Short: Lightweight TCP/IP network file server and mounter
Author: Timm S. Mueller, Claude Sonnet
Uploader: tmueller@schulze-mueller.de
Type: comm/tcp
Version: 0.8rc1
Architecture: m68k-amigaos, Unixoid (Linux, FreeBSD, etc.)


Overview
---------------------------------------------------------------------

Fizz is a lightweight TCP/IP network file server and mounter.

No configuration files, no daemons, no encryption, no hassle - just a
single command line program for sharing and mounting directories
ad hoc style.

WARNING: no authentication. Use on trusted LANs only! - a crossover
cable, a home switch, or a VPN, and use the READONLY option when
appropriate.

Currently supported: Amiga, Unixoid (FUSE3 for mounting e.g. on
Linux, FreeBSD)

Fizz goes both ways: You can share and mount - on all supported
platforms, both directions are supported. So of course you can share
an Amiga directory with other Amigas. You can run as many instances
as you like. There is no central server.

Feedback welcome.


Requirements
---------------------------------------------------------------------

Amiga:
OS >= v37, bsdsocket.library v4, 68000 CPU
~150k for mounting or sharing a directory

POSIX/FUSE, build requirements:
gcc or clang, FUSE3 library and headers (libfuse3-dev/fuse3-devel),
pkg-config, pthreads. If your OS doesn't support FUSE for mounting,
you can probably run the server at least, because it is clean POSIX
and should be very portable.


Build and install
---------------------------------------------------------------------

On Amiga, just:

  # copy fizz C:

On Unixoid fizz goes into /usr/local/bin:

  $ gmake all
  $ sudo make install
  
Building for Amiga requires the vbcc toolchain:

  $ make amiga

Use 'make help' to see a list of targets.


Getting started
---------------------------------------------------------------------

Things to keep in mind:

1. Start by sharing an empty directory.

2. Make sure you don't expose a share on a host or network interface
that is reachable from untrusted networks, such as the internet.
Typically it is safe to use behind a home router which is also a NAT
gateway, but make sure that this is the case.

3. Copy the things to share into the shared directory. While clients
have no means to create links inside a share, if YOU place symlinks
in a share, these can be traversed by clients, even if they cannot
resolve them to their actual paths.

4. When there is no need for clients to write to a share, use the
READONLY option, so data can't be devastated, not even by accident.


Usage
---------------------------------------------------------------------

Share a directory:

  $ fizz serve [--readonly] [--interface ADDR] [ROOTDIR [PORT]]
  Amiga:
  # fizz serve [ROOTDIR] [PORT num] [READONLY] [IFACE addr] [TZOFFS sec]

  ROOTDIR defaults to the current directory.
  PORT defaults to 7777.
  READONLY rejects all write operations with EROFS.
  IFACE binds to a specific IP address only (e.g. 127.0.0.1).
  If not specified, it binds to all of a machine's interfaces!

  Examples:
  $ fizz serve                        share current directory on port 7777
  $ fizz serve /home/shared           share a specific directory
  # fizz serve RAM:                   share the RAM: disk (Amiga)
  $ fizz serve /srv/pub 8888          share on a different port
  # fizz serve SYS:T READONLY         read-only share (Amiga)
  $ fizz serve --interface 127.0.0.1  localhost only

Mount a share (client side):

  # fizz mount HOST[:PORT] [DEVNAME] [OMITHIDDEN] [TZOFFS sec]
  $ fizz mount HOST[:PORT] MOUNTPOINT [--omithidden] [fuse-options]

  MOUNTPOINT must exist and should be an empty directory.
  OMITHIDDEN hides dot-files from listings (still accessible).

  The client reconnects automatically if the server restarts; operations
  block during reconnect and resume transparently (open files excepted).

  Examples:
  # fizz mount hostname               mounts hostname:7777 to FIZZ: (Amiga)
  # fizz mount hostname NETZ:         mounts hostname:7777 to NETZ: (Amiga)
  $ fizz mount a1200 ~/net -f         mount, running in foreground
  $ fizz mount 192.168.1.5:8888 ~/net

Unmount on Unixoid:
  $ umount ~/net
  $ fusermount3 -u ~/net              if needed (I don't)

Unmount on Amiga:
  press CTRL-C or send a break signal.


More Amiga-specific notes
---------------------------------------------------------------------

- A great place for setting up shares on an Amiga is in
AmiTCP:db/user-startnet, e.g.:

run <>NIL: fizz mount hostname SHARE: tzoffs 7200

With this method shares can come up and go away by starting and
stopping the network.
 
- For correct datestamps on Amiga, use the TZOFFS argument to
normalize your time towards UTC. The server always carries
timestamps in UTC. The offset is specified in seconds. If your
Amiga is running in CEST, local time, in summer, you would specify
TZOFFS 7200 for both clients and servers running on this Amiga.
Ideally you get the system time using some ntp syncing tool and
calculate TZOFFS with some help from TZUtil or similar.

- On the Amiga client side, use the experimental option LOCKING/S to
enable full file-lock semantics locally, per client mount. No locking
goes over the wire protocol and so isn't enforced between remote
clients yet, only between Amiga applications. If you encounter
problems, please report them.


Disclaimer
---------------------------------------------------------------------

See also COPYRIGHT.

This software was created under the influence of drugs and alcohol.
The only thing that can be guaranteed is that it can corrupt your
data, silently, when you least expect it.
It hasn't been sufficiently tested yet. For more details, see the
Limitations section in this document, and the files SECURITY,
DESIGN, and TODO. (However these documents can be erroneous and 
misleading, too.)

Short version: Consider everything here experimental, and don't
entrust it important data that you cannot recover.


Rationale
---------------------------------------------------------------------

Created for lack of a better tool.

Samba: The smbfs mounter on Amiga is great. But the Samba server is a
pile of bloat and obsolescence, and a nuisance to configure. You are
building dozens of megabytes of cruft, and then try to make sense of
weird compatibility options to disable 95% of that. And you keep
wondering when your distribution will finally drop them for godawful
security - which you couldn't care less about in your home network.

NFS: ch_nfsmount on Amiga is great. NFSv2 is fast and easy to setup -
for the 1993 Unix aficionado. In the kernel you enable options nobody
has bothered to play with in a decade or two. The NFSv2 userland
support, which any sane distribution has abandoned a long time ago,
you build yourself from sources you picked up in a back-alley
scrapyard on the internet. After that it's awesome.

I admit I haven't tried many newer mounters (NFSv3, possibly some 
other for Samba). What I've seen was that I had to write mountlist
entries again, so shares cannot be terminated by the break signal,
and the network stack cannot remove them automatically. And then, it
still doesn't work the other way round - and setting up a Samba or
NFS server on an Amiga would be even more insane.

In my opinion, ch_nfsmount and smbfs show how it's done: They are not
handlers that go into L:, but are started as regular programs that
provide the volumes dynamically, and so go away on arrival of the
break signal. That way starting/stopping the network can bring up and
remove shares naturally and cleanly.

These were the reasons why I wanted to write such a thing for a long
time. Now with the arrival of some modern programming languages
(English) and methods (betreutes Coden) I found a good reason to give
these things a try and craft it in exactly the way I wanted.

The result is an Amiga binary about 40KB in size which is both
server and client, and works swiftly and nicely even on an Amiga 500.
With it I can not only mount my Unix machines, but even the smallest
Amigas can exchange data between each other. Oh, and you can also use
it for sharing a directory on your laptop in a guest LAN - for you
and your friends to collaborate on some small project. Like, for
example, making an Amiga demo.


Known Limitations
---------------------------------------------------------------------

No authentication
  Any host that can reach the port has full read/write access.
  Use READONLY, --interface and firewall rules when in doubt.

Locking
  Lock() works correctly for normal use: shared locks, directory
  references, Examine, NameFromLock, etc. Full locking semantics
  can be enforced per Amiga mount using the LOCKING option, but it
  is not enforced on the server side and between remote clients yet.

No symlinks or hard links
  The protocol does not support creating symlinks or hard links.
  Existing symlinks on the server appear as NT_LINK entries in
  directory listings; there is no way for clients to resolve their
  targets. File operations (open, readdir) on the server do follow
  symlinks, so a path that crosses a symlink will work if the client
  already knows it - but symlinks pointing outside the share root
  are not blocked. Clients that do not support NT_LINK should skip
  such entries rather than treating them as errors. Directory
  symlinks in the share can cause infinite traversal loops in
  recursive client operations (e.g. recursive copy or backup).

Concurrent truncate + read (AmigaOS server)
  SetFileSize() may be blocked or silently ignored while another
  client has the file open for reading. The server survives; the
  truncation may not take effect.

File sizes > 2 GB (AmigaOS server)
  AmigaOS DOS file offsets are signed 32-bit. The server rejects
  operations beyond 2 GB.

Timestamps (AmigaOS server)
  AmigaOS time resolution is 1/50 second (20 ms). Sub-tick
  precision is lost on round-trips through the Amiga server.
