akeyconvert - Import keys from rxkad.keytab to an AFS KeyFileExt
akeyconvert -all
The akeyconvert command is used when upgrading an AFS cell from the 1.6.x release series to the 1.8.x release series. When using the rxkad-k5 security extension, the 1.6.x release series stored the AFS long-term Kerberos keys in a krb5 keytab file named rxkad.keytab. The 1.8.x series releases avoid widespread linking against libkrb5, and instead store the AFS long-term Kerberos keys in an OpenAFS-specific file format, the KeyFileExt(5).
akeyconvert provides an easy way to convert the AFS long-term Kerberos keys from the krb5 keytab format to the KeyFileExt format. The same functionality is possible via repeated use of asetkey(8), but akeyconvert is provided to simplify the process.
By default, akeyconvert will only migrate the newest key (highest kvno) for each Kerberos principal with a key in the rxkad.keytab. The ability to convert all keys, regardless of kvno, is provided as akeyconvert -all.
The KeyFileExt format is slightly less flexible than the krb5 keytab format -- the KeyFileExt identifies keys only by the type (rxkad-k5), kvno, and enctype ("subtype"), whereas the krb5 keytab also stores the principal name associated with each key. This means that a krb5 keytab which contained keys of identical kvno and enctype, but for different principals, would not be representable as a KeyFileExt. akeyconvert detects such a situation and does not perform any key conversions until the conflict is removed.
Many of the concerns given in asetkey(8) regarding extracting new Kerberos keys with ktadd are also applicable to changes involving the rxkad.keytab.
In a cell which is using the rxkad-k5 extension, the following command will read the newest keys from the rxkad.keytab and write them to the KeyFileExt in the appropriate format.
% akeyconvert
In a cell which has a key of kvno 2 and enctype aes128-cts-hmac-sha1-96 for both afs/example.com@EXAMPLE.COM and a different key with the same kvno and enctype but for the principal afs@EXAMPLE.COM, akeyconvert will detect the kvno/enctype collision and refuse to continue. The appropriate Kerberos keytab-manipulation tools should be used to generate a new key (of higher kvno) for one of the colliding principals and remove the old (colliding) key for that principal before akeyconvert is used.
% akeyconvert -all
Duplicate kvno/enctype 2/17
FATAL: duplicate key identifiers found.
The issuer must be able to read the rxkad.keytab and write the KeyFile and KeyFileExt, normally /usr/afs/etc/KeyFile and /usr/afs/etc/KeyFileExt. In practice, this means that the issuer must be the local superuser root on the AFS file server or database server.
KeyFile(5), KeyFileExt(5), asetkey(8),
Copyright 2015 Massachusetts Institute of Technology.
This documentation is covered by the IBM Public License Version 1.0. This man page was written by Benjamin Kaduk for OpenAFS.