illumos: manual page: idmap.8

IDMAP(8) Maintenance Commands and Procedures IDMAP(8)

NAME

idmap - configure and manage the Native Identity Mapping service

SYNOPSIS

idmap

idmap -f command-file

idmap add [-d] name1 name2

idmap dump [-n] [-v]

idmap export [-f file] format

idmap get-namemap name

idmap help

idmap import [-F] [-f file] format

idmap list

idmap remove [-t|-f] name

idmap remove -a

idmap remove [-d] name1 name2

idmap set-namemap [-a authenticationMethod] [-D bindDN]
[-j passwdfile] name1 name2

idmap show [-c] [-v] identity [target-type]

idmap unset-namemap [-a authenticationMethod] [-D bindDN]
[-j passwdfile] name [target-type]

DESCRIPTION

The idmap utility is used to configure and manage the Native Identity
Mapping service.

The Native Identity Mapping service supports the following types of
mappings between Windows security identities (SIDs) and POSIX user IDs
and group IDs (UIDs and GIDs):

o Name-based mapping. An administrator maps Windows and UNIX
users and groups by name.

o Ephemeral ID mapping. A UID or GID is dynamically allocated
for every SID that is not already mapped by name.

o Local-SID mapping. A non-ephemeral UID or GID is mapped to an
algorithmically generated local SID.

The idmap utility can be used to create and manage the name-based
mappings and to monitor the mappings in effect.

If the idmap utility is invoked without a subcommand or option, it reads
the subcommands from standard input. When standard input is a TTY, the
idmap command prints the usage message and exits.

Mapping Mechanisms

The idmapd(8) daemon maps Windows user and group SIDs to UNIX UIDs and
GIDs as follows:

1. SIDs are mapped by name.

This mapping uses the name-based mappings that are manually
set up by the system administrator.

2. If no name-based mapping is found, the SID is mapped to a
dynamically allocated ephemeral ID.

This allocation uses the next available UID or GID from 2^31
to 2^32 - 2.

Local SID mappings are used to map from UNIX to Windows.

To prevent aliasing problems, all file systems, archive and backup
formats, and protocols must store SIDs or map all UIDs and GIDs in the
2^31 to 2^32 - 2 range to the nobody user and group.

It is possible to create also diagonal mappings. They are the mappings
between Windows groups and Solaris users and between Solaris groups and
Windows users. They are needed when Windows uses a group identity as a
file owner or vice versa.

Name-based Mappings
Name-based mappings establish name equivalence between Windows users and
groups and their counterparts in the UNIX name service. These mappings
persist across reboots. For example, the following command maps Windows
users to UNIX users with the same name:

# idmap add "winuser:*@example.com" "unixuser:*"

If configured to use a directory service, idmapd(8) will first try to use
the mapping information that is stored in user or group objects in the
Active Directory (AD) and/or the native LDAP directory service. For
example, an AD object for a given Windows user or group can be augmented
to include the corresponding Solaris user or group name or numeric id.
Similarly, the native LDAP object for a given Solaris user or group can
be augmented to include the corresponding Windows user or group name.

idmapd(8) can be configured to use AD and/or native LDAP directory-based
name mappings by setting the appropriate service management facility
(SMF) properties of the idmap service. See "Service Properties," below,
for more details.

If directory-based name mapping is not configured or if configured but
not found, then idmapd(8) will process locally stored name-based mapping
rules.

idmap supports the mapping of Windows well-known names. A few of these
are listed below:

Administrator
Guest
KRBTGT
Domain Admins
Domain Users
Domain Guest
Domain Computers
Domain Controllers

When idmap rules are added, these well-known names will be expanded to
canonical form. That is, either the default domain name will be added
(for names that are not well-known) or an appropriate built-in domain
name will be added. Depending on the particular well-known name, this
domain name might be null, BUILTIN, or the local host name.

The following sequence of idmap commands illustrate the treatment of the
non-well-known name fred and the well-known names administrator and
guest.

# idmap add winname:fred unixuser:fredf
add winname:fred unixuser:fredf

# idmap add winname:administrator unixuser:root
add winname:administrator unixuser:root

# idmap add winname:guest unixuser:nobody
add winname:guest unixuser:nobody

# idmap add wingroup:administrators sysadmin
add wingroup:administrators unixgroup:sysadmin

# idmap list
add winname:Administrator@examplehost unixuser:root
add winname:Guest@examplehost unixuser:nobody
add wingroup:Administrators@BUILTIN unixgroup:sysadmin
add winname:fred@example.com unixuser:fredf

Ephemeral Mappings

The idmapd daemon attempts to preserve ephemeral ID mappings across
daemon restarts. However, when IDs cannot be preserved, the daemon maps
each previously mapped SID to a new ephemeral UID or GID value. The
daemon will never re-use ephemeral UIDs or GIDs. If the idmapd daemon
runs out of ephemeral UIDs and GIDs, it returns an error as well as a
default UID or GID for SIDs that cannot be mapped by name.

The dynamic ID mappings are not retained across reboots. So, any SIDs
that are dynamically mapped to UNIX UIDs or GIDs are most likely mapped
to different IDs after rebooting the system.

Local SID Mappings

If no name-based mapping is found, a non-ephemeral UID or GID is mapped
to an algorithmically generated local SID. The mapping is generated as
follows:

local SID for UID = <machine SID> - <1000 + UID>
local SID for GID = <machine SID> - <2^31 + GID>

<machine SID> is a unique SID generated by the idmap service for the host
on which it runs.

Rule Lookup Order

When mapping a Windows name to a UNIX name, lookup for name-based mapping
rules is performed in the following order:

1. windows-name@domain to ""

2. windows-name@domain to unix-name

3. windows-name@* to ""

4. windows-name@* to unix-name

5. *@domain to *

6. *@domain to ""

7. *@domain to unix-name

8. *@* to *

9. *@* to ""

10. *@* to unix-name

When mapping a UNIX name to a Windows name, lookup for name-based mapping
rules is performed in the following order:

1. unix-name to ""

2. unix-name to windows-name@domain

3. * to *@domain

4. * to ""

5. * to windows-name@domain

Service Properties

The service properties determine the behavior of the idmapd(8) daemon.
These properties are stored in the SMF repository (see smf(7)) under
property group config. They can be accessed and modified using svccfg(8),
which requires solaris.smf.value.idmap authorization. The service
properties for the idmap service are:

config/ad_unixuser_attr

Specify the name of the AD attribute that contains the UNIX user
name. There is no default.

config/ad_unixgroup_attr

Specify the name of the AD attribute that contains the UNIX group
name. There is no default.

config/nldap_winname_attr

Specify the name of the Native LDAP attribute that contains the
Windows user/group name. There is no default.

config/directory_based_mapping

Controls support for identity mapping using data stored in a
directory service.

none disables directory-based mapping.

name enables name-based mapping using the properties described above.

idmu enables mapping using Microsoft's Identity Management for UNIX
(IDMU). This Windows component allows the administrator to specify a
UNIX user ID for each Windows user, mapping the Windows identity to
the corresponding UNIX identity. Only IDMU data from the domain the
Solaris system is a member of is used.

Changes to service properties do not affect a running idmap service. The
service must be refreshed (with svcadm(8)) for the changes to take
effect.

OPERANDS

The idmap command uses the following operands:

format

Specifies the format in which user name mappings are described for
the export and import subcommands. The Netapp usermap.cfg and Samba
smbusers external formats are supported. These external formats are
only for users, not groups.

o The usermap.cfg rule-mapping format is as follows:

windows-username [direction] unix-username

windows-username is a Windows user name in either the
domain\username or username@domain format.

unix-username is a UNIX user name.

direction is one of the following:

o == means a bidirectional mapping, which is the
default.

o => or <= means a unidirectional mapping.
The IP qualifier is not supported.

o The smbusers rule-mapping format is as follows:

unixname = winname1 winname2 ...

If winname includes whitespace, escape the whitespace by
enclosing the value in double quotes. For example, the
following file shows how to specify whitespace in a valid
format for the idmap command:

$ cat myusermap
terry="Terry Maddox"
pat="Pat Flynn"
cal=cbrown

The mappings are imported as unidirectional mappings from
Windows names to UNIX names.

The format is based on the "username map" entry of the
smb.conf man page, which is available on the samba.org web
site. The use of an asterisk (*) for windows-name is
supported. However, the @group directive and the chaining
of mappings are not supported.

By default, if no mapping entries are in the smbusers
file, Samba maps a windows-name to the equivalent unix-
name, if any. If you want to set up the same mapping as
Samba does, use the following idmap command:

idmap add -d "winuser:*@*" "unixuser:*"

identity

Specifies a user name, user ID, group name, or group ID. identity is
specified as type:value. type is one of the following:

usid
Windows user SID in text format

gsid
Windows group SID in text format

sid
Windows group SID in text format that can belong either
to a user or to a group

uid
Numeric POSIX UID

gid
Numeric POSIX GID

unixuser
UNIX user name

unixgroup
UNIX group name

winuser
Windows user name

wingroup
Windows group name

winname
Windows user or group name

value is a number or string that is appropriate to the specified
type. For instance, unixgroup:staff specifies the UNIX group name,
staff. The identity gid:10 represents GID 10, which corresponds to
the UNIX group staff.

name

Specifies a UNIX name (unixuser, unixgroup) or a Windows name
(winuser, wingroup) that can be used for name-based mapping rules.

A Windows security entity name can be specified in one of these ways:

o domain\name

o name@domain

o name, which uses the default mapping domain
If name is the empty string (""), mapping is inhibited. Note that a
name of "" should not be used to preclude logins by unmapped Windows
users.

If name uses the wildcard (*), it matches all names that are not
matched by other mappings. Similarly, if name is the wildcard Windows
name (*@*), it matches all names in all domains that are not matched
by other mappings.

If name uses the wildcard on both sides of the mapping rule, the name
is the same for both Windows and Solaris users. For example, if the
rule is "*@domain" == "*", the jp@domain Windows user name matches
this rule and maps to the jp Solaris user name.

Specifying the type of name is optional if the type can be deduced
from other arguments or types specified on the command line.

target-type

Used with the show and unset-namemap subcommands. For show, specifies
the mapping type that should be shown. For example, if target-type is
sid, idmap show returns the SID mapped to the identity specified on
the command line. For unset-namemap, identifies an attribute within
the object specified by the name operand.

OPTIONS

The idmap command supports one option and a set of subcommands. The
subcommands also have options.

Command-Line Option
-f command-file

Reads and executes idmap subcommands from command-file. The idmap -f
- command reads from standard input. This option is not used by any
subcommands.

Subcommands

The following subcommands are supported:

add [-d] name1 name2

Adds a name-based mapping rule. By default, the name mapping is
bidirectional. If the -d option is used, a unidirectional mapping is
created from name1 to name2.

Either name1 or name2 must be a Windows name, and the other must be a
UNIX name. For the Windows name, the winname identity type must not
be used. Instead, specify one of the winuser or wingroup types. See
"Operands" for information about the name operand.

Note that two unidirectional mappings between the same two names in
two opposite directions are equivalent to one bidirectional mapping.

This subcommand requires the solaris.admin.idmap.rules authorization.

dump [-n] [-v]

Dumps all the mappings cached since the last system boot. The -n
option shows the names, as well. By default, only sids, uids, and
gids are shown. The -v option shows how the mappings were generated.

export [-f file] format

Exports name-based mapping rules to standard output in the specified
format. The -f file option writes the rules to the specified output
file.

get-namemap name

Get the directory-based name mapping information from the AD or
native LDAP user or group object represented by the specified name.

help

Displays the usage message.

import [-F] [-f file] format

Imports name-based mapping rules from standard input by using the
specified format. The -f file option reads the rules from the
specified file. The -F option flushes existing name-based mapping
rules before adding new ones.

Regardless of the external format used, the imported rules are
processed by using the semantics and order described in the section
"Rule Lookup Order," above.

This subcommand requires the solaris.admin.idmap.rules authorization.

list

Lists all name-based mapping rules. Each rule appears in its idmap
add form.

remove [-t|-f] name

Removes any name-based mapping rule that involves the specified name.
name can be either a UNIX or Windows user name or group name.

The -f option removes rules that use name as the source. The -t
option removes rules that use name as the destination. These options
are mutually exclusive.

This subcommand requires the solaris.admin.idmap.rules authorization.

remove -a

Removes all name-based mapping rules.

This subcommand requires the solaris.admin.idmap.rules authorization.

remove [-d] name1 name2

Removes name-based mapping rules between name1 and name2. If the -d
option is specified, rules from name1 to name2 are removed.

Either name1 or name2 must be a Windows name, and the other must be a
UNIX name.

This subcommand requires the solaris.admin.idmap.rules authorization.

set-namemap [-a authenticationMethod] [-D bindDN] [-j passwdfile] name1
name2

Sets name mapping information in the AD or native LDAP user or group
object. Either name1 or name2 must be a Windows name, and the other
must be a UNIX name.

If name1 is a Windows name, then the UNIX name name2 is added to the
AD object represented by name1. Similarly, if name1 is a UNIX name
then the Windows name name2 is added to the native LDAP entry
represented by name1.

The following options are supported:

-a authenticationMethod

Specify authentication method when modifying native LDAP entry.
See ldapaddent(8) for details. Default value is sasl/GSSAPI.

-D bindDN

Uses the distinguished name bindDN to bind to the directory.

-j passwdfile

Specify a file containing the password for authentication to the
directory.

show [-c] [-v] name [target-type]

Shows the identity of type, target-type, that the specified name maps
to. If the optional target-type is omitted, the non-diagonal mapping
is shown.

By default, this subcommand shows only mappings that have been
established already. The -c option forces the evaluation of name-
based mapping configurations or the dynamic allocation of IDs.

The -v option shows how the mapping was generated and also whether
the mapping was just generated or was retrieved from the cache.

unset-namemap [-a authenticationMethod] [-D bindDN] [-j passwdfile] name
[target-type]

Unsets directory-based name mapping information from the AD or native
LDAP user or group object represented by the specified name and
optional target type.

See the set-namemap subcommand for options.

EXAMPLES

Example 1: Using a Wildcard on Both Sides of a Name-Based Mapping Rule

The following command maps all Windows user names in the example.com
domain to the UNIX users with the same names provided that one exists and
is not otherwise mapped. If such a rule is matched but the UNIX user name
does not exist, an ephemeral ID mapping is used.

# idmap add "winuser:*@example.com" "unixuser:*"

Example 2: Using a Wildcard on One Side of a Name-Based Mapping Rule

The following command maps all unmapped Windows users in the example.com
domain to the guest UNIX user. The -d option specifies a unidirectional
mapping from *@example.com users to the guest user.

# idmap add -d "winuser:*@example.com" unixuser:guest

Example 3: Adding a Bidirectional Name-Based Mapping Rule

The following command maps Windows user, foobar@example.com, to UNIX
user, foo, and conversely:

# idmap add winuser:foobar@example.com unixuser:foo

This command shows how to remove the mapping added by the previous
command:

# idmap remove winuser:foobar@example.com unixuser:foo

Example 4: Showing a UID-to-SID Mapping

o The following command shows the SID that the specified UID,
uid:50000, maps to:

# idmap show uid:50000 sid
uid:50000 -> usid:S-1-5-21-3223191800-2000

o The following command shows the UNIX user name that the
specified Windows user name, joe@example.com, maps to:

# idmap show joe@example.com unixuser
winuser:joe@example.com -> unixuser:joes

Example 5: Listing the Cached SID-to-UID Mappings

The following command shows all of the SID-to-UID mappings that are in
the cache:

# idmap dump | grep "uid:"
usid:S-1-5-21-3223191800-2000 == uid:50000
usid:S-1-5-21-3223191800-2001 == uid:50001
usid:S-1-5-21-3223191800-2006 == uid:50010
usid:S-1-5-21-3223191900-3000 == uid:2147491840
usid:S-1-5-21-3223191700-4000 => uid:60001

Example 6: Batching idmap Requests

The following commands show how to batch idmap requests. This particular
command sequence does the following:

o Removes any previous rules for foobar@example.com.

o Maps Windows user foobar@example.com to UNIX user bar and
vice-versa.

o Maps Windows group members to UNIX group staff and vice-versa.

# idmap <<EOF
remove winuser:foobar@example.com
add winuser:foobar@example.com unixuser:bar
add wingroup:members unixgroup:staff
EOF

Example 7: Listing Name-Based Mapping Rules

The following command shows how to list the name-based mapping rules:

# idmap list
add winuser:foobar@example.com unixuser:bar
add wingroup:members unixgroup:staff

Example 8: Importing Name-Based Mapping Rules From the usermap.cfg File

The usermap.cfg file can be used to configure name-based mapping rules.
The following usermap.cfg file shows mapping rules that map Windows user
foo@example.com to UNIX user foo, and that map foobar@example.com to the
UNIX user foo.

# cat usermap.cfg
foo@example.com == foo
foobar@example.com => foo

The following idmap command imports usermap.cfg information to the idmapd
database:

# cat usermap.cfg | idmap import usermap.cfg

This command does the same as the previous command:

# idmap import -f usermap.cfg usermap.cfg

The following commands are equivalent to the previous idmap import
commands:

# idmap <<EOF
add winuser:foo@example.com unixuser:foo
add -d winuser:foobar@example.com unixuser:foo
EOF

Example 9: Using Name-Based and Ephemeral ID Mapping With Identity

Function Mapping and Exceptions

The following commands map all users in the example.com Windows domain to
UNIX user accounts of the same name. The command also specifies mappings
for the following Windows users: joe@example.com, jane.doe@example.com,
administrator@example.com. The administrator from all domains is mapped
to nobody. Any Windows users without corresponding UNIX accounts are
mapped dynamically to available ephemeral UIDs.

# idmap import usermap.cfg <<EOF
joe@example.com == joes
jane.doe@example.com == janed
administrator@* => nobody
*@example.com == *
*@example.com => nobody
EOF

Example 10: Adding Directory-based Name Mapping to AD User Object

The following command maps Windows user joe@example.com to UNIX user joe
by adding the UNIX name to AD object for joe@example.com.

# idmap set-namemap winuser:joe@example.com joes

Example 11: Adding Directory-based Name Mapping to Native LDAP User Object

The following command maps UNIX user foo to Windows user
foobar@example.com by adding the Windows name to native LDAP object for
foo.

# idmap set-namemap unixuser:foo foobar@example.com

Example 12: Removing Directory-based Name Mapping from AD User Object

The following command removes the UNIX username unixuser from the AD
object representing joe@example.com.

# idmap unset-namemap winuser:joe@example.com unixuser

EXIT STATUS

0
Successful completion.

>0
An error occurred. A diagnostic message is written to standard
error.

ATTRIBUTES

NOTES

The idmapd service is managed by the service management facility, smf(7).
The service identifier for the idmapd service is svc:/system/idmap.

Use the svcadm command to perform administrative actions on this service,
such as enabling, disabling, or restarting the service. These actions
require the solaris.smf.manage.idmap authorization. Use the svcs command
to query the service's status.

Windows user names are case-insensitive, while UNIX user names are case-
sensitive. The case of Windows names as they appear in idmap name-rules
and idmap show command lines is irrelevant.

Because common practice in UNIX environments is to use all-lowercase user
names, wildcard name-rules map Windows names to UNIX user/group names as
follows: first, the canonical Windows name (that is, in the case as it
appears in the directory) is used as a UNIX user or group name. If there
is no such UNIX entity, then the Windows name's case is folded to
lowercase and the result is used as the UNIX user or group name.

As a result of this differing treatment of case, user names that appear
to be alike might not be recognized as matches. You must create rules to
handle such pairings of strings that differ only in case. For example, to
map the Windows user sam@example to the Solaris user Sam, you must create
the following rules:

# idmap add "winuser:*@example" "unixuser:*"
# idmap add winuser:sam@example unixuser:Sam

For guidance on modifying an Active Directory schema, consult the
Microsoft document, Step-by-Step Guide to Using Active Directory Schema
and Display Specifiers, which you can find at their technet web site,
http://technet.microsoft.com/.

November 22, 2021 IDMAP(8)