When using union - provided IT equipment or accounts you agree to be bound by the acceptable use policy enforced by the University. The full text of this document can be found at:
Please pay particular attention to section
3 (Keeping your IT Credentials Secure).
Section 2 3 means you are not allowed to use your credentials to enable someone else to use the University networks or IT systems - this restriction includes SU computers. (There are procedures in place for getting accounts created for visiting presenters, volunteers, temporary staff etc.)