Maybe some of you want to add a system-user, for irssi, centerim, or won't allow root login on ssh.
With this command we'll add the user homersimpson with the password springfield.
The Option -d defined the homefolder and -m creat it. -u set the UID (take care if you'll add more than one user). -g add the user to group users and -s setup the default bash.
# useradd -g users -u 1001 -d /home/homersimpson -s /bin/bash -m -p springfield homersimpson
Now you should login as homersimpson. If login failed, set the password for homersimpson again.
# passwd homersimpson
Before we finished, we have to get a .bashrc and have to add an alias for su.
$ cp /etc/bashrc ~/.bashrc
Just open ~/.bashrc with your favorite editor and add this line.
alias su='su -l'
Finally reload you ~/.bashrc like that.
$ source ~/.bashrc
WARNING: Take care! Just do it if login as user works or you have physical access to the hardware!
To forbid root login via ssh, edit in /etc/ssh/sshd_config this line like that.
If you can't login as homersimpson, add this lines to you sshd_config.
UserPAM yes AllowUsers homersimpson
Finally restart your sshd.
# /etc/init.d/sshd restart