Using FreeRadius 1.0.5 I have attempted using Toby Zimmerer's post, but have not yet been able to get this work on CentOS 4.2. CentOS4.2 should resemble RedHat ES closely. I am just wondering, if anyone has gotten this to work properly. I am trying to use PAM_RADIUS, but having some issues. I am trying to use the pam_radius_auth.so (I was able to compile it on CentOS4.2) to use RADIUS as primary authentication and if RADIUS server is not reachable, then use native unix_auth. I have the client configured in RADIUS, I have created a /etc/raddb/server file to point to the RADIUS servers, modified /etc/pam.d/sshd as following: #%PAM-1.0 # auth required pam_stack.so service=system-auth auth required pam_radius_auth.so # auth required pam_nologin.so # account required pam_stack.so service=system-auth account required pam_radius_auth.so password required pam_stack.so service=system-auth session required pam_stack.so service=system-auth session required pam_loginuid.so But I am not getting the authentication to work. /var/log/secure shows following: Feb 16 12:44:53 eastern-dge-2 sshd[24372]: pam_radius_auth: DEBUG: getservbyname(radius, udp) returned 2433732. Feb 16 12:44:55 eastern-dge-2 sshd[24372]: Failed password for invalid user ICHONG from ::ffff:172.25.1.190 port 4145 Feb 16 12:45:25 eastern-dge-2 sshd[24465]: Invalid user ichong from ::ffff:172.25.1.190 Feb 16 12:45:26 eastern-dge-2 sshd[24465]: pam_radius_auth: DEBUG: getservbyname(radius, udp) returned 3883716. Feb 16 12:45:29 eastern-dge-2 sshd[24465]: Failed password for invalid user ichong from ::ffff:172.25.1.190 port 4146 /var/log/messages shows following: Feb 16 12:44:53 eastern-dge-2 sshd(pam_unix)[24372]: check pass; user unknown Feb 16 12:45:14 eastern-dge-2 sshd(pam_unix)[24372]: 1 more authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=172.25.1.190 Feb 16 12:45:26 eastern-dge-2 sshd(pam_unix)[24465]: check pass; user unknown Feb 16 12:45:26 eastern-dge-2 sshd(pam_unix)[24465]: authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=172.25.1.190 Please help. Thanks, InCho