Setting up SAMBA based home directories on a Linux workstation can be a rather painfull experience. I'll explain the settings we had to change on a debian (etch) Linux client to make it work with a Linux based SAMBA server (PDC).
Before you follow this guide: pam_cifs and/or ldap may be a better choice depending on what you try to achieve.
This howto does not strive to be a complete help guide! These settings work for us, your mileage may vary. I do not explain the settings in detail but
man smb.confcan be of help to understand them;-)
You may want to start with a system update, in other words
apt-get update apt-get install kernel-image-2.6-686 apt-get dist-upgrade update-grub sync reboot
The packages we need for this to work are:
apt-get install winbind apt-get install smbfs apt-get install libpam-mount apt-get install lsof cd /usr/lib/ ln -s /lib/libnss_wins.so.2 libnss_wins.so ln -s /lib/libnss_winbind.so.2 libnss_winbind.so
We need to edit the /etc/samba/smb.conf settings to set the right domain name. Here is a sample setup for the machine fast02 in the domain GZH with the primary domain controller (PDC) at 10.10.10.5
workgroup = GZH netbios name = fast02 server string = %h server (Samba %v) wins support = no wins server = 10.10.10.5 dns proxy = no log level = 1 log file = /var/log/samba/log.%m max log size = 1000 syslog = 0 security = domain encrypt passwords = true obey pam restrictions = yes invalid users = root unix password sync = no load printers = no disable spoolss = yes socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192 winbind use default domain = yes #winbind separator = idmap backend = rid:"BUILTIN=2000-9999,GZH=10000-50000" allow trusted domains = No idmap uid = 2000-50000 idmap gid = 2000-50000 winbind enum users = yes winbind enum groups = yes template shell = /bin/bash # use %U for the user, use %D for the domain template homedir = /import/smbhome/%U #template primary group = users
Once you have smb.conf configured, you are ready to join the domain.
/etc/init.d/winbind stop; /etc/init.d/samba stop /etc/init.d/samba start; /etc/init.d/winbind start net join GZH -S <your_server_name> -U <your_domain_admin>
As you may notice we are using the rid backend to map windows user/group sids to unix uid/gid. This gives a consistent mapping accross client unix machines (lower limit + last part of sid). Make sure that the results are within the upper limit.
However, be aware that winbindd has an unexpected memory - once it has mapped a sid to a uid it stores the results in its tdb files to keep the mapping constant - even if the backend is rid. If you want to change your mappings you also have to delete these files. Also removing group mappings from previous configurations can be grucial.
/etc/init.d/winbind stop rm -f /var/cache/sammba/winbindd_cache.tdb rm -rf /var/lib/samba/winbindd_idmap.tdb net groupmap cleanup /etc/init.d/winbind start
You are ready to check if winbind is working. With
wbinfo -p wbinfo -g wbinfo -u
If this worked, we shall get winbind into our user/group name resolution; so let's edit /etc/nsswitch.conf . Be sure to make a backup and dont log out, before you either made it work or copied back the old version.
passwd: files winbind group: files winbind shadow: compat hosts: files wins dns networks: files
Having done this, we should be able to see the users and groups with getent.
getent group getent passwd groups <some_user_name>
Some people have trouble when their windows group names contain spaces. So you may want to consider renaming those i.e.
net rpc group rename "Domain Users" "Domain_Users" -U <your_domain_admin>
In order for pam_mount to work with ssh, we need to change the /etc/ssh/sshd_config settings. Make sure that you understand what this change means in terms of security (I mean it). Make your backup copy and do not log out until it works or you restored the backup.
ChallengeResponseAuthentication no PasswordAuthentication yes UsePAM yes
You will have to restart sshd to see if your system still works. sshd is pretty smart about restarting itself - existing sessions stay open, so you can do this from remote.
After the ssh restart, make sure that you can still login - especially as root.
This is where the real fun begins. You will be modifying the pam settings. Please be aware, that PAM is anything but trivial. Doing a wrong manipulation may lock you out of your system to the point where only single user mode works. So backup any pam file you change and dont logout your primary ssh session before you verified (in a different session) that you can still login!
The following assumes that your system is setup rather defaultish - i.e. the pam config files for the different daemans import common-auth and common-session. Here are the settings that work for us.
# allow users with valid unix account or valid winbind account # success=3 jumps over the next 3 commands auth [success=2 default=ignore] pam_unix.so nullok_secure auth [success=1 default=ignore] pam_winbind.so use_first_pass auth requisite pam_deny.so auth optional pam_mount.so use_first_pass
session required pam_unix.so # we create the user home directory as a mount point for smbmount session optional pam_mkhomedir.so silent session optional pam_mount.so
In the session phase pam_mount tries to mount the user home directory. For this to work, the mount point needs to exist - hence I'm calling pam_mkhomedir. The session entry is also responsibe for unmounting (end of session).
In the auth phase, pam_mount does nothing but storing the user password. This is confusing, but it's the only way for pam_mount to get hold of the password for the later mounting process. We deliberatly use the rather convincing "goto" style configuration where pam_unix and pam_winbind are called before pam_mount and pam_mount is never called if the login didn't succeed. As pam_mount is no longer maintained, this is mainly to give a little protection against possible remote exploits in pam_mount.
pam_mount uses a counter to decide when a user is no longer logged in and his share can be unmounted. We need to create the directory for the counters and set the permissions:
mkdir /var/run/pam_mount/ chmod 777 /var/run/pam_mount/
I'm not kidding - this is world writable. You may find a smarter solution for your specific setup later on, but keep it like this for the moment. pam_mount will be called by a user process when trying to unmount and it tries to unlink its file in /var/run/pam_mount/.
Last step is to tell pam_mount about our required mounts. We need to change /etc/security/pam_mount.conf
smbmount /usr/bin/sudo -u \#%(USERUID) -P /usr/bin/smbmount //%(SERVER)/%(VOLUME) %(MNTPT) -o "username=%(USER),uid=%(USERUID),gid=100%(before=\",\" OPTIONS)" volume * smbfs filer_zh_1 & /import/smbhome/& - - -
The first line is not strictly required. However, without the sudo trick you may realise, that user home directories are not correctly unmounted on logout. That's because the mount is performed while sshd is still running with uid=root but the unmount happens when sshd runs with uid=<the_user_uid>
Well that's it. I hope I didn't forget any other changes I had to made to the system.
(c) joachim(et)buechse.ch. This description is in the public domain.