Limiting user access in ftp, ssh, samba, etc... 'passwords'

[Percival <linux@percival.org>]

I run a domain and host websites for myself and some friends.  I am trying to learn all about linux/system administration/security and I want to run a responsible host as I have 24/7 Internet through a DSL.  I try to run a secure box.

I want to have easy freedom in limiting user access.  I have killed telnetd, and only sshd.  I want to allow some users access through ssh, some through ftpd, and some through samba.  How can I turn off user access through ssh, but keep their account, and allow them access through ftp?  Can I allow users access to shares through samba, and allow them to ftp in, but not ssh or telnet?

Basically, I want the default for each service to be no access, and then add users to services indepently - each service allowing access on it own.

Does this make sense?  Is there an authentication package out there to deal with this?

-Percival