debian man page for dropbear

dropbear(8)						      System Manager's Manual						       dropbear(8)

NAME
       dropbear - lightweight SSH2 server

SYNOPSIS
       dropbear [-FEmwsgjki] [-b banner] [-d dsskey] [-r rsakey] [-p [address:]port]

DESCRIPTION
       dropbear  is  a	SSH  2 server designed to be small enough to be used in small memory environments, while still being functional and secure
       enough for general use.

OPTIONS
       -b banner
	      bannerfile.  Display the contents of the file banner before user login (default: none).

       -d dsskey
	      dsskeyfile.  Use the contents of the file dsskey for the DSS host key  (default:	/etc/dropbear/dropbear_dss_host_key).	Note  that
	      some  SSH  implementations  use  the  term "DSA" rather than "DSS", they mean the same thing.  This file is generated with dropbear-
	      key(8).

       -r rsakey
	      rsakeyfile.  Use the contents of the file rsakey for the rsa host key (default: /etc/dropbear/dropbear_rsa_host_key).  This file	is
	      generated with dropbearkey(8).

       -F     Don't fork into background.

       -E     Log to standard error rather than syslog.

       -m     Don't display the message of the day on login.

       -w     Disallow root logins.

       -s     Disable password logins.

       -g     Disable password logins for root.

       -j     Disable local port forwarding.

       -k     Disable remote port forwarding.

       -p [address:]port
	      Listen  on  specified address and TCP port.  If just a port is given listen on all addresses.  up to 10 can be specified (default 22
	      if none specified).

       -i     Service program mode.  Use this option to run dropbear under TCP/IP servers like inetd, tcpsvd, or tcpserver.  In program  mode  the
	      -F option is implied, and -p options are ignored.

       -P pidfile
	      Specify a pidfile to create when running as a daemon. If not specified, the default is /var/run/dropbear.pid

       -a     Allow remote hosts to connect to forwarded ports.

       -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.

       -I idle_timeout
	      Disconnect the session if no traffic is transmitted or received for idle_timeout seconds.

FILES
       Authorized Keys

	      ~/.ssh/authorized_keys can be set up to allow remote login with a RSA or DSS key. Each line is of the form

       [restrictions] ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAIgAsp... [comment]

	      and can be extracted from a Dropbear private host key with "dropbearkey -y". This is the same format as used by OpenSSH, though  the
	      restrictions are a subset (keys with unknown restrictions are ignored).  Restrictions are comma separated, with double quotes around
	      spaces in arguments.  Available restrictions are:

       no-port-forwarding
	      Don't allow port forwarding for this connection

       no-agent-forwarding
	      Don't allow agent forwarding for this connection

       no-X11-forwarding
	      Don't allow X11 forwarding for this connection

       no-pty Disable PTY allocation. Note that a user can still obtain most of the same functionality with other means even if no-pty is set.

       command="forced_command"
	      Disregard the command provided by the user and always run forced_command.

	      The authorized_keys file and its containing ~/.ssh directory must only be writable by the user, otherwise Dropbear will not allow  a
	      login using public key authentication.

       Host Key Files

	      Host  key files are read at startup from a standard location, by default /etc/dropbear/dropbear_dss_host_key and /etc/dropbear/drop-
	      bear_rsa_host_key or specified on the commandline with -d or -r. These are of the form generated by dropbearkey.

       Message Of The Day

	      By default the file /etc/motd will be printed for any login shell (unless disabled at compile-time). This can also be disabled  per-
	      user by creating a file ~/.hushlogin .

ENVIRONMENT VARIABLES
       Dropbear sets the standard variables USER, LOGNAME, HOME, SHELL, PATH, and TERM.

       The variables below are set for sessions as appropriate.

       SSH_TTY
	      This is set to the allocated TTY if a PTY was used.

       SSH_CONNECTION
	      Contains "<remote_ip> <remote_port> <local_ip> <local_port>".

       DISPLAY
	      Set X11 forwarding is used.

       SSH_ORIGINAL_COMMAND
	      If  a  'command=' authorized_keys option was used, the original command is specified in this variable. If a shell was requested this
	      is set to an empty value.

       SSH_AUTH_SOCK
	      Set to a forwarded ssh-agent connection.

AUTHOR
       Matt Johnston (matt@ucc.asn.au).
       Gerrit Pape (pape@smarden.org) wrote this manual page.

SEE ALSO
       dropbearkey(8), dbclient(1)

       http://matt.ucc.asn.au/dropbear/dropbear.html

																       dropbear(8)