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DC_SERVER(1)			   distcache			  DC_SERVER(1)

NAME
       dc_server - Distributed session cache server

SYNOPSIS
       dc_server -listen <address> [options]

DESCRIPTION
       dc_server  runs	a  cache server	and starts listening on	a configurable
       network address for connections.	Incoming connections are  expected  to
       communicate using the distcache(8) protocol, and	would typically	be in-
       stances of dc_client(1) running on other	machines.

OPTIONS
       -daemon
	   After  initialising,	dc_server will detach from the parent process,
	   close standard file-descriptors, etc. If  this  flag	 is  not  set,
	   dc_server will run in the foreground. It is recommended to use this
	   flag	 in combination	with the pidfile flag to simplify stopping and
	   restarting services.

       -user user
	   This	switch will attempt to change user privileges of dc_server  to
	   the	given user ID after initialising its listening socket. On most
	   systems, this can only work if dc_server is	started	 as  the  root
	   user. It is important to note that the change of user ID occurs af-
	   ter the listening socket is create. This ensures that the listening
	   socket  is  created with the	most restrictive permissions, and that
	   the ability to connect to servers at	run-time  corresponds  to  the
	   given   user	 (rather  than	having	unusual	 root  permissions  on
	   startup).

       -listen address
	   Configures the address on which dc_server should listen for	incom-
	   ing	connections.   The  syntax  is that defined by the libnal API.
	   Some	examples follow;

	       # Listen	on port	9001 for all TCP/IPv4 interfaces
	       dc_server -listen IP:9001

	       # Listen	on port	9001 on	a specific TCP/IPv4 interface
	       dc_server -listen IP:192.168.0.1:9001
	       dc_server -listen IP:cacheserver.localnet:9001

	       # Listen	on a unix domain socket	in the /tmp directory
	       dc_server -listen UNIX:/tmp/cacheserver

       -sockowner user
	   This	switch is only useful when listening (see -listen) on unix do-
	   main	sockets.  It will attempt to change ownership of  the  created
	   socket file.

       -sockgroup group
	   This	switch is only useful when listening (see -listen) on unix do-
	   main	 sockets.   It	will  attempt to change	group ownership	of the
	   created socket file.

       -sockperms perms
	   This	switch is only useful when listening (see -listen) on unix do-
	   main	sockets.  It will attempt to change file permissions  for  the
	   created  socket  file, and is specified in the standard octal nota-
	   tion	used for unix file permissions.	Eg. to start dc_server to  run
	   as the nobody user, listening on a unix domain socket that can only
	   be connected	to by the root user or members of the dcclient group;

	       # dc_server -listen UNIX:/tmp/cacheserver -user nobody \
		     -sockgroup	dcclient -sockperms 440

       -sessions num
	   Specifies a maximum number of sessions that should be stored	in the
	   cache.  All	sessions  in  a	cache have an expiry time so that they
	   will, if they have not been forcibly	removed	before that  time,  be
	   expired  out	of the cache. If it is desirable to allow long session
	   timeouts under normal situations yet	protect	 against  the  session
	   cache  growing  without  limit periods of high-load,	this limit can
	   provide the required	balance. If the	 session  cache	 reaches  this
	   limit, it will automatically	rotate out those sessions in the cache
	   that	are due	to expire soonest. It is not (yet) possible to have no
	   limit at all, though	a future version should	support	this by	allow-
	   ing the user	to specify zero.

	   The default value for this flag is 512.

       -progress num
	   dc_server will, by default, log a line of output to stdout whenever
	   there  is cache activity, but will make sure	to do so no more often
	   than	once a second.	If -progress  is  specified,  this  will  take
	   precedence	so that	output will be emitted whenever	num operations
	   have	occurred since the last	output,	 irrespective  of  how	little
	   time	 has  elapsed. The once-a-second logic remains behind this, so
	   that	if less	than num operations has	taken place but	at  least  one
	   second  has	passed,	 output	will still be logged. This flag	has no
	   effect if -daemon is	used.

       -pidfile	path
	   This	is a standard flag for many programs, and most useful in  com-
	   bination  with  -daemon.  When -pidfile is specified	dc_server will
	   write its process ID	to a file at the specified path	upon  success-
	   ful initialisation. To use this path	file to	later kill the running
	   dc_server  instance,	use something like (where pidfile.pid is what-
	   ever	path was);

	       kill `cat pidfile.pid`

       -killable
	   The default behaviour of dc_server is to  silently  ignore  SIGUSR1
	   and	SIGUSR2	 signals,  but with this switch	enabled	it will	handle
	   these signals and close down	cleanly	(mainly	useful for  developers
	   as  an  alternative	to  SIGKILL which is less useful for debugging
	   memory leaks).

       -h, -help, -?
	   Any of these	flags will cause dc_server to display  a  brief	 usage
	   summary  to	the  console and exit cleanly. Any other flags are ig-
	   nored.

SEE ALSO
       dc_client(1)
	   Distributed caching client proxy.

       dc_snoop(1)
	   Distcache protocol analyser and debugging tool.

       distcache(8)
	   Overview of the distcache architecture.

       http://www.distcache.org/
	   Distcache home page.

AUTHOR
       This toolkit was	designed and implemented by Geoff Thorpe  for  Crypto-
       graphic	Appliances  Incorporated.  Since the project was released into
       open source, it has a home page and a project environment where	devel-
       opment,	mailing	 lists,	 and releases are organised. For problems with
       the software or this man	page please check  for	new  releases  at  the
       project web-site	below, mail the	users mailing list described there, or
       contact the author at geoff@geoffthorpe.net.

       Home Page: http://www.distcache.org

1.5.1				  2004.10.19			  DC_SERVER(1)

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