Hi Neil,

Without the logs, it is difficult to tell.  It /could/ be related to time
drift, but I'd find it unlikely that that would prevent writing to disk.

More likely, I'd investigate number of open file handles.  Did some httpd
sub-process (e.g., a CGI or PHP) possibly create an egregious number of
handles?  This would likely show in error messages printed to the logs.
 lsof could also be your friend here.

Matt


On May 19, 2017 11:15 AM, "Neil Sabol" <[email protected]> wrote:

Hello CAS Community,

I hope this message finds you all well.

As time permits, I am hoping to pick your brains about a mysterious issue
we experienced recently with mod_auth_cas (suspect it was not mod_auth_cas
itself but something related).

We have been running mod_auth_cas (version 1.1) in production for a long
time without incident. Yesterday, we began to experience a strange behavior
on one of our production servers:


   - mod_auth_cas stopped creating cookies in the defined CASCookiePath (no
   users were able to login to the application - all requests for
   CAS-protected resources resulted in a redirect back to the CAS login page
   and a 401 error upon return to the application)

   - Debug logs did not reveal anything interesting - the only related
   entries I noticed were the following


*[debug] mod_auth_cas.c(930): [client X.X.X.X] Cache entry
   'ae0aa61bf431d62b9e4be00089e87df8' could not be opened, referer:
   http://something.unm.edu <http://something.unm.edu> [debug]
   mod_auth_cas.c(1676): [client X.X.X.X] Cookie
   'ae0aa61bf431d62b9e4be00089e87df8' is corrupt or invalid, referer:
   http://something.unm.edu <http://something.unm.edu>*

   - Permissions, file system status, etc. were all good - from all
   appearances, mod_auth_cas was not attempting to create cookies in the
   CASCookiePath (confirmed apache could write to the path, etc.)

   - The CASCookiePath directory contained only a .metadata file about 2-3
   hours after this issue started occurring


We ended up using the IT hammer to restore the affected VM from snapshot,
so I no longer have the specific logs or state of the system available. The
restore did the trick (mod_auth_cas resumed normal operation and began
creating cookies in the CASCookiePath), but I am concerned this issue may
recur.

The only possible explanation for this that I can think of (in hindsight)
is time drift between the application server/clients/cas server. Does that
sound possible? If yes, would something like that be logged with debug
logging enabled?

If you have any insight or guidance into what could cause this sort of
situation with mod_auth_cas, please let me know.

Thank you in advance for your time and expertise!
-Neil

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