Found the problem after some investigation based on your suggestions. In the openldap configuration file /etc/openldap/ldap.conf, the entry TLS_CACERT is pointed to a certificate file in a directory which is accessible only by root user. After I move the file to a directory which all user can access it, now it works. I can start the kamailio as a service with "service kamailio start" with the running user and group is kamailio. Thank you all for your helps and suggestions! Best Regards, Laura On Tue, Jun 21, 2011 at 5:44 PM, laura testi &lt;lau.testi(a)gmail.com <mailto:lau.testi@gmail.com>> wrote: The SELinux is disabled. On Tue, Jun 21, 2011 at 5:26 PM, Andrew Pogrebennyk &lt;andrew.pogrebennyk(a)portaone.com <mailto:andrew.pogrebennyk@portaone.com>> wrote: On 21.06.2011 17 <tel:21.06.2011%2017>:30, laura testi wrote: Should I need to set a some special environment variable to load ldap.so in the /etc/init.d/kamailio? The env output for root does not confirm my theory :) I'm not sure what is preventing kamailio from communication with LDAP, could it be that SELinux is enabled and denying it in some way? -- Sincerely, Andrew Pogrebennyk _______________________________________________ sr-dev mailing list sr-dev(a)lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-dev