Web Hosting Web Hosting, web hosting, JSP, Servlets, Tomcat, website hosting, web site hosting
Web Hosting, web hosting, JSP, Servlets, Tomcat, website hosting, web site hosting
Web Hosting, web hosting, JSP, Servlets, Tomcat, website hosting, web site hosting

Alden Hosting provides professional, efficient, and reliable business-class Web hosting and Website Design services.

WWW.

Call Us Toll-Free
(877) 256-0328

Outside USA
1 - (201) 505-0430

WELCOME HOSTING PLANS FUND RAISING RESELLERS WEB DESIGN EXTRA SERVICES SITE STUDIO TRAFFIC BOOSTER TECH SUPPORT WEBMASTER TIPS 30 DAY GUARANTEE LEGAL NOTICES GLOSSARY CONTACT INFO TECH NEWS

Site Map

LINUX Web Hosting Commands and tools ssh



     ssh [-afgknqstvxACNPTX1246] [-b bind_address] [-c cipher_spec]
         [-e escape_char] [-i identity_file] [-l login_name] [-m mac_spec]
         [-o option] [-p port] [-F configfile] [-L port:host:hostport] [-R
         port:host:hostport] [-D port] hostname | user@hostname [command]


DESCRIPTION

     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/IP ports can also be forwarded over the secure channel.

     ssh connects and logs into the specified hostname.  The user must prove
     his/her identity to the remote machine using one of several methods
     depending on the protocol version used:

   SSH protocol version 1

     First, if the machine the user logs in from is listed in /etc/hosts.equiv
     or /etc/ssh/shosts.equiv on the remote machine, and the user names are
     the same on both sides, the user is immediately permitted to log in.
     Second, if .rhosts or .shosts exists in the user's home directory on the
     remote machine and contains a line containing the name of the client
     machine and the name of the user on that machine, the user is permitted
     to log in.  This form of authentication alone is normally not allowed by
     the server because it is not secure.

     The second authentication method is the rhosts or hosts.equiv method com-
     bined with RSA-based host authentication.  It means that if the login
     would be permitted by $HOME/.rhosts, $HOME/.shosts, /etc/hosts.equiv, or
     /etc/ssh/shosts.equiv, and if additionally the server can verify the
     client's host key (see /etc/ssh/ssh_known_hosts and
     $HOME/.ssh/known_hosts in the FILES section), only then login is permit-
     ted.  This authentication method closes security holes due to IP spoof-
     ing, DNS spoofing and routing spoofing.  [Note to the administrator:
     /etc/hosts.equiv, $HOME/.rhosts, and the rlogin/rsh protocol in general,
     are inherently insecure and should be disabled if security is desired.]

     As a third authentication method, ssh supports RSA based authentication.
     The scheme is based on public-key cryptography: there are cryptosystems
     where encryption and decryption are done using separate keys, and it is
     not possible to derive the decryption key from the encryption key.  RSA
     is one such system.  The idea is that each user creates a public/private
     key pair for authentication purposes.  The server knows the public key,
     and only the user knows the private key.  The file
     $HOME/.ssh/authorized_keys lists the public keys that are permitted for
     logging in.  When the user logs in, the ssh program tells the server
     which key pair it would like to use for authentication.  The server
     checks if this key is permitted, and if so, sends the user (actually the
     ssh program running on behalf of the user) a challenge, a random number,
     encrypted by the user's public key.  The challenge can only be decrypted

     The most convenient way to use RSA authentication may be with an authen-
     tication agent.  See ssh-agent(1) for more information.

     If other authentication methods fail, ssh prompts the user for a pass-
     word.  The password is sent to the remote host for checking; however,
     since all communications are encrypted, the password cannot be seen by
     someone listening on the network.

   SSH protocol version 2

     When a user connects using protocol version 2 similar authentication
     methods are available.  Using the default values for
     PreferredAuthentications, the client will try to authenticate first using
     the hostbased method; if this method fails public key authentication is
     attempted, and finally if this method fails keyboard-interactive and
     password authentication are tried.

     The public key method is similar to RSA authentication described in the
     previous section and allows the RSA or DSA algorithm to be used: The
     client uses his private key, $HOME/.ssh/id_dsa or $HOME/.ssh/id_rsa, to
     sign the session identifier and sends the result to the server.  The
     server checks whether the matching public key is listed in
     $HOME/.ssh/authorized_keys and grants access if both the key is found and
     the signature is correct.  The session identifier is derived from a
     shared Diffie-Hellman value and is only known to the client and the
     server.

     If public key authentication fails or is not available a password can be
     sent encrypted to the remote host for proving the user's identity.

     Additionally, ssh supports hostbased or challenge response authentica-
     tion.

     Protocol 2 provides additional mechanisms for confidentiality (the traf-
     fic is encrypted using 3DES, Blowfish, CAST128 or Arcfour) and integrity
     (hmac-md5, hmac-sha1).  Note that protocol 1 lacks a strong mechanism for
     ensuring the integrity of the connection.

   Login session and remote execution

     When the user's identity has been accepted by the server, the server
     either executes the given command, or logs into the machine and gives the
     user a normal shell on the remote machine.  All communication with the
     remote command or shell will be automatically encrypted.

     If a pseudo-terminal has been allocated (normal login session), the user
     may use the escape characters noted below.

     If no pseudo tty has been allocated, the session is transparent and can
     be used to reliably transfer binary data.  On most systems, setting the
     escape character to ``none'' will also make the session transparent even
     ter can be changed in configuration files using the EscapeChar configura-
     tion directive or on the command line by the -e option.

     The supported escapes (assuming the default `~') are:

     ~.      Disconnect

     ~^Z     Background ssh

     ~#      List forwarded connections

     ~&      Background ssh at logout when waiting for forwarded connection /
             X11 sessions to terminate

     ~?      Display a list of escape characters

     ~R      Request rekeying of the connection (only useful for SSH protocol
             version 2 and if the peer supports it)

   X11 and TCP forwarding

     If the ForwardX11 variable is set to ``yes'' (or, see the description of
     the -X and -x options described later) and the user is using X11 (the
     DISPLAY environment variable is set), the connection to the X11 display
     is automatically forwarded to the remote side in such a way that any X11
     programs started from the shell (or command) will go through the
     encrypted channel, and the connection to the real X server will be made
     from the local machine.  The user should not manually set DISPLAY.  For-
     warding of X11 connections can be configured on the command line or in
     configuration files.

     The DISPLAY value set by ssh will point to the server machine, but with a
     display number greater than zero.  This is normal, and happens because
     ssh creates a ``proxy'' X server on the server machine for forwarding the
     connections over the encrypted channel.

     ssh will also automatically set up Xauthority data on the server machine.
     For this purpose, it will generate a random authorization cookie, store
     it in Xauthority on the server, and verify that any forwarded connections
     carry this cookie and replace it by the real cookie when the connection
     is opened.  The real authentication cookie is never sent to the server
     machine (and no cookies are sent in the plain).

     If the user is using an authentication agent, the connection to the agent
     is automatically forwarded to the remote side unless disabled on the com-
     mand line or in a configuration file.

     Forwarding of arbitrary TCP/IP connections over the secure channel can be
     specified either on the command line or in a configuration file.  One
     possible application of TCP/IP forwarding is a secure connection to an
     electronic purse; another is going through firewalls.

     The options are as follows:

     -a      Disables forwarding of the authentication agent connection.

     -A      Enables forwarding of the authentication agent connection.  This
             can also be specified on a per-host basis in a configuration
             file.

     -b bind_address
             Specify the interface to transmit from on machines with multiple
             interfaces or aliased addresses.

     -c blowfish|3des|des
             Selects the cipher to use for encrypting the session.  3des is
             used by default.  It is believed to be secure.  3des (triple-des)
             is an encrypt-decrypt-encrypt triple with three different keys.
             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 interoperability with legacy protocol 1 implementations that
             do not support the 3des cipher.  Its use is strongly discouraged
             due to cryptographic weaknesses.

     -c cipher_spec
             Additionally, for protocol version 2 a comma-separated list of
             ciphers can be specified in order of preference.  See Ciphers for
             more information.

     -e ch|^ch|none
             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
             fully transparent.

     -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.

     -g      Allows remote hosts to connect to local forwarded ports.

     -i identity_file
             Selects a file from which the identity (private key) for RSA or
             DSA authentication is read.  The default is $HOME/.ssh/identity
             for protocol version 1, and $HOME/.ssh/id_rsa and
             $HOME/.ssh/id_dsa 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 identi-
             ties specified in configuration files).
             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      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
             option.)

     -N      Do not execute a remote command.  This is useful for just for-
             warding ports (protocol version 2 only).

     -o option
             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.

     -p port
             Port to connect to on the remote host.  This can be specified on
             a per-host basis in the configuration file.

     -P      Use a non-privileged port for outgoing connections.  This can be
             used if a firewall does not permit connections from privileged
             ports.  Note that this option turns off RhostsAuthentication and
             RhostsRSAAuthentication for older servers.

     -q      Quiet mode.  Causes all warning and diagnostic messages to be
             suppressed.

     -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). The subsystem is specified as the remote com-
             mand.

     -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.

     -T      Disable pseudo-tty allocation.

     -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 increases
             the verbosity.  Maximum is 3.

     -F configfile
             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 $HOME/.ssh/config.

     -L port:host:hostport
             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,
             and whenever a connection 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.  Only root can for-
             ward privileged ports.  IPv6 addresses can be specified with an
             alternative syntax: port/host/hostport

     -R port:host:hostport
             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 forward-
             ings 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 with an alternative
             syntax: port/host/hostport

     -D port
             Specifies a local ``dynamic'' application-level port forwarding.
             This works by allocating a socket to listen to port on the local
             side, and whenever a connection is made to this port, the connec-
             tion 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 protocol is supported, and
             ssh will act as a SOCKS4 server.  Only root can forward privi-
             leged ports.  Dynamic port forwardings can also be specified in
             the configuration file.

     -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.


CONFIGURATION FILES

     ssh obtains configuration data from the following sources in the follow-
     ing order: command line options, user's configuration file
     ($HOME/.ssh/config), and system-wide configuration file
     Otherwise a line is of the format ``keyword arguments''.  Configuration
     options may be separated by whitespace or optional whitespace and exactly
     one `='; the latter format is useful to avoid the need to quote whites-
     pace when specifying configuration options using the ssh, scp and sftp -o
     option.

     The possible keywords and their meanings are as follows (note that key-
     words are case-insensitive and arguments are case-sensitive):

     Host    Restricts the following declarations (up to the next Host key-
             word) to be only for those hosts that match one of the patterns
             given after the keyword.  `*' and `'?  can be used as wildcards
             in the patterns.  A single `*' as a pattern can be used to pro-
             vide global defaults for all hosts.  The host is the hostname
             argument given on the command line (i.e., the name is not con-
             verted to a canonicalized host name before matching).

     AFSTokenPassing
             Specifies whether to pass AFS tokens to remote host.  The argu-
             ment to this keyword must be ``yes'' or ``no''.  This option
             applies to protocol version 1 only.

     BatchMode
             If set to ``yes'', passphrase/password querying will be disabled.
             This option is useful in scripts and other batch jobs where no
             user is present to supply the password.  The argument must be
             ``yes'' or ``no''.  The default is ``no''.

     BindAddress
             Specify the interface to transmit from on machines with multiple
             interfaces or aliased addresses.  Note that this option does not
             work if UsePrivilegedPort is set to ``yes''.

     CheckHostIP
             If this flag is set to ``yes'', ssh will additionally check the
             host IP address in the known_hosts file.  This allows ssh to
             detect if a host key changed due to DNS spoofing.  If the option
             is set to ``no'', the check will not be executed.  The default is
             ``yes''.

     Cipher  Specifies the cipher to use for encrypting the session in proto-
             col version 1.  Currently, ``blowfish'', ``3des'', and ``des''
             are supported.  des is only supported in the ssh client for
             interoperability with legacy protocol 1 implementations that do
             not support the 3des cipher.  Its use is strongly discouraged due
             to cryptographic weaknesses.  The default is ``3des''.

     Ciphers
             Specifies the ciphers allowed for protocol version 2 in order of
             preference.  Multiple ciphers must be comma-separated.  The
             default is


     CompressionLevel
             Specifies the compression level to use if compression is enabled.
             The argument must be an integer from 1 (fast) to 9 (slow, best).
             The default level is 6, which is good for most applications.  The
             meaning of the values is the same as in gzip(1).  Note that this
             option applies to protocol version 1 only.

     ConnectionAttempts
             Specifies the number of tries (one per second) to make before
             falling back to rsh or exiting.  The argument must be an integer.
             This may be useful in scripts if the connection sometimes fails.
             The default is 1.

     DynamicForward
             Specifies that a TCP/IP port on the local machine be forwarded
             over the secure channel, and the application protocol is then
             used to determine where to connect to from the remote machine.
             The argument must be a port number.  Currently the SOCKS4 proto-
             col is supported, and ssh will act as a SOCKS4 server.  Multiple
             forwardings may be specified, and additional forwardings can be
             given on the command line.  Only the superuser can forward privi-
             leged ports.

     EscapeChar
             Sets the escape character (default: `~').  The escape character
             can also be set on the command line.  The argument should be a
             single character, `^' followed by a letter, or ``none'' to dis-
             able the escape character entirely (making the connection trans-
             parent for binary data).

     FallBackToRsh
             Specifies that if connecting via ssh fails due to a connection
             refused error (there is no sshd(8) listening on the remote host),
             rsh(1) should automatically be used instead (after a suitable
             warning about the session being unencrypted).  The argument must
             be ``yes'' or ``no''.  The default is ``no''.

     ForwardAgent
             Specifies whether the connection to the authentication agent (if
             any) will be forwarded to the remote machine.  The argument must
             be ``yes'' or ``no''.  The default is ``no''.

     ForwardX11
             Specifies whether X11 connections will be automatically redi-
             rected over the secure channel and DISPLAY set.  The argument
             must be ``yes'' or ``no''.  The default is ``no''.

     GatewayPorts
             Specifies whether remote hosts are allowed to connect to local
             forwarded ports.  By default, ssh binds local port forwardings to
             the loopback addresss.  This prevents other remote hosts from
             only and is similar to RhostsRSAAuthentication.

     HostKeyAlgorithms
             Specifies the protocol version 2 host key algorithms that the
             client wants to use in order of preference.  The default for this
             option is: ``ssh-rsa,ssh-dss''.

     HostKeyAlias
             Specifies an alias that should be used instead of the real host
             name when looking up or saving the host key in the host key
             database files.  This option is useful for tunneling ssh connec-
             tions or for multiple servers running on a single host.

     HostName
             Specifies the real host name to log into.  This can be used to
             specify nicknames or abbreviations for hosts.  Default is the
             name given on the command line.  Numeric IP addresses are also
             permitted (both on the command line and in HostName specifica-
             tions).

     IdentityFile
             Specifies a file from which the user's RSA or DSA authentication
             identity is read. The default is $HOME/.ssh/identity for protocol
             version 1, and $HOME/.ssh/id_rsa and $HOME/.ssh/id_dsa for proto-
             col version 2.  Additionally, any identities represented by the
             authentication agent will be used for authentication.  The file
             name may use the tilde syntax to refer to a user's home direc-
             tory.  It is possible to have multiple identity files specified
             in configuration files; all these identities will be tried in
             sequence.

     KeepAlive
             Specifies whether the system should send TCP keepalive messages
             to the other side.  If they are sent, death of the connection or
             crash of one of the machines will be properly noticed.  However,
             this means that connections will die if the route is down tem-
             porarily, and some people find it annoying.

             The default is ``yes'' (to send keepalives), and the client will
             notice if the network goes down or the remote host dies.  This is
             important in scripts, and many users want it too.

             To disable keepalives, the value should be set to ``no''.

     KerberosAuthentication
             Specifies whether Kerberos authentication will be used.  The
             argument to this keyword must be ``yes'' or ``no''.

     KerberosTgtPassing
             Specifies whether a Kerberos TGT will be forwarded to the server.
             This will only work if the Kerberos server is actually an AFS
             kaserver.  The argument to this keyword must be ``yes'' or
             BOSE, DEBUG, DEBUG1, DEBUG2 and DEBUG3.  The default is INFO.
             DEBUG and DEBUG1 are equivalent.  DEBUG2 and DEBUG3 each specify
             higher levels of verbose output.

     MACs    Specifies the MAC (message authentication code) algorithms in
             order of preference.  The MAC algorithm is used in protocol ver-
             sion 2 for data integrity protection.  Multiple algorithms must
             be comma-separated.  The default is
             ``hmac-md5,hmac-sha1,hmac-ripemd160,hmac-sha1-96,hmac-md5-96''.

     NoHostAuthenticationForLocalhost
             This option can be used if the home directory is shared across
             machines.  In this case localhost will refer to a different
             machine on each of the machines and the user will get many warn-
             ings about changed host keys.  However, this option disables host
             authentication for localhost.  The argument to this keyword must
             be ``yes'' or ``no''.  The default is to check the host key for
             localhost.

     NumberOfPasswordPrompts
             Specifies the number of password prompts before giving up.  The
             argument to this keyword must be an integer.  Default is 3.

     PasswordAuthentication
             Specifies whether to use password authentication.  The argument
             to this keyword must be ``yes'' or ``no''.  The default is
             ``yes''.

     Port    Specifies the port number to connect on the remote host.  Default
             is 22.

     PreferredAuthentications
             Specifies the order in which the client should try protocol 2
             authentication methods. This allows a client to prefer one method
             (e.g.  keyboard-interactive) over another method (e.g.  password)
             The default for this option is:
             ``hostbased,publickey,keyboard-interactive,password''.

     Protocol
             Specifies the protocol versions ssh should support in order of
             preference.  The possible values are ``1'' and ``2''.  Multiple
             versions must be comma-separated.  The default is ``2,1''.  This
             means that ssh tries version 2 and falls back to version 1 if
             version 2 is not available.

     ProxyCommand
             Specifies the command to use to connect to the server.  The com-
             mand string extends to the end of the line, and is executed with
             /bin/sh.  In the command string, `%h' will be substituted by the
             host name to connect and `%p' by the port.  The command can be
             basically anything, and should read from its standard input and
             write to its standard output.  It should eventually connect an
             local machine.  The first argument must be a port number, and the
             second must be host:port.  IPv6 addresses can be specified with
             an alternative syntax: host/port.  Multiple forwardings may be
             specified, and additional forwardings can be given on the command
             line.  Only the superuser can forward privileged ports.

     RhostsAuthentication
             Specifies whether to try rhosts based authentication.  Note that
             this declaration only affects the client side and has no effect
             whatsoever on security.  Disabling rhosts authentication may
             reduce authentication time on slow connections when rhosts
             authentication is not used.  Most servers do not permit Rhost-
             sAuthentication because it is not secure (see
             RhostsRSAAuthentication).  The argument to this keyword must be
             ``yes'' or ``no''.  The default is ``yes''.  This option applies
             to protocol version 1 only.

     RhostsRSAAuthentication
             Specifies whether to try rhosts based authentication with RSA
             host authentication.  The argument must be ``yes'' or ``no''.
             The default is ``yes''.  This option applies to protocol version
             1 only.

     RSAAuthentication
             Specifies whether to try RSA authentication.  The argument to
             this keyword must be ``yes'' or ``no''.  RSA authentication will
             only be attempted if the identity file exists, or an authentica-
             tion agent is running.  The default is ``yes''.  Note that this
             option applies to protocol version 1 only.

     ChallengeResponseAuthentication
             Specifies whether to use challenge response authentication.  The
             argument to this keyword must be ``yes'' or ``no''.  The default
             is ``yes''.

     SmartcardDevice
             Specifies which smartcard device to use. The argument to this
             keyword is the device ssh should use to communicate with a smart-
             card used for storing the user's private RSA key. By default, no
             device is specified and smartcard support is not activated.

     StrictHostKeyChecking
             If this flag is set to ``yes'', ssh will never automatically add
             host keys to the $HOME/.ssh/known_hosts file, and refuses to con-
             nect to hosts whose host key has changed.  This provides maximum
             protection against trojan horse attacks, however, can be annoying
             when the /etc/ssh/ssh_known_hosts file is poorly maintained, or
             connections to new hosts are frequently made.  This option forces
             the user to manually add all new hosts.  If this flag is set to
             ``no'', ssh will automatically add new host keys to the user
             known hosts files.  If this flag is set to ``ask'', new host keys
             will be added to the user known host files only after the user
             ferent user name is used on different machines.  This saves the
             trouble of having to remember to give the user name on the com-
             mand line.

     UserKnownHostsFile
             Specifies a file to use for the user host key database instead of
             $HOME/.ssh/known_hosts.

     UseRsh  Specifies that rlogin/rsh should be used for this host.  It is
             possible that the host does not at all support the ssh protocol.
             This causes ssh to immediately execute rsh(1).  All other options
             (except HostName) are ignored if this has been specified.  The
             argument must be ``yes'' or ``no''.

     XAuthLocation
             Specifies the location of the xauth(1) program.  The default is
             /usr/X11R6/bin/xauth.


ENVIRONMENT

     ssh will normally set the following environment variables:

     DISPLAY
             The DISPLAY variable indicates the location of the X11 server.
             It is automatically set by ssh to point to a value of the form
             ``hostname:n'' where hostname indicates the host where the shell
             runs, and n is an integer >= 1.  ssh uses this special value to
             forward X11 connections over the secure channel.  The user should
             normally not set DISPLAY explicitly, as that will render the X11
             connection insecure (and will require the user to manually copy
             any required authorization cookies).

     HOME    Set to the path of the user's home directory.

     LOGNAME
             Synonym for USER; set for compatibility with systems that use
             this variable.

     MAIL    Set to the path of the user's mailbox.

     PATH    Set to the default PATH, as specified when compiling ssh.

     SSH_ASKPASS
             If ssh needs a passphrase, it will read the passphrase from the
             current terminal if it was run from a terminal.  If ssh does not
             have a terminal associated with it but DISPLAY and SSH_ASKPASS
             are set, it will execute the program specified by SSH_ASKPASS and
             open an X11 window to read the passphrase.  This is particularly
             useful when calling ssh from a .Xsession or related script.
             (Note that on some machines it may be necessary to redirect the
             input from /dev/null to make this work.)

     SSH_AUTH_SOCK
             This is set to the name of the tty (path to the device) associ-
             ated with the current shell or command.  If the current session
             has no tty, this variable is not set.

     TZ      The timezone variable is set to indicate the present timezone if
             it was set when the daemon was started (i.e., the daemon passes
             the value on to new connections).

     USER    Set to the name of the user logging in.

     Additionally, ssh reads $HOME/.ssh/environment, and adds lines of the
     format ``VARNAME=value'' to the environment.


FILES

     $HOME/.ssh/known_hosts
             Records host keys for all hosts the user has logged into that are
             not in /etc/ssh/ssh_known_hosts.  See sshd(8).

     $HOME/.ssh/identity, $HOME/.ssh/id_dsa, $HOME/.ssh/id_rsa
             Contains the authentication identity of the user.  They are for
             protocol 1 RSA, protocol 2 DSA, and protocol 2 RSA, respectively.
             These files contain sensitive data and should be readable by the
             user but not accessible by others (read/write/execute).  Note
             that ssh ignores a private key file if it is accessible by oth-
             ers.  It is possible to specify a passphrase when generating the
             key; the passphrase will be used to encrypt the sensitive part of
             this file using 3DES.

     $HOME/.ssh/identity.pub, $HOME/.ssh/id_dsa.pub, $HOME/.ssh/id_rsa.pub
             Contains the public key for authentication (public part of the
             identity file in human-readable form).  The contents of the
             $HOME/.ssh/identity.pub file should be added to
             $HOME/.ssh/authorized_keys on all machines where the user wishes
             to log in using protocol version 1 RSA authentication.  The con-
             tents of the $HOME/.ssh/id_dsa.pub and $HOME/.ssh/id_rsa.pub file
             should be added to $HOME/.ssh/authorized_keys on all machines
             where the user wishes to log in using protocol version 2 DSA/RSA
             authentication.  These files are not sensitive and can (but need
             not) be readable by anyone.  These files are never used automati-
             cally and are not necessary; they are only provided for the con-
             venience of the user.

     $HOME/.ssh/config
             This is the per-user configuration file.  The format of this file
             is described above.  This file is used by the ssh client.  This
             file does not usually contain any sensitive information, but the
             recommended permissions are read/write for the user, and not
             accessible by others.

     $HOME/.ssh/authorized_keys
             Lists the public keys (RSA/DSA) that can be used for logging in
             as this user.  The format of this file is described in the
             page.

             The canonical system name (as returned by name servers) is used
             by sshd(8) to verify the client host when logging in; other names
             are needed because ssh does not convert the user-supplied name to
             a canonical name before checking the key, because someone with
             access to the name servers would then be able to fool host
             authentication.

     /etc/ssh/ssh_config
             Systemwide configuration file.  This file provides defaults for
             those values that are not specified in the user's configuration
             file, and for those users who do not have a configuration file.
             This file must be world-readable.

     /etc/ssh/ssh_host_key, /etc/ssh/ssh_host_dsa_key,
             /etc/ssh/ssh_host_rsa_key
             These three files contain the private parts of the host keys and
             are used for RhostsRSAAuthentication and HostbasedAuthentication.
             Since they are readable only by root ssh must be setuid root if
             these authentication methods are desired.

     $HOME/.rhosts
             This file is used in .rhosts authentication to list the host/user
             pairs that are permitted to log in.  (Note that this file is also
             used by rlogin and rsh, which makes using this file insecure.)
             Each line of the file contains a host name (in the canonical form
             returned by name servers), and then a user name on that host,
             separated by a space.  On some machines this file may need to be
             world-readable if the user's home directory is on a NFS parti-
             tion, because sshd(8) reads it as root.  Additionally, this file
             must be owned by the user, and must not have write permissions
             for anyone else.  The recommended permission for most machines is
             read/write for the user, and not accessible by others.

             Note that by default sshd(8) will be installed so that it
             requires successful RSA host authentication before permitting
             .rhosts authentication.  If the server machine does not have the
             client's host key in /etc/ssh/ssh_known_hosts, it can be stored
             in $HOME/.ssh/known_hosts.  The easiest way to do this is to con-
             nect back to the client from the server machine using ssh; this
             will automatically add the host key to $HOME/.ssh/known_hosts.

     $HOME/.shosts
             This file is used exactly the same way as .rhosts.  The purpose
             for having this file is to be able to use rhosts authentication
             with ssh without permitting login with rlogin(1) or rsh(1).

     /etc/hosts.equiv
             This file is used during .rhosts authentication. It contains
             canonical hosts names, one per line (the full format is described
             on the sshd(8) manual page).  If the client host is found in this

     $HOME/.ssh/rc
             Commands in this file are executed by ssh when the user logs in
             just before the user's shell (or command) is started.  See the
             sshd(8) manual page for more information.

     $HOME/.ssh/environment
             Contains additional definitions for environment variables, see
             section ENVIRONMENT above.


DIAGNOSTICS

     ssh exits with the exit status of the remote command or with 255 if an
     error occurred.


AUTHORS

     OpenSSH is a derivative of the original and free ssh 1.2.12 release by
     Tatu Ylonen.  Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo
     de Raadt and Dug Song removed many bugs, re-added newer features and cre-
     ated OpenSSH.  Markus Friedl contributed the support for SSH protocol
     versions 1.5 and 2.0.


SEE ALSO

     rlogin(1), rsh(1), scp(1), sftp(1), ssh-add(1), ssh-agent(1),
     ssh-keygen(1), telnet(1), sshd(8)

     T. Ylonen, T. Kivinen, M. Saarinen, T. Rinne, and S. Lehtinen, SSH
     Protocol Architecture, draft-ietf-secsh-architecture-09.txt, July 2001,
     work in progress material.

BSD                           September 25, 1999                           BSD

Web Hosting, web hosting, JSP, Servlets, Tomcat, website hosting, web site hosting
Add to My Yahoo!

XML icon

Add to Google

 

 

 

 

 

 

 

 

 

 

 

http://alden-servlet-Hosting.com
JSP at alden-servlet-Hosting.com
Servlets at alden-servlet-Hosting.com
Servlet at alden-servlet-Hosting.com
Tomcat at alden-servlet-Hosting.com
MySQL at alden-servlet-Hosting.com
Java at alden-servlet-Hosting.com
sFTP at alden-servlet-Hosting.com
http://alden-tomcat-Hosting.com
JSP at alden-tomcat-Hosting.com
Servlets at alden-tomcat-Hosting.com
Servlet at alden-tomcat-Hosting.com
Tomcat at alden-tomcat-Hosting.com
MySQL at alden-tomcat-Hosting.com
Java at alden-tomcat-Hosting.com
sFTP at alden-tomcat-Hosting.com
http://alden-sftp-Hosting.com
JSP at alden-sftp-Hosting.com
Servlets at alden-sftp-Hosting.com
Servlet at alden-sftp-Hosting.com
Tomcat at alden-sftp-Hosting.com
MySQL at alden-sftp-Hosting.com
Java at alden-sftp-Hosting.com
sFTP at alden-sftp-Hosting.com
http://alden-jsp-Hosting.com
JSP at alden-jsp-Hosting.com
Servlets at alden-jsp-Hosting.com
Servlet at alden-jsp-Hosting.com
Tomcat at alden-jsp-Hosting.com
MySQL at alden-jsp-Hosting.com
Java at alden-jsp-Hosting.com
sFTP at alden-jsp-Hosting.com
http://alden-java-Hosting.com
JSp at alden-java-Hosting.com
Servlets at alden-java-Hosting.com
Servlet at alden-java-Hosting.com
Tomcat at alden-java-Hosting.com
MySQL at alden-java-Hosting.com
Java at alden-java-Hosting.com
sFTP at alden-java-Hosting.com
JSP Servlets Tomcat mysql Java JSP Servlets Tomcat mysql Java JSP Servlets Tomcat mysql Java JSP Servlets Tomcat mysql Java JSP at JSP.aldenWEBhosting.com Servlets at servlets.aldenWEBhosting.com Tomcat at Tomcat.aldenWEBhosting.com mysql at mysql.aldenWEBhosting.com Java at Java.aldenWEBhosting.com Web Hosts Portal Web Links Web Links JSP Web Links servlet Tomcat Docs Web Links Web Links JSP Web Links servlet Web Hosting Tomcat Docs JSP Solutions Web Links JSP Solutions Web Hosting Servlets Solutions Web Links Servlets Solutions Web Hosting Web Links Web Links . .
.
.
. .
. . . . jsp hosting servlets hosting web hosting web sites designed cheap web hosting web site hosting myspace web hosting