this is my /etc/pam.d/sshd content.
auth requisite pam_oath.so usersfile=/etc/users.oath window=20 digits=6
auth required pam_sepermit.so
auth include password-auth
account required pam_nologin.so
account include password-auth
password include password-auth
# pam_selinux.so close should be the first session rule
session required pam_selinux.so close
session required pam_loginuid.so
# pam_selinux.so open should only be followed by sessions to be executed in the user context
session required pam_selinux.so open env_params
session optional pam_keyinit.so force revoke
session include password-auth。
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And I have other machine which is Ubuntu10.04(also in Vbox4.1.6),the pam_oath.so works very well both in su and ssh.
So I think there maybe some wrongs in the CentOS /etc/pam.d/sshd.
I am look for your helping, thanks!