Academic Commons

Articles

The "Session Tty" Manager

Bellovin, Steven Michael

In many UNIX systems, it is possible for a program to retain access to the login terminal after the user has logged out. This poses obvious security risks and can also confuse the modem control signals. We solve this for System V by adding a layer of indirection known as the session tty driver. At login time, a session device is linked to the physical terminal. User programs have access to the session device only, and may not open the physical line. Upon logout or carrier drop, the link is severed. New login sessions are given new session devices, and are thus insulated from persistent processes. Use of session devices is controlled by a new system process known as the session manager; by means of suitable plumbing primitives, a "reconnect after line drop" facility can easily be implemented.

Subjects

Files

More About This Work

Academic Units
Computer Science
Published Here
June 24, 2010

Notes

Proceedings of the Summer 1988 USENIX Conference: June 20-24, 1988, San Francisco, California, USA (Berkeley, Calif.: USENIX Association), pp. 339-354.

Academic Commons provides global access to research and scholarship produced at Columbia University, Barnard College, Teachers College, Union Theological Seminary and Jewish Theological Seminary. Academic Commons is managed by the Columbia University Libraries.