man1/ahost.1

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    AHOST(1)							     AHOST(1)

    NAME
      ahost	- server access	control	program	for AF

    SYNOPSIS
      ahost	[[+-]hostname ...]

    DESCRIPTION
      The ahost program is used to add and delete hosts to the list	of machines
      that are allowed to make connections to the AF server.  This provides	a
      rudimentary form of privacy control and security.  It	is only	sufficient
      for a	workstation (single user) environment, although	it does	limit the
      worst	abuses.

      The server initially allows network connections only from programs running
      on the same machine or from machines listed in the file /etc/AF*.hosts
      (where * is the device number	of the server).	 The ahost program is usually
      run either from a startup file or interactively to give access to other
      users.

      Hostnames that are followed by two colons (::) are used in checking DECnet
      connections; all other hostnames are used for	TCP/IP connections.

    OPTIONS
      Ahost	accepts	the following command line options described below.  For
      security, the	options	that effect access control may only be run from	the
      same machine as the server.

      [+]hostname
    	  The given hostname (the plus sign is optional) is added to the list
    	  of machines that are allowed to connect to the AF server.

      -hostname
    	  The given hostname is	removed	from the list of machines that are
    	  allowed to connect to	the server.  Existing connections are not
    	  broken, but new connection attempts will be denied.  Note that the
    	  current machine is allowed to	be removed; however, further connec-
    	  tions	(including attempts to add it back) will not be	permitted.
    	  There	is currently no	way to break all existing connections.

      +	  Access is granted to everyone, even if they aren't on	the list of
    	  allowed hosts	(i.e. access control is	turned off).

      -	  Access is restricted to only those machines on the list of allowed
    	  hosts	(i.e. access control is	turned on).

      nothing If no	command	line arguments are given, the list of hosts that are
    	  allowed to connect is	printed	on the standard	output along with a
    	  message indicating whether or	not access control is currently
    	  enabled.  This is the	only option that may be	used from machines
    	  other	than the one on	which the server is running.

    FILES
      /etc/AF*.hosts

    SEE ALSO
      AF(1)

    ENVIRONMENT

      AUDIOFILE
    	  to get the default host and server to	use.

    BUGS

    COPYRIGHT
      Copyright 1988, Massachusetts	Institute of Technology.  Copyright 1991-
      1994,	Digital	Equipment Corporation.
      See AF(1) for	a full statement of rights and permissions.

    AUTHORS
      Bob Scheifler, MIT Laboratory	for Computer Science,
      Jim Gettys, MIT Project Athena (DEC),
      Win Treese, Cambridge	Research Lab, Digital Equipment	Corporation.