General :: Login Incorrect Via Getty

I try to setup a small Debian system running on command line. Remote access shall be possible via ssh (for now also telnet) and a serial connected minicom via getty. I need the serial access as fallback in case the network is down.

As long as the package adduser is not installed, I can login as root via telnet and getty without problem. But from the moment "adduser" is installed with apt-get, the serial root login always fails after entering the right password with the message "Login incorrect". Even de-installing "adduser", or using a brand new "adduser test" user. When installing and using SSH it allows to login successfully, like telnet.

BTW: A dangerous behavior I observed with telnet: When I opening the connection via telnet, I'm immediately logged in as root - without asking for a password! I set a password with passwd which also is requested by SSH and getty (before the adduser installation) but not by telnet?!?!?

The /var/log/messages adds a line if login with su, but nothing when fails with getty

Here is my inittab:

Code:
# /etc/inittab: init(8) configuration.
# inittab,v 1.1 2006-07-27 08:58:03 lothar Exp
# The default runlevel.
id:2:initdefault:

[Code].....