Binary package “x11-session-utils” in ubuntu xenial

X session utilities

 This package provides the X session manager and related tools:
  - rstart;
  - smproxy, a session manager proxy for X clients that do not use the X
    session manager protocol;
  - xsm, a session manager for X sessions;
 Installation of an rsh or ssh daemon (server) is necessary if rstartd is
 to be used, and installation of an rsh or ssh client is necessary if
 rstart is to be used.