The link you posted is an older way to config sshd. Depending on your version of sshd, you should be able to set these config directives and get rid of the ForceCommand directive.
/etc/pam.d/ssh:
Add yubico module
Remove/comment line "auth include password-auth"
Code:
#%PAM-1.0
auth required pam_sepermit.so
auth sufficient pam_yubico.so id=N authfile=/etc/sysconfig/yubikey
#auth include password-auth
/etc/sshd/sshd_config:
Ensure these directive are set. Shouldn't clash with most other sshd directives.
Code:
Protocol 2
RequiredAuthentications2 publickey,keyboard-interactive
ChallengeResponseAuthentication yes
UsePAM yes
My output looks like this
Code:
[root@admin1a.domain ~]$ scp RHEL-6.2-x86_64-kvm.cfg admin1b.domain:
Authenticated with partial success.
Yubikey for `root':
RHEL-6.2-x86_64-kvm.cfg 100% 1460 1.4KB/s 00:00