System Administration Guide: Naming and Directory Services (NIS+)

NIS+ Security Problems

This section describes common password, credential, encryption, and other security-related problems.

NIS+ Security Problem Symptoms

Error messages with operative clauses such as:

User or root unable to perform any namespace operations or tasks. (See also NIS+ Ownership and Permission Problems.)

Login Incorrect Message

The most common cause of a “login incorrect” message is the user mistyping the password. Have the user try it again. Make sure the user knows the correct password and understands that passwords are case-sensitive and also that the letter “o” is not interchangeable with the numeral “0,” nor is the letter “l” the same as the numeral “1.”

Other possible causes of the “login incorrect” message are:

See Chapter 16, Administering NIS+ Passwords for general information on passwords.

Password Locked, Expired, or Terminated

A common cause of a Permission denied, password expired, type message is that the user's password has passed its age limit or the user's password privileges have expired. See Chapter 16, Administering NIS+ Passwords for general information on passwords.

Stale and Outdated NIS+ Credential Information

Occasionally, you may find that even though you have created the proper credentials and assigned the proper access rights, some client requests still get denied. This may be due to out-of-date information residing somewhere in the namespace.

Storing and Updating NIS+ Credential Information

Credential-related information, such as public keys, is stored in many locations throughout the namespace. NIS+ updates this information periodically, depending on the time-to-live values of the objects that store it, but sometimes, between updates, it gets out of sync. As a result, you may find that operations that should work, don't work. Table 24–2 lists all the objects, tables, and files that store credential-related information and how to reset it.

Table 24–2 Where NIS+ Credential-Related Information Is Stored



To Reset or Change 

cred table 

NIS+ principal's secret key and public key. These are the master copies of these keys. 

Use nisaddcred to create new credentials; it updates existing credentials. An alternative is chkey.

Directory object 

A copy of the public key of each server that supports it. 

Run the /usr/lib/nis/nisupdkeys command on the directory object.


The secret key of the NIS+ principal that is currently logged in. 

Run keylogin for a principal user or keylogin -r for a principal machine.

NIS+ daemon 

Copies of directory objects, which in turn contain copies of their servers' public keys. 

Stop the rpc.nisd daemon and the cache manager by disabling the NIS+ service, and then remove NIS_SHARED_DIRCACHE from /var/nis. Then restart the NIS+ service.

Directory cache 

A copy of directory objects, which in turn contain copies of their servers' public keys. 

Restart the NIS+ cache manager with the -i option.

Cold-start file 

A copy of a directory object, which in turn contains copies of its servers' public keys. 

Stop the NIS+ service. Remove the NIS_COLD_START and NIS_SHARED_DIRCACHE files from /var/nis. Restart the NIS+ service.

passwd table 

A user's password or a machine's superuser password. 

Use the passwd -r nisplus command. It changes the password in the NIS+ passwd table and updates it in the cred table.

passwd file

A user's password or a machine's superuser password. 

Use the passwd -r nisplus command, whether logged in as superuser or as yourself, whichever is appropriate.

passwd map


A user's password or a machine's superuser password. 

Use passwd -r nisplus.

Updating Stale Cached NIS+ Keys

The most commonly encountered out-of-date information is the existence of stale objects with old versions of a server's public key. You can usually correct this problem by running nisupdkeys on the domain you are trying to access. (See Chapter 12, Administering NIS+ Credentials for information on using the nisupdkeys command.)

Because some keys are stored in files or caches, nisupdkeys cannot always correct the problem. At times you might need to update the keys manually. To do that, you must understand how a server's public key, once created, is propagated through namespace objects. The process usually has five stages of propagation. Each stage is described below.

Stage 1: Server's Public Key Is Generated

An NIS+ server is first an NIS+ client. So, its public key is generated in the same way as any other NIS+ client's public key: with the nisaddcred command. The public key is then stored in the cred table of the server's home domain, not of the domain the server will eventually support.

Stage 2: Public Key Is Propagated to Directory Objects

Once you have set up an NIS+ domain and an NIS+ server, you can associate the server with a domain. This association is performed by the nismkdir command. When the nismkdir command associates the server with the directory, it also copies the server's public key from the cred table to the domain's directory object. For example, assume the server is a client of the root domain, and is made the master server of the domain.

Figure 24–1 Public Key Is Propagated to NIS+ Directory Objects

Graphic illustrates a public key copied from the
domain and placed in the directory object.

Its public key is copied from the domain and placed in the directory object. This can be verified with the niscat -o command.

Stage 3: Directory Objects Are Propagated Into Client Files

All NIS+ clients are initialized with the nisinit utility or with the nisclient script.

Among other things, nisinit (or nisclient) creates a cold-start file /var/nis/NIS_COLDSTART. The cold-start file is used to initialize the client's directory cache /var/nis/NIS_SHARED_DIRCACHE. The cold-start file contains a copy of the directory object of the client's domain. Since the directory object already contains a copy of the server's public key, the key is now propagated into the cold-start file of the client.

In addition when a client makes a request to a server outside its home domain, a copy of the remote domains directory object is stored in the client's NIS_SHARED_DIRCACHE file. You can examine the contents of the client's cache by using the nisshowcache command, described on page 184.

This is the extent of the propagation until a replica is added to the domain or the server's key changes.

Stage 4: When a Replica is Added to the Domain

When a replica server is added to a domain, the nisping command (described in nisping Command) is used to download the NIS+ tables, including the cred table, to the new replica. Therefore, the original server's public key is now also stored in the replica server's cred table.

Stage 5: When the Server's Public Key Is Changed

If you decide to change DES credentials for the server (that is, for the root identity on the server), its public key will change.

As a result, the public key stored for that server in the cred table will be different from those stored in:

Most of these locations will be updated automatically within a time ranging from a few minutes to 12 hours. To update the server's keys in these locations immediately, use the commands.

Table 24–3 Updating an NIS+ Server's Keys




Cred table of replica servers (instead of using nisping, you can wait a few minutes until the table is updated automatically)


nisping Command

Directory object of domain supported by server 


nisupdkeys Command

NIS_COLDSTART file of clients

nisinit -c

nisinit Command

NIS_SHARED_DIRCACHE file of clients


nis_cachemgr Daemon

Note –

You must stop the existing nis_cachemgr before restarting nis_cachemgr. To stop nis_cachemgr, disable the NIS+ service by using svcadm disable /network/rpc/nisplus:default.

Corrupted NIS+ Credentials

When a principal (user or machine) has a corrupt credential, that principal is unable to perform any namespace operations or tasks, not even nisls. This is because a corrupt credential provides no permissions at all, not even the permissions granted to the nobody class.


User or root cannot perform any namespace tasks or operations. All namespace operations fail with a “permission denied” type of error message. The user or root cannot even perform a nisls operation.

Possible Cause:

Corrupted keys or a corrupt, out-of-date, or otherwise incorrect /etc/.rootkey file.


Use snoop to identify the bad credential.

Or, if the principal is listed, log in as the principal and try to run an NIS+ command on an object for which you are sure that the principal has proper authorization. For example, in most cases an object grants read authorization to the nobody class. Thus, the nisls object command should work for any principal listed in the cred table. If the command fails with a “permission denied” error, then the principal's credential is likely corrupted.


Keyserv Failure

The keyserv is unable to encrypt a session. There are several possible causes for this type of problem:

Possible Causes and Solutions:

Machine Previously Was an NIS+ Client

If this machine has been initialized before as an NIS+ client of the same domain, try keylogin -r and enter the root login password at the Secure RPC password prompt.

No Entry in the NIS+ cred Table

To make sure that an NIS+ password for the principal (user or host) exists in the cred table, run the following command in the principal's home domain

nisgrep -A cname=principal cred.org_dir.domainname

If you are running nisgrep from another domain, the domainname must be fully qualified.

Changed NIS+ Domain Name

Do not change a domain name.

If you change the name of an existing domain you will create authentication problems because the fully qualified original domain name is embedded in objects throughout your network.

If you have already changed a domain name and are experiencing authentication problems, or error messages containing terms like “malformed” or “illegal” in relation to a domain name, change the domain name back to its original name. The recommended procedure for renaming your domains is to create a new domain with the new name, set up your machines as servers and clients of the new domain, make sure they are performing correctly, and then remove the old domain.

When Changing a Machine to a Different NIS+ Domain

If this machine is an NIS+ client and you are trying to change it to a client of a different domain, remove the /etc/.rootkey file, and then rerun the nisclient script using the network password supplied by your network administrator or taken from the nispopulate script.

NIS+ and Login Passwords in /etc/passwd File

Your NIS+ password is stored in the NIS+ passwd table. Your user login password may be stored in NIS+ passwd table or in your /etc/passwd file. (Your user password and NIS+ password can be the same or different.) To change a password in an /etc/passwd file, you must run the passwd command with the nsswitch.conf file set to files or with the -r files flag.

The nsswitch.conf file specifies which password is used for which purpose. If the nsswitch.conf file is directing system queries to the wrong location, you will get password and permission errors.

Secure RPC Password and NIS+ Login Passwords Are Different

When a principal's login password is different from his or her Secure RPC password, keylogin cannot decrypt it at login time because keylogin defaults to using the principal's login password, and the private key was encrypted using the principal's Secure RPC password.

When this occurs the principal can log in to the system, but for NIS+ purposes is placed in the authorization class of nobody because the keyserver does not have a decrypted private key for that user. Since most NIS+ environments are set up to deny the nobody class create, destroy, and modify rights to most NIS+ objects this results in “permission denied” types errors when the user tries to access NIS+ objects.

Note –

In this context network password is sometimes used as a synonym for Secure RPC password. When prompted for your “network password,” enter your Secure RPC password.

To be placed in one of the other authorization classes, a user in this situation must explicitly run the keylogin program and give the principal's Secure RPC password when keylogin prompts for password. (See Keylogin With NIS+.)

But an explicit keylogin provides only a temporary solution that is good only for the current login session. The keyserver now has a decrypted private key for the user, but the private key in the user's cred table is still encrypted using the user's Secure RPC password, which is different than the user's login password. The next time the user logs in, the same problem reoccurs. To permanently solve the problem the user needs to change the private key in the cred table to one based on the user's login ID rather than the user's Secure RPC password. To do this, the user need to run the chkey program as described in Changing Keys for an NIS+ Principal.

    Thus, to permanently solve a Secure RPC password different than login password problems, the user (or an administrator acting for the user) must perform the following steps:

  1. Log in using the login password.

  2. Run the keylogin program to temporarily get a decrypted private key stored in the keyserver and thus gain temporary NIS+ access privileges.

  3. Run chkey -pto permanently change the encrypted private key in the cred table to one based on the user's login password.

Preexisting /etc/.rootkey File


Various insufficient permission to and permission denied error messages.

Possible Cause:

An /etc/.rootkey file already existed when you set up or initialized a server or client. This could occur if NIS+ had been previously installed on the machine and the .rootkey file was not erased when NIS+ was removed or the machine returned to using NIS or /etc files.


Run ls -l on the /etc directory and nisls -l org_dir and compare the date of the /etc/.rootkey to the date of the cred table. If the /etc/.rootkey date is clearly earlier than that of the cred table, it may be a preexisting file.


Run keylogin -r as root on the problem machine and then set up the machine as a client again.

Root Password Change Causes Problem in NIS+


You change the root password on a machine, and the change either fails to take effect or you are unable to log in as superuser.

Possible Cause:

Note –

For security reasons, you should not have User ID 0 listed in the passwd table.

You changed the root password, but root's key was not properly updated. Either because you forgot to run chkey -p for root or some problem came up.


Log in as a user with administration privileges (that is, a user who is a member of a group with administration privileges) and use passwd to restore the old password. Make sure that old password works. Now use passwd to change root's password to the new one, and then run chkey -p.

Caution – Caution –

Once your NIS+ namespace is set up and running, you can change the root password on the root master machine. But do not change the root master keys, as these are embedded in all directory objects on all clients, replicas, and servers of subdomains. To avoid changing the root master keys, always use the -p option when running chkey as root.