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.