##. Note that a simple bind (##-x -D##) is used instead of an ##EXTERNAL## bind since write access to the dc=example,dc=com DIT is necessary:
145 145  
146 146  
147 -===== Create your krb5.conf: =====
40 +{{{# ldapadd -x -D cn=admin,dc=example,dc=com -W <<EOF
41 +dn: ou=Services,dc=example,dc=com
42 +objectClass: organizationalUnit
43 +objectClass: top
44 +ou: Services
148 148  
149 -Over to adjusting /etc/krb5.conf so that it will point to the right thing later. It should look something like this:
46 +dn: ou=kerberos,ou=Services,dc=example,dc=com
47 +objectClass: organizationalUnit
48 +objectClass: top
49 +ou: kerberos
150 150  
51 +dn: uid=kdc,ou=kerberos,ou=Services,dc=example,dc=com
52 +uid: kdc
53 +objectClass: account
54 +objectClass: simpleSecurityObject
55 +userPassword: {CRYPT}x
56 +description: Kerberos KDC Account
151 151  
152 -{{{[libdefaults]
153 - default_realm = EXAMPLE.COM
154 - dns_lookup_realm = false
155 - dns_lookup_kdc = false
156 - ticket_lifetime = 24h
157 - forwardable = true
158 - proxiable = true
159 - rdns = false
58 +dn: uid=kadmin,ou=kerberos,ou=Services,dc=example,dc=com
59 +uid: kadmin
60 +objectClass: account
61 +objectClass: simpleSecurityObject
62 +userPassword: {CRYPT}x
63 +description: Kerberos Admin Server Account
64 +EOF
65 +Enter LDAP Password: SECRET
160 160  
161 -[realms]
162 - EXAMPLE.COM = {
163 - kdc = debian.example.com
164 - admin_server = debian.example.com
165 - default_domain = example.com
166 - }
167 - [domain_realm]
168 - .example.com = EXAMPLE.COM
169 - example.com = EXAMPLE.COM}}}
67 +adding new entry "ou=Services,dc=example,dc=com"
170 170  
171 -Make sure your designated debian server have ports 88, 464 and 749 open, both for TCP and UDP, in its firewall. 88 is for the kdc, 464 and 749 is for kadmin.
69 +adding new entry "ou=kerberos,ou=Services,dc=example,dc=com"
172 172  
173 -Next, we need to write up /etc/krb5kdc/kdc.conf. Something like this should work
71 +adding new entry "uid=kdc,ou=kerberos,ou=Services,dc=example,dc=com"
174 174  
73 +adding new entry "uid=kadmin,ou=kerberos,ou=Services,dc=example,dc=com"}}}
175 175  
176 -[libdefaults]
177 177  
178 -[realms]
179 - TRUDHEIM.COM = {
180 - database_module = openldap_ldapconf
181 - max_life = 7d
182 - max_renewable_life = 6d
183 - }
184 -
185 -[dbdefaults]
186 - ldap_kerberos_container_dn = cn=krbContainer,ou=kerberos,dc=trudheim,dc=com
187 -
188 -[dbmodules]
189 - openldap_ldapconf = {
190 - db_library = kldap
191 - disable_last_success = false
192 - disable_lockout = false
193 - ldap_conns_per_server = 5
194 - ldap_servers = ldaps:~/~/ds723.trudheim.com
195 - ldap_kdc_dn = "cn=kdc,ou=kerberos,dc=trudheim,dc=com"
196 - ldap_kadmind_dn = "cn=kadmin,ou=kerberos,dc=trudheim,dc=com"
197 - ldap_service_password_file = /etc/krb5kdc/service.keyfile
198 - }
199 -
200 -
201 -Then you need to create ##/etc/krb5kdc/kadm5.acl and put in it##
202 -
203 -
204 -##*/admin@EXAMPLE.COM *##
205 -
206 -
207 -so that administrator principals can run kadmin. Now we are ready to create the domain. And that we do with
208 -
209 -
210 -#
211 -
212 -kdb5_ldap_util -D uid=root,cn=users,dc=trudheim,dc=com -H ldaps:~/~/ds723.trudheim.com -r TRUDHEIM.COM create -subtrees dc=trudheim,dc=com -maxtktlife '7 Days' -maxrenewlife '6 Days' -s
213 -Password for "uid=root,cn=users,dc=trudheim,dc=com":
214 -Initializing database for realm 'TRUDHEIM.COM'
215 -You will be prompted for the database Master Password.
216 -It is important that you NOT FORGET this password.
217 -Enter KDC database master key:
218 -Re-enter KDC database master key to verify:
219 -
220 -kdb5_ldap_util -D uid=root,cn=users,dc=trudheim,dc=com -H ldaps:~/~/ds723.trudheim.com stashsrvpw -f /etc/krb5kdc/service.keyfile cn=kdc,ou=kerberos,dc=trudheim,dc=com
221 -Password for "uid=root,cn=users,dc=trudheim,dc=com":
222 -Password for "cn=kdc,ou=kerberos,dc=trudheim,dc=com":
223 -Re-enter password for "cn=kdc,ou=kerberos,dc=trudheim,dc=com":
224 -
225 -kdb5_ldap_util -D uid=root,cn=users,dc=trudheim,dc=com -H ldaps:~/~/ds723.trudheim.com stashsrvpw -f /etc/krb5kdc/service.keyfile cn=kadmin,ou=kerberos,dc=trudheim,dc=com
226 -Password for "uid=root,cn=users,dc=trudheim,dc=com":
227 -Password for "cn=kadmin,ou=kerberos,dc=trudheim,dc=com":
228 -Re-enter password for "cn=kadmin,ou=kerberos,dc=trudheim,dc=com":
229 -
230 230