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5.5. Change Password Protocol Provider
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Introduction
The Change Password service is a protocol provider that implements RFC 3244 to service Kerberos Change Password and Set Password Protocol requests. Change Password is a request-reply protocol that uses Kerberos infrastructure to allow users to securely set initial passwords or to change existing passwords. The Change Password protocol interoperates with the original Kerberos Change Password protocol, while adding the ability for an administrator to set a password for a new user.
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- Original Kerberos password changing service
- Initial password setting service (RFC 3244)
- Optional LDAP management
- UDP and TCP Support (MINA)
- Traffic throttling (MINA)
- Overload shielding (MINA)
- Easy POJO embeddability for containers such as Geronimo, JBoss, and OSGi
Configuration
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Change Password Property
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Default Value
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Description
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changepw.principal
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kadmin/changepw@EXAMPLE.COM
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Principal for this Change Password server
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changepw.primary.realm
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EXAMPLE.COM
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Primary realm this Change Password service serves
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changepw.port
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464
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The port for the Change Password protocol to use
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changepw.entry.basedn
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ou=Users,dc=example,dc=com
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Base DN for looking up users
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changepw.encryption.types
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des-cbc-md5
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Allowed Kerberos Cipher Text type(s)
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changepw.empty.addresses.allowed
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true
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Whether tickets issued with empty Host Addresses are allowed
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changepw.allowable.clockskew
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5 minutes
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Allowable clockskew for all Change Password transactions
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changepw.password.length
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6 characters
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Minimum password length
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changepw.category.count
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3 (out of 4)
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Number of character categories required (A - Z), (a - z), (0 - 9), non-alphanumeric (!, $, #, %, ... )
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changepw.token.size
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3 characters
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Password must not contain tokens larger than 3 characters that occur in the user's principal name.
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changepw.buffer.size
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1024
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Buffer size for MINA ByteBuffers
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krb5Key
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MANDATORY for JNDI to return Kerberos keys as binary, not String
Changing Passwords with Windows 2003
Configure the Windows 2003 workstation to use an Apache Change Password server:
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C:> Ksetup /addkpasswd REALM.EXAMPLE.COM kdc.realm.example.com |
Change a password using Windows Security:
1. After logging on, press CTRL+ALT+DEL.
2. Click on the button labeled "Change Password ..."
3. Enter the Old Password and New Password (twice) and click OK.
Or change a password using the Command Prompt:
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C:> Ksetup /domain /changepassword <old-password> <new-password> |
Implementation Notes
- RFC 3244 Microsoft Windows 2000 Kerberos Password Change Protocol.
- UDP frontend on port 464 (KPASSWD).
- Default principal kadmin/changepw@REALM.tld.
- AP-REQ, KRB-PRIV, and PRIV-BODY.
- Request-Response protocol - 1 request, 1 response
- AP-REQ requires Authenticator with PRNG subsession key.
- usec and sequence present and same value as seq-number from Authenticator.
- New ASN.1 structure, ChangePasswdData SEQUENCE.
- ChangepwService, needs access to PrincipalStore
- Interceptor for policy checks.
- Eventually need configurable auto-generation of keytypes.
- 9 Error types, with UTF-8 optional/omitted result string.
Roadmap
Change Password 0.5 (chain update)
- split KdcConfig into KdcConfig and ChangepwConfig
- formatting updates
- refactor changepw-protocol to chain
- documentation of the steps in the chain
- documentation of configuration
- update MINA to 0.7.3
Change Password 0.5.1 (refactoring)
- refactor common code to protocol-common
- update MINA to 0.8
Change Password 0.6 (first stable release)
- first release as part of ApacheDS 0.9.3
Change Password 0.7 (unstable feature release)
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