Skip to Content
0 Votes

Changes for page KerberosAndLDAP

Last modified by Sirius Rayner-Karlsson on 2024/05/09 10:54
From version 37.1
edited by Sirius Rayner-Karlsson
on 2024/05/09 10:54
Change comment: There is no comment for this version
To version 32.1
edited by Sirius Rayner-Karlsson
on 2024/05/09 05:53
Change comment: There is no comment for this version

Summary

Details

Page properties
Content
... ... @@ -13,7 +13,7 @@
13 13  **The guide is for illustration. Expectation is that you do not follow it verbatim but adapt it to your needs.**
14 14  
15 15  
16 -=== Install packages ===
16 +===== Install packages: =====
17 17  
18 18  (% class="wikigeneratedid" %)
19 19  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.
... ... @@ -22,178 +22,156 @@
22 22  ##{{{$ sudo apt install krb5-kdc-ldap krb5-admin-server schema2ldif}}}##
23 23  
24 24  
25 -=== Load kerberos LDAP schema ===
25 +===== Load ##kerberos LDAP## schema: =====
26 26  
27 -Now you need to load the kerberos schema into the LDAP server on the Synology. Use the ##cn=config## DN.
27 +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.
28 28  
29 29  (% style="color:#400" %)
30 -##{{{$ zcat /usr/share/doc/krb5-kdc-ldap/kerberos.openldap.ldif.gz | ldapadd -H ldaps://nas.example.com/ -D cn=config -W Enter LDAP Password: adding new entry "cn=kerberos,cn=schema,cn=config" $}}}##
30 +##{{{$ zcat /usr/share/doc/krb5-kdc-ldap/kerberos.openldap.ldif.gz | ldapadd -H ldaps://nas.example.com/ -D cn=config -W}}}##
31 +##{{{Enter LDAP Password:}}}##
32 +##{{{adding new entry "cn=kerberos,cn=schema,cn=config"}}}##
33 +##{{{$}}}##
31 31  
32 32  
33 -=== Create Index on krbPrincipalName ===
36 +===== Create Index on krbPrincipalName: =====
34 34  
35 -Having an index on the ##krbPrincipalName## improves performance. Synology OpenLDAP does not use ##mdb## format, it uses ##bdb##. Debian ##slapd## uses ##mdb## format. It is different database format, but the principle is the same. Again, as you are modifying config, the DN is ##cn=config##. Use the main password you set for the Synology LDAP server. Create a file ##step1.ldif## with the following content:
38 +Having an index on the ##krbPrincipalName## improves performance and also suppresses some log messages if ##slapd## is configured to log more than default for the database(s) where you intend to store Kerberos data. As this is OpenLDAP on the Synology, it does not use ##mdb## format, it uses ##bdb##. If you install ##slapd## on Debian, it uses ##mdb## format. It is different database format, but the principle is the same. Again, as you are modifying config, the DN is ##cn=config##. Interestingly, it is still the main password you set for the Synology LDAP server.
36 36  
37 37  (% style="color:#400" %)
38 -##{{{
39 -dn: olcDatabase={1}bdb,cn=config
40 -add: olcDbIndex
41 -olcDbIndex: krbPrincipalName eq,pres,sub}}}##
41 +##{{{$ ldapmodify -H ldaps://nas.example.com/ -D cn=config -W <<EOF}}}##
42 +##{{{dn: olcDatabase={1}bdb,cn=config}}}##
43 +##{{{add: olcDbIndex}}}##
44 +##{{{olcDbIndex: krbPrincipalName eq,pres,sub}}}##
45 +##{{{EOF}}}##
46 +##{{{Enter LDAP Password:}}}##
47 +##{{{modifying entry "olcDatabase={1}bdb,cn=config"}}}##
48 +##{{{$}}}##
42 42  
43 43  
44 -and apply it with
51 +===== Create principals kadmin and kdc: =====
45 45  
53 +Next, you create and configure two entries which will be used by the Kerberos servers to connect to OpenLDAP. As you will not run the Kerberos KDC and Admin Server on the same host as OpenLDAP, these steps are required. In order to keep things nicely separated, everything will be created under a separate ##organizationalUnit##. I diverge from the official Debian guide here as I do not agree with the DN they use. I also had to make changes to the DNs of ##kdc## and ##kadmin## due to ##pwdPolicy## applied by Synology to their LDAP server. The official guide will have you use placeholder passwords and that does not work with the Synology LDAP server. You need to generate them upfront with ##slappasswd -h {SSHA}##.
54 +
46 46  (% style="color:#400" %)
47 -##{{{$ ldapmodify -H ldaps://nas.example.com/ -D cn=config -W -f step1.ldif
48 -Enter LDAP Password:
56 +##{{{$ ldapadd -H ldap://nas.example.com/ -D uid=root,cn=users,dc=example,dc=com -W <<EOF}}}##
57 +##{{{dn: ou=kerberos,dc=example,dc=com}}}##
58 +##{{{objectClass: organizationalUnit}}}##
59 +##{{{objectClass: top}}}##
60 +##{{{ou: kerberos}}}##
49 49  
50 -modifying entry "olcDatabase={1}bdb,cn=config"
62 +(% style="color:#400" %)
63 +##{{{dn: cn=kdc,ou=kerberos,dc=example,dc=com}}}##
64 +##{{{cn: kdc}}}##
65 +##{{{sn: kdc}}}##
66 +##{{{objectClass: person}}}##
67 +##{{{objectClass: pwdPolicy}}}##
68 +##{{{pwdAttribute: userPassword}}}##
69 +##{{{pwdMinLength: 8}}}##
70 +##{{{pwdCheckQuality: 2}}}##
71 +##{{{pwdPolicySubentry: cn=kdc,ou=kerberos,dc=example,dc=com}}}##
72 +##{{{userPassword: {SSHA}<password-hash>}}}##
73 +##{{{description: Kerberos KDC Account}}}##
51 51  
52 -$ }}}##
75 +(% style="color:#400" %)
76 +##{{{dn: cn=kadmin,ou=kerberos,dc=example,dc=com}}}##
77 +##{{{cn: kadmin}}}##
78 +##{{{sn: kadmin}}}##
79 +##{{{objectClass: person}}}##
80 +##{{{objectClass: pwdPolicy}}}##
81 +##{{{pwdAttribute: userPassword}}}##
82 +##{{{pwdMinLength: 8}}}##
83 +##{{{pwdCheckQuality: 2}}}##
84 +##{{{pwdPolicySubentry: cn=kadmin,ou=kerberos,dc=example,dc=com}}}##
85 +##{{{userPassword: {SSHA}<password-hash>}}}##
86 +##{{{description: Kerberos KDC Account}}}##
87 +##{{{EOF}}}##
88 +##{{{Enter LDAP Password:}}}##
53 53  
90 +(% style="color:#400" %)
91 +##{{{adding new entry "ou=kerberos,dc=example,dc=com"}}}##
54 54  
55 -=== Create principals kadmin and kdc ===
56 -
57 -Next, you create and configure two entries which will be used by the Kerberos servers to connect to OpenLDAP. Not running the Kerberos KDC and Admin Server on the same host as OpenLDAP, these steps are required. Keeping things confined, everything will be created under a separate ##organizationalUnit##. My guide differs from the official Debian guide here. Due to Synology OpenLDAP having a strict password policy, it was necessary to adjust the DNs of ##kdc## and ##kadmin##. The official guide use placeholder passwords which does not work with the Synology LDAP server.
58 -Generate the passwords upfront with ##slappasswd -h {SSHA}##. Then create a file ##step2.ldif## with the following content:
59 -
60 60  (% style="color:#400" %)
61 -##{{{
62 -dn: ou=kerberos,dc=example,dc=com
63 -objectClass: organizationalUnit
64 -objectClass: top
65 -ou: kerberos
94 +##{{{adding new entry "cn=kdc,ou=kerberos,dc=example,dc=com"}}}##
66 66  
67 -dn: cn=kdc,ou=kerberos,dc=example,dc=com
68 -cn: kdc
69 -sn: kdc
70 -objectClass: person
71 -objectClass: pwdPolicy
72 -pwdAttribute: userPassword
73 -pwdMinLength: 8
74 -pwdCheckQuality: 2
75 -pwdPolicySubentry: cn=kdc,ou=kerberos,dc=example,dc=com
76 -userPassword: {SSHA}<password-hash>
77 -description: Kerberos KDC Account
78 -
79 -dn: cn=kadmin,ou=kerberos,dc=example,dc=com
80 -cn: kadmin
81 -sn: kadmin
82 -objectClass: person
83 -objectClass: pwdPolicy
84 -pwdAttribute: userPassword
85 -pwdMinLength: 8
86 -pwdCheckQuality: 2
87 -pwdPolicySubentry: cn=kadmin,ou=kerberos,dc=example,dc=com
88 -userPassword: {SSHA}<password-hash>
89 -description: Kerberos KDC Account}}}##
90 -
91 -
92 -Apply it with
93 -
94 94  (% style="color:#400" %)
95 -##{{{$ ldapadd -H ldaps://nas.example.com/ -D uid=root,cn=users,dc=example,dc=com -W -f step2.ldif
96 -Enter LDAP Password:
97 +##{{{adding new entry "cn=kadmin,ou=kerberos,dc=example,dc=com"}}}##
97 97  
98 -adding new entry "ou=kerberos,dc=example,dc=com"
99 99  
100 -adding new entry "cn=kdc,ou=kerberos,dc=example,dc=com"
100 +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.
101 101  
102 -adding new entry "cn=kadmin,ou=kerberos,dc=example,dc=com"
103 103  
104 -$ }}}##
103 +===== Grant kdc and kadmin permissions: =====
105 105  
105 +This switches back to the ##cn=config## DN as you are changing the permissions.
106 106  
107 -A small note on this section:
108 -The ##objectClass: pwdPolicy## must be added to a, to LDAP, physical thing. ##objectClass: person## fits the criteria, but can not have ##uid##. So to make it work, the ##uid## is replaced with ##sn## and ##cn## (yes, both are needed). Then you can set the other four attributes and add the hashed password you got from ##slappasswd##.
107 +$ ldapmodify -H ldaps:~/~/ds723.trudheim.com -W -D cn=config <<EOF
109 109  
110 -
111 -=== Grant kdc and kadmin permissions ===
112 -
113 -This switches back to the ##cn=config## DN as you are changing the permissions. 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 too many login failures. We like security.
114 -
115 -Create ##step3.ldif## with the following content:
116 -
117 -(% style="color:#400" %)
118 -##{{{
119 119  dn: olcDatabase={1}bdb,cn=config
120 120  add: olcAccess
121 121  olcAccess: {0}to attrs=krbPrincipalKey
122 122   by anonymous auth
123 - by dn.exact="cn=kdc,ou=kerberos,dc=example,dc=com" write
124 - by dn.exact="cn=kadmin,ou=kerberos,dc=example,dc=com" write
113 + by dn.exact="cn=kdc,ou=kerberos,dc=trudheim,dc=com" write
114 + by dn.exact="cn=kadmin,ou=kerberos,dc=trudheim,dc=com" write
125 125   by self write
126 126   by * none
127 127  -
128 128  add: olcAccess
129 129  olcAccess: {1}to dn.subtree="cn=krbContainer,ou=kerberos,dc=example,dc=com"
130 - by dn.exact="cn=kdc,ou=kerberos,dc=example,dc=com" write
131 - by dn.exact="cn=kadmin,ou=kerberos,dc=example,dc=com" write
120 + by dn.exact="cn=kdc,ou=kerberos,dc=trudheim,dc=com" write
121 + by dn.exact="cn=kadmin,ou=kerberos,dc=trudheim,dc=com" write
132 132   by * none
133 -}}}##
134 134  
124 +EOF
135 135  
136 -**Do not get the domain part above wrong. If you do, you may not be able to use ##kadmin## or ##kinit## and fixing the permissions without breaking something else is a nervous task. Trust me on this (as I screwed them up).**
137 -
138 -Apply it with
139 -
140 -(% style="color:#400" %)
141 -##{{{
142 -$ ldapmodify -H ldaps://nas.example.com -W -D cn=config -f step3.ldif
143 143  Enter LDAP Password:
144 -
145 145  modifying entry "olcDatabase={1}bdb,cn=config"
146 146  
147 -$ }}}##
129 +$
148 148  
149 149  
150 -=== Create krb5.conf ===
132 +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.
151 151  
152 -Next we create (or modify) ##/etc/krb5.conf## so that it will point to the right thing later. It should look something like this:
153 153  
154 -(% style="color:#400" %)
155 -##{{{
156 -[libdefaults]
157 - default_realm = EXAMPLE.COM
158 - dns_lookup_realm = false
159 - dns_lookup_kdc = false
160 - ticket_lifetime = 24h
161 - forwardable = true
162 - proxiable = true
163 - rdns = false
135 +===== Create your krb5.conf: =====
164 164  
165 -[realms]
166 - EXAMPLE.COM = {
167 - kdc = debian.example.com
168 - admin_server = debian.example.com
169 - default_domain = example.com
170 - }
171 -[domain_realm]
172 - .example.com = EXAMPLE.COM
173 - example.com = EXAMPLE.COM
174 -}}}##
137 +Over to adjusting /etc/krb5.conf so that it will point to the right thing later. It should look something like this:
175 175  
176 176  
177 -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.
140 +{{{[libdefaults]
141 + default_realm = EXAMPLE.COM
142 + dns_lookup_realm = false
143 + dns_lookup_kdc = false
144 + ticket_lifetime = 24h
145 + forwardable = true
146 + proxiable = true
147 + rdns = false
178 178  
149 +[realms]
150 + EXAMPLE.COM = {
151 + kdc = debian.example.com
152 + admin_server = debian.example.com
153 + default_domain = example.com
154 + }
155 + [domain_realm]
156 + .example.com = EXAMPLE.COM
157 + example.com = EXAMPLE.COM}}}
179 179  
180 -=== Create kdc.conf ===
159 +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.
181 181  
182 -Now we do /etc/krb5kdc/kdc.conf. Something like this should work
161 +Next, we need to write up /etc/krb5kdc/kdc.conf. Something like this should work
183 183  
184 -(% style="color:#400" %)
185 -##{{{
163 +
186 186  [libdefaults]
187 187  
188 188  [realms]
189 - EXAMPLE.COM = {
190 - database_module = openldap_ldapconf
191 - max_life = 7d
192 - max_renewable_life = 6d
167 + TRUDHEIM.COM = {
168 + database_module = openldap_ldapconf
169 + max_life = 7d
170 + max_renewable_life = 6d
193 193   }
194 194  
195 195  [dbdefaults]
196 - ldap_kerberos_container_dn = cn=krbContainer,ou=kerberos,dc=example,dc=com
174 + ldap_kerberos_container_dn = cn=krbContainer,ou=kerberos,dc=trudheim,dc=com
197 197  
198 198  [dbmodules]
199 199   openldap_ldapconf = {
... ... @@ -201,142 +201,39 @@
201 201   disable_last_success = false
202 202   disable_lockout = false
203 203   ldap_conns_per_server = 5
204 - ldap_servers = ldaps:~/~/nas.example.com
205 - ldap_kdc_dn = "cn=kdc,ou=kerberos,dc=example,dc=com"
206 - ldap_kadmind_dn = "cn=kadmin,ou=kerberos,dc=example,dc=com"
182 + ldap_servers = ldaps:~/~/ds723.trudheim.com
183 + ldap_kdc_dn = "cn=kdc,ou=kerberos,dc=trudheim,dc=com"
184 + ldap_kadmind_dn = "cn=kadmin,ou=kerberos,dc=trudheim,dc=com"
207 207   ldap_service_password_file = /etc/krb5kdc/service.keyfile
208 208   }
209 -}}}##
210 210  
211 211  
212 -=== Create kadm5.acl ===
189 +Then you need to create ##/etc/krb5kdc/kadm5.acl and put in it##
213 213  
214 -Create ##/etc/krb5kdc/kadm5.acl with the following content so that kerberos administrator principals can run ##kadmin##
215 215  
216 -(% style="color:#400" %)
217 -##{{{
218 -*/admin@EXAMPLE.COM *
219 -}}}##
192 +##*/admin@EXAMPLE.COM *##
220 220  
221 221  
222 -=== Create the kerberos domain ===
195 +so that administrator principals can run kadmin. Now we are ready to create the domain. And that we do with
223 223  
224 -Now we are ready to create the domain. And that we do with ##kdb5_ldap_util## as ##root##. Note that this commandline is deceptive and you need all of it.
225 225  
226 -(% style="color:#400" %)
227 -##{{{
228 -# kdb5_ldap_util -D uid=root,cn=users,dc=example,dc=com -H ldaps://nas.example.com -r EXAMPLE.COM create -subtrees dc=example,dc=com -maxtktlife '7 Days' -maxrenewlife '6 Days' -s
198 +#
199 +
200 +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
229 229  Password for "uid=root,cn=users,dc=trudheim,dc=com":
230 -Initializing database for realm 'EXAMPLE.COM'
202 +Initializing database for realm 'TRUDHEIM.COM'
231 231  You will be prompted for the database Master Password.
232 232  It is important that you NOT FORGET this password.
233 233  Enter KDC database master key:
234 234  Re-enter KDC database master key to verify:
235 -# }}}##
236 236  
208 +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
209 +Password for "uid=root,cn=users,dc=trudheim,dc=com":
210 +Password for "cn=kdc,ou=kerberos,dc=trudheim,dc=com":
211 +Re-enter password for "cn=kdc,ou=kerberos,dc=trudheim,dc=com":
237 237  
238 -=== Stash the passwords for ##kdc## and ##kadmin## ===
213 +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
214 +Password for "uid=root,cn=users,dc=trudheim,dc=com":
215 +Password for "cn=kadmin,ou=kerberos,dc=trudheim,dc=com":
216 +Re-enter password for "cn=kadmin,ou=kerberos,dc=trudheim,dc=com":
239 239  
240 -Most likely, you will want your KDC and KAdmin server to start at boot, and for that, we can stash the passwords (into LDAP) for ##cn=kdc,ou=kerberos,dc=example,dc=com## and ##cn=kdc,ou=kerberos,dc=example,dc=com## using the same tool as in the previous step.
241 -
242 -(% style="color:#400" %)
243 -##{{{
244 -# kdb5_ldap_util -D uid=root,cn=users,dc=example,dc=com -H ldaps://nas.example.com stashsrvpw -f /etc/krb5kdc/service.keyfile cn=kdc,ou=kerberos,dc=example,dc=com
245 -Password for "uid=root,cn=users,dc=example,dc=com":
246 -Password for "cn=kdc,ou=kerberos,dc=example,dc=com":
247 -Re-enter password for "cn=kdc,ou=kerberos,dc=example,dc=com":
248 -# kdb5_ldap_util -D uid=root,cn=users,dc=example,dc=com -H ldaps://nas.example.com stashsrvpw -f /etc/krb5kdc/service.keyfile cn=kadmin,ou=kerberos,dc=example,dc=com
249 -Password for "uid=root,cn=users,dc=example,dc=com":
250 -Password for "cn=kadmin,ou=kerberos,dc=example,dc=com":
251 -Re-enter password for "cn=kadmin,ou=kerberos,dc=example,dc=com":
252 -# }}}##
253 -
254 -
255 -=== Start the services ===
256 -
257 -We are now ready to start the services. If this does not work, you need to backtrack and find out where you made a mistake, rectify it, and then walk forward again.
258 -
259 -(% style="color:#400" %)
260 -##{{{
261 -# systemctl enable --now krb5-kdc krb5-admin-server
262 -#
263 -}}}##
264 -
265 -
266 -Check that they are running and not giving off errors with ##systemctl status krb5-kdc## and ##systemctl status krb5-admin-server##.
267 -
268 -
269 -=== Create the first regular principals ===
270 -
271 -Providing you got to here without issues it is now time to generate your principals that you will use to authenticate into systems with. Run ##kadmin.local## as root to create first a regular user, and then an admin version of that user.
272 -
273 -(% style="color:#400" %)
274 -##{{{
275 -# kadmin.local
276 -
277 -Authenticating as principal root/admin@EXAMPLE.COM with password.
278 -kadmin.local:  addprinc user
279 -
280 -No policy specified for user@EXAMPLE.COM; defaulting to no policy
281 -Enter password for principal "user@EXAMPLE.COM":
282 -Re-enter password for principal "user@EXAMPLE.COM":
283 -Principal "user@EXAMPLE.COM" created.
284 -
285 -kadmin.local:  addprinc user/admin
286 -No policy specified for user/admin@EXAMPLE.COM; defaulting to no policy
287 -Enter password for principal "user/admin@EXAMPLE.COM":
288 -Re-enter password for principal "user/admin@EXAMPLE.COM":
289 -Principal "user/admin@EXAMPLE.COM" created.
290 -kadmin.local:  q
291 -
292 -# }}}##
293 -
294 -
295 -Worth to note here is that ##user@EXAMPLE.COM## and ##user/admin@EXAMPLE.COM## can have (and probably should have) different passwords. The admin variant is allowed to do things to the kerberos database and should therefore have greater security. This is why you want to have the registering of failures to login enabled. Should you have the system exposed to the internet, you can and should expect intrusion attempts. Having Kerberos deployed makes it harder for perpetrators to gain access, but not impossible.
296 -
297 -If you later kerberise your storage and leverage it for NFS4 mounts from your NAS, you can have NFS exposed to the internet as well. Unless someone has a valid kerberos ticket, even if they somehow could mount a share, they see nothing on it without the krbtgt.
298 -
299 -
300 -=== Test your new principal ===
301 -
302 -Acid test is, can you authenticate with kinit?
303 -
304 -(% style="color:#400" %)
305 -##{{{
306 -$ kinit user@EXAMPLE.COM
307 -
308 -Password for user@EXAMPLE.COM:
309 -
310 -$ klist
311 -Ticket cache: FILE:/tmp/krb5cc_1000
312 -Default principal: user@EXAMPLE.COM
313 -
314 -Valid starting     Expires            Service principal
315 -09/05/24 08:07:35  10/05/24 08:07:35  krbtgt/EXAMPLE.COM@EXAMPLE.COM
316 -
317 -$ }}}##
318 -
319 -
320 -Congratulations - you now have Kerberos working, and to boot, the database sits in LDAP. Which you can inspect with something like:
321 -
322 -(% style="color:#400" %)
323 -##{{{
324 -$ ldapsearch -H ldaps://nas.example.com -D uid=root,cn=users,dc=example,dc=com -W -b ou=kerberos,dc=example,dc=com
325 -}}}##
326 -
327 -
328 -=== Set up pam and sssd ===
329 -
330 - To fully leverage your shiny new KDC, you will want to install the Kerberos authentication pieces for ##PAM## and also ##sssd## to facilitate caching of authentication, in case your KDC is offline for some reason when you try to authenticate into another system.
331 -
332 -(% style="color:#400" %)
333 -##{{{
334 -$ sudo apt install krb5-user libpam-krb5 sssd-krb5
335 -...
336 -$ sudo pam-auth-update
337 -}}}##
338 -
339 -
340 -With ##pam-auth-update## you want to enable Kerberos and SSS authentication (and flip on the auto-creation of home directories while you are there). If you now want to test login on another system with kerberos, you need ##/etc/krb5.conf## and the ##krb5-user##, ##libpam-krb5## and ##sssd-krb5## packages installed on this new system and you need to run ##pam-auth-update## to enable Kerberos and SSS. After that, the system does not need local ##user## (in /etc/passwd) - the kerberos ##user## will work instead.
341 -
342 -/S