How do I change user password on non-AD Windows Server from a Mac?
You could install Samba3 through Macports and then you'll have smbpasswd available again.


Install Xcode from Apple - If you download Xcode from the Mac App Store, be sure to use the Xcode preferences to subsequently download the command line tools or use the xcode-select tool to get the BSD command line tools placed in your path. MacPorts needs make, gcc and other tools from Xcode to compile the samba3 code.
Install Macports for Lion (or whatever OS X version you are using)
Run sudo port -d selfupdate - just to be up-to-date
Install Samba3 in Macports: sudo port install samba3
Setup smb.conf: sudo cp /opt/local/etc/samba3/smb.conf.sample /opt/local/etc/samba3/smb.conf


You are done, and now you should be able to call smbpasswd -r &lt;serverIPaddress&gt; -U &lt;username&gt; again.