[horde] Can't log in: GSSAPI and PHP errors

[Jaap Winius]

Hi all,

Distro:   Debian testing (squeeze)
Horde:   3.1.5 (installed separately on Debian lenny, Dec. 2007)
IMP:       4.1.5 (idem)
PHP5:    5.3.2-1 (current Debian package)

An upgrade from Debian lenny to squeeze has landed me in some trouble. 
Now, when I try to log into Horde, I can't and messages like these 
appear in /var/log/mail.info:

Jul 18 06:48:52 bitis imapd[4593]: Failed to acquire credentials for 
imap at bitis.umrk.nl
Jul 18 06:48:52 bitis imapd[4593]: GSSAPI mechanism status: Key table 
entry not found
Jul 18 06:48:52 bitis imapd[4593]: AUTHENTICATE GSSAPI failure 
host=bitis.umrk.nl [2001:888:1d5f:1::a]
Jul 18 06:48:52 bitis imapd[4593]: Logout user=??? host=bitis.umrk.nl 
[2001:888:1d5f:1::a]

The same machine also runs an MIT Kerberos V server and an OpenLDAP 
server, with the latter using the former for authentication via GSSAPI. 
I tried adding an imap at bitis.umrk.nl entry to the Kerberos server, but 
that only gets rid of the first two of the four error lines shown above. 
The real question is, why is Horde using GSSAPI to authenticate in the 
first place? When I test the same imapd with Thunderbird, it works fine:

Jul 19 20:18:27 bitis imapd[21509]: Authenticated user=jwinius 
host=atheris.umrk.nl [2001:888:1d5f:1::14] mech=PLAIN

That's what I was expecting in both cases, but alas. What's frustrating 
is that, while OpenLDAP must be configured specifically to use GSSAPI 
and Kerberos, uw-imapd (which I'm using) has no configuration files to 
speak of (not counting /etc/c-client.cf). So, why does Horde insist on 
using IMAP that way? How can I get it to use mech=PLAIN instead? Should 
I consider using a different IMAP daemon?

Perhaps this all has something to do with the many error messages that 
are filling up my /var/log/horde/horde3.log. Many lines like this appear 
any time the Horde login screen is displayed, or if I try to log in:

[Mon Jul 19 20:48:08 2010] [error] [client 2001:888:1d5f:1::14] PHP 
Deprecated:  Assigning the return value of new by reference is 
deprecated in /var/www/horde3/mnemo/lib/api.php on line 336
[Mon Jul 19 20:48:08 2010] [error] [client 2001:888:1d5f:1::14] PHP 
Deprecated:  Assigning the return value of new by reference is 
deprecated in /var/www/horde3/mnemo/lib/api.php on line 422
[Mon Jul 19 20:48:08 2010] [error] [client 2001:888:1d5f:1::14] PHP 
Deprecated:  Assigning the return value of new by reference is 
deprecated in /var/www/horde3/nag/lib/api.php on line 393
[Mon Jul 19 20:48:08 2010] [error] [client 2001:888:1d5f:1::14] PHP 
Deprecated:  Assigning the return value of new by reference is 
deprecated in /var/www/horde3/nag/lib/api.php on line 499
[Mon Jul 19 20:48:08 2010] [error] [client 2001:888:1d5f:1::14] PHP 
Deprecated:  Assigning the return value of new by reference is 
deprecated in /var/www/horde3/nag/lib/api.php on line 595
[Mon Jul 19 20:48:08 2010] [error] [client 2001:888:1d5f:1::14] PHP 
Deprecated:  Assigning the return value of new by reference is 
deprecated in /var/www/horde3/imp/lib/IMP.php on line 359
[Mon Jul 19 20:48:08 2010] [error] [client 2001:888:1d5f:1::14] PHP 
Deprecated:  Assigning the return value of new by reference is 
deprecated in /var/www/horde3/imp/lib/IMP.php on line 533
[Mon Jul 19 20:48:08 2010] [error] [client 2001:888:1d5f:1::14] PHP 
Deprecated:  Assigning the return value of new by reference is 
deprecated in /var/www/horde3/imp/templates/login/login.inc on line 110

After scouring the 'net, I get the impression these are just warnings, 
but uncertain whether they are irrelevant to my inability to log in. At 
any rate, they are damned irritating: adding something like 
"error_reporting = E_ALL & ~E_DEPRECATED & ~E_USER_DEPRECATED & 
~E_NOTICE" to /etc/php5/apache2/php.ini makes no difference.

Any help would definitely be appreciated.

Cheers,

Jaap