disable login over internet
 

is possible to diable login for one user over internet remotly.... so he could login only at the console?

Eh? What are you trying to do? Do you have one specific user that you don't want to access the machine by ssh, but still allow him/her access to the machine locally?

yes, he could login at the console.

well HOW are they logging in over the internet?? some useful information really wouldn't go amiss... are they using.. ssh, telnet, telnet-ssl, ftp, smb...?

since thymox mentioned ssh, you can restrict ssh logins with a line like

denyusers that_user

in sshd_config, or maybe a broader restriction in /etc/security/access.conf:

-:that_user:ALL EXCEPT LOCAL

Also if your distro supports PAM and if your service does too have a look at this.
Look at the security enforcing rules in /etc/security and /etc/usertty.
Another way is a module called pam_listfile.so, for instance: add the line to the service you want to deny access for:
"auth required /lib/security/pam_listfile.so item=user sense=allow file=/etc/pam.d/users.deny onerr=fail" (w/o quotes). Now touch and chmod 0600 the /etc/pam.d/users.deny and add the name of the user to it.

the easies way is to comment the vc/1 - vc/x out in the file securetty (/etc)

sorry i can`t ensure that it will work, i never try it out...