.TH VNC 1
.SH NAME
vncs, vncv \- remote frame buffer server and viewer for Virtual Network Computing (VNC)
.SH SYNOPSIS
.B vncs
[
.B -v
]
[
.B -c
.I cert
]
[
.B -d
.BI : display
]
[
.B -g
.IB width x height
]
[
.B -p
.I pixfmt
]
[
.B -x
.I net
]
[
.I cmd
[
.I args
...
]
]
.PP
.B vncs
.B -k
.BI : display
[
.B -x
.I net
]
.PP
.B vncv
[
.B -cstv
]
[
.B -e
.I encodings
]
.IR host [\fL: n ]
.SH DESCRIPTION
VNC is a lightweight protocol
for accessing graphical applications
remotely.  The protocol allows one or more
clients to connect to a server.
While connected, clients display the frame buffer
presented by the server and can send mouse events,
keyboard events, and exchange snarf buffers.
The server persists across viewer sessions, so that
the virtual application can be accessed from various locations
as its owner moves around.
.PP
VNC displays have names of the form
.IB host : n \fR,
where
.I host
is the machine's network name and
.I n
is a small integer identifier; display
.I n
is served on TCP port
.RI 5900+ n .
.PP
.I Vncs
starts a new virtual frame buffer in memory, simulating
a Plan 9 terminal running
.I cmd
.IR args ,
by default an interactive shell.
As viewers connect, each is authenticated using a 
(rather breakable) challenge-response protocol using
the user's Inferno/POP password.
.PP
The options are:
.TP
.B -c \fIcert
start TLS on each viewer connection using the certificate
in the file
.IR cert .
The corresponding private key must be loaded into
the server's
.IR factotum (4).
When serving TLS connections, the base port is
35729 rather than 5900.
.TP
.B -d :\fIn
run on display
.I n ;
without this option, the server searches
for an unused display.
.TP
.B -g \fIwidth\fBx\fIheight\fR
set the virtual frame buffer to be
.IB width x height
(default
1024x768)
pixels.
.TP
.B -p \fIpixfmt
set the virtual frame buffer's internal pixel format to
.I pixfmt
(default
.BR r5g6b5 ).
.TP
.B -v
print verbose output to standard error.
.TP
.B -x \fInet
announce on an alternate network interface.
Because of the weak authentication protocol and
default lack of encryption, this option must
be accompanied by
.BR -c .
.PD
.PP
The command
.B vncs
.B -k
.BI : n
kills the VNC server running on display
.IR n .
.PP
.I Vncv
provides access to remote display
.IB host : n \fR.
It resizes its window to be the smaller of the
remote frame buffer size and the local screen.
.PP
The options are:
.TP
.B -c
when connecting to 8-bit displays, request
.B r4g4b4
pixels rather than 
.B r3g3b2
pixels.
This takes up more bandwidth but usually gives
significantly better matching to the Plan 9 color map.
.TP
.B -e \fIencodings
set the ordered list of allowed frame buffer update encodings.
The default (and full) set is
.B copyrect
.B corre
.B hextile
.B rre
.BR raw .
The encodings should be given as a single space-separated argument
(quoted when using the shell).
.TP
.B -s
share the display with extant viewers;
by default extant viewers are closed
when a new viewer connects.
.TP
.B -t
start TLS on the connection.
.TP
.B -v
print verbose output to standard error.
.PD
.PP
The VNC protocol represents keyboard input as
key up/down events.
Plan 9 does not expose the state of the
Ctl and Shift keys except as it can be inferred
from receipt of control or shifted characters.
It does not expose the state of the Alt key at all,
since the Alt key is used to compose Unicode characters
(see
.IR keyboard (6)).
.I Vncv
correctly handles the sending of control and shifted
characters.
To support systems that use key sequences like Alt-X
(or worse, Alt-mouse-click), typing the Plan 9 compose
sequences
.B Alt
.B Z
.B A
(for Alt), 
.B Alt
.B Z
.B C
(for Ctrl),
and
.B Alt
.B Z
.B S
(for Shift)
will send a ``key down'' message for
the given key.
A corresponding ``key up'' message
will be sent after the next key is pressed,
or when the sequence is retyped,
whichever happens first.
.SH SOURCE
.B /sys/src/cmd/vnc
.SH "SEE ALSO
.IR drawterm (8)
.br
.B http://www.uk.research.att.com/vnc
.SH BUGS
If the remote frame buffer is larger than the local screen,
only the upper left corner can be accessed.
.PP
.I Vncv
does no verification of the TLS certificate presented
by the server.