Fun fun fun – server consolidation time.

Dell P4, 2GB RAM, 1TB storage (4x 300GB SATA RAID 5)

Install SLES 10, no GUI, runlevel 3 only. Disable pretty much everything not needed.

I chose ext3 for /, xfs for my NAS filesystem; I’ve had good results using xfs – reliability and performance.

Next optimisation of the filesystem:

#/etc/sysctl.conf
# Reduces the amount of work the TCP stack does.
net.ipv4.tcp_sack = 0
# The number of inodes (fs.inode-nr) available to the Linux kernel should be 3-4 times
# greater than the fs.file-max parameter
fs.inode-nr = 128000
# Maximum number of file handles that can open at a given time (default=4096)
fs.file-max = 64000

Apply the configuration and reboot:

chkconfig boot.sysctl on

Install Kerberos Client libraries. This can be done from YAST or the ZENworks updater. The basic modules needed are:

• krb5
• krb5-client
• pam-krb5

Install the SAMBA pieces:

• samba
• samba-client
• samba-winbind

Next configuration of SAMBA and the Kerberos environment; I found that using YAST wouldn’t let me set this up correctly. The two files are /etc/krb5.conf and /etc/samba/smb.conf

Note that krb5.conf expects everything AD related in upper case. Took me a few tries to realise that.

I’ve cleansed the real information – for the record there is no AD infrastructure at evilzenscientist.com – it’s just illustrative.

Active Directory server: 192.68.0.16, EZS-KDC
Active Directory tree: ezs-ad.evilzenscientist.com
Active Directory ‘domain’: EZS-AD

#/etc/krb5.conf

[libdefaults]
default_realm = EVILZENSCIENTIST.COM
clockskew = 300

[realms]
EVILZENSCIENTIST.COM = {
kdc = 192.168.0.16
default_domain = EZS-AD
admin_server = 192.168.0.16
}

[logging]
kdc = FILE:/var/log/krb5/krb5kdc.log
admin_server = FILE:/var/log/krb5/kadmind.log
default = SYSLOG:NOTICE:DAEMON
[domain_realm]
.EZS-AD = EVILZENSCIENTIST.COM
[appdefaults]
pam = {
ticket_lifetime = 1d
renew_lifetime = 1d
forwardable = true
proxiable = false
retain_after_close = false
minimum_uid = 0
try_first_pass = true
}

Next is the SAMBA configuration /etc/samba/smb.conf

#/etc/samba/smb.conf
[global]
workgroup = EZS-AD
realm = EZS-AD.EVILZENSCIENTIST.COM
password server = EZS-KDC.EZS-AD.EVILZENSCIENTIST.COM
security = ADS
encrypt passwords = yes
server string = %h SAMBA %v SLES 10

winbind separator = +
idmap uid = 10000-20000
idmap gid = 10000-20000
winbind enum users = yes
winbind enum groups = yes

[data]
comment = data
read only = no
path = /data
user = @”EZS-AD+domain users”

Next is the Active Directory authentication configuration.

Edit /etc/nsswitch.conf – and make sure that these lines are present:

#/etc/nsswitch.conf
passwd: compat winbind
group: compat winbind

Reboot and then test the Kerberos implementation:

Test the Kerberos implementation:

kinit administrator@EZS-AD.EVILZENSCIENTIST.COM

This should prompt for a password and return no errors. Note that time sync between the client and the AD KDC server needs to be pretty tight. Look at using NTP.

Join the server to the AD domain:

net ads join

Using short domain name — EZS-AD
Joined ‘EZS-NAS’ to realm ‘EZS-AD.EVILZENSCIENTIST.COM’

There are some testing steps; look at the getent tool:

getent passwd
getent groups

These should return users and groups from the AD world.

That’s it for now; I’m the happy owner of a good, fast NAS box that is integrated into my Active Directory.

For the record – I have found that SLES 10 + SAMBA is about 30% faster than a Windows 2003 server on the same hardware. Cheaper and Faster – now that’s a result.