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[See also]
ssh - secure shell client (remote login program)
ssh [-l login_name] hostname [command]
ssh [-a] [-c idea|blowfish|des|3des|arcfour|tss|none]
[-e escape_char] [-i identity_file] [-l login_name] [-n]
[-o option] [-p port] [-q] [-t] [-v] [-x] [-C]
[-L port:host:hostport] [-R port:host:hostport] hostname
[command]
Ssh (Secure Shell) a program for logging into a remote
machine and for executing commands in 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.
First, if the machine the user logs in from is listed in
%ETC%/hosts.equiv or %ETC%/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 (and primary) authentication method is the
rhosts or hosts.equiv method combined with RSA-based host
authentication. It means that if the login would be permitted
by .rhosts, .shosts, %ETC%/hosts.equiv, or
%ETC%/shosts.equiv, and additionally it can verify the
client's host key (see %HOME%/.ssh/known_hosts and
%ETC%/ssh_known_hosts in the Files section), only then
login is permitted. This authentication method closes
security holes due to IP spoofing, DNS spoofing and routing
spoofing. [Note to the administrator:
%ETC%/hosts.equiv, .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: these 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 using the proper private key. The
user's client then decrypts the challenge using the private
key, proving that he/she knows the private key but
without disclosing it to the server.
Ssh implements the RSA authentication protocol automatically.
The user creates his/her RSA key pair by running
ssh-keygen. This stores the private
key in .ssh/identity
and the public key in .ssh/identity.pub in the user's
home directory. The user then copies the identity.pub
to the remote machine and appends it to the file
.ssh/authorized_keys in her home directory
(the authorized_keys file corresponds
to the conventional .rhosts file, and has one key
per line, though the lines can be very long). After this,
the user can log in without giving the password. RSA
authentication is much more secure than rhosts authentication.
The most convenient way to use RSA authentication may be
with an authentication agent. See ssh-agent for more
information.
If other authentication methods fail, ssh prompts the user
for a password. 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.
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 can disconnect with "~.".
All forwarded connections can be listed with
"~#". All available escapes can be listed with "~?".
A single tilde character can be sent as "~~" (or by following
the tilde by a character other than those described
above). The escape character must always follow a newline
to be interpreted as special. The escape character can be
changed in configuration files or on the command line.
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 if a tty is
used.
The session terminates when the command or shell in on the
remote machine exists and all X11 and TCP/IP connections
have been closed. The exit status of the remote program
is returned as the exit status of ssh.
If the user is using X11 (the DISPLAY environment variable
is set on the local machine), the connection to the X11 display is automatically
forwarded to the remote side in such a way that any
X11 programs started from the remote 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. Forwarding of X11
connections can be configured on the command line or in
configuration files.
The DISPLAY value set by ssh on the remote machine 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 command line or in a configuration
file.
Forwarding of arbitrary TCP/IP connections over the secure
channel can be specified either on 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 trough firewalls.
Ssh automatically maintains and checks a database containing
RSA-based identifications for all hosts it has ever
been used with. The database is stored in the file
.ssh/known_hosts in the user's home directory. Additionally,
the file %ETC%/ssh_known_hosts is automatically
checked for known hosts. Any new hosts are automatically
added to the user's file. If a host's identification ever
changes, ssh warns about this and disables password
authentication to prevent a trojan horse from getting the
user's password. Another purpose of this mechanism is to
prevent man-in-the-middle attacks which could otherwise be
used to circumvent the encryption. The StrictHostKeyChecking
option (see below) can be used to prevent logins
to machines whose host key is not known or has changed.
Considerable work has been put into making ssh secure.
However, if you find a security problem, please report it
immediately to <ssh-bugs@cs.hut.fi>.
The current OS/2 version of ssh is based on version 1.2.16.
There is a newer version 1.2.17 available, the main difference is
that it uses a different mechanism for passing data to and from the
authentication agent ssh-agent.
This mechanism is based on local sockets and I could not yet
get it working under OS/2. Furthermore, this mechanism was deemed
to be less safe than the mechanism currently implemented in the
OS/2 version. Quote from the original ssh-agent manual page:
On some machines, an alternative method is used. A unix-domain
socket is created and the name of this socket is stored in the
SSH_AUTHENTICATION_SOCKET environment
variable. The socket is made accessible only to the current user.
This method is easily abused by root or another instance of the same
user.
Since ssh originates in the Unix environment certain "unicisms"
also surface in the OS/2 version.
- Filenames reported by verbose output,
error messages and the like use forward slashes to separate directories.
- Files use Unix line end conventions separating lines by a line feed
instead of the combination carriage return and line feed.
- The ssh programs use a number of files which usually do not exist under OS/2.
Many of them are related to the fact that Unix is a multi-user system
where many people log in from a number of different sources. The code
using these files has not been disabled for the OS/2 version of ssh as
long as the absence of these files does not have a negative impact.
- Options and functionality which makes no sense under OS/2 are
disabled.
- -a
- Disables forwarding of the authentication agent
connection. This may also be specified on a perhost
basis in the configuration file.
- -c idea|des|3des|blowfish|arcfour|tss|none
-
Selects the cipher to use for encrypting the session.
idea is used by default. It is believed to
be secure. des is the data encryption standard,
but is breakable by governments, large corporations,
and major criminal organizations. 3des
(triple-des) is encrypt-decrypt-encrypt triple with
three different keys. It is presumably more secure
than DES. It is used as default if both sites do
not support IDEA. blowfish is an encryption algorithm
invented by Bruce Schneier. It uses 128 bit
keys. arcfour is an algorithm published in the
Usenet News in 1995. This algorithm is believed to
be equivalent with the RC4 cipher from RSA Data
Security (RC4 is a trademark of RSA Data Security).
This is the fastest algorithm currently supported.
TSS is a fast home-grown algorithm based on MD5.
none disables encryption entirely; it is only
intended for debugging, and it renders the connection
insecure.
- -d
-
Disables the VT220 emulation which by default is enabled.
The VT220 emulator is writtem by Robert Muchsel.
It is fast enough (although it uses the 16 Bit VIO calls)
and passes the vttest (OS/2 telnet does not, check it!) and other vt100
test suites. The code was also enhanced to support all extended Linux
escape codes and key codes. This enables you to log into a Linux box, set
term=console and everything will work. The function keys return Linux
key codes, however SHIFT-F1 to SHIFT-F4 return the standard vt100 key codes.
- -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 a number sign (#) lists forwared connections,
followed by the letter 'r' resets the terminal emulation,
followed by a question mark (?) lists supported escape sequences,
and followed by itself sends the escape character once.
Setting the character to `none' disables any
escapes and makes the session fully transparent.
- -i identity_file
-
Selects the file from which the identity (private
key) for RSA authentication is read. Default is
.ssh/identity in the user's home directory. 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).
- -l login_name
-
Specifies the user to log in as on the remote
machine. This may also be specified on a per-host
basis in the configuration file.
- -o option
-
Can be used to give options in the format used in
the config file. This is useful for specifying
options for which there is no separate command-line
flag. The option has the same format as a line in
the configuration file.
- -p port
-
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 all warning and diagnostic messages
to be suppressed. Only fatal errors are displayed.
- -t
-
Force pseudo-tty allocation. This can be used to
execute arbitary screen-based programs on a remote
machine, which can be very useful e.g. when implementing
menu services.
- -v
-
Verbose mode. Causes ssh to print debugging messages
about its progress. This is helpful in
debugging connection, authentication, and configuration
problems.
- -x
-
Disables X11 forwarding. This can also be specified
on a per-host basis in a configuration file.
- -C
-
Requests compression of all data (including stdin,
stdout, stderr, and data for forwarded X11 and
TCP/IP connections). The compression algorithm is
the same used by gzip, and the "level" can be controlled
by the CompressionLevel option (see below).
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 Compress option below.
- -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:hostport from the
remote machine. Port forwardings can also be specified
in the configuration file. Only root can
forward privileged ports.
- -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
connection is forwarded over the secure channel,
and a connection is made to host: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.
Ssh obtains configuration data from the following sources
(in this order): command line options, user's configuration
file (%HOME%/.ssh/config), and system-wide configuration
file (%ETC%/ssh_config). For each parameter, the
first obtained value will be used. The configuration
files contain sections bracketed by "Host" specifications,
and that section is only applied for hosts that match one
of the patterns given in the specification. The matched
host name is the one given on the command line.
Since the first obtained value for each parameter is used,
more host-specific declarations should be given near the
beginning of the file, and general defaults at the end.
The configuration file has the following format:
Empty lines and lines starting with `#' are comments.
Otherwise a line is of the format "keyword arguments".
The possible keywords and their meanings
are as follows (note that the configuration files
are case-sensitive):
- Host
-
Restricts the following declarations (up to the
next Host keyword) to be only for those hosts that
match one of the patterns given after the keyword.
`*' and `?' can be as wildcards in the patterns. A
single `*' as a pattern can be used to provide
global defaults for all hosts. The host is the
hostname argument given on the command line (i.e.,
the name is not converted to a canonicalized host
name before matching).
- BatchMode
-
If set to "yes", passphrase/password querying will
be disabled. This option is useful in scripts and
other batch jobs where you have no user to supply
the password. The argument must be "yes" or "no".
- Cipher
-
Specifies the cipher to use for encrypting the session.
Currently, idea, des, 3des, blowfish,
arcfour, tss, and none are supported. The default is
"idea" (or "3des" if "idea" is not supported by
both hosts). Using "none" (no encryption) is
intended only for debugging, and will render the
connection insecure.
- Compression
-
Specifies whether to use compression. The argument
must be "yes" or "no".
- CompressionLevel
-
Specifies the compression level to use if compression
is enable. 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 GNU GZIP.
- 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.
- 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 disable the escape
character entirely (making the connection transparent
for binary data).
- FallBackToRsh
-
Specifies that if connecting via ssh fails due to a
connection refused error (there is no sshd listening
on the remote host), rsh should automatically
be used instead (after a suitable warning about the
session being unencrypted). The argument must be
"yes" or "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".
- ForwardX11
-
Specifies whether X11 connections will be automatically
redirected over the secure channel and DISPLAY set.
The argument must be "yes" or "no".
- GlobalKnownHostsFile
-
Specifies a file to use instead of
%ETC%/ssh_known_hosts.
- HostName
-
Specifies the real host name to log into. This can
be used to specify nicnames 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 specifications).
- IdentityFile
-
Specifies the file from which the user's RSA
authentication identity is read (default .ssh/identity
in the user's home directory). 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 directory. 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 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 temporarily, 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" in both the server and the client configuration
files.
- LocalForward
-
Specifies that a TCP/IP port on the local machine
be forwarded over the secure channel to given
host:port from the remote machine. The first argument
must be a port number, and the second must be
host:port. Multiple forwardings may be specified,
and additional forwardings can be given on the command
line. Only the root can forward privileged
ports.
- PasswordAuthentication
-
Specifies whether to use password authentication.
The argument to this keyword must be "yes" or "no".
- Port
-
Specifies the port number to connect on the remote
host. Default is 22.
- ProxyCommand
-
Specifies the command to use to connect to the
server. The command 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
stdin and write to its stdout. It should eventually
connect an sshd server running on some
machine, or execute "sshd -i" somewhere. Host key
management will be done using the HostName of the
host being connected (defaulting to the name typed
by the user).
Note that ssh can also be configured to support the
SOCKS system using the --with-socks4 or --with
socks5 compile-time configuration option.
- RemoteForward
-
Specifies that a TCP/IP port on the remote machine
be forwarded over the secure channel to given
host:port from the local machine. The first argument
must be a port number, and the second must be
host:port. Multiple forwardings may be specified,
and additional forwardings can be given on the command
line. Only the root 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 RhostsAuthentication because it is not
secure (see RhostsRSAAuthentication). The argument
to this keyword must be "yes" or "no".
- RhostsRSAAuthentication
-
Specifies whether to try rhosts based authentication
with RSA host authentication. This is the
primary authentication method for most sites. The
argument must be "yes" or "no".
- 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 authentication agent is
running.
- StrictHostKeyChecking
-
If this flag is set to "yes", ssh ssh will never
automatically add host keys to the
%HOME%/.ssh/known_hosts file, and refuses to connect
hosts whose host key has changed. This provides
maximum protection against trojan horse attacks.
However, it can be somewhat annoying if you don't
have good %ETC%/ssh_known_hosts files installed and
frequently connect new hosts. Basically this
option forces the user to manually add any new
hosts. Normally this option is disabled, and new
hosts will automatically be added to the known host
files. The host keys of known hosts will be verified
automatically in either case. The argument
must be "yes" or "no".
- User
-
Specifies the user to log in as. This can be useful
if you have a different user name in different
machines. This saves the trouble of having to
remember to give the user name on the command line.
- UserKnownHostsFile
-
Specifies a file to use 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
exec rsh. All other options (except HostName)
are ignored if this has been specified. The
argument must be "yes" or "no".
Ssh expects the following environment variables to be set
when invoked on the OS/2 machine.
They are best defined in config.sys. Environment
variables marked with * usually are already defined there,
the other ones need to be added.
- COMSPEC *
-
Full path name of OS/2 command interpreter.
- DISPLAY
-
Defined if an X server is installed on the local machine, e.g. IBM's PMX.
- ETC *
-
Path of the directory storing TCP/IP administrative and configuration data.
- HOME
-
Path of the user's home directory.
- HOSTNAME *
-
Hostname of the local machine.
- TMP *
-
Name of the directory where temporary files are stored.
- TERM
-
Type of the terminal. Should be aither vt220 or console for
remote Linux machines.
- USER
-
Account name of the user.
- SSH_UID
-
(OS/2 specific) If this variable is defined its value determines the
userid ssh and all other programs run under. By default, all programs
run with userid 0 i.e. root. This effects the way ports are selected. For example,
ssh to connect to the remote sshd will use a privileged port < 1024
by default and a non-privileged port > 1024 if SSH_UID is set to a value
different from 0. Set this variable if you want to connect to a remote
machine which refuses the usage of privileged ports.
Ssh will normally set the following environment variables
in the remote shell (or command):
- 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 point the user's mailbox.
- PATH
-
Set to the default PATH, as specified when compiling
ssh or, on some systems, %ETC%/environment or
%ETC%/default/login.
- SSH_AUTHENTICATION_FD
-
This is set to an integer value if you are using
the authentication agent and a connection to it has
been forwarded. The value indicates a file
descriptor number used for communicating with the
agent.
- SSH_CLIENT
-
Identifies the client end of the connection. The
variable contains three space-separated values:
client ip-address, client port number, and server
port number.
- SSH_TTY
-
This is set to the name of the tty (path to the
device) associated 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 (e.i., the daemon passes the value on to
new connections).
- USER
-
Set to the name of the user logging in.
Additionally, ssh reads %ETC%/environment and
%HOME%/.ssh/environment, and adds lines of the format
VARNAME=value to the environment. Some systems may have
still additional mechanisms for setting up the environment,
such as %ETC%/default/login on Solaris.
Note that ssh under OS/2 uses the Unix line end convention
which terminates lines in textual files with a Line Feed character
only whereas OS/2 usually terminates lines with a two character
combination consisting of Carriage Return and Line Feed. Note that
you must save all files following this convention when you edit a file
(this can be done with EPM if you use the save /u command).
Especially having an additional carriage return character separate the
lines in the key files (e.g. .ssh/identity) will lead
to strange error messages.
- %HOME%/.ssh/known_hosts
-
Records host keys for all hosts the user has logged
into (that are not in %ETC%/ssh_known_hosts). See
sshd manual page.
- %HOME%/.ssh/random_seed
-
Used for seeding the random number generator. This
file contains sensitive data and should read/write
for the user and not accessible for others. This
file is created the first time the program is run
and updated automatically. The user should never
need to read or modify this file.
- %HOME%/.ssh/identity
-
Contains the RSA authentication identity of the
user. This file contains sensitive data and should
be readable by the user but not accessible by others.
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 IDEA.
- %HOME%/.ssh/identity.pub
-
Contains the public key for authentication (public
part of the identity file in human-readable form).
The contents of this file should be added to
%HOME%/.ssh/authorized_keys on all machines where
you wish to log in using RSA authentication. This
file is not sensitive and can (but need not) be
readable by anyone. This file is never used automatically
and is not necessary; it is only provided
for the convenience 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 RSA keys that can be used for logging in
as this user. The format of this file is described
in the sshd manual page. In the simplest form the
format is the same as the .pub identity files (that
is, each line contains the number of bits in modulus,
public exponent, modulus, and comment fields,
separated by spaces). This file is not highly sensitive,
but the recommended permissions are
read/write for the user, and not accessible by others.
- %ETC%/ssh_known_hosts
-
Systemwide list of known host keys. This file
should be prepared by the system administrator to
contain the public host keys of all machines in the
organization. This file should be world-readable.
This file contains public keys, one per line, in
the following format (fields separated by spaces):
system name, number of bits in modulus, public
exponent, modulus, and optional comment field.
When different names are used for the same machine,
all such names should be listed, separated by commas.
The format is described on the sshd manual
page.
The canonical system name (as returned by name
servers) is used by sshd 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_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.
- %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.
This file must be owned by the user, and must not
have write permissions for anyone else. The recommended
permission is read/write for the user, and
not accessible by others.
Note that by default sshd will be installed so that
it requires successful RSA host authentication
before permitting .rhosts authentication. If your
server machine does not have the client's host key
in %ETC%/ssh_known_hosts, you can store it in
%HOME%/.ssh/known_hosts. The easiest way to do this
is to connect back to the client from the server
machine using ssh; this will automatically add the
host key in %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 or rsh.
- %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 manual
page). If the client host is found in this file,
login is automatically permitted provided client
and server user names are the same. Additionally,
successful RSA host authentication is normally
required. This file should only be writable by
root.
- %ETC%/shosts.equiv
-
This file is processed exactly as %ETC%/hosts.equiv.
This file may be useful to permit logins using ssh
but not using rsh/rlogin.
- %ETC%/sshrc.cmd
-
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 manual page for
more information.
- %HOME%/.ssh/rc.cmd
-
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 manual page for
more information.
Tatu Ylönen <ylo@cs.hut.fi>;
VT220 emulation by Robert Muchsel <muchsel@acm.org>;
OS/2 adaptation by Hans-Michael Stahl <hmstahl@berlin.snafu.de>
Information about new releases, mailing lists, and other
related issues can be found from the ssh WWW home page at
http://www.cs.hut.fi/ssh/.
sshd,
ssh-keygen,
ssh-agent,
ssh-add,
scp,
rsh,
telnet
Last update: 13 February 1997 by hmstahl@berlin.snafu.de