summaryrefslogtreecommitdiff
path: root/manpages/dropbear.8
diff options
context:
space:
mode:
authorMatt Johnston <matt@ucc.asn.au>2023-03-06 21:50:51 +0800
committerMatt Johnston <matt@ucc.asn.au>2023-03-06 21:50:51 +0800
commit9ddedcc53ca1c00b94c7de1ea1edf7a5e34297b2 (patch)
tree5796a1a4348b925bef0b0807a1203593589ae279 /manpages/dropbear.8
parent3292b8c6f1e5fcc405fa0f7a20e90a60f74037b2 (diff)
parenta992d3f0be411e0ba2b93e744df07e2189c7af0d (diff)
downloaddropbear-9ddedcc53ca1c00b94c7de1ea1edf7a5e34297b2.tar.gz
Merge branch 'build/folder-reorg' of github.com:tjkolev/dropbear
Diffstat (limited to 'manpages/dropbear.8')
-rw-r--r--manpages/dropbear.8228
1 files changed, 228 insertions, 0 deletions
diff --git a/manpages/dropbear.8 b/manpages/dropbear.8
new file mode 100644
index 0000000..d9bbfc2
--- /dev/null
+++ b/manpages/dropbear.8
@@ -0,0 +1,228 @@
+.TH dropbear 8
+.SH NAME
+dropbear \- lightweight SSH server
+.SH SYNOPSIS
+.B dropbear
+[\fIflag arguments\fR] [\-b
+.I banner\fR]
+[\-r
+.I hostkeyfile\fR] [\-p [\fIaddress\fR:]\fIport\fR]
+.SH DESCRIPTION
+.B dropbear
+is a small SSH server
+.SH OPTIONS
+.TP
+.B \-b \fIbanner
+bannerfile.
+Display the contents of the file
+.I banner
+before user login (default: none).
+.TP
+.B \-r \fIhostkey
+Use the contents of the file
+.I hostkey
+for the SSH hostkey.
+This file is generated with
+.BR dropbearkey (1)
+or automatically with the '-R' option. See "Host Key Files" below.
+.TP
+.B \-R
+Generate hostkeys automatically. See "Host Key Files" below.
+.TP
+.B \-F
+Don't fork into background.
+.TP
+.B \-E
+Log to standard error rather than syslog.
+.TP
+.B \-e
+Pass on the server environment to all child processes. This is required, for example,
+if Dropbear is launched on the fly from a SLURM workload manager. The environment is not
+passed by default. Note that this could expose secrets in environment variables from
+the calling process - use with caution.
+.TP
+.B \-m
+Don't display the message of the day on login.
+.TP
+.B \-w
+Disallow root logins.
+.TP
+.B \-s
+Disable password logins.
+.TP
+.B \-g
+Disable password logins for root.
+.TP
+.B \-t
+Enable two-factor authentication. Both password login and public key authentication are
+required. Should not be used with the '-s' option.
+.TP
+.B \-j
+Disable local port forwarding.
+.TP
+.B \-k
+Disable remote port forwarding.
+.TP
+.B \-p\fR [\fIaddress\fR:]\fIport
+Listen on specified
+.I address
+and TCP
+.I port.
+If just a port is given listen
+on all addresses.
+Up to 10 can be specified (default 22 if none specified).
+.TP
+.B \-i
+Service program mode.
+Use this option to run
+.B dropbear
+under TCP/IP servers like inetd, tcpsvd, or tcpserver.
+In program mode the \-F option is implied, and \-p options are ignored.
+.TP
+.B \-P \fIpidfile
+Specify a pidfile to create when running as a daemon. If not specified, the
+default is /var/run/dropbear.pid
+.TP
+.B \-a
+Allow remote hosts to connect to forwarded ports.
+.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
+of 0 disables keepalives. If no response is received for 3 consecutive keepalives the connection will be closed.
+.TP
+.B \-I \fIidle_timeout
+Disconnect the session if no traffic is transmitted or received for \fIidle_timeout\fR seconds.
+.TP
+.B \-z
+By default Dropbear will send network traffic with the \fBAF21\fR setting for QoS, letting network devices give it higher priority. Some devices may have problems with that, \fI-z\fR can be used to disable it.
+.TP
+.B \-T \fImax_authentication_attempts
+Set the number of authentication attempts allowed per connection. If unspecified the default is 10 (MAX_AUTH_TRIES)
+.TP
+.B \-c \fIforced_command
+Disregard the command provided by the user and always run \fIforced_command\fR. This also
+overrides any authorized_keys command= option. The original command is saved in the
+SSH_ORIGINAL_COMMAND environment variable (see below).
+.TP
+.B \-V
+Print the version
+
+.SH FILES
+
+.TP
+Authorized Keys
+
+~/.ssh/authorized_keys can be set up to allow remote login with a RSA,
+ECDSA, Ed25519 or DSS
+key. Each line is of the form
+.TP
+[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:
+
+.TP
+.B no-port-forwarding
+Don't allow port forwarding for this connection
+
+.TP
+.B no-agent-forwarding
+Don't allow agent forwarding for this connection
+
+.TP
+.B no-X11-forwarding
+Don't allow X11 forwarding for this connection
+
+.TP
+.B 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.
+
+.TP
+.B restrict
+Applies all the no- restrictions listed above.
+
+.TP
+.B permitopen=\fR"\fIhost:port\fR"
+Restrict local port forwarding so that connection is allowed only to the
+specified host and port. Multiple permitopen options separated by commas
+can be set in authorized_keys. Wildcard character ('*') may be used in
+port specification for matching any port. Hosts must be literal domain names or
+IP addresses.
+
+.TP
+.B command=\fR"\fIforced_command\fR"
+Disregard the command provided by the user and always run \fIforced_command\fR.
+The -c command line option overrides this.
+
+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.
+
+.TP
+Host Key Files
+
+Host key files are read at startup from a standard location, by default
+/etc/dropbear/dropbear_dss_host_key, /etc/dropbear/dropbear_rsa_host_key,
+/etc/dropbear/dropbear_ecdsa_host_key and /etc/dropbear/dropbear_ed25519_host_key
+
+If the -r command line option is specified the default files are not loaded.
+Host key files are of the form generated by dropbearkey.
+The -R option can be used to automatically generate keys
+in the default location - keys will be generated after startup when the first
+connection is established. This had the benefit that the system /dev/urandom
+random number source has a better chance of being securely seeded.
+
+.TP
+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 .
+
+.SH ENVIRONMENT VARIABLES
+Dropbear sets the standard variables USER, LOGNAME, HOME, SHELL, PATH, and TERM.
+
+The variables below are set for sessions as appropriate.
+
+.TP
+.B SSH_TTY
+This is set to the allocated TTY if a PTY was used.
+
+.TP
+.B SSH_CONNECTION
+Contains "<remote_ip> <remote_port> <local_ip> <local_port>".
+
+.TP
+.B DISPLAY
+Set X11 forwarding is used.
+
+.TP
+.B 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.
+
+.TP
+.B SSH_AUTH_SOCK
+Set to a forwarded ssh-agent connection.
+
+.SH NOTES
+Dropbear only supports SSH protocol version 2.
+
+.SH AUTHOR
+Matt Johnston (matt@ucc.asn.au).
+.br
+Gerrit Pape (pape@smarden.org) wrote this manual page.
+.SH SEE ALSO
+dropbearkey(1), dbclient(1), dropbearconvert(1)
+.P
+https://matt.ucc.asn.au/dropbear/dropbear.html