Problem(Abstract)
After configuring LPA (Loadable Password Algorithm) on AIX, you see -951 and -952 errors when trying to connect as user informix. -and using PAM is not an immediate option
Cause
AIX has made the /etc/security/pwdalg.cfg file unreadable to normal users (users other than root), hence -attempting to authenticate as user informix does not work.
Resolving the problem
You can use PAM to get around this problem, but if that is not an immediate option and re-writing applications to handle PAM can not be completed immediately - you can use the following work-around:
Warning: You need to ensure you are in a secure environment to use this work-around - i.e. your Informix Server machine is secure and you really trust user 'informix'. If this is true, then you can proceed.
Add user 'informix' to the 'security' group on AIX - this will allow the /etc/security/pwdalg.cfg to be read by user informix and authentication should work without throwing an error.
Note - using PAM is the preferred method for handling this situation, so use this as a temporary work-around only while taking steps to properly remedy the issue.
http://www-01.ibm.com/support/docview.wss?uid=swg21664590