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The Administrator's guide to grid security middleware

How to use this guide

The material in this guide will help you set up the basic grid security middleware. If you already know what you want, just follow the links to the relevant chapters. If you are not sure which services you should set up and are confused by the options, start by reading the chapter on Security middleware deployment planning after which you should be able to make a well-founded decision on how proceed.

This guide will not explain how to set up site security in general.

Prerequisites

This guide is aimed at grid site administrators. Although it contains ready-to-use example configurations that should result in a working setup, the advised way to configure middleware is through the use of YAIM and some knowledge of the use of YAIM is assumed. The guide will indicate which examples will be produced by YAIM, and which will have to be done manually.


The following text applies to sites that are part of the EGEE grid infrastructure[1]. For other Grids, a separate guide will be provided.

Old versus New


Step 2: Resource configuration

Depending on the selections in step 1, apply the detailed configurations below.

The configurations are marked with symbols to indicate how well they are supported:

  • Currently in production Configurations with this marker are found in production systems all over, and are proven to work well.
  • YAIM configurable
  • Certified configuration

Central account mapping

Managing the (pool) user and group account mappings on a site is typically done centrally. If for some reason a central authorization service is not chosen, the gridmapdir and/or groupmapdir could be shared (with NFS) among all services where mappings are performed, for consistency.

Node-local mapping

In special cases the scope of the account mappings is kept local to a node; these use-cases are typically found when users are mapped to a job slot on a worker node. Node local mapping can be mixed with centralized mapping, for instance when using secondary group ids from the central group mapping.

Special Cases

The following items should be considered before a final choice can be made.

LDAP enforcement

The LCMAPS plugin for LDAP enforcement is used for sites that have dynamic mappings to users and groups, which requires a modification of the LDAP database every time a (new) mapping is done. Zie elders. Applies to: WN, CE.

This plugin will not work together with the ARGUS framework. Currently in production Certified configuration


LDAP enforcement with SCAS

(This situation is supposed to work, but not found in production as such.)

On the WN:

get_account_on_wn:
verify_proxy -> scas_client
scas_client -> ldap_enf
ldap_enf -> posix_enf

On the CE:

get_account_on_ce:
scas_client -> ldap_enf
ldap_enf -> posix_enf

On SCAS:

get_account_on_scas:
voms_pool_group -> voms_local_group | voms_local_group
voms_local_group -> voms_pool_account

LDAP enforcement with node-local mapping

On the WN:

get_account_on_wn:
verify_proxy -> voms_pool_group | voms_local_group
voms_pool_group -> voms_local_group
voms_local_group -> voms_pool_account
voms_pool_account -> ldap_enf
ldap_enf -> posix_enf

On the CE:

get_account_on_ce:
voms_pool_group -> voms_local_group | voms_local_group
voms_local_group -> voms_pool_account
voms_pool_account -> ldap_enf
ldap_enf -> posix_enf

AFS integration

If your site makes use of AFS for file access (e.g. AFS home directories that require AFS tokens) then you need the AFS enforcement plugin. Applies to: CE, WN.

using an ARGUS backend

On the WN:

get_account_on_wn:
verify_proxy -> pepc
pepc -> afs_enf
afs_enf -> posix_enf

On the CE:

get_account_on_ce:
pepc -> afs_enf
afs_enf -> posix_enf

using a SCAS backend

On the WN:

get_account_on_wn:
verify_proxy -> scas_client
scas_client -> afs_enf
afs_enf -> posix_enf

On the CE:

get_account_on_ce:
scas_client -> afs_enf
afs_enf -> posix_enf

On SCAS:

get_account_on_scas:
voms_local_group -> voms_pool_account

AFS enforcement with node-local mapping

This case is used when there is no centrally arranged authorization; the gridmapdir should be shared (e.g. through NFS) between services for consistent mappings.

On the WN: Certified configuration Currently in production YAIM configurable

get_account_on_wn:
verify_proxy -> voms_local_group
voms_local_group -> voms_pool_account
voms_pool_account -> afs_enf
afs_enf -> posix_enf

On the CE:

get_account_on_ce:
voms_local_group -> voms_pool_account
voms_pool_account -> afs_enf
afs_enf -> posix_enf

Third party plugins

Some sites use LCMAPS plugins not provided with the base LCMAPS software; the functioning and side-effects of such plugins is specific to the site and the implementation. In general, it cannot be determined a priori if a plugin will or will not work with either ARGUS or SCAS. YMMV.


Service types

Worker Node

Compute Element

CREAM CE

There are two services that independently use LCMAPS on a CREAM CE: gLExec and gridftpd. It is vital that mappings for both are consistent, otherwise e.g. proxies and sandboxes cannot be read. Differences between the configuration for gLExec and the gridftpd are allowed only if the flow of the plugin execution and the initialization parameters of the plugins result in a consistent mapping.

Examples:

gridftpd:

withvoms:
vomslocalgroup -> vomslocalaccount
vomslocalaccount -> posix_enf | vomspoolaccount
vomspoolaccount -> posix_enf

standard:
localaccount -> posix_enf | poolaccount
poolaccount -> posix_enf

gLExec:

withvoms:
verify_proxy -> vomslocalgroup
vomslocalgroup -> vomslocalaccount
vomslocalaccount -> posix_enf | vomspoolaccount
vomspoolaccount -> posix_enf

standard:
verify_proxy -> localaccount
localaccount -> posix_enf | poolaccount
poolaccount -> posix_enf


LCG-CE

Storage Element

Workload Management System