Jim Zimmerman's Technical Blog

I used the following procedure to join a simple Windows 2003 Active Directory.

Ensure that your time is synced with the ADS machines via ntp.conf.

I used the following to sync time to my NTP server:
# cat /etc/ntp.conf
restrict default kod nomodify notrap nopeer noquery

restrict 127.0.0.1
restrict -6 ::1

server 127.127.1.0
fudge 127.127.1.0 stratum 10

driftfile /var/lib/ntp/drift

keys /etc/ntp/keys

server ntp.domain.com
restrict ntp.domain.com mask 255.255.255.255 nomodify notrap noquery

Ensure that your name resolution is configured properly. If needed, modify via /etc/sysconfig/network with the fully qualified name. Also, the /etc/resolv.conf should use the same DNS servers that handle the dynamic updates for the ADS domain.

For example:
# hostname
rhel5.domain.local

# cat /etc/resolv.conf
search domain.local
nameserver 192.168.0.31
nameserver 192.168.0.32

Configure kerberos:

For example:
# cat /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 = DOMAIN.LOCAL
dns_lookup_realm = false
dns_lookup_kdc = false
ticket_lifetime = 24h
forwardable = yes

[realms]
DOMAIN.LOCAL = {
kdc = pdc.domain.local:88
admin_server = pdc.domain.local:749
default_domain = domain.local
}

[domain_realm]
.domain.local = DOMAIN.LOCAL
domain.local = DOMAIN.LOCAL

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

Test kerberos:
kinit -V administrator@domain.local

You should get the following kind of output:
Authenticated to Kerberos v5

Configure samba:
# cat /etc/samba/smb.conf
#GLOBAL PARAMETERS
[global]
workgroup = DOMAIN
realm = DOMAIN.LOCAL
preferred master = no
server string = Linux Test Machine
security = ADS
encrypt passwords = yes
log level = 3
log file = /var/log/samba/%m
max log size = 50
printcap name = cups
printing = cups
winbind enum users = Yes
winbind enum groups = Yes
winbind use default domain = Yes
winbind nested groups = Yes
winbind separator = +
idmap uid = 600-200000
idmap gid = 600-200000
;template primary group = “Domain Users”
template shell = /bin/bash

[homes]
comment = Home Direcotries
valid users = %S
read only = No
browseable = No

[printers]
comment = All Printers
path = /var/spool/cups
browseable = no
printable = yes
guest ok = yes

Use the testparm command to verify your samba configuration:
# testparm
Load smb config files from /etc/samba/smb.conf
Processing section “[homes]”
Processing section “[printers]”
Loaded services file OK.
‘winbind separator = +’ might cause problems with group membership.
Server role: ROLE_DOMAIN_MEMBER
Press enter to see a dump of your service definitions
…

Join the domain:
net ads join -U administrator

You will be prompted for the administrator password. If successful a message will be displayed stating as such.
For example:
Using short domain name – DOMAIN

Joined ‘RHEL5′ to realm ‘domain’

From here you can execute several commands to test:

# net ads testjoin DOMAIN
Join is OK

The following will list both local user IDs and ADS user IDs:
# wbinfo -u

The will list ADS group names:
# wbinfo -g

The following will verify ADS authentication (In this example, “password” is the administrator account password.):
# wbinfo -a administrator%password
plaintext password authentication succeeded
challenge/response password authentication succeeded

Modify nsswitch.conf to support ADS authentication:
# cat /etc/nsswitch.conf
passwd: files winbind
shadow: files winbind
group: files winbind
hosts: files dns
bootparams: nisplus [NOTFOUND=return] files
ethers: files
netmasks: files
networks: files
protocols: files
rpc: files
services: files
netgroup: nisplus
publickey: nisplus
automount: files nisplus
aliases: files nisplus

This is very important. Make sure you are logged into a couple virtual terminals as root in case there is a problem. You can end up locking yourself out.

Make a backup copy of /etc/pam.d/system-auth-ac:
# cd /etc/pam.d
# cp -rp system-auth-ac system-auth-ac.orig

Edit the system-auth-ac file:
# cat /etc/pam.d/system-auth-ac
#%PAM-1.0
auth required pam_env.so
auth sufficient pam_unix.so likeauth nullok
auth sufficient pam_winbind.so use_first_pass
auth required pam_deny.so

account required pam_unix.so
account sufficient pam_succeed_if.so uid < 100 quiet
account sufficient pam_winbind.so use_first_pass
account required pam_permit.so

password requisite pam_cracklib.so retry=3 type=
password sufficient pam_unix.so nullok use_authtok md5 shadow
password sufficient pam_winbind.so use_first_pass
password required pam_deny.so

session required pam_limits.so
session required pam_unix.so
session required pam_winbind.so use_first

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I was getting the following messages in my samba logs when I would try to access a samba 3.0.33 share on CentOS 5.4 from a Windows 7 Enterprise client:

[2010/03/04 14:07:12, 0] lib/util_sock.c:read_data(534)
read_data: read failure for 4 bytes to client 172.18.31.155. Error = Connection reset by peer

I tried adding the following to my /etc/samba/smb.conf global configuration, but it did not seem to work.

client ntlmv2 auth = yes

I got the same kind of messages.

I ended up having to change the Windows 7 local security policy by modifying the “LAN Manager authentication level”, the “Minimum session security for NTLM SSP based (including secure RPC) clients”, and the “Minimum session security for NTLM SSP based (including secure RPC) servers” policies.

I used the following procedure:

Control Panel -> System and Security -> Administrative Tools -> Local Security Policy

From the Local Security Policy, I went into “Security Options” and then looked under the “Network security” policies.

From here, I set the new policies.

Network security: LAN Manager authentication level
Send LM & NTML responses

Network security: Minimum session security for NTLM SSP based (including secure RPC) clients
Uncheck “Require 128-bit encryption.”

Network security: Minimum session security for NTLM SSP based (including secure RPC) servers
Uncheck “Require 128-bit encryption.”

I am hoping to figure out the issue with samba not accepting ntlmv2 authentication, so I can set the client policies back to the default.

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