$ ssh [option] [*user]@[host] [command]
-i [key] : ローカルにある秘密鍵を指定
-l : ログインユーザーを指定
-p : ポート番号の指定（デフォルト:22）
-1 : プロトコルバージョン１を使用
-2 : プロトコルバージョン２を使用
-4 : IPv4を使用
-6 : IPv6を使用
-A : フォワリングを有効
-a : フォワリングを無効
-L : フォワリングの際にローカルで使用するポート
-X : X11を有効
-x : X11を無効
$ ssh hoge.com
$ ssh firstname.lastname@example.org
$ ssh -l user hoge.com
$ ssh -i ~/common/hoge.txt hoge,com
$ ssh email@example.com ls
$ ssh -L 8000:192.168.1.2:22 firstname.lastname@example.org
$ password **
## local -> server1.com -> server2.com の多段アクセス
$ ssh -t email@example.com "ssh firstname.lastname@example.org"
$ ssh server2.com -o ProxyCommand="ssh email@example.com -W %h:%p"
mosh, sshfs, rsync
ssh (SSH client) is a program for logging into a remote machine and for
executing commands on a remote machine. It is intended to replace rlogin
and rsh, and provide secure encrypted communications between two
untrusted hosts over an insecure network. X11 connections and arbitrary
TCP ports can also be forwarded over the secure channel.
ssh connects and logs into the specified hostname (with optional user
name). The user must prove his/her identity to the remote machine using
one of several methods depending on the protocol version used (see
If command is specified, it is executed on the remote host instead of a
The options are as follows:
-1 Forces ssh to try protocol version 1 only.
-2 Forces ssh to try protocol version 2 only.
-4 Forces ssh to use IPv4 addresses only.
-6 Forces ssh to use IPv6 addresses only.
-A Enables forwarding of the authentication agent connection. This
can also be specified on a per-host basis in a configuration
Agent forwarding should be enabled with caution. Users with the
ability to bypass file permissions on the remote host (for the
agent's UNIX-domain socket) can access the local agent through
the forwarded connection. An attacker cannot obtain key material
from the agent, however they can perform operations on the keys
that enable them to authenticate using the identities loaded into
-a Disables forwarding of the authentication agent connection.
Use bind_address on the local machine as the source address of
the connection. Only useful on systems with more than one
-C Requests compression of all data (including stdin, stdout,
stderr, and data for forwarded X11 and TCP connections). The
compression algorithm is the same used by gzip(1), and the
``level'' can be controlled by the CompressionLevel option for
protocol version 1. Compression is desirable on modem lines and
other slow connections, but will only slow down things on fast
networks. The default value can be set on a host-by-host basis
in the configuration files; see the Compression option.
Selects the cipher specification for encrypting the session.
Protocol version 1 allows specification of a single cipher. The
supported values are ``3des'', ``blowfish'', and ``des''. 3des
(triple-des) is an encrypt-decrypt-encrypt triple with three dif-
ferent keys. It is believed to be secure. blowfish is a fast
block cipher; it appears very secure and is much faster than
3des. des is only supported in the ssh client for interoperabil-
ity with legacy protocol 1 implementations that do not support
the 3des cipher. Its use is strongly discouraged due to crypto-
graphic weaknesses. The default is ``3des''.
For protocol version 2, cipher_spec is a comma-separated list of
ciphers listed in order of preference. See the Ciphers keyword
in ssh_config(5) for more information.
Specifies a local ``dynamic'' application-level port forwarding.
This works by allocating a socket to listen to port on the local
side, optionally bound to the specified bind_address. Whenever a
connection is made to this port, the connection is forwarded over
the secure channel, and the application protocol is then used to
determine where to connect to from the remote machine. Currently
the SOCKS4 and SOCKS5 protocols are supported, and ssh will act
as a SOCKS server. Only root can forward privileged ports.
Dynamic port forwardings can also be specified in the configura-
IPv6 addresses can be specified by enclosing the address in
square brackets. Only the superuser can forward privileged
ports. By default, the local port is bound in accordance with
the GatewayPorts setting. However, an explicit bind_address may
be used to bind the connection to a specific address. The
bind_address of ``localhost'' indicates that the listening port
be bound for local use only, while an empty address or `*' indi-
cates that the port should be available from all interfaces.
Sets the escape character for sessions with a pty (default: `~').
The escape character is only recognized at the beginning of a
line. The escape character followed by a dot (`.') closes the
connection; followed by control-Z suspends the connection; and
followed by itself sends the escape character once. Setting the
character to ``none'' disables any escapes and makes the session
Specifies an alternative per-user configuration file. If a con-
figuration file is given on the command line, the system-wide
configuration file (/etc/ssh/ssh_config) will be ignored. The
default for the per-user configuration file is ~/.ssh/config.
-f Requests ssh to go to background just before command execution.
This is useful if ssh is going to ask for passwords or
passphrases, but the user wants it in the background. This
implies -n. The recommended way to start X11 programs at a
remote site is with something like ssh -f host xterm.
If the ExitOnForwardFailure configuration option is set to
``yes'', then a client started with -f will wait for all remote
port forwards to be successfully established before placing
itself in the background.
-g Allows remote hosts to connect to local forwarded ports.
Specify the PKCS#11 shared library ssh should use to communicate
with a PKCS#11 token providing the user's private RSA key.
Selects a file from which the identity (private key) for public
key authentication is read. The default is ~/.ssh/identity for
protocol version 1, and ~/.ssh/id_dsa, ~/.ssh/id_ecdsa and
~/.ssh/id_rsa for protocol version 2. Identity files may also be
specified on a per-host basis in the configuration file. It is
possible to have multiple -i options (and multiple identities
specified in configuration files). ssh will also try to load
certificate information from the filename obtained by appending
-cert.pub to identity filenames.
-K Enables GSSAPI-based authentication and forwarding (delegation)
of GSSAPI credentials to the server.
-k Disables forwarding (delegation) of GSSAPI credentials to the
Specifies that the given port on the local (client) host is to be
forwarded to the given host and port on the remote side. This
works by allocating a socket to listen to port on the local side,
optionally bound to the specified bind_address. Whenever a con-
nection is made to this port, the connection is forwarded over
the secure channel, and a connection is made to host port
hostport from the remote machine. Port forwardings can also be
specified in the configuration file. IPv6 addresses can be spec-
ified by enclosing the address in square brackets. Only the
superuser can forward privileged ports. By default, the local
port is bound in accordance with the GatewayPorts setting. How-
ever, an explicit bind_address may be used to bind the connection
to a specific address. The bind_address of ``localhost'' indi-
cates that the listening port be bound for local use only, while
an empty address or `*' indicates that the port should be avail-
able from all interfaces.
Specifies the user to log in as on the remote machine. This also
may be specified on a per-host basis in the configuration file.
-M Places the ssh client into ``master'' mode for connection shar-
ing. Multiple -M options places ssh into ``master'' mode with
confirmation required before slave connections are accepted.
Refer to the description of ControlMaster in ssh_config(5) for
Additionally, for protocol version 2 a comma-separated list of
MAC (message authentication code) algorithms can be specified in
order of preference. See the MACs keyword for more information.
-N Do not execute a remote command. This is useful for just for-
warding ports (protocol version 2 only).
-n Redirects stdin from /dev/null (actually, prevents reading from
stdin). This must be used when ssh is run in the background. A
common trick is to use this to run X11 programs on a remote
machine. For example, ssh -n shadows.cs.hut.fi emacs & will
start an emacs on shadows.cs.hut.fi, and the X11 connection will
be automatically forwarded over an encrypted channel. The ssh
program will be put in the background. (This does not work if
ssh needs to ask for a password or passphrase; see also the -f
Control an active connection multiplexing master process. When
the -O option is specified, the ctl_cmd argument is interpreted
and passed to the master process. Valid commands are: ``check''
(check that the master process is running), ``forward'' (request
forwardings without command execution), ``cancel'' (cancel for-
wardings), ``exit'' (request the master to exit), and ``stop''
(request the master to stop accepting further multiplexing
Can be used to give options in the format used in the configura-
tion 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
Port to connect to on the remote host. This can be specified on
a per-host basis in the configuration file.
-q Quiet mode. Causes most warning and diagnostic messages to be
Specifies that the given port on the remote (server) host is to
be forwarded to the given host and port on the local side. This
works by allocating a socket to listen to port on the remote
side, and whenever a connection is made to this port, the connec-
tion is forwarded over the secure channel, and a connection is
made to host port hostport from the local machine.
Port forwardings can also be specified in the configuration file.
Privileged ports can be forwarded only when logging in as root on
the remote machine. IPv6 addresses can be specified by enclosing
the address in square brackets.
By default, the listening socket on the server will be bound to
the loopback interface only. This may be overridden by specify-
ing a bind_address. An empty bind_address, or the address `*',
indicates that the remote socket should listen on all interfaces.
Specifying a remote bind_address will only succeed if the
server's GatewayPorts option is enabled (see sshd_config(5)).
If the port argument is `0', the listen port will be dynamically
allocated on the server and reported to the client at run time.
When used together with -O forward the allocated port will be
printed to the standard output.
Specifies the location of a control socket for connection shar-
ing, or the string ``none'' to disable connection sharing. Refer
to the description of ControlPath and ControlMaster in
ssh_config(5) for details.
-s May be used to request invocation of a subsystem on the remote
system. Subsystems are a feature of the SSH2 protocol which
facilitate the use of SSH as a secure transport for other appli-
cations (eg. sftp(1)). The subsystem is specified as the remote
-T Disable pseudo-tty allocation.
-t Force pseudo-tty allocation. This can be used to execute arbi-
trary screen-based programs on a remote machine, which can be
very useful, e.g. when implementing menu services. Multiple -t
options force tty allocation, even if ssh has no local tty.
-V Display the version number and exit.
-v Verbose mode. Causes ssh to print debugging messages about its
progress. This is helpful in debugging connection, authentica-
tion, and configuration problems. Multiple -v options increase
the verbosity. The maximum is 3.
Requests that standard input and output on the client be for-
warded to host on port over the secure channel. Implies -N, -T,
ExitOnForwardFailure and ClearAllForwardings. Works with Proto-
col version 2 only.
Requests tunnel device forwarding with the specified tun(4)
devices between the client (local_tun) and the server
The devices may be specified by numerical ID or the keyword
``any'', which uses the next available tunnel device. If
remote_tun is not specified, it defaults to ``any''. See also
the Tunnel and TunnelDevice directives in ssh_config(5). If the
Tunnel directive is unset, it is set to the default tunnel mode,
which is ``point-to-point''.
-X Enables X11 forwarding. This can also be specified on a per-host
basis in a configuration file.
X11 forwarding should be enabled with caution. Users with the
ability to bypass file permissions on the remote host (for the
user's X authorization database) can access the local X11 display
through the forwarded connection. An attacker may then be able
to perform activities such as keystroke monitoring.
For this reason, X11 forwarding is subjected to X11 SECURITY
extension restrictions by default. Please refer to the ssh -Y
option and the ForwardX11Trusted directive in ssh_config(5) for
-x Disables X11 forwarding.
-Y Enables trusted X11 forwarding. Trusted X11 forwardings are not
subjected to the X11 SECURITY extension controls.
-y Send log information using the syslog(3) system module. By
default this information is sent to stderr.
ssh may additionally obtain configuration data from a per-user configura-
tion file and a system-wide configuration file. The file format and con-
figuration options are described in ssh_config(5).