.TH radius_shell 8
.\" Copyright 2018 Cumulus Networks, Inc.  All rights reserved.
.SH NAME
radius_shell - front end shell for radius users
.SH SYNOPSIS
.B /sbin/radius_shell
is  RADIUS client front end shell that will ensure that the uid is set
to the auid (the accounting uid).
.SH DESCRIPTION
This shell front-end needed because at login, it's
not possible to determine if a user is privileged up front, because
the RADIUS protocol combines authentication and authorization in a single
transaction.
.P
That means that all RADIUS users login as the same base mapped user and therefore
the same UID, although the auid will be set differently.
.P
The
.B radius_shell
is installed with setcap permissions that allow it to set the uid.
It is set as the login shell for the radius users via the
.I libnss-mapuser
package.
.P
For security, the uid of the process is only changed if the auid is set,
and is 1000 or larger (this is the normal minimum uid for non-privileged
users via
.I adduser
and
.IR useradd .
The value is hardcoded in the source, it is not read from the
.I adduser.conf
configuration file.
.P
Whether the uid is changed or not, a login shell is exec'ed.
At this time, the login shell is only
.BR /bin/bash ,
although the other shells listed in
.I /etc/shells
may be allowed in the future.
.SH "SEE ALSO"
.BR setcap (8),
.BR pam_radius_auth (8),
.BR nss_mapuser (5)
.SH FILES
.SH AUTHOR
Dave Olson <olson@cumulusnetworks.com>