Logging in to a running Legion system

Table of Contents
About the log in procedure
About AuthenticationObjects
Logging in
Checking your log in status
Logging out
Other on-line tutorials & documentation

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Depending on how your system is set up, you may need to set up your access to your system before you can run Legion commands. This will probably involve running a command such as this:
$ . ~legion/setup.sh
$ source ~legion/setup.csh
The exact syntax will depend on what kind of shell you are using and where your Legion files are installed (i.e., the value of ~legion will depend on your individual Legion net). Consult your system administrator for more information.

About the log in procedure
Legion comes with security features that can be enabled or not, as appropriate to your system. If your system adminstrator chooses to use them, they will be enabled when the system is first initialized. In a secured system all users must have a user id and must log in before starting to work. Your system's log in procedure may differ from what is described here: please see your system administrator for exact instructions. The default system requires that all users have user ids and passwords. This allows Legion to keep track of your objects and to know what kind of user privileges you have. It also prevents malicious users from interfering with your objects or gaining illicit access to your system.

About AuthenticationObjectsaltering the AuthenticationObject
When you log in to a Legion system you are identified by a special object called the AuthenticationObject: this object contains your password, initial implicit parameters (the Legion equivalent of a the Unix "environment"), and other information. AuthenticationObjects are created when you create a user id. When an authenticated user runs a Legion process a certificate confirming his or her identify is passed along to verify that this person has permission to run the process. This certificate is created and signed by your AuthenticationObject.

Logging increating new user ids
You need a user id before you can log in. Ask your system administrator to create one for you, if necessary. You log in with the legion_login command. The system will request your password and verify your identity and your security privileges.

To login, run legion_login with just your user id or with no arguments at all. Usage is:

legion_login [-l <user LOID> | <user id>]
Notice that if you give the user id as a parameter you need to use the full path name (/users/<user id>):
$ legion_login /users/bob
Password: xxxx


$ legion_login 
Legion login: /users/bob
Password: xxxx

Objects created while logged in will be owned by you and only you will be able to use them. Any processes that you start after you log in will be accompanied by a copy of your AuthenticationObject's certificate.

Checking your log in status
If you can't remember whether or not you are logged in or which user id you are using, run the legion_whoami command. Your output will look something like this:
$ legion_whoami
This means that you are logged in as user nemo. If you are not logged in or your system administrator has not enabled security there will be no output.

While logged in, you can change your password and other parameters of your environment. The password may be changed with the legion_passwd command. Note that you must include your user name:

$ legion_passwd /users/nemo
New Legion password: xxxx
Retype new password: xxxx
Password changed.

Logging out
To log out, run legion_logout.
$ legion_logout

This will remove your credentials file. (Note that you are not in a separate shell, so if you type exit you will close your window.)

Other relevant on-line documents:
Click on the to go to the page.
Logging in to a running Legion system
Legion graphical user interface
Introduction to Legion context space
Context-related commands
How to start remote programs in Legion
Sample makefile for remote programs
Adapting a parameter space study for Legion
Object permissions
Legion tty objects
Running a PVM code in Legion
Running a Legion MPI code
Running native MPI code
Quick list of all Legion commands (1.6.4)
Usage of all Legion commands (1.6.4)
Starting a new Legion system
Using Legion security features
Legion host and vault objects
Adding host and vault objects
Brief descriptions of all on-line 1.6 tutorials

Last modified: Tue Jun 29 13:30:10 1999

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