NOTA BENE Gli esempi citati in questa guida si intendono per MIT Kerberos 5 versione 1.6 su Scientific Linux 5.1.

kdc.example.com: KDC del realm EXAMPLE.COM e DNS di example.com

client.example.com: client Kerberizzato appartenente al realm EXAMPLE.COM

server.example.com: server applicativo Kerberizzato appartenente al realm EXAMPLE.COM

lab1.d1.example.com: KDC del realm D1.EXAMPLE.COM e DNS di d1.example.com

lab2.d2.example.com: KDC del realm D2.EXAMPLE.COM e DNS di d2.example.com

….

….

….

labn.dn.example.com: KDC del realm Dn.EXAMPLE.COM e DNS di dn.example.com

[root@kdc ~]$ yum install krb5-server

[root@kdc ~]$ vi /etc/krb5.conf

[logging]
 default = FILE:/var/log/krb5libs.log
 kdc = FILE:/var/log/krb5kdc.log
 admin_server = FILE:/var/log/kadmind.log

[libdefaults]
 default_realm = EXAMPLE.COM
 dns_lookup_realm = false
 dns_lookup_kdc = false
 ticket_lifetime = 24h
 forwardable = yes

[realms]
 EXAMPLE.COM = {
  kdc = kerberos.example.com:88
  admin_server = kerberos.example.com:749
  default_domain = example.com
 }

[domain_realm]
 .example.com = EXAMPLE.COM
 example.com = EXAMPLE.COM

[appdefaults]
 pam = {
   debug = false
   ticket_lifetime = 36000
   renew_lifetime = 36000
   forwardable = true
   krb4_convert = false
 }

[root@kdc ~]# vi /var/kerberos/krb5kdc/kdc.conf

[kdcdefaults]
 v4_mode = nopreauth
 kdc_tcp_ports = 88

[realms]
 EXAMPLE.COM = {
  #master_key_type = des3-hmac-sha1
  acl_file = /var/kerberos/krb5kdc/kadm5.acl
  dict_file = /usr/share/dict/words
  admin_keytab = /var/kerberos/krb5kdc/kadm5.keytab
  supported_enctypes = des3-hmac-sha1:normal arcfour-hmac:normal des-hmac-sha1:normal des-cbc-md5:normal des-cbc-crc:normal des-cbc-crc:v4 des-cbc-crc:afs3
 }

[root@kdc ~]$ kdb5_util create -s

[root@kdc ~]$ service krb5kdc start

[root@kdc ~]$ service kadmin start

[root@kdc ~]$ service krb524 start

[root@kdc ~]$ kadmin.local

kadmin.local: listprincs

kadmin.local: addprinc admin/admin

[root@kdc ~]$ vi /var/kerberos/krb5kdc/kadm5.acl

[root@kdc ~]$ kinit admin/admin

[root@kdc ~]$ kadmin

kadmin: addprinc user1

kadmin: addprinc -randkey host/kdc.example.com

kadmin: ktadd host/kdc.example.com

kadmin: exit

[root@kdc ~] vi /etc/ssh/sshd_config

GSSAPIAuthentication yes

GSSAPICleanupCredentials yes (elimina il ticket alla chiusura della sessione ssh)

[root@kdc ~]$ service sshd restart

[root@kdc ~]$ vi /etc/ssh/ssh_config

GSSAPIDelegateCredentials yes (abilita il client ssh al forwarding del ticket)

[root@kdc ~]$ adduser -m user1

[root@kdc ~]$ kinit user1

[root@kdc ~]$ klist

[root@kdc ~]$ ssh user1@kdc.example.com

[user1@kdc ~]$ klist (la cache delle credenziali è vuota)

[user1@kdc ~]$ exit

[root@kdc ~]$ kinit -f user1

[root@kdc ~]$ klist -f

[root@kdc ~]$ ssh user1@kdc.example.com

[user1@kdc ~]$ klist -f (notare che il TGT è ancora forwardabile)

[user1@kdc ~]$ exit

[root@kdc ~]$ authconfig –update –enablekrb5

[root@kdc ~]$ vi /etc/pam.d/system-auth (aggiungere validate)

auth sufficient pam_krb5.so use_first_pass validate

[root@kdc ~]$ vi /etc/xinetd.d/krb5-telnet (verificare che disable = no)

[root@kdc ~]$ service xinetd restart

[root@kdc ~]$ telnet -f -a -l user1 kdc.example.com

[user1@kdc ~]$ exit

[root@kdc ~]$ vi /var/named/data/example.db

_kerberos IN TXT "EXAMPLE.COM"

_kerberos._udp IN SRV 0 0 88 kerberos

_kerberos._tcp IN SRV 0 0 88 kerberos

_kerberos-master._udp IN SRV 0 0 88 kerberos

_kerberos-adm._tcp IN SRV 0 0 749 kerberos

_kpasswd._udp IN SRV 0 0 464 kerberos