This document describes the security implementation in AllegroGraph. See Security Overview for an overview of all security features in AllegroGraph.

Database security is primarily concerned with protecting the database from unauthorized access. This includes preventing unauthorized people from accessing data in any fashion (reading, adding, or deleting), and preventing authorized persons from doing things they are not authorized to do (preventing, for example, someone authorized only to read data from modifying data).

AllegroGraph uses industry-leading security features which allow you to protect your databases from unauthorized access and modification.

It does this by (1) only permitting registered users to access the system, (2) defining roles which grant specific permissions, and (3) assigning each user to one or more roles.

The distinction between authentication and authorization is important.

Users are authenticated when they access the database by providing a username and password which are known to AllegroGraph or, optionally depending on configuration parameters, when they provide an SSL certificate (see the various configuration options relating to SSL authentication in the Top-level directives for SSL section in the Server Configuration and Control document).

Authorization is an aspect of a role: are users assigned to a role authorized to access, add, or modify specific data? Roles are defined by an administrator, as described below, and users assigned to a role have a specific list of permissions, as we describe below. A user may have more than one role.

Note that user security depends in part on users keeping their relevant information secure. If someone other than the actual user knows the username and password and has access to other relevant information, the AllegroGraph will not be able to prevent that person from accessing data. There is support for anonymous users. These usually have a single, typically limited role assigned to them

All administrators and users should note that security is a joint responsibility. AllegroGraph cannot protect against access when passwords are compromised or when people can access the machine running the AllegroGraph server when they should not.

Administrators can use the tools provided by AllegroGraph along with their own policies and common sense to protect data from unauthorized use and modification and to facilitate authorized users in performing their legitimate tasks.

What can a role specify?

AllegroGraph administrators can define roles, and assign each user to one or more roles.

Here is what can be done to an AllegroGraph database:

  1. Triples can be queried.

  2. Triples can be added.

  3. Triples can be deleted.

  4. Configuration parameters can be modified.

If you can modify configuration parameters, then in fact you can do 1-3 as well. In general, only a few roles (typically assigned to users called superusers) should be authorized to do so.

For 1-3, it is desirable to be able to limit which triples can be accessed. The limits might be different for querying, adding, or deleting. Suppose, for example, the database contains information about employees at a company. Here are some possible roles and permissions:

Implementing security

Security in AllegroGraph is implemented by:

Classes of roles

Users can be grouped in various ways. Here are some suggested broad categories (these aren't AllegroGraph categories, just ideas about how you might classify your users):

Accessing AllegroGraph

A typical way to access AllegroGraph is through the AGWebView interface. It can also be accessed using a Java or Python client, Gruff, or Lisp (see Lisp Quick Start). We will discuss AGWebView access security in this document.

Managing Users

To open an AllegroGraph repository in AGWebView or using one of the AllegroGraph clients or to issue most commands using agtool or using the REST interface, you must either supply an AllegroGraph user name and password (except the anonymous user which, if created, does not need a password) or authenticate with an SSL certificate. Passwords must be set up even if SSL authentication is used (see the various configuration options relating to SSL authentication in the Top-level directives for SSL section in the Server Configuration and Control document).

This section briefly describes user-related tasks and how to perform them. The Managing Users document describes how to use AGWebView and agtool to create and manage users.

Initial Superuser

An initial superuser is usually created during the AllegroGraph server installation. This user typically appears in AllegroGraph documentation as user "test" with password "xyzzy". You should choose a completely different username and password for your superuser account.

This superuser can create and manage other users, start sessions, evaluate arbitrary code, and has read/write access to all repositories in all catalogs.

Note that you want to have at least one superuser at all times, because only a superuser can manage permissions and access for other accounts.

Usernames and passwords

User names and passwords are case-sensitive. A password is required for all users except for the anonymous user.

User passwords

A number of configuration options control user passwords (see Server Configuration and Control) These options allow:

Other restrictions on users

Other configuration options control other aspects of user behavior. In particular, sessions can timeout or users can be suspended or even deleted if:

Email notification of certain changes to user status

If you set up the SMTPHost configuration option to specify an email account and also the AuditEventsToEmail option, then emails will be sent via the specified SMTP host to the specified admin email address about user account status changes (suspended/unsuspended, disabled/enabled, password expired).


By default, the AllegroGraph server's HTTP API will open a random TCP port with a number greater than 1024 for new sessions (see the Sessions section in the HTTP Protocol - SPARQL Endpoint document). In order to allow a firewall more effective control over access to the AllegroGraph server, we recommend specifying a SessionPorts range in the agraph.cfg file, and then filtering only these ports.

Issues with transferring passwords over the internet

When running an AllegroGraph server that is accessible from untrusted networks (e.g. the Internet), administrators need to be aware that passwords will be transferred in unencrypted form between AllegroGraph clients and the server. To avoid exposing users' AllegroGraph passwords to malicious third parties, you should open the AllegroGraph service to untrusted networks only on an SSLPort (using the correct SSLCertificate settings) or through an SSL-enabled reverse proxy.

Security filters

A security filter can be set by an administrator (a superuser). It can prevent access (both read and write) to triples with a specified value for subject, predicate, object and/or graph.

What threats do triple-level security filters prevent?

Security filters can prevent users from accessing (both reading and writing) privacy-sensitive data. When querying, triples filtered out by a security filter will appear as if they weren't in the store in the first place. In contrast, attempts to add them or remove filtered triples will result in an error.

The administrator must take care to allow users access only to those triples that are safe for these users to see; this can be hard to accomplish with only subject/predicate/object-based filters when there is deep graph structure involved. In these cases, it is advisable to put triples that should be (or should not be) accessed by a certain set of users into their own graph, and define a filter set using that graph.

Setting security filters for a user or a role

Security filters can be set by a superuser in the user administration screen of AllegroGraph WebView. If you assign filters to roles, these filters will be merged into a set of effective filters for each user with that role accessing a store.

Enter the criteria for the filter pattern in the subject, predicate, object, graph fields of the filter table (use the regular part syntax for URIs: , and literals "literal" for literals), select either "allow" or "disallow" and click "add" to define a new filter.

To remove a filter, click the X mark next to the filter pattern.

Security Filter in WebView

Updating the set of filter patterns takes effect only for new sessions; sessions that are running while you modify the set of filters will still use the same triple pattern as before.

Effect of "allowing" or "disallowing" a triple pattern

Each security filter pattern can specify to "allow" or "disallow" a certain pattern of triples. Both types of pattern can remove triples from the set of triples that a user will see:

This makes allow the more restrictive of the two filter types: it will remove every triple that doesn't match the filter pattern, whereas disallow only removes those triples that exactly match.

Composing security filters

As security filters are based on set intersection and set difference, a filter set with both allow and disallow filters will always result in the same set of triples when applied to a store, no matter in which order the filters are applied to the store.

The composition of the filters:

will result in a store that appears to contain (from the perspective of the affected user/role) only triples with the predicates <> or <> and object <>, but will never contain any triples with the subject <>.

Effect of security filters on local stores (security relevant)

Per-user and role security filters only affect HTTP clients, which does not include local Lisp clients. These have total access (read and write) to the store, no matter what security filters are in place.