You can edit the adduser file, since it's just a frontend script for the useradd program. Just open /usr/sbin/adduser in your favorite editor and comment out the following lines:
elif [ ! -z "$( echo $LOGIN | grep '\.' )" ]; then
echo "- User '$LOGIN' contains illegal characters (period/dot); please choose another"
I don't know whether or not you'll have further troubles with those usernames, though.
Last edited by Cerbere; 09-05-2003 at 04:02 AM.