I'm looking for a way to change the password for some user of a Windows box remotely from a Linux Box. Really I have to do it by running some program/system script on the Linux Box but without running anything more than standard services on the windows system.
You can update the "unicodePwd" attribute of the user object using LDAP over SSL to reset a user's password. This is probably the most straightforward "cross-platform friendly" way to make such a change because, on the Linux site, you won't need any MSRPC infrastructure.
I am somewhat in doubt about what you are going to accomplish - changing a Windows user's password? By script?
If so, take a look into winexe - it uses RPC calls and allows you to run commands on the Windows machine without prior software installation (the Windows firewall must be configured for letting RPC through, tough). Running a
net user <username> <password> on the Windows machine would do.