Provided by: dropbear-bin_2017.75-3build1_amd64 
NAME
dbclient - lightweight SSH client
SYNOPSIS
dbclient [flag arguments] [-p port] [-i id] [-L l:h:p] [-R l:h:p] [-l user] host [more flags] [command]
dbclient [args] [user1]@host1[^port1],[user2]@host2[^port2],...
DESCRIPTION
dbclient is a small SSH client
OPTIONS
command
A command to run on the remote host. This will normally be run by the remote host using the user's
shell. The command begins at the first hyphen argument after the host argument. If no command is
specified an interactive terminal will be opened (see -t and -T).
-p port
Connect to port on the remote host. Alternatively a port can be specified as hostname^port.
Default is 22.
-i idfile
Identity file. Read the identity key from file idfile (multiple allowed). This file is created
with dropbearkey(1) or converted from OpenSSH with dropbearconvert(1). The default path
~/.ssh/id_dropbear is used
-L [listenaddress]:listenport:host:port
Local port forwarding. Forward the port listenport on the local host through the SSH connection
to port port on the host host.
-R [listenaddress]:listenport:host:port
Remote port forwarding. Forward the port listenport on the remote host through the SSH connection
to port port on the host host.
-l user
Username. Login as user on the remote host.
-t Allocate a PTY. This is the default when no command is given, it gives a full interactive remote
session. The main effect is that keystrokes are sent remotely immediately as opposed to local
line-based editing.
-T Don't allocate a PTY. This is the default a command is given. See -t.
-N Don't request a remote shell or run any commands. Any command arguments are ignored.
-f Fork into the background after authentication. A command argument (or -N) is required. This is
useful when using password authentication.
-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.
-y Always accept hostkeys if they are unknown. If a hostkey mismatch occurs the connection will abort
as normal. If specified a second time no host key checking is performed at all, this is usually
undesirable.
-A Forward agent connections to the remote host. dbclient will use any OpenSSH-style agent program if
available ($SSH_AUTH_SOCK will be set) for public key authentication. Forwarding is only enabled
if -A is specified.
-W windowsize
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.
-K timeout_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. If no response is received for 3 consecutive keepalives the
connection will be closed.
-I idle_timeout
Disconnect the session if no traffic is transmitted or received for idle_timeout seconds.
-J proxy_command
Use the standard input/output of the program proxy_command rather than using a normal TCP
connection. A hostname should be still be provided, as this is used for comparing saved hostkeys.
This command will be executed as "exec proxy_command ..." with the default shell.
-B endhost:endport
"Netcat-alike" mode, where Dropbear will connect to the given host, then create a forwarded
connection to endhost. This will then be presented as dbclient's standard input/output.
-c cipherlist
Specify a comma separated list of ciphers to enable. Use -c help to list possibilities.
-m MAClist
Specify a comma separated list of authentication MACs to enable. Use -m help to list
possibilities.
-o option
Can be used to give options in the format used by OpenSSH config file. This is useful for
specifying options for which there is no separate command-line flag. For full details of the
options listed below, and their possible values, see ssh_config(5).
For now following options have been implemented:
ExitOnForwardFailure
Specifies whether dbclient should terminate the connection if it cannot set up all
requested local and remote port forwardings. The argument must be “yes” or “no”. The
default is “no”.
UseSyslog
Send dbclient log messages to syslog in addition to stderr.
-s The specified command will be requested as a subsystem, used for sftp. Dropbear doesn't implement
sftp itself but the OpenSSH sftp client can be used eg sftp -S dbclient user@host
-V Print the version
MULTI-HOP
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 caret (eg matt@martello^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 matt@martello,root@wrt,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.
ESCAPE CHARACTERS
Typing a newline followed by the key sequence ~. (tilde, dot) will terminate a connection. The sequence
~^Z (tilde, ctrl-z) will background the connection. This behaviour only applies when a PTY is used.
ENVIRONMENT
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.
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.
NOTES
If compiled with zlib support and if the server supports it, dbclient will always use compression.
AUTHOR
Matt Johnston (matt@ucc.asn.au). Mihnea Stoenescu wrote initial Dropbear client support Gerrit Pape (pape@smarden.org) wrote this manual page.
SEE ALSO
dropbear(8), dropbearkey(1) https://matt.ucc.asn.au/dropbear/dropbear.html dbclient(1)