nisaddcred Command

Purpose

Creates NIS+ credential information.

Syntax

nisaddcred [ -p principal ] [ -P nis_principal ] [ -l login_password ] auth_type [ domain_name ]

nisaddcred -r [ nis_principal ] [ domain_name ]

Description

The nisaddcred command is used to create security credentials for NIS+ principals. NIS+ credentials serve two purposes. The first is to provide authentication information to various services; the second is to map the authentication service name into a NIS+ principal name.

When the nisaddcred command is run, these credentials get created and stored in a table named cred.org_dir in the default NIS+ domain. If domain_name is specified, the entries are stored in the cred.org_dir of the specified domain. The specified domain must either be the one to which you belong or one in which you are authenticated and authorized to create credentials, that is, a subdomain. Credentials of normal users must be stored in the same domain as their passwords.

It is simpler to add credentials using the nisclient command because it obtains the required information itself. The nispopulate command is used for bulk updates and can also be used to add credentials for entries in the hosts and the passwd NIS+ tables.

NIS+ principal names are used in specifying clients that have access rights to NIS+ objects. Various other services can also implement access control based on these principal names.

The cred.org_dir table is organized as follows :

Item Description
cname auth_type auth_name public_data private_data
user1.foo.com. LOCAL 2990 10,102,44  
user1.foo.com. DES unix.2990@foo.com 098...819 3b8...ab2

The cname column contains a canonical representation of the NIS+ principal name. By convention, this name is the login name of a user or the host name of a machine followed by a dot ('.') followed by the fully qualified home domain of that principal. For users, the home domain is defined to be the domain where their DES credentials are kept. For hosts, their home domain is defined to be the domain name returned by the domainname command executed on that host.

There are two types of auth_type entries in the cred.org_dir table. Those with authentication type LOCAL and those with authentication type DES. auth_type, specified on the command line in upper or lower case, should be either local or des.

Entries of type LOCAL are used by the NIS+ service to determine the correspondence between fully qualified NIS+ principal names and users identified by UIDs in the domain containing the cred.org_dir table. This correspondence is required when associating requests made using the AUTH_SYS RPC authentication flavor to a NIS+ principal name. It is also required for mapping a UID in one domain to its fully qualified NIS+ principal name whose home domain may be elsewhere. The principal's credentials for any authentication flavor may then be sought for within the cred.org_dir table in the principal's home domain (extracted from the principal name). The same NIS+ principal may have LOCAL credential entries in more than one domain. Only users, and not machines, have LOCAL credentials. In their home domain, users of NIS+ should have both types of credentials.

The auth_name associated with the LOCAL type entry is a UID that is valid for the principal in the domain containing the cred.org_dir table. This may differ from that in the principal's home domain. The public information stored in public_data for this type contains a list of GIDs for groups in which the user is a member. The GIDs also apply to the domain in which the table resides. There is no private data associated with this type. Neither a UID nor a principal name should appear more than once among the LOCAL entries in any one cred.org_dir table.

The DES auth_type is used for Secure RPC authentication.

The authentication name associated with the DES auth_type is a Secure RPC netname. A Secure RPC netname has the form unix.id@domain.com, where domain must be the same as the domain of the principal. For principals that are users, the id must be the UID of the principal in the principal's home domain. For principals that are hosts, the id is the host's name. In Secure RPC, processes running under effective UID 0 (root) are identified with the host principal. Unlike LOCAL, there cannot be more than one DES credential entry for one NIS+ principal in the NIS+ namespace.

The public information in an entry of authentication type DES is the public key for the principal. The private information in this entry is the private key of the principal encrypted by the principal's network password.

User clients of NIS+ should have credentials of both types in their home domain. In addition, a principal must have a LOCAL entry in the cred.org_dir table of each domain from which the principal wishes to make authenticated requests. A client of NIS+ that makes a request from a domain in which it does not have a LOCAL entry is unable to acquire DES credentials. A NIS+ service running at security level 2 or higher considers such users unauthenticated and assign them the name nobody for determining access rights.

This command can only be run by those NIS+ principals who are authorized to add or delete the entries in the cred table.

If credentials are being added for the caller itself, nisaddcred automatically performs a keylogin for the caller.

You can list the cred entries for a particular principal with nismatch.

Flags

Item Description
-l login_password Use the login_password specified as the password to encrypt the secret key for the credential entry. This overrides the prompting for a password from the shell. This flag is intended for administration scripts only. Prompting guarantees not only that no one can see your password on the command line using the ps command, but it also checks to make sure you have not made any mistakes.
Note: login_password does not have to be the user's password; but, if it is, it simplifies logging in.
-p principal Specifies the name of the principal as defined by the naming rules for that specific mechanism. For example, LOCAL credential names are supplied with this flag by including a string specifying a UID. For DES credentials, the name should be a Secure RPC netname of the form unix.id@domain.com, as described earlier. If the -p flag is not specified, the auth_name field is constructed from the effective UID of the current process and the name of the local domain.
-P nis_principal Use the NIS+ principal name nis_principal. This flag should be used when creating LOCAL or DES credentials for users whose home domain is different than the local machine's default domain. Whenever the -P flag is not specified, nisaddcred constructs a principal name for the entry as follows. When it is not creating an entry of type LOCAL, nisaddcred calls nis_local_principal, which looks for an existing LOCAL entry for the effective UID of the current process in the cred.org_dir table and uses the associated principal name for the new entry. When creating an entry of authentication type LOCAL, nisaddcred constructs a default NIS+ principal name by taking the login name of the effective UID for its own process and appending to it a dot ('.') followed by the local machine's default domain. If the caller is a superuser, the machine name is used instead of the login name.
-r [ nis_principal ] Remove all credentials associated with the principal nis_principal from the cred.org_dir table. This flag can be used when removing a client or user from the system. If nis_principal is not specified, the default is to remove credentials for the current user. If domain_name is not specified, the operation is executed in the default NIS+ domain.

Exit Status

This command returns the following exit values:

Item Description
0 Success
1 Failure

Examples

  1. To add the LOCAL and DES credentials for some user, user1, with a UID of 2990, who is an NIS+ user principal in the some.domain.com. NIS+ domain, enter: 
    nisaddcred -p 2990 -P user1.some.domain.com. local

    Credentials are always added in the cred.org_dir table in the domain where nisaddcred is run, unless domain_name is specified as the last parameter on the command line. If credentials are being added from the domain server for its clients, then domain_name should be specified. The caller should have adequate permissions to create entries in the cred.org_dir table.

  2. To add a DES credential for the same user, the system administrator can enter: 
    nisaddcred -p unix.2990@some.domain.com -P user1.some.domain.com. des

    DES credentials can be added only after the LOCAL credentials have been added. The secure RPC netname does not end with a dot ('.') while the NIS+ principal name (specified with the -P flag) does. This command should be executed from a machine in the same domain as is the user.

  3. To add a machine's DES credentials in the same domain, enter: 
    nisaddcred -p unix.foo@some.domain.com -P foo.some.domain.com. des

    No LOCAL credentials are needed in this case.

  4. To add a NIS+ workstation's principal DES credential, enter: 
    nisaddcred -p unix.host1@sub.some.domain.com \
-P newhost.sub.some.domain.com. des sub.some.domain.com.

    This format is particularly useful if you are running this command from a server that is in a higher domain than sub.some.domain.com. Without the last option for domain name, nisaddcred would fail because it would attempt to use the default domain of some.domain.com.

  5. To add DES credentials without being prompted for the root login password, enter: 
    nisaddcred -p unix.2990@some.domain.com -P user1.some.domain.com. -l
login_password des