Sds-hd CIFS: Difference between revisions

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For security reasons, Server-side permission checks cannot be overriden. The permission checks done by the server will always correspond to the credentials used to mount the share, and not necessarily to the user who is accessing the share.
For security reasons, Server-side permission checks cannot be overriden. The permission checks done by the server will always correspond to the credentials used to mount the share, and not necessarily to the user who is accessing the share.


Although mapping of POSIX UIDs and SIDs is not needed mounting a CIFS share '''it might become necessary when working with files on the share, e.g. when modifying ACLs'''.

<!--
For this reason the mount option <pre>cifsacl</pre> together with a working '''ID Mapping''' setup is required, to allow correct permission handling and changes. It offers also the tools
For this reason the mount option <pre>cifsacl</pre> together with a working '''ID Mapping''' setup is required, to allow correct permission handling and changes. It offers also the tools
<pre>
<pre>
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</pre>
</pre>
to work with ACLs.
to work with ACLs.

== ID Mapping ==

Although mapping of POSIX UIDs and SIDs is not needed mounting a CIFS share '''it might become necessary when working with files on the share, e.g. when modifying ACLs'''.


With version 5.9 of cifs-utils a plugin interface was introduced by Jeff Layton to allow services other than winbind to handle the mapping of POSIX UIDs and SIDs. SSSD will provide a plugin to allow the cifs-utils to ask SSSD to map the ID. With this plugin a SSSD client can access a CIFS share with the same functionality as a client running Winbind.
With version 5.9 of cifs-utils a plugin interface was introduced by Jeff Layton to allow services other than winbind to handle the mapping of POSIX UIDs and SIDs. SSSD will provide a plugin to allow the cifs-utils to ask SSSD to map the ID. With this plugin a SSSD client can access a CIFS share with the same functionality as a client running Winbind.


For this reason we can use the same [[Sds-hd_nfs#configure kerberos environment for SDS@hd|SSSD setup]] for cifs like we use for the kerberized nfs-Setup.
For this reason we can use the same [[Sds-hd_nfs#configure kerberos environment for SDS@hd|SSSD setup]] for cifs like we use for the kerberized nfs-Setup.
-->

{{:Sds-hd_idmapping}}


Additionally we need the cifs packages:
Additionally we need the cifs packages:
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</pre>
</pre>


== Mount a Share ==
== Mounting a SDS@hd Share ==

Mounting a SDS@hd CIFS share can be done by using username/password credentials or by using kerberos tickets.
Information about settting up a kerberos environment for SDS@hd can be found [[Sds-hd_kerberos|*here*]]'''.


=== Single-User Environment ===
=== Single-User Environment ===
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==== Mount over /etc/fstab ====
==== Mount over /etc/fstab ====

Mounting a SDS@hd cifs share via /etc/fstab can be done by using username/password credentials or by using kerberos tickets.


'''Example:'''
'''Example:'''
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> kinit hd_xy123
> kinit hd_xy123
Passwort für hd_xy123@BWSERVICES.UNI-HEIDELBERG.DE:
Passwort für hd_xy123@BWSERVICES.UNI-HEIDELBERG.DE:



>mount /mnt/mountpoint
>mount /mnt/mountpoint
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=== Multiuser Environment ===
=== Multiuser Environment ===


By default, CIFS mounts only use a single set of user credentials (the mount credentials) when accessing a share. To support different user session on the same mountpoint the mount option <pre>multiuser</pre> has to be used. Because the kernel cannot prompt for passwords, '''multiuser mounts are limited to mounts using passwordless sec= options, like with [[Sds-hd_nfs|kerberos (sec=krb5)]]'''
By default, CIFS mounts only use a single set of user credentials (the mount credentials) when accessing a share. To support different user session on the same mountpoint the mount option <pre>multiuser</pre> has to be used. Because the kernel cannot prompt for passwords, '''multiuser mounts are limited to mounts using passwordless sec= options, like with sec=krb5. Information about settting up a kerberos environment can be found [[Sds-hd_kerberos|*here*]]'''



==== AutoFS Setup ====
==== AutoFS Setup ====


Because cifs shares, in contrast to nfs-Mounts, has to be mounted directly, the root user can not simply mount them into a global folder. Instead the shares have to be initially mounted by a user who has access to the Speichervorhaben. To achieve this, we recommend the automounter "autofs".
Because CIFS shares, in contrast to nfs-Mounts, have to be mounted directly, the root user can not simply mount them into a global folder. Instead the shares have to be initially mounted by a user who has access to the Share. To achieve this, youcan use the automounter "autofs".


* RedHat/CentOS:
* RedHat/CentOS:
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> systemctl start autofs
> systemctl start autofs
</pre>
</pre>
<!--
* debian/ubuntu:
* debian/ubuntu:
<pre>
<pre>
> apt install ....
> apt install ....
</pre>
</pre>
-->

Afterwards you can configure the needed SDS@hd shares in a new map file:
Afterwards you can configure the needed SDS@hd shares in a new map file:
<pre>
<pre>
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[...]
[...]
</pre>
</pre>
otherwise each share-folder will only be visible after a user has mounted.


Of course you can adopt all other autofs options, like timeouts, etc to the specific needs of your environment.
Of course you can adopt all other autofs options, like timeouts, etc. to the specific needs of your environment or use any other method for dynamically mounting the CIFS shares.

After changing the configuration, you should restart the autofs daemon
After changing the configuration, you should restart the autofs daemon, e.g.:
<pre>
<pre>
systemctl restart autofs
systemctl restart autofs
Line 211: Line 215:


==== Access the Share ====
==== Access the Share ====

Now each user should be able to mount a SDS@hd share, which is configured for this machine. If a share is allready mounted, other users will access this share with their own credentials without mounting again.
Now each user should be able to mount a SDS@hd share, which is configured for the machine. If a share is allready mounted, other users will access this share with their own credentials without mounting again.


To get access, each user needs a valid kerberos ticket, which can be fetched with
To get access, each user needs a valid kerberos ticket, which can be fetched with

Revision as of 10:43, 24 April 2020

Prerequisites

Attention: To access data served by SDS@hd via CIFS, You need a Service Password. See details SDS@hd Access.

Additionally the access to SDS@hd is currently only available inside the belwue-Network.

This means you have to use the VPN Service of your HomeOrganization, if you want to access SDS@hd from outside the bwHPC-Clusters (e.g. via eduroam or from your personal Laptop)

Using SMB/CIFS for UNIX client

A UNIX like operating system needs a CIFS client to use a share. CIFS clients are part of Samba implementation for Linux and other UNIX like operating systems (http://www.samba.org)

Attention: The core CIFS protocol does not provide unix ownership information or mode for files and directories. Because of this, files and directories will generally appear to be owned by whatever values the uid= or gid= options are set, and will have permissions set to the default file_mode and dir_mode for the mount. Attempting to change these values via chmod/chown will return success but have no effect.

For security reasons, Server-side permission checks cannot be overriden. The permission checks done by the server will always correspond to the credentials used to mount the share, and not necessarily to the user who is accessing the share.

Although mapping of POSIX UIDs and SIDs is not needed mounting a CIFS share it might become necessary when working with files on the share, e.g. when modifying ACLs.


Sds-hd-logo.png

SDS@hd is a central service for securely storing scientific data (Scientific Data Storage). The service is provided as a state service to researchers of higher education institutions of Baden-Württemberg. It is intended to be used for data that is frequently accessed ('hot data').

News
  • November 2022: No special entitlement is needed anymore to participate in an existing storage project.
  • September 2023: Service has now been opened for DFN AAI & eduGAIN federation members to participate on existing storage projects.
Training & Support
User Documentation
Storage Funding

Additionally we need the cifs packages:

  • RedHat/CentOS:
> yum install cifs-utils
  • debian/ubuntu:
> apt install cifs-utils

After installing SSSD you have to ensure that it will be used for cifs name resolution. e.g.

  • RedHat/CentOS:
> alternatives --display cifs-idmap-plugin

cifs-idmap-plugin - Status ist automatisch.
 Link verweist auf /usr/lib64/cifs-utils/cifs_idmap_sss.so
/usr/lib64/cifs-utils/cifs_idmap_sss.so - priority 20
/usr/lib64/cifs-utils/idmapwb.so - priority 10
Zur Zeit ist die `best' Version /usr/lib64/cifs-utils/cifs_idmap_sss.so.
  • debian/ubuntu:
> update-alternatives --display idmap-plugin

idmap-plugin - automatischer Modus
  beste Version des Links ist /usr/lib/x86_64-linux-gnu/cifs-utils/cifs_idmap_sss.so
  Link verweist zur Zeit auf /usr/lib/x86_64-linux-gnu/cifs-utils/cifs_idmap_sss.so
  Link idmap-plugin ist /etc/cifs-utils/idmap-plugin
  Slave idmap-plugin.8.gz ist /usr/share/man/man8/idmap-plugin.8.gz
/usr/lib/x86_64-linux-gnu/cifs-utils/idmapwb.so - Priorität 20
  Slave idmap-plugin.8.gz: /usr/share/man/man8/idmapwb.8.gz


SMB Client

Example: To list the files in a SMB share, use the program smbclient.

smbclient -U 'BWSERVICESAD\hd_xy123'  //lsdf02.urz.uni-heidelberg.de/<sv-acronym>
Enter BWSERVICESAD\hd_xy123's password: 

The program allows you to access the files with a FTP like tool in an interactive shell.

>smbclient //lsdf02.urz.uni-heidelberg.de/<sv-acronym> -U 'BWSERVICESAD\hd_xy123'
Enter BWSERVICESAD\hd_xy123's password:
smb: \> ls
  .                               D        0  Thu Apr 23 12:51:48 2020
  ..                              D        0  Wed Apr 22 21:54:04 2020
  bench                       D        0  Fri Jul 26 10:24:05 2019
  benchmark_test         D        0  Tue Oct 30 16:12:21 2018
  checksums               D        0  Mon Sep 18 10:24:21 2017
  test.multiuser             A        6  Thu Apr 23 12:36:07 2020
  test                           A        7  Thu Apr 23 09:38:13 2020
  .....
  .snapshots                DHR        0  Thu Jan  1 01:00:00 1970

                115343360000 blocks of size 1024. 108260302848 blocks available
smb:\

Mounting a SDS@hd Share

Mounting a SDS@hd CIFS share can be done by using username/password credentials or by using kerberos tickets. Information about settting up a kerberos environment for SDS@hd can be found *here*.

Single-User Environment

A share can be mounted to a local directory, (e.g. /mnt/sds-hd ). Depending on your system setup, root privileges may be required.

Mount over command line

Example:

>mkdir /mnt/sds-hd

>mount -t cifs -o username=hd_xy123,domain=BWSERVICESAD,cifsacl  //lsdf02.urz.uni-heidelberg.de/<sv-acronym> /mnt/sds-hd
Password:

or

> kinit hd_xy123
Passwort für hd_xy123@BWSERVICES.UNI-HEIDELBERG.DE: 
>mount -t cifs -o sec=krb5,cifsacl //lsdf02.urz.uni-heidelberg.de/<sv-acronym>  /mnt/sds-hd

>df -h | grep sds-hd
//lsdf02.urz.uni-heidelberg.de/sd16j007  108T    6,6T  101T    7% /mnt/sds-hd

>cd /mnt/sds-hd/
>ls

Verify the success of the mount invoking the mount command without any arguments:

mount | grep sds-hd
//lsdf02.urz.uni-heidelberg.de/sd16j007 on /mnt/sds-hd type cifs (rw,relatime,vers=3.0,cache=strict,username=xxxx,domain=BWSERVICESAD,uid=1000,forceuid,gid=0,noforcegid,addr=xxxxx,file_mode=0755,dir_mode=0755,soft,nounix,serverino,mapposix,rsize=1048576,wsize=1048576,echo_interval=60,actimeo=1)

Mount over /etc/fstab

Example:

>mkdir /mnt/mountpoint

/etc/fstab
//lsdf02.urz.uni-heidelberg.de/<sv_acronym>   /mnt/mountpoint   cifs  cifsacl,credentials=<path_to_user_HOME>/credentialsfile,noauto  0 0

>cat /path_to_user_HOME/credentialsfile
username=hd_ xy123
password=<your_servicepassword>
domain=BWSERVICESAD

or

/etc/fstab
//lsdf02.urz.uni-heidelberg.de/<sv_acronym>   /mnt/mountpoint   cifs  cifsacl,sec=krb5,noauto  0 0

> kinit hd_xy123
Passwort für hd_xy123@BWSERVICES.UNI-HEIDELBERG.DE: 

>mount /mnt/mountpoint

Verify the success of the mount invoking the mount command without any arguments:

mount | grep cifs 
//lsdf02.urz.uni-heidelberg.de/sd16j007 on /mnt/mountpoint type cifs (rw,relatime,vers=3.0,cache=strict,username=xxxx,domain=BWSERVICESAD,uid=1000,forceuid,gid=0,noforcegid,addr=xxxxx,file_mode=0755,dir_mode=0755,soft,nounix,serverino,mapposix,rsize=1048576,wsize=1048576,echo_interval=60,actimeo=1)


Multiuser Environment

By default, CIFS mounts only use a single set of user credentials (the mount credentials) when accessing a share. To support different user session on the same mountpoint the mount option
multiuser
has to be used. Because the kernel cannot prompt for passwords, multiuser mounts are limited to mounts using passwordless sec= options, like with sec=krb5. Information about settting up a kerberos environment can be found *here*

AutoFS Setup

Because CIFS shares, in contrast to nfs-Mounts, have to be mounted directly, the root user can not simply mount them into a global folder. Instead the shares have to be initially mounted by a user who has access to the Share. To achieve this, youcan use the automounter "autofs".

  • RedHat/CentOS:
> yum install autofs
> systemctl enable autofs 
> systemctl start autofs 

Afterwards you can configure the needed SDS@hd shares in a new map file:

> cat /etc/auto.sds-hd
<sv-acronym1>    -fstype=cifs,cifsacl,multiuser,sec=krb5,cruid=${UID},vers=3.0  ://lsdf02.urz.uni-heidelberg.de/<sv-acronym1>
<sv-acronym2>    -fstype=cifs,cifsacl,multiuser,sec=krb5,cruid=${UID},vers=3.0  ://lsdf02.urz.uni-heidelberg.de/<sv-acronym2>
....

You have to include the new map into the auto.master file:

cat /etc/auto.master
[...]
/mnt/sds-hd   /etc/auto.sds-hd
[...]

To display all available SDS@hd shares on this machine to the users, you should enable "browser_mode":

cat /etc/autofs.conf
[...]
# to display all available SDS-hd shares on this to the users
browse_mode=yes
[...]

otherwise each share-folder will only be visible after a user has mounted.

Of course you can adopt all other autofs options, like timeouts, etc. to the specific needs of your environment or use any other method for dynamically mounting the CIFS shares.

After changing the configuration, you should restart the autofs daemon, e.g.:

systemctl restart autofs

Access the Share

Now each user should be able to mount a SDS@hd share, which is configured for the machine. If a share is allready mounted, other users will access this share with their own credentials without mounting again.

To get access, each user needs a valid kerberos ticket, which can be fetched with

> kinit hd_xy123

Using SMB/CIFS for Windows client

You can use a CIFS share from a Microsoft operating system.

Adopting Universal Naming Convention (UNC) syntax

Use Windows Explorer entering the path to the share in UNC syntax:

Examples:

\\lsdf02.urz.uni-heidelberg.de 
or
\\lsdf02.urz.uni-heidelberg.de\<sv-acronym>

Following the input of the UNC path, a window will pop up:
Loginname: BWSERVICESAD\hd_xy123
Password: Service Password

Following authentication a new window pops up, showing the content of the share. You can now manipulate your files as accustomed. Sds-hd-smb-auth.png

Creation of a network (pseudo) drive with Windows Explorer

To connect to a network share in Windows Explorer select the control field
Select a drive letter to be associated with the network share and enter the network path (e.g. \\lsdf02.urz.uni-heidelberg.de). Select ‘use a different identification‘, as these differ from your credential used locally.

Path: \\lsdf02.urz.uni-heidelberg.de\<sv-acronym>
Username: BWSERVICESAD\hd_xy123
Password: Service Password

Sds-hd-smb-netdrive.png

Using SMB/CIFS for Mac OS client


Creation of a network drive with Finder

To connect to a network share in Finder select the control field
Select a drive letter to be associated with the network share and enter the network path (e.g. \\lsdf02.urz.uni-heidelberg.de). Select ‘use a different identification‘, as these differ from your credential used locally.

Path: smb://lsdf02.urz.uni-heidelberg.de/<sv-acronym>
Username: BWSERVICESAD\hd_xy123
Password: Service Password

Sds smb mac mountpath.png
Sds smb mac login.png