sssd-ad(5)
NAME
sssd-ad - SSSD Active Directory provider
DESCRIPTION
This manual page describes the configuration of the AD provider for sssd(8). For a detailed syntax reference, refer to the "FILE FORMAT" section of the sssd.conf(5) manual page. The AD provider is a back end used to connect to an Active Directory server. This provider requires that the machine be joined to the AD domain and a keytab is available. The AD provider supports connecting to Active Directory 2008 R2 or later. Earlier versions may work, but are unsupported. The AD provider can be used to get user information and authenticate users from trusted domains. Currently only trusted domains in the same forest are recognized. In addition servers from trusted domains are always auto-discovered. The AD provider accepts the same options used by the sssd-ldap(5) identity provider and the sssd-krb5(5) authentication provider with some exceptions described below. However, it is neither necessary nor recommended to set these options. The AD provider can also be used as an access, chpass, sudo and autofs provider. No configuration of the access provider is required on the client side. By default, the AD provider will map UID and GID values from the objectSID parameter in Active Directory. For details on this, see the "ID MAPPING" section below. If you want to disable ID mapping and instead rely on POSIX attributes defined in Active Directory, you should set ldap_id_mapping = False In order to retrieve users and groups using POSIX attributes from trusted domains, the AD administrator must make sure that the POSIX attributes are replicated to the Global Catalog. Users, groups and other entities served by SSSD are always treated as case-insensitive in the AD provider for compatibility with Active Directory's LDAP implementation.
CONFIGURATION OPTIONS
Refer to the section "DOMAIN SECTIONS" of the sssd.conf(5) manual page
for details on the configuration of an SSSD domain.
ad_domain (string)
Specifies the name of the Active Directory domain. This is
optional. If not provided, the configuration domain name is used.
For proper operation, this option should be specified as the
lower-case version of the long version of the Active Directory
domain.
The short domain name (also known as the NetBIOS or the flat name)
is autodetected by the SSSD.
ad_server, ad_backup_server (string)
The comma-separated list of hostnames of the AD servers to which
SSSD should connect in order of preference. For more information on
failover and server redundancy, see the "FAILOVER" section.
This is optional if autodiscovery is enabled. For more information
on service discovery, refer to the "SERVICE DISCOVERY" section.
Note: Trusted domains will always auto-discover servers even if the
primary server is explicitly defined in the ad_server option.
ad_hostname (string)
Optional. May be set on machines where the hostname(5) does not
reflect the fully qualified name used in the Active Directory
domain to identify this host.
This field is used to determine the host principal in use in the
keytab. It must match the hostname for which the keytab was issued.
ad_enable_dns_sites (boolean)
Enables DNS sites - location based service discovery.
If true and service discovery (see Service Discovery paragraph at
the bottom of the man page) is enabled, the SSSD will first attempt
to discover the Active Directory server to connect to using the
Active Directory Site Discovery and fall back to the DNS SRV
records if no AD site is found. The DNS SRV configuration,
including the discovery domain, is used during site discovery as
well.
Default: true
ad_access_filter (string)
This option specifies LDAP access control filter that the user must
match in order to be allowed access. Please note that the
"access_provider" option must be explicitly set to "ad" in order
for this option to have an effect.
The option also supports specifying different filters per domain or
forest. This extended filter would consist of:
"KEYWORD:NAME:FILTER". The keyword can be either "DOM", "FOREST" or
missing.
If the keyword equals to "DOM" or is missing, then "NAME" specifies
the domain or subdomain the filter applies to. If the keyword
equals to "FOREST", then the filter equals to all domains from the
forest specified by "NAME".
Multiple filters can be separated with the "?" character,
similarly to how search bases work.
The most specific match is always used. For example, if the option
specified filter for a domain the user is a member of and a global
filter, the per-domain filter would be applied. If there are more
matches with the same specification, the first one is used.
Examples:
# apply filter on domain called dom1 only:
dom1:(memberOf=cn=admins,ou=groups,dc=dom1,dc=com)
# apply filter on domain called dom2 only:
DOM:dom2:(memberOf=cn=admins,ou=groups,dc=dom2,dc=com)
# apply filter on forest called EXAMPLE.COM only:
FOREST:EXAMPLE.COM:(memberOf=cn=admins,ou=groups,dc=example,dc=com)
Default: Not set
ad_site (string)
Specify AD site to which client should try to connect. If this
option is not provided, the AD site will be auto-discovered.
Default: Not set
ad_enable_gc (boolean)
By default, the SSSD connects to the Global Catalog first to
retrieve users from trusted domains and uses the LDAP port to
retrieve group memberships or as a fallback. Disabling this option
makes the SSSD only connect to the LDAP port of the current AD
server.
Please note that disabling Global Catalog support does not disable
retrieving users from trusted domains. The SSSD would connect to
the LDAP port of trusted domains instead. However, Global Catalog
must be used in order to resolve cross-domain group memberships.
Default: true
ad_gpo_access_control (string)
This option specifies the operation mode for GPO-based access
control functionality: whether it operates in disabled mode,
enforcing mode, or permissive mode. Please note that the
"access_provider" option must be explicitly set to "ad" in order
for this option to have an effect.
GPO-based access control functionality uses GPO policy settings to
determine whether or not a particular user is allowed to logon to a
particular host.
NOTE: If the operation mode is set to enforcing, it is possible
that users that were previously allowed logon access will now be
denied logon access (as dictated by the GPO policy settings). In
order to facilitate a smooth transition for administrators, a
permissive mode is available that will not enforce the access
control rules, but will evaluate them and will output a syslog
message if access would have been denied. By examining the logs,
administrators can then make the necessary changes before setting
the mode to enforcing.
There are three supported values for this option:
* disabled: GPO-based access control rules are neither evaluated
nor enforced.
* enforcing: GPO-based access control rules are evaluated and
enforced.
* permissive: GPO-based access control rules are evaluated, but
not enforced. Instead, a syslog message will be emitted
indicating that the user would have been denied access if this
option's value were set to enforcing.
Default: enforcing
ad_gpo_cache_timeout (integer)
The amount of time between lookups of GPO policy files against the
AD server. This will reduce the latency and load on the AD server
if there are many access-control requests made in a short period.
Default: 5 (seconds)
ad_gpo_map_interactive (string)
A comma-separated list of PAM service names for which GPO-based
access control is evaluated based on the InteractiveLogonRight and
DenyInteractiveLogonRight policy settings.
Note: Using the Group Policy Management Editor this value is called
"Allow log on locally" and "Deny log on locally".
It is possible to add another PAM service name to the default set
by using "+service_name" or to explicitly remove a PAM service name
from the default set by using "-service_name". For example, in
order to replace a default PAM service name for this logon right
(e.g. "login") with a custom pam service name (e.g.
"my_pam_service"), you would use the following configuration:
ad_gpo_map_interactive = +my_pam_service, -login
Default: the default set of PAM service names includes:
* login
* su
* su-l
* gdm-fingerprint
* gdm-password
* gdm-smartcard
* kdm
* lightdm
* lxdm
* sddm
* unity
* xdm
ad_gpo_map_remote_interactive (string)
A comma-separated list of PAM service names for which GPO-based
access control is evaluated based on the
RemoteInteractiveLogonRight and DenyRemoteInteractiveLogonRight
policy settings.
Note: Using the Group Policy Management Editor this value is called
"Allow log on through Remote Desktop Services" and "Deny log on
through Remote Desktop Services".
It is possible to add another PAM service name to the default set
by using "+service_name" or to explicitly remove a PAM service name
from the default set by using "-service_name". For example, in
order to replace a default PAM service name for this logon right
(e.g. "sshd") with a custom pam service name (e.g.
"my_pam_service"), you would use the following configuration:
ad_gpo_map_remote_interactive = +my_pam_service, -sshd
Default: the default set of PAM service names includes:
* sshd
* cockpit
ad_gpo_map_network (string)
A comma-separated list of PAM service names for which GPO-based
access control is evaluated based on the NetworkLogonRight and
DenyNetworkLogonRight policy settings.
Note: Using the Group Policy Management Editor this value is called
"Access this computer from the network" and "Deny access to this
computer from the network".
It is possible to add another PAM service name to the default set
by using "+service_name" or to explicitly remove a PAM service name
from the default set by using "-service_name". For example, in
order to replace a default PAM service name for this logon right
(e.g. "ftp") with a custom pam service name (e.g.
"my_pam_service"), you would use the following configuration:
ad_gpo_map_network = +my_pam_service, -ftp
Default: the default set of PAM service names includes:
* ftp
* samba
ad_gpo_map_batch (string)
A comma-separated list of PAM service names for which GPO-based
access control is evaluated based on the BatchLogonRight and
DenyBatchLogonRight policy settings.
Note: Using the Group Policy Management Editor this value is called
"Allow log on as a batch job" and "Deny log on as a batch job".
It is possible to add another PAM service name to the default set
by using "+service_name" or to explicitly remove a PAM service name
from the default set by using "-service_name". For example, in
order to replace a default PAM service name for this logon right
(e.g. "crond") with a custom pam service name (e.g.
"my_pam_service"), you would use the following configuration:
ad_gpo_map_batch = +my_pam_service, -crond
Default: the default set of PAM service names includes:
* crond
ad_gpo_map_service (string)
A comma-separated list of PAM service names for which GPO-based
access control is evaluated based on the ServiceLogonRight and
DenyServiceLogonRight policy settings.
Note: Using the Group Policy Management Editor this value is called
"Allow log on as a service" and "Deny log on as a service".
It is possible to add a PAM service name to the default set by
using "+service_name". Since the default set is empty, it is not
possible to remove a PAM service name from the default set. For
example, in order to add a custom pam service name (e.g.
"my_pam_service"), you would use the following configuration:
ad_gpo_map_service = +my_pam_service
Default: not set
ad_gpo_map_permit (string)
A comma-separated list of PAM service names for which GPO-based
access is always granted, regardless of any GPO Logon Rights.
It is possible to add another PAM service name to the default set
by using "+service_name" or to explicitly remove a PAM service name
from the default set by using "-service_name". For example, in
order to replace a default PAM service name for unconditionally
permitted access (e.g. "sudo") with a custom pam service name
(e.g. "my_pam_service"), you would use the following
configuration:
ad_gpo_map_permit = +my_pam_service, -sudo
Default: the default set of PAM service names includes:
* sudo
* sudo-i
* systemd-user
ad_gpo_map_deny (string)
A comma-separated list of PAM service names for which GPO-based
access is always denied, regardless of any GPO Logon Rights.
It is possible to add a PAM service name to the default set by
using "+service_name". Since the default set is empty, it is not
possible to remove a PAM service name from the default set. For
example, in order to add a custom pam service name (e.g.
"my_pam_service"), you would use the following configuration:
ad_gpo_map_deny = +my_pam_service
Default: not set
ad_gpo_default_right (string)
This option defines how access control is evaluated for PAM service
names that are not explicitly listed in one of the ad_gpo_map_*
options. This option can be set in two different manners. First,
this option can be set to use a default logon right. For example,
if this option is set to 'interactive', it means that unmapped PAM
service names will be processed based on the InteractiveLogonRight
and DenyInteractiveLogonRight policy settings. Alternatively, this
option can be set to either always permit or always deny access for
unmapped PAM service names.
Supported values for this option include:
* interactive
* remote_interactive
* network
* batch
* service
* permit
* deny
Default: deny
ad_maximum_machine_account_password_age (integer)
SSSD will check once a day if the machine account password is older
than the given age in days and try to renew it. A value of 0 will
disable the renewal attempt.
Default: 30 days
ad_machine_account_password_renewal_opts (string)
This option should only be used to test the machine account renewal
task. The option expect 2 integers seperated by a colon (':'). The
first integer defines the interval in seconds how often the task is
run. The second specifies the inital timeout in seconds before the
task is run for the first time after startup.
Default: 86400:750 (24h and 15m)
dyndns_update (boolean)
Optional. This option tells SSSD to automatically update the Active
Directory DNS server with the IP address of this client. The update
is secured using GSS-TSIG. As a consequence, the Active Directory
administrator only needs to allow secure updates for the DNS zone.
The IP address of the AD LDAP connection is used for the updates,
if it is not otherwise specified by using the "dyndns_iface"
option.
NOTE: On older systems (such as RHEL 5), for this behavior to work
reliably, the default Kerberos realm must be set properly in
/etc/krb5.conf
Default: true
dyndns_ttl (integer)
The TTL to apply to the client DNS record when updating it. If
dyndns_update is false this has no effect. This will override the
TTL serverside if set by an administrator.
Default: 3600 (seconds)
dyndns_iface (string)
Optional. Applicable only when dyndns_update is true. Choose the
interface or a list of interfaces whose IP addresses should be used
for dynamic DNS updates. Special value "*" implies that IPs from
all interfaces should be used.
Default: Use the IP addresses of the interface which is used for AD
LDAP connection
Example: dyndns_iface = em1, vnet1, vnet2
dyndns_refresh_interval (integer)
How often should the back end perform periodic DNS update in
addition to the automatic update performed when the back end goes
online. This option is optional and applicable only when
dyndns_update is true.
Default: 86400 (24 hours)
dyndns_update_ptr (bool)
Whether the PTR record should also be explicitly updated when
updating the client's DNS records. Applicable only when
dyndns_update is true.
Default: True
dyndns_force_tcp (bool)
Whether the nsupdate utility should default to using TCP for
communicating with the DNS server.
Default: False (let nsupdate choose the protocol)
dyndns_server (string)
The DNS server to use when performing a DNS update. In most setups,
it's recommended to leave this option unset.
Setting this option makes sense for environments where the DNS
server is different from the identity server.
Please note that this option will be only used in fallback attempt
when previous attempt using autodetected settings failed.
Default: None (let nsupdate choose the server)
override_homedir (string)
Override the user's home directory. You can either provide an
absolute value or a template. In the template, the following
sequences are substituted:
%u
login name
%U
UID number
%d
domain name
%f
fully qualified user name (user@domain)
%P
UPN - User Principal Name (name@REALM)
%o
The original home directory retrieved from the identity
provider.
%H
The value of configure option homedir_substring.
%%
a literal '%'
This option can also be set per-domain.
example:
override_homedir = /home/%u
Default: Not set (SSSD will use the value retrieved from LDAP)
homedir_substring (string)
The value of this option will be used in the expansion of the
override_homedir option if the template contains the format string
%H. An LDAP directory entry can directly contain this template so
that this option can be used to expand the home directory path for
each client machine (or operating system). It can be set per-domain
or globally in the [nss] section. A value specified in a domain
section will override one set in the [nss] section.
Default: /home
krb5_use_enterprise_principal (boolean)
Specifies if the user principal should be treated as enterprise
principal. See section 5 of RFC 6806 for more details about
enterprise principals.
Default: true
Note that this default differs from the traditional Kerberos
provider back end.
krb5_confd_path (string)
Absolute path of a directory where SSSD should place Kerberos
configuration snippets.
To disable the creation of the configuration snippets set the
parameter to 'none'.
Default: not set (krb5.include.d subdirectory of SSSD's pubconf
directory)
FAILOVER
The failover feature allows back ends to automatically switch to a different server if the current server fails. Failover Syntax The list of servers is given as a comma-separated list; any number of spaces is allowed around the comma. The servers are listed in order of preference. The list can contain any number of servers. For each failover-enabled config option, two variants exist: primary and backup. The idea is that servers in the primary list are preferred and backup servers are only searched if no primary servers can be reached. If a backup server is selected, a timeout of 31 seconds is set. After this timeout SSSD will periodically try to reconnect to one of the primary servers. If it succeeds, it will replace the current active (backup) server. The Failover Mechanism The failover mechanism distinguishes between a machine and a service. The back end first tries to resolve the hostname of a given machine; if this resolution attempt fails, the machine is considered offline. No further attempts are made to connect to this machine for any other service. If the resolution attempt succeeds, the back end tries to connect to a service on this machine. If the service connection attempt fails, then only this particular service is considered offline and the back end automatically switches over to the next service. The machine is still considered online and might still be tried for another service. Further connection attempts are made to machines or services marked as offline after a specified period of time; this is currently hard coded to 30 seconds. If there are no more machines to try, the back end as a whole switches to offline mode, and then attempts to reconnect every 30 seconds.
SERVICE DISCOVERY
The service discovery feature allows back ends to automatically find the appropriate servers to connect to using a special DNS query. This feature is not supported for backup servers. Configuration If no servers are specified, the back end automatically uses service discovery to try to find a server. Optionally, the user may choose to use both fixed server addresses and service discovery by inserting a special keyword, "_srv_", in the list of servers. The order of preference is maintained. This feature is useful if, for example, the user prefers to use service discovery whenever possible, and fall back to a specific server when no servers can be discovered using DNS. The domain name Please refer to the "dns_discovery_domain" parameter in the sssd.conf(5) manual page for more details. The protocol The queries usually specify _tcp as the protocol. Exceptions are documented in respective option description. See Also For more information on the service discovery mechanism, refer to RFC 2782.
ID MAPPING
The ID-mapping feature allows SSSD to act as a client of Active
Directory without requiring administrators to extend user attributes to
support POSIX attributes for user and group identifiers.
NOTE: When ID-mapping is enabled, the uidNumber and gidNumber
attributes are ignored. This is to avoid the possibility of conflicts
between automatically-assigned and manually-assigned values. If you
need to use manually-assigned values, ALL values must be
manually-assigned.
Please note that changing the ID mapping related configuration options
will cause user and group IDs to change. At the moment, SSSD does not
support changing IDs, so the SSSD database must be removed. Because
cached passwords are also stored in the database, removing the database
should only be performed while the authentication servers are
reachable, otherwise users might get locked out. In order to cache the
password, an authentication must be performed. It is not sufficient to
use sss_cache(8) to remove the database, rather the process consists
of:
* Making sure the remote servers are reachable
* Stopping the SSSD service
* Removing the database
* Starting the SSSD service
Moreover, as the change of IDs might necessitate the adjustment of
other system properties such as file and directory ownership, it's
advisable to plan ahead and test the ID mapping configuration
thoroughly.
Mapping Algorithm
Active Directory provides an objectSID for every user and group object
in the directory. This objectSID can be broken up into components that
represent the Active Directory domain identity and the relative
identifier (RID) of the user or group object.
The SSSD ID-mapping algorithm takes a range of available UIDs and
divides it into equally-sized component sections - called "slices"-.
Each slice represents the space available to an Active Directory
domain.
When a user or group entry for a particular domain is encountered for
the first time, the SSSD allocates one of the available slices for that
domain. In order to make this slice-assignment repeatable on different
client machines, we select the slice based on the following algorithm:
The SID string is passed through the murmurhash3 algorithm to convert
it to a 32-bit hashed value. We then take the modulus of this value
with the total number of available slices to pick the slice.
NOTE: It is possible to encounter collisions in the hash and subsequent
modulus. In these situations, we will select the next available slice,
but it may not be possible to reproduce the same exact set of slices on
other machines (since the order that they are encountered will
determine their slice). In this situation, it is recommended to either
switch to using explicit POSIX attributes in Active Directory
(disabling ID-mapping) or configure a default domain to guarantee that
at least one is always consistent. See "Configuration" for details.
Configuration
Minimum configuration (in the "[domain/DOMAINNAME]" section):
ldap_id_mapping = True
ldap_schema = ad
The default configuration results in configuring 10,000 slices, each
capable of holding up to 200,000 IDs, starting from 10,001 and going up
to 2,000,100,000. This should be sufficient for most deployments.
Advanced Configuration
ldap_idmap_range_min (integer)
Specifies the lower bound of the range of POSIX IDs to use for
mapping Active Directory user and group SIDs.
NOTE: This option is different from "min_id" in that "min_id"
acts to filter the output of requests to this domain, whereas
this option controls the range of ID assignment. This is a
subtle distinction, but the good general advice would be to
have "min_id" be less-than or equal to "ldap_idmap_range_min"
Default: 200000
ldap_idmap_range_max (integer)
Specifies the upper bound of the range of POSIX IDs to use for
mapping Active Directory user and group SIDs.
NOTE: This option is different from "max_id" in that "max_id"
acts to filter the output of requests to this domain, whereas
this option controls the range of ID assignment. This is a
subtle distinction, but the good general advice would be to
have "max_id" be greater-than or equal to
"ldap_idmap_range_max"
Default: 2000200000
ldap_idmap_range_size (integer)
Specifies the number of IDs available for each slice. If the
range size does not divide evenly into the min and max values,
it will create as many complete slices as it can.
NOTE: The value of this option must be at least as large as the
highest user RID planned for use on the Active Directory
server. User lookups and login will fail for any user whose RID
is greater than this value.
For example, if your most recently-added Active Directory user
has objectSid=S-1-5-21-2153326666-2176343378-3404031434-1107,
"ldap_idmap_range_size" must be at least 1108 as range size is
equal to maximal SID minus minimal SID plus one (e.g. 1108 =
1107 - 0 + 1).
It is important to plan ahead for future expansion, as changing
this value will result in changing all of the ID mappings on
the system, leading to users with different local IDs than they
previously had.
Default: 200000
ldap_idmap_default_domain_sid (string)
Specify the domain SID of the default domain. This will
guarantee that this domain will always be assigned to slice
zero in the ID map, bypassing the murmurhash algorithm
described above.
Default: not set
ldap_idmap_default_domain (string)
Specify the name of the default domain.
Default: not set
ldap_idmap_autorid_compat (boolean)
Changes the behavior of the ID-mapping algorithm to behave more
similarly to winbind's "idmap_autorid" algorithm.
When this option is configured, domains will be allocated
starting with slice zero and increasing monatomically with each
additional domain.
NOTE: This algorithm is non-deterministic (it depends on the
order that users and groups are requested). If this mode is
required for compatibility with machines running winbind, it is
recommended to also use the "ldap_idmap_default_domain_sid"
option to guarantee that at least one domain is consistently
allocated to slice zero.
Default: False
ldap_idmap_helper_table_size (integer)
Maximal number of secondary slices that is tried when
performing mapping from UNIX id to SID.
Note: Additional secondary slices might be generated when SID
is being mapped to UNIX id and RID part of SID is out of range
for secondary slices generated so far. If value of
ldap_idmap_helper_table_size is equal to 0 then no additional
secondary slices are generated.
Default: 10
Well-Known SIDs
SSSD supports to look up the names of Well-Known SIDs, i.e. SIDs with a
special hardcoded meaning. Since the generic users and groups related
to those Well-Known SIDs have no equivalent in a Linux/UNIX environment
no POSIX IDs are available for those objects.
The SID name space is organized in authorities which can be seen as
different domains. The authorities for the Well-Known SIDs are
* Null Authority
* World Authority
* Local Authority
* Creator Authority
* NT Authority
* Built-in
The capitalized version of these names are used as domain names when
returning the fully qualified name of a Well-Known SID.
Since some utilities allow to modify SID based access control
information with the help of a name instead of using the SID directly
SSSD supports to look up the SID by the name as well. To avoid
collisions only the fully qualified names can be used to look up
Well-Known SIDs. As a result the domain names "NULL AUTHORITY", "WORLD
AUTHORITY", " LOCAL AUTHORITY", "CREATOR AUTHORITY", "NT AUTHORITY" and
"BUILTIN" should not be used as domain names in sssd.conf.
EXAMPLE
The following example assumes that SSSD is correctly configured and
example.com is one of the domains in the [sssd] section. This example
shows only the AD provider-specific options.
[domain/EXAMPLE]
id_provider = ad
auth_provider = ad
access_provider = ad
chpass_provider = ad
ad_server = dc1.example.com
ad_hostname = client.example.com
ad_domain = example.com
NOTES
The AD access control provider checks if the account is expired. It has
the same effect as the following configuration of the LDAP provider:
access_provider = ldap
ldap_access_order = expire
ldap_account_expire_policy = ad
However, unless the "ad" access control provider is explicitly
configured, the default access provider is "permit". Please note that
if you configure an access provider other than "ad", you need to set
all the connection parameters (such as LDAP URIs and encryption
details) manually.
When the autofs provider is set to "ad", the RFC2307 schema attribute
mapping (nisMap, nisObject, ...) is used, because these attributes are
included the default Active Directory schema.
SEE ALSO
sssd(8), sssd.conf(5), sssd-ldap(5), sssd-krb5(5), sssd-simple(5), sssd-ipa(5), sssd-ad(5), sssd-sudo(5), sss_cache(8), sss_debuglevel(8), sss_groupadd(8), sss_groupdel(8), sss_groupshow(8), sss_groupmod(8), sss_useradd(8), sss_userdel(8), sss_usermod(8), sss_obfuscate(8), sss_seed(8), sssd_krb5_locator_plugin(8), sss_ssh_authorizedkeys(8), sss_ssh_knownhostsproxy(8), sssd-ifp(5), pam_sss(8). sss_rpcidmapd(5)
AUTHORS
The SSSD upstream - http://fedorahosted.org/sssd
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
