view dbclient.1 @ 516:7fc4ba3c1cbb

- Bump to 0.52 - Clarify that hosts are resolved on the remote end for multihop
author Matt Johnston <matt@ucc.asn.au>
date Tue, 11 Nov 2008 14:08:48 +0000
parents fe30d2a2d626
children 52d7301e46bd
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.TH dbclient 1
.SH NAME
dbclient \- lightweight SSH2 client
.SH SYNOPSIS
.B dbclient
[\-Tt] [\-p
.I port\fR] [\-i
.I id\fR] [\-L
.I l\fR:\fIh\fR:\fIr\fR] [\-R
.I l\fR:\fIh\fR:\fIr\fR] [\-l
.IR user ]
.I host
.RI [ command ]

.B dbclient
[
.I args ]
.I [user1]@host1[/port1],[user2]@host2[/port2],...

.SH DESCRIPTION
.B dbclient
is a SSH 2 client designed to be small enough to be used in small memory
environments, while still being functional and secure enough for general use.
.SH OPTIONS
.TP
.B \-p \fIport
Remote port.
Connect to port
.I port
on the remote host.
Default is 22.
.TP
.B \-i \fIidfile
Identity file.
Read the identity from file
.I idfile
(multiple allowed).
.TP
.B \-L \fIlistenport\fR:\fIhost\fR:\fIport\fR
Local port forwarding.
Forward the port
.I listenport
on the local host through the SSH connection to port
.I port
on the host
.IR host .
.TP
.B \-R \fIlistenport\fR:\fIhost\fR:\fIport\fR
Remote port forwarding.
Forward the port
.I listenport
on the remote host through the SSH connection to port
.I port
on the host
.IR host .
.TP
.B \-l \fIuser
Username.
Login as
.I user
on the remote host.
.TP
.B \-t
Allocate a pty.
.TP
.B \-T
Don't allocate a pty.
.TP
.B \-N
Don't request a remote shell or run any commands. Any command arguments are ignored.
.TP
.B \-f
Fork into the background after authentication. A command argument (or -N) is required.
This is useful when using password authentication.
.TP
.B \-g
Allow non-local hosts to connect to forwarded ports. Applies to -L and -R
forwarded ports, though remote connections to -R forwarded ports may be limited
by the ssh server.
.TP
.B \-y
Always accept hostkeys if they are unknown. If a hostkey mismatch occurs the
connection will abort as normal.
.TP
.B \-W \fIwindowsize
Specify the per-channel receive window buffer size. Increasing this 
may improve network performance at the expense of memory use. Use -h to see the
default buffer size.
.TP
.B \-K \fItimeout_seconds
Ensure that traffic is transmitted at a certain interval in seconds. This is
useful for working around firewalls or routers that drop connections after
a certain period of inactivity. The trade-off is that a session may be
closed if there is a temporary lapse of network connectivity. A setting
if 0 disables keepalives.
.TP
.B \-I \fIidle_timeout
Disconnect the session if no traffic is transmitted or received for \fIidle_timeout\fR seconds.
.TP
.B \-J \fIproxy_command
Use the standard input/output of the program \fIproxy_command\fR rather than using
a normal TCP connection. A hostname should be still be provided, as this is used for
comparing saved hostkeys.
.TP
.B \-B \fIendhost:endport
"Netcat-alike" mode, where Dropbear will connect to the given host, then create a
forwarded connection to \fIendhost\fR. This will then be presented as dbclient's
standard input/output.

Dropbear will also allow multiple "hops" to be specified, separated by commas. In
this case a connection will be made to the first host, then a TCP forwarded 
connection will be made through that to the second host, and so on. Hosts other than
the final destination will not see anything other than the encrypted SSH stream. 
A port for a host can be specified with a slash (eg [email protected]/44 ).
This syntax can also be used with scp or rsync (specifying dbclient as the 
ssh/rsh command). A file can be "bounced" through multiple SSH hops, eg

scp -S dbclient [email protected],[email protected],canyons:/tmp/dump .

Note that hostnames are resolved by the prior hop (so "canyons" would be resolved by the host "wrt")
in the example above, the same way as other -L TCP forwarded hosts are. Host keys are 
checked locally based on the given hostname.

.SH ENVIRONMENT
.TP
.B DROPBEAR_PASSWORD
A password to use for remote authentication can be specified in the environment
variable DROPBEAR_PASSWORD. Care should be taken that the password is not
exposed to other users on a multi-user system, or stored in accessible files.
.TP
.B SSH_ASKPASS
dbclient can use an external program to request a password from a user.
SSH_ASKPASS should be set to the path of a program that will return a password
on standard output. This program will only be used if either DISPLAY is set and
standard input is not a TTY, or the environment variable SSH_ASKPASS_ALWAYS is
set.
.SH AUTHOR
Matt Johnston ([email protected]).
.br
Mihnea Stoenescu wrote initial Dropbear client support
.br
Gerrit Pape ([email protected]) wrote this manual page.
.SH SEE ALSO
dropbear(8), dropbearkey(8)
.P
http://matt.ucc.asn.au/dropbear/dropbear.html