NFS in Plan 9


			    mkf



			  ABSTRACT

	  Using	NFS server in Plan 9



Background

Historically, there have been two ways to access remote	file
systems	 in  UNIX.  Sun's NFS and AT&T's RFS, ultimately NFS
took over as de	facto remote file system for UNIX.  NFS	 had
multiple versions, NFSv2 was first version that	got released
into public (and Plan 9	has a server for, but not a client),
NFSv3  addresses  some issues with old model and improves it
in ways	(and Plan 9 has	a client for,  but  not	 a  server).
NFSv4  and later do some radical changes and makes it (more)
suitable for a modern networked	file system, however  it  is
currently just supported by FreeBSD and	Linux at the time of
writing	this guide.


Server

Plan 9 ships with a NFSv2 server, which	is old,	 but  works.
it's  code  is located in  /sys/src/cmd/9nfs/nfsserver.c:63.
In  order  to  use  it,	 there	is  a  helper  script  in
/rc/bin/service/startnfs.    Unlike  rest  of  scripts	in
/rc/bin/service/ this one  needs  to  be  executed  manually
(perhaps  in  cpurc).  You may want to remove  9fs lines and
tweak  aux/nfsserver arguments to add file servers you	need
to  serve over nfs, for	example, to serve  /srv/boot change
startnfs like:

  aux/nfsserver	-f /srv/boot -c	/lib/ndb/nfs >>[2] /sys/log/nfsserver

to serve other directories, you	can use	  srvfs(8)  in	your
cpurc.

Afterwards, you	need to	change	  /lib/ndb/nfs,	 Here  is  a
example:

  #server client  uidfile gidfile
  !9fs files
  .+	 .+	 /n/files/passwd /n/files/group


		     November 23, 2024






			   - 2 -


Server and clients are in forms	of  regular  expressions  of
domain names.  Note that  .+ means all possible	strings, and
thus allows every computer to connect to your  file  system,
this  isn't  usually  what  you	want.  You can limit clients
that access your  system  by  setting  a  more	strict	name
instead	 of  .+.  For example, for a setup that	only allows
unix.cloud9p.org:

  .+	 unix.cloud9p.org	 /dev/null	 /dev/null


Names are checked via their reverse DNS	name, so you  likely
need to	ensure it works	(clients can't connect otherwise).
uidfile	and  gidfile are used to map  users  and  groups  of
Plan 9 machine to UNIX uids and	gids, they are	NOT used for
auth.  Both may	be  /dev/null.


Finally, to connect you	may use	the  following	command	 (in
OpenBSD):

  $ doas mount_nfs -2 server:spec /mnt


where spec is the name of file server you are sharing (via
-f or  -a ).  for example,

  $ doas mount_nfs -2 wm:boot /mnt

to mount  /srv/boot in	/mnt.  note that  -2 is	required, we
(only) speak NFSv2 currently.

see  nfsserver(8) manual page for more information.























		     November 23, 2024