NAME
dropbear - lightweight SSH2 server
SYNOPSIS
dropbear [-FEmwsgjki] [-b banner] [-d dsskey] [-r rsakey] [-p 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
dropbearkey(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/dropbear_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 .
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)