search for: pcname123

I am trying to use ntlm_auth for machine authentication requests against a Win2003/AD from my RADIUS server. Normal, user authentication works fine, but not machine authentication. The username passed from RADIUS to ntlm-auth looks like host/pcname123. I'm wondering if the "/" is killing it? The ntlm_auth man page says that it expects only Samba's unix charset. Does anyone have any ideas about how I can accomplish this? Thanks.