Login Failures: When You Are Unable to Log In
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Logins can fail for any number of reasons. One of your passwords might have changed, or your account might have expired. You might be attempting to log in over the network or from a modem but be unauthorized to do so. Table 3-3 “Reasons for Login Failure” summarizes common reasons for login failure.
Table 3-3 Reasons for Login Failure
| Failure Indicator | Reason |
|---|---|
No response from the terminal. | A defective terminal, a terminal that requires a system password, a terminal that is not powered on, or a communications problem caused by defective wiring or by a misconfigured or malfunctioning modem. |
No response from any terminal. | The system is down or overloaded. |
No response from the terminal when you enter the system password. | The system password changed. |
System messages: | |
“User authorization failure” | A typing error in your user name or password. The account or password expired. |
“Not authorized to log in from this source” | Your particular class of login (local, dialup, remote, interactive, batch, or network) is prohibited. |
“Not authorized to log in at this time” | You do not have access to log in during this hour or this day of the week. |
“User authorization failure” (and no known user failure occurred) | An apparent break-in has been attempted at the terminal using your user name, and the system has temporarily disabled all logins at that terminal by your user name. |
The following sections describe the reasons for login failure in more detail.
You cannot log in if the terminal you attempt to use requires a system password and you are unaware of the requirement. All attempts at logging in fail until you enter the system password.
If you know the system password, perform the steps described in “Entering a System Password”. If your attempts fail, it is possible that the system password has been changed. Move to a different terminal that does not require a system password, or request the new system password.
If you do not know the system password and you suspect that this is the problem, try logging in at another terminal.
If you attempt a class of login that is prohibited in your UAF record, your login fails. For example, your security administrator can restrict you from logging in over the network. If you attempt a network login, you receive a message stating that you are not authorized to log in from this source.
Network jobs are not terminated when the allocated work shift for network jobs is exceeded. This restriction applies only to new network connections, not to existing ones.
Your security administrator can restrict your logins to include or exclude any of the following classes: local, remote, dialup, batch, or network. (For a description of these classes, see “Logging In Interactively: Local, Dialup, and Remote Logins” and “When the System Logs In for You: Network and Batch Logins”.)
Another cause of login difficulty is failure to observe your shift restrictions. A system manager or security administrator can control access to the system based on the time of day or the day of the week. These restrictions are imposed on classes of logins. The security administrator can apply the same work-time restrictions to all classes of logins or choose to place different restrictions on different login classes. If you attempt a login during a time prohibited for that login class, your login fails. The system notifies you that you are not authorized to log in at this time.
When shift restrictions apply to batch jobs, jobs you submit that are scheduled to run outside your permitted work times are not run. The system does not automatically resubmit such jobs during your next available permitted work time. Similarly, if you have initiated any kind of job and attempt to run it beyond your permitted time periods, the job controller aborts the uncompleted job when the end of your allocated work shift is reached. This job termination behavior applies to all jobs.
Your security administrator can control the number of chances you are given to enter a correct password during a dialup login before the connection is automatically broken.
If your login fails and you have attempts remaining, press the Return key and try again. You can do this until you succeed or reach the limit. If the connection is lost, you can redial the access line and start again.
The typical reason for limiting the number of dialup login failures is to discourage unauthorized users attempting to learn passwords by trial and error. They already have the advantage of anonymity because of the dialup line. Of course, limiting the number of tries for each dialup does not necessarily stop this kind of intrusion. It only requires the would-be perpetrator to redial and start another login.
If anyone has made a number of failed attempts to log in at the same terminal with your user name, the system concludes that an intruder is attempting to gain illegal access to the system by using your user name.
At the discretion of your security administrator, break-in evasion measures can be in effect for all users of the system. The security administrator controls how many password attempts are allowed over what period of time. Once break-in evasion tactics are triggered, you cannot log in to the terminal---even with your correct password---during a defined interval. Your security administrator can tell you how long you must wait before reattempting the login, or you can move to another terminal to attempt a login.
If you suspect that break-in evasion is preventing your login and you have not personally experienced any login failures, you should contact your security administrator immediately. Together, you should attempt another login and check the message that reveals the number of login failures since the last login to confirm or deny your suspicion of intrusion attempts. (If your system does not normally display the login message, your security administrator can use the Authorize utility (AUTHORIZE) to examine the data in your UAF record.) With prompt action, your security administrator can locate someone attempting logins at another terminal.