Kerberos setup - 1 (Kerberos Server)

Install

1. OS (AMI Linux 2)

$ cat /etc/system-release
Amazon Linux release 2 (Karoo)

2. Installed Package

• releated krb5
• ntp

$ sudo yum list installed | grep krb
krb5-devel.x86_64                     1.15.1-19.amzn2.0.3            @amzn2-core
krb5-libs.x86_64                      1.15.1-19.amzn2.0.3            @amzn2-core
krb5-server.x86_64                    1.15.1-19.amzn2.0.3            @amzn2-core
krb5-workstation.x86_64               1.15.1-19.amzn2.0.3            @amzn2-core
pam_krb5.x86_64                       2.4.8-6.amzn2.0.2              @amzn2-core

$ sudo yum list installed | grep ntp
fontpackages-filesystem.noarch        1.44-8.amzn2                   @amzn2-core

Reference

• https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/managing_smart_cards/installing-kerberos
• https://gist.github.com/ashrithr/4767927948eca70845db

 

Settings

Summary

1. EC2 (2EA) - master, slave (HA)

2. DNS (Route 53, abcdef.com for sample)

- kdc.abcdef.com

- kdc2.abcdef.com

 

Configuration

1. /etc/krb5.conf 설정

- realm domain should upper string

$ cat /etc/krb5.conf
# Configuration snippets may be placed in this directory as well
includedir /etc/krb5.conf.d/

[logging]
 kdc = FILE:/var/log/kerberos/krb5kdc.log
 admin_server = FILE:/var/log/kerberos/kadmin.log
 default = FILE:/var/log/kerberos/krb5lib.log

[libdefaults]
 default_realm = ABCDEF.COM
 dns_lookup_realm = false
 dns_lookup_kdc = false
 rdns = false
 ticket_lifetime = 24h
 renew_lifetime = 7d
 forwardable = true

[realms]
 ABCDEF.COM = {
  kdc = kdc.abcdef.com:88
  kdc = kdc2.abcdef.com:88
  admin_server = kdc.abcdef.com:749
  default_tkt_enctypes = aes256-cts-hmac-sha1-96 aes128-cts-hmac-sha1-96 aes256-cts-hmac-sha384-192 aes128-cts-hmac-sha256-128 des3-cbc-sha1 arcfour-hmac-md5 camellia256-cts-cmac camellia128-cts-cmac des-cbc-crc des-cbc-md5 des-cbc-md4
  default_tgs_enctypes = aes256-cts-hmac-sha1-96 aes128-cts-hmac-sha1-96 aes256-cts-hmac-sha384-192 aes128-cts-hmac-sha256-128 des3-cbc-sha1 arcfour-hmac-md5 camellia256-cts-cmac camellia128-cts-cmac des-cbc-crc des-cbc-md5 des-cbc-md4
  permitted_enctypes = aes256-cts-hmac-sha1-96 aes128-cts-hmac-sha1-96 aes256-cts-hmac-sha384-192 aes128-cts-hmac-sha256-128 des3-cbc-sha1 arcfour-hmac-md5 camellia256-cts-cmac camellia128-cts-cmac des-cbc-crc des-cbc-md5 des-cbc-md4
 }

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

 

 

2. /var/kerberos/krb5kdc/kdc.conf 

[kdcdefaults]
 kdc_ports = 88
 kdc_tcp_ports = 88

[realms]
 ABCDEF.COM = {
  kadmind_port = 749
  max_life = 9h 0m 0s
  max_renewable_life = 7d 0h 0m 0s
  master_key_type = des3-hmac-sha1
  supported_enctypes = aes256-cts-hmac-sha1-96:normal aes128-cts-hmac-sha1-96:normal des3-cbc-sha1:normal arcfour-hmac-md5:normal
  database_name = /var/kerberos/krb5kdc/principal
  admin_keytab = /var/kerberos/krb5kdc/kadm5.keytab
  acl_file = /var/kerberos/krb5kdc/kadm5.acl
  dict_file = /var/kerberos/krb5kdc/kadm5.dict
  key_stash_file = /var/kerberos/krb5kdc/.k5.ABCDEF.COM
 }

 

 

3. /var/kerberos/krb5kdc/kadm5.acl 

*/admin@ABCDEF.COM  *

 

 

4. Create KDC database

kdb5_util create -r ABCDEF.COM -s

 

 

5. Create KDC admin

• https://web.mit.edu/kerberos/krb5-1.5/krb5-1.5.4/doc/krb5-install/Add-Administrators-to-the-Kerberos-Database.html

# kadmin.local
kadmin.local:  addprinc account/admin@ABCDEF.COM
     
NOTICE: no policy specified for "admin/admin@ABCDEF.COM";
assigning "default".

Enter password for principal admin/admin@ATHENA.MIT.EDU:  (Enter a password.)
Re-enter password for principal admin/admin@ATHENA.MIT.EDU: (Type it again.)

Principal "admin/admin@ABCDEF.COM" created.
 
kadmin.local:

 

 

6. KDC database Backup & Restore

• https://docs.oracle.com/cd/E19683-01/817-0365/aadmin-3/index.html
• https://docs.oracle.com/cd/E19496-01/806-1971/6jb7j7amu/index.html

Create script & run crontab & propagate to slave server

#!/bin/bash

/usr/sbin/kdb5_util dump /var/kerberos/slave_datatrans


/usr/sbin/kprop -f /var/kerberos/slave_datatrans mgmt-krb-kdc02.abcdef.com > /dev/null

• FYI, domain information in /etc/hosts

% cat /etc/hosts

... 
10.100.125.156     mgmt-krb-kdc02.abcdef.com mgmt-krb-kdc02

 

7. Daemon start & enable

systemctl start krb5kdc.service
systemctl start kadmin.service
systemctl enable krb5kdc.service
systemctl enable kadmin.service