Ubuntu SSH + AD

Installing and Configuring Kerberos, Samba, and Winbind on Ubuntu Server 5

Steps

Step 1: Install the Required Packages

Note: Enter Y when asked if you want to install the additional packages


apt-get install krb5-user
apt-get install winbind samba

Step 2: Edit the /etc/krb5.conf File

Code:

[logging]
    default = FILE10000:/var/log/krb5lib.log
[libdefaults]
    ticket_lifetime = 24000
    default_realm = DOMAIN.INTERNAL
    default_tkt_enctypes = des3-hmac-sha1 des-cbc-crc
    default_tgs_enctypes = des3-hmac-sha1 des-cbc-crc
[realms]
    DOMAIN.INTERNAL = {
        kdc = domainserver.domain.internal
        admin_server = domainserver.domain.internal
        default_domain = DOMAIN.INTERNAL
}
[domain_realm]
    .domain.internal = DOMAIN.INTERNAL
    domain.internal = DOMAIN.INTERNAL

Step 3: Edit /etc/samba/smb/conf

Notes: Change the NETBIOS name parameter to be correct for the server. Make a backup copy of the original file!!!

1) Make the edits. The configuration shown is the bare minimum and doesn't share anything.

Code:

[global]
        security = ads
        netbios name = CMHRG02
        realm = DOMAIN.INTERNAL
        password server = domainserver.domain.internal
        workgroup = DOMAIN
        idmap uid = 500-10000000
        idmap gid = 500-10000000
        winbind separator = +
        winbind enum users = no
        winbind enum groups = no
        winbind use default domain = yes
        template homedir = /home/%D/%U
        template shell = /bin/bash
        client use spnego = yes
        domain master = no

2) Test the configuration with the testparm command

Step 4: Edit /etc/nsswitch.conf to look like the example below

Code:

passwd:         compat winbind
group:          compat winbind
shadow:         compat
hosts:          files dns wins
networks:       files
protocols:      db files
services:       db files
ethers:         db files
rpc:            db files
netgroup:       nis

Step 5: Modify the PAM settings

1) /etc/pam.d/common-account should contain only the following lines

Code:

account sufficient pam_winbind.so
account required  pam_unix.so

2) /etc/pam.d/common-auth should contain only the following lines

Code:

auth    sufficient      pam_winbind.so
auth    required        pam_unix.so nullok_secure use_first_pass

3) Modify the /etc/pam.d/common-password file, so the max parameter is set to 50, similar to the one shown below

Code:

password   required   pam_unix.so nullok obscure min=4 max=50 md5

4) Make sure the /etc/pam.d/common-session file contains the following line

Code:

session required        pam_mkhomedir.so umask=0022 skel=/etc/skel

Step 6: Make a directory to hold domain user home directories

Note: Use the value you put in the WORKGROUP tag of the /etc/samba/smb.conf file

Code:

mkdir /home/DOMAIN

Step 7: Initialize Kerberos

1)

Code:

kinit domain_admin_account@DOMAIN.INTERNAL

Next check to be sure you got a ticket from the domain controller

2)

Code:

klist

Step 8: Join the system to the

Code:

net ads join -U domainadminuser@DOMAIN.INTERNAL

Step 9: Restart Samba-related Services (Or reboot the server)

Note: The order is important

Code:

/etc/init.d/samba stop
/etc/init.d/winbind stop
/etc/init.d/samba start
/etc/init.d/winbind start

Step 10: Restart SSH and Test Connectivity

Note: If you rebooted the server in the previous step, just try and login.

Code:

/etc/init.d/ssh restart

ssh useraccount@server

If you can login using your active directory username and password then everything is working!

Step 11: Configure SUDO

1) First create a group in Active Directory called UnixAdmins and add the names of people whom you want to be able to use sudo to admin the server.

2) Next, add the UnixAdmins group to the /etc/sudoers so these users can use sudo

Code:

%UnixAdmins ALL=(ALL) ALL

HELPFUL COMMAND LINES

1) List the derived UNIX GID values for Active Directory groups

Code:

for gid in $(wbinfo -r ); \
do SID=$(wbinfo -G $gid);GROUP=$(wbinfo -s $SID); echo $gid is $GROUP; done

2) See the Active Directory SID for a particular named user

Code:

wbinfo –n