Passwords
Good passwords
A good password contains
Never use a natural language word as a password, not even backwards. Never use rows of characters directly from your keyboard as a password (qwerty is a very bad password).
Your password should not refer to your person, your family, your affiliation etc.
Your password should be easy to remember (to you!), so you have no need of carrying it on a piece of paper with you. Nevertheless, it should be nonsense to other people.
You can create a mnemonic password by taking a funny sentence and picking up the first letter of each word. For example, the sentence "You can create good passwords with this rule." provides a password "YccGpwtR". (Naturally, I've now spoiled the good password by phrasing it out.)
The password becomes easier to remember if it is pronounceable.
If you still need some time to learn your new password,
hide your notes properly. Never store a password into a file,
never tell stories about your tricks of hiding passwords,
never keep the computer name together with the password.
Changing your password
Please do change your password at least every six months. If you fail to change the password even after warning messages, the user account will be disabled.
a) Staff members and visitors
have a separate local password for their private computer in their
offices. In addition, they have a normal "master" password
that is applicable to all other computers of the CS Department.
Most users have an additional user account to the IT Department's Unix
system. When required, the password command queries which password
to change:
username@computer:~$ passwd
Do you want to change username's local password or master password?
Answer l for local, m for master: l
Changing local password for username
Enter old login password:
New password:
Re-enter new password:
OK, local password successfully changed.
The changed password is propagated to all computers of the department within the next 15 minutes, except for the mailserver, which is updated nightly.
b) Students have two accounts, one for the IT Department's Unix system, and another for the departmental system. Although the user names are identical for these systems, the accounts are isolated, and thus, the passwords are separate. The passwords need to be changed separately in both systems, for example, in melkki.cs.helsinki.fi and in vesuri.helsinki.fi. The password for the departmental system can be changed in any of the Linux computers controlled by the department.
The changed password is propagated to all computers that need it within the next 15 minutes, except for the mailserver, which is updated nightly. The passwords are not exchanged between the systems of the CS Department and the IT Department. The password is changed with the command passwd. The passwords you type are never shown on screen.
Remarks for users of kontti and vesuri:
The IT Department's Unix servers vesuri and kontti
have a slightly different method of manipulating long passwords
(more than 8 characters)
than the other Unix servers. If your password exceeds 8 characters,
only feed the first 8 for kontti and vesuri!
If you forget your password
If you forgot your password on the departmental system, take an identification card, passport or such with you and visit any member of the computing facilities staff (rooms A230, A229, A212, A213, A215).
If you forgot your password for the IT Department's Unix system, visit the IT Department help desk.
Back to the instructions page
itsupport@cs.helsinki.fi