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gPlazma specific dCache configuration

dCache has many parameters that can be used to configure the systems behaviour. You can find all these parameters well documented and together with their default values in the properties files in /usr/share/dcache/defaults/. To use non-default values, you have to set the new values in /etc/dcache/dcache.conf or in the layout file. Do not change the defaults in the properties files! After changing a parameter you have to restart the concerned cells.

Refer to the file for a full list of properties for gPlazma One commonly used property is gplazma.cell.limits.threads, which is used to set the maximum number of concurrent requests to gPlazma. The default value is 30.

Setting the value for gplazma.cell.limits.threads too high may result in large spikes of CPU activity and the potential to run out of memory. Setting the number too low results in potentially slow login activity.

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Enabling Username/Password Access for WebDAV

This section describes how to activate the Username/Password access for WebDAV. It uses dcache.kwpd file as an example format for storing Username/Password information. First make sure gPlazma2 is enabled in the /etc/dcache/dcache.conf or in the layout file.


Check your WebDAV settings: enable the HTTP access, disallow the anonymous access, disable requesting and requiring the client authentication and activate basic authentication.


Adjust the /etc/dcache/gplazma.conf to use the kpwd plug-in (for more information see also the section called “Plug-ins”).

It will look something like this:

auth optional kpwd
map requisite kpwd
session requisite kpwd

The /etc/dcache/dcache.kpwd file is the place where you can specify the username/password record. It should contain the username and the password hash, as well as UID, GID, access mode and the home, root and fsroot directories:

# set passwd
passwd tanja 6a4cd089 read-write 500 100 / / /

The passwd-record could be automatically generated by the dCache kpwd-utility, for example:

[root] # dcache kpwd dcuseradd -u 500 -g 100 -h / -r / -f / -w read-write -p dickerelch tanja

Some file access examples:

curl -u tanja:dickerelch
wget --user=tanja --password=dickerelch

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gPlazma config example to work with authenticated webadmin

This section describes how to configure gplazma to enable the webadmin servlet in authenticated mode with a grid certificate as well as with a username/password and how to give a user administrator access.


In this example for the /etc/dcache/gplazma.conf file the X.509 plug-in plugin is used for the authentication step with the grid certificate and the kpwd plug-in plugin is used for the authentication step with username/password.

auth optional x509
auth optional kpwd
map requisite kpwd
session requisite kpwd

The following example will show how to set up the /etc/dcache/dcache.kpwd file:

version 2.1

mapping "/C=DE/O=ExampleOrganisation/OU=EXAMPLE/CN=John Doe" john
# the following are the user auth records
login john read-write 1700 1000 / / /
/C=DE/O=ExampleOrganisation/OU=EXAMPLE/CN=John Doe

# set pwd
passwd john 8402480 read-write 1700 1000 / / /

This maps the DN of a grid certificate subject=/C=DE/O=ExampleOrganisation/OU=EXAMPLE/CN=John Doe to the user john and the entry

login john read-write 1700 1000 / / /
  /C=DE/O=GermanGrid/OU=DESY/CN=John Doe

applies unix-like values to john, most important is the 1000, because it is the assigned GID. This must match the value of the httpd.authz.admin-gid configured in your webadmin. This is sufficient for login using a certificate. The entry:

passwd john 8402480 read-write 1700 1000 / / /

enables username/password login, such as a valid login would be user john with some password. The password is encrypted with the kpwd-algorithm (also see the section called “The kpwd plug-in”) and then stored in the file. Again the 1000 here is the assigned GID.