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ubuntu:login_banners

Login Banners

The primary reason for login banners in a system is to cater for legal and privacy purposes. They should inform ALL users that access to the system is only for authorized users and that everyone else should leave. The banner is there to strip away any privacy rights users have on the system; and that everything that users do on the system is being monitored.

This way users can’t complain they are being watched. With a banner or warning sign you also gain the effect of preventing things from happening. We also call this is deterrent measure, which helps users not to cross the line.

Besides the login banner, banners can also be defined on common services like FTP and SSH. They could also be added to the login page on a web applications, to make it clear what happens after logging in.

Good versus bad banners

With these insights in mind, it is a lot easier to come up with a good banner. So here are some tips:

Don’t:

  • Welcome the user
  • Provide information only authorized people should know
  • Share system resources or performance

Do:

  • Share that only authorized people and services are allowed to proceed
  • Explain that monitoring is active on the system
  • Add a line stating that by proceeding, you accept to the terms

Now the legal system varies a lot in the world. So for exact wording, it is advised to contact your legal department, if you have any. If you don’t have access to a legal person, then look at examples of banners used by companies and government facilities with high level of security needs.

Example issue.net file

/etc/issue.net
***************************************************************************
NOTICE TO USERS
 
This computer system is the private property of its owner, whether
individual, corporate or government. It is for authorized use only.
Users (authorized or unauthorized) have no explicit or implicit
expectation of privacy.
 
Any or all uses of this system and all files on this system may be
intercepted, monitored, recorded, copied, audited, inspected, and
disclosed to your employer, to authorized site, government, and law
enforcement personnel, as well as authorized officials of government
agencies, both domestic and foreign.
 
By using this system, the user consents to such interception, monitoring,
recording, copying, auditing, inspection, and disclosure at the discretion
of such personnel or officials. Unauthorized or improper use of this
system may result in civil and criminal penalties and administrative
or disciplinary action, as appropriate. By continuing to use this system
you indicate your awareness of and consent to these terms and
conditions of use. LOG OFF IMMEDIATELY if you do not agree to the
conditions stated in this warning.
 
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ubuntu/login_banners.txt · Last modified: 2020/07/15 09:30 by 127.0.0.1

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