CIFS Shares

A shared resource, or share, is a local resource on a server that is accessible to CIFS clients on the network. For the Solaris CIFS service, a share is typically a directory. Each share is identified by a name on the network. A CIFS client sees the share as a complete entity on the CIFS server, and does not see the local directory path to the share on the server.

Note - A share and a directory are independent entities. Removing a share does not affect the underlying directory.

Shares are commonly used to provide network access to home directories on a network file server. Each user is assigned a home directory. A share is persistent and remains defined regardless of whether users are connected to the server.

The Solaris CIFS service provides a special kind of share called an autohome CIFS share. An autohome share is a transient share of a user's home directory that is created when a user logs in and removed when the user logs out.

When a user browses the system, only statically defined shares and his autohome share will be listed.

Autohome Shares

The autohome share feature eliminates the administrative task of defining and maintaining home directory shares for each user that accesses the system through the SMB protocol. The system creates autohome shares when a user logs in, and removes them when the user logs out. This process reduces the administrative effort needed to maintain user accounts, and increases the efficiency of service resources.

For example, if /home is a home directory that contains subdirectories for users bob and sally, you can manually define the shares as follows:

bob: /home/bob
sally: /home/sally

However, defining and maintaining directory shares in this way for each user is inconvenient. Instead, you can use the autohome feature.

Note - The Solaris CIFS client does not support autohome shares.

To configure the autohome feature, you need to specify autohome share rules. For example, if a user's home directory is /fort/sally, the autohome path is /fort. The temporary share is named sally. Note that the user's home directory name must be the same as the user's login name. See How to Create a Specific Autohome Share Rule.

When a user logs in, the Solaris CIFS service looks for a subdirectory that matches the user's name based on any rules that have been specified. If the service finds a match and if that share does not already exist, the subdirectory is added as a transient share. When the user logs out, the service removes that transient share.

Some Windows clients log a user out after 15 minutes of inactivity, which results in the autohome share disappearing from the list of defined shares. This behavior is expected for CIFS autohome shares. Even after a CIFS autohome share is removed, the share reappears when the user attempts to access the system (for example, in an Explorer window).

Note - All autohome shares are removed when the Solaris CIFS service is restarted.

Autohome Entries

The Solaris CIFS service can automatically share home directories when a CIFS client connects. The autohome map file, /etc/smbautohome, uses the search options and rules to determine whether to share a home directory when a CIFS client connects to the service.

For example, the following entries specify the autohome rules for a particular environment:

+nsswitch        dn=ads,dn=sun,dn=com,ou=users
jane    /home/?/&    dn=ads,dn=sun,dn=com,ou=users

The nsswitch autohome entry uses the naming service to match users to home directories. The second autohome entry specifies that the home directory for user jane is /home/j/jane.

Autohome Map Entry Format

A map entry, also referred to as a mapping, uses the following format:

key location [ container ]

key is a user name, location is the fully qualified path for the user's home directory, and container is an optional AD container.

If you intend to publish the share in AD, you must specify an AD container name, which is specified as a comma-separated list of attribute name-value pairs. The attributes use the Lightweight Data Access Protocol (LDAP) distinguished name (DN) or relative distinguished name (RDN) format.

The DN or RDN must be specified in LDAP format by using the following attribute types:

cn= represents the common name
ou= represents the organizational unit
dc= represents the domain component

Note - The attribute type that is used to describe an object's RDN is called a naming attribute.

AD uses the naming attributes as follows:

cn for the user object class
ou for the OU (organizational unit) object class
dc for the domainDns object class

Autohome Map Key Substitution

The autohome feature supports the following wildcard substitutions for the value of the key field:

The ampersand character (&) is expanded to the value of the key field for the entry in which it occurs. In the following example, & expands to jane:
```
jane /home/&
```
The question mark character (?) is expanded to the value of the first character in the key field for the entry in which it occurs. In the following example, the path is expanded to /home/jj/jane:
```
jane /home/??/&
```

Wildcard Rule

When supplied in the key field, the asterisk character (*) is recognized as the “catch-all” entry. Such an entry matches any key not previously matched.

For example, the following entry would map any user to a home directory in /home in which the home directory name was the same as the user name:

*    /home/&

Note - The wildcard rule is only applied if an appropriate rule is not matched by another map entry.

`nsswitch` Map

The nsswitch map is used to request that the home directory be obtained from a password database, such as the local, NIS, or LDAP database. If an AD path is appended, it is used to publish shares.

+nsswitch

Like the “catch-all” entry, the nsswitch map is only searched if an appropriate rule is not matched by another map entry.

Note - The wildcard and nsswitch rules are mutually exclusive. Do not include an nsswitch rule if a wildcard rule has already been defined.