i just added the line account required /lib/security/pam_access.so to /etc/pam.d/login to prevent some users from logging into my server. The result was that no user is able to login any more. (error msg: module unknown) In syslog I can read

Feb 13 10:06:37 tina login: PAM unable to dlopen(/lib/security/pam_access.so) Feb 13 10:06:37 tina login: PAM [dlerror: /lib/security/pam_access.so: undefined symbol: yp_get_default_domain] Feb 13 10:06:37 tina login: PAM adding faulty module: /lib/security/pam_access.so Feb 13 10:06:38 tina login: Module is unknown

after trying to log in.

What may be the reason for this behaviour?

I asked google 4 you and my personal interest following question : pam_access.so login It answered at 4th position http://linux.oreillynet.com/pub/a/linux/2001/10/05/PamModules.html?page=2 snip ------ pam_access.so This module controls access by user name, host name, domain names, IP addresses, and terminal lines. It is configured in /etc/security/access.conf. This module only has an account component. It is recommended for use on NIS machines and other servers where accounts need to exist, but do not have login capability. ---- snap and on some other links meant the error is related to NIS - but at first go to /etc/security/access.conf and modify it to your needs (maybe you can disable the NIS-lookups there too :O) - did not look so deep into) Michael Appeldorn