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Diff for /src/usr.bin/ssh/ssh.1 between version 1.175 and 1.175.2.2

version 1.175, 2003/07/22 13:35:22

version 1.175.2.2, 2004/08/19 22:37:32

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.Nd OpenSSH SSH client (remote login program)

.Sh SYNOPSIS

.Nm ssh

.Op Fl l Ar login_name

.Op Fl 1246AaCfgkMNnqsTtVvXxY

.Ar hostname | user@hostname

.Op Ar command

.Pp

.Nm ssh

.Bk -words

.Op Fl afgknqstvxACNTVX1246

.Op Fl b Ar bind_address

.Op Fl c Ar cipher_spec

.Bk -words

.Op Fl D Ar port

.Op Fl e Ar escape_char

.Op Fl i Ar identity_file

.Op Fl l Ar login_name

.Op Fl m Ar mac_spec

.Op Fl o Ar option

.Op Fl p Ar port

.Op Fl F Ar configfile

.Op Fl i Ar identity_file

.Oo Fl L Xo

.Sm off

.Ar port :

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.Xc

.Oc

.Ek

.Op Fl l Ar login_name

.Op Fl m Ar mac_spec

.Op Fl o Ar option

.Bk -words

.Op Fl p Ar port

.Ek

.Oo Fl R Xo

.Sm off

.Ar port :

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.Sm on

.Xc

.Oc

.Op Fl D Ar port

.Op Fl S Ar ctl

.Ar hostname | user@hostname

.Oo Ar user Ns @ Oc Ns Ar hostname

.Op Ar command

.Ek

.Sh DESCRIPTION

.Nm

(SSH client) is a program for logging into a remote machine and for

executing commands on a remote machine.

It is intended to replace

It is intended to replace rlogin and rsh,

rlogin and rsh, and provide secure encrypted communications between

and provide secure encrypted communications between

two untrusted hosts over an insecure network.

X11 connections and

X11 connections and arbitrary TCP/IP ports

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

can also be forwarded over the secure channel.

.Pp

.Nm

connects and logs into the specified

.Ar hostname .

.Ar hostname

(with optional

.Ar user

name).

The user must prove

his/her identity to the remote machine using one of several methods

depending on the protocol version used:

depending on the protocol version used.

.Pp

.Ar command

is specified,

.Ar command

is executed on the remote host instead of a login shell.

.Ss SSH protocol version 1

.Pp

First, if the machine the user logs in from is listed in

.Pa /etc/hosts.equiv

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on the remote machine, and the user names are

the same on both sides, the user is immediately permitted to log in.

Second, if

.Pa \&.rhosts

.Pa .rhosts

.Pa \&.shosts

.Pa .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

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allowed by the server because it is not secure.

.Pp

The second authentication method is the

.Pa rhosts

.Em rhosts

.Pa hosts.equiv

.Em hosts.equiv

method combined with RSA-based host authentication.

It means that if the login would be permitted by

.Pa $HOME/.rhosts ,

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.Pa $HOME/.ssh/known_hosts

in the

.Sx FILES

section), only then login is permitted.

section), only then is login permitted.

This authentication method closes security holes due to IP

spoofing, DNS spoofing and routing spoofing.

[Note to the administrator:

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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.

.Pp

The file

.Pa $HOME/.ssh/authorized_keys

lists the public keys that are permitted for logging

lists the public keys that are permitted for logging in.

in.

When the user logs in, the

.Nm

program tells the server which key pair it would like to use for

authentication.

The server checks if this key is permitted, and if

The server checks if this key is permitted, and if so,

so, sends the user (actually the

sends the user (actually the

.Nm

program running on behalf of the user) a challenge, a random number,

encrypted by the user's public key.

The challenge can only be

The challenge can only be decrypted using the proper private key.

decrypted using the proper private key.

The user's client then decrypts the challenge using the private key,

The user's client then decrypts the

proving that he/she knows the private key

challenge using the private key, proving that he/she knows the private

but without disclosing it to the server.

key but without disclosing it to the server.

.Pp

.Nm

implements the RSA authentication protocol automatically.

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.Xr ssh-keygen 1 .

This stores the private key in

.Pa $HOME/.ssh/identity

and the public key in

and stores the public key in

.Pa $HOME/.ssh/identity.pub

in the user's home directory.

The user should then copy the

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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

RSA authentication is much more secure than

more secure than rhosts authentication.

.Em rhosts

authentication.

.Pp

The most convenient way to use RSA authentication may be with an

authentication agent.

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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.

.Pp

.Ss SSH protocol version 2

.Pp

When a user connects using protocol version 2,

When a user connects using protocol version 2

similar authentication methods are available.

Using the default values for

.Cm PreferredAuthentications ,

the client will try to authenticate first using the hostbased method;

if this method fails public key authentication is attempted,

if this method fails, public key authentication is attempted,

and finally if this method fails keyboard-interactive and

and finally if this method fails, keyboard-interactive and

password authentication are tried.

.Pp

The public key method is similar to RSA authentication described

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The session identifier is derived from a shared Diffie-Hellman value

and is only known to the client and the server.

.Pp

If public key authentication fails or is not available a password

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.

can be sent encrypted to the remote host to prove the user's identity.

.Pp

Additionally,

.Nm

supports hostbased or challenge response authentication.

.Pp

Protocol 2 provides additional mechanisms for confidentiality

(the traffic is encrypted using 3DES, Blowfish, CAST128 or Arcfour)

(the traffic is encrypted using AES, 3DES, Blowfish, CAST128 or Arcfour)

and integrity (hmac-md5, hmac-sha1).

and integrity (hmac-md5, hmac-sha1, hmac-ripemd160).

Note that protocol 1 lacks a strong mechanism for ensuring the

integrity of the connection.

.Pp

.Ss Login session and remote execution

.Pp

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.

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If a pseudo-terminal has been allocated (normal login session), the

user may use the escape characters noted below.

.Pp

If no pseudo tty has been allocated, the

If no pseudo-tty has been allocated,

session is transparent and can be used to reliably transfer binary

the session is transparent and can be used to reliably transfer binary data.

data.

On most systems, setting the escape character to

.Dq none

will also make the session transparent even if a tty is used.

.Pp

The session terminates when the command or shell on the remote

machine exits and all X11 and TCP/IP connections have been closed.

The exit status of the remote program is returned as the exit status

The exit status of the remote program is returned as the exit status of

.Nm ssh .

.Pp

.Ss Escape Characters

When a pseudo-terminal has been requested,

.Nm

supports a number of functions through the use of an escape character.

.Pp

When a pseudo terminal has been requested, ssh supports a number of functions

through the use of an escape character.

.Pp

A single tilde character can be sent as

.Ic ~~

or by following the tilde by a character other than those described below.

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are:

.Bl -tag -width Ds

.It Cm ~.

Disconnect

Disconnect.

.It Cm ~^Z

Background ssh

Background

.Nm ssh .

.It Cm ~#

List forwarded connections

List forwarded connections.

.It Cm ~&

Background ssh at logout when waiting for forwarded connection / X11 sessions

Background

to terminate

.Nm

at logout when waiting for forwarded connection / X11 sessions to terminate.

.It Cm ~?

Display a list of escape characters

Display a list of escape characters.

.It Cm ~B

Send a BREAK to the remote system (only useful for SSH protocol version 2

Send a BREAK to the remote system

and if the peer supports it)

(only useful for SSH protocol version 2 and if the peer supports it).

.It Cm ~C

Open command line (only useful for adding port forwardings using the

Open command line.

Currently this allows the addition of port forwardings using the

.Fl L

and

.Fl R

options)

options (see below).

It also allows the cancellation of existing remote port-forwardings

using

.Fl KR Ar hostport .

Basic help is available, using the

.Fl h

option.

.It Cm ~R

Request rekeying of the connection (only useful for SSH protocol version 2

Request rekeying of the connection

and if the peer supports it)

(only useful for SSH protocol version 2 and if the peer supports it).

.El

.Pp

.Ss X11 and TCP forwarding

.Pp

If the

.Cm ForwardX11

variable is set to

.Dq yes

(or, see the description of the

(or see the description of the

.Fl X

and

.Fl x

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.Ev DISPLAY

value set by

.Nm

will point to the server machine, but with a display number greater

will point to the server machine, but with a display number greater than zero.

than zero.

This is normal, and happens because

.Nm

creates a

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.Cm ForwardAgent

variable is set to

.Dq yes

(or, see the description of the

(or see the description of the

.Fl A

and

.Fl a

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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.

.Pp

.Ss Server authentication

.Pp

.Nm

automatically maintains and checks a database containing

identifications for all hosts it has ever been used with.

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.Pa /etc/ssh/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

If a host's identification ever changes,

ever changes,

.Nm

warns about this and disables password authentication to prevent a

trojan horse from getting the user's password.

Another purpose of

Another purpose of this mechanism is to prevent man-in-the-middle attacks

this mechanism is to prevent man-in-the-middle attacks which could

which could otherwise be used to circumvent the encryption.

otherwise be used to circumvent the encryption.

The

.Cm StrictHostKeyChecking

option can be used to prevent logins to machines whose

host key is not known or has changed.

.Pp

.Nm

can be configured to verify host identification using fingerprint resource

records (SSHFP) published in DNS.

The

.Cm VerifyHostKeyDNS

option can be used to control how DNS lookups are performed.

SSHFP resource records can be generated using

.Xr ssh-keygen 1 .

.Pp

The options are as follows:

.Bl -tag -width Ds

.It Fl a

.It Fl 1

Disables forwarding of the authentication agent connection.

Forces

.Nm

to try protocol version 1 only.

.It Fl 2

Forces

.Nm

to try protocol version 2 only.

.It Fl 4

Forces

.Nm

to use IPv4 addresses only.

.It Fl 6

Forces

.Nm

to use IPv6 addresses only.

.It Fl A

Enables forwarding of the authentication agent connection.

This can also be specified on a per-host basis in a configuration file.

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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 the agent.

.It Fl a

Disables forwarding of the authentication agent connection.

.It Fl b Ar bind_address

Specify the interface to transmit from on machines with multiple

interfaces or aliased addresses.

.It Fl c Ar blowfish|3des|des

.It Fl C

Selects the cipher to use for encrypting the session.

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

.Xr gzip 1 ,

and the

.Dq level

can be controlled by the

.Cm 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

.Cm Compression

option.

.It Fl c Ar cipher_spec

Selects the cipher specification for encrypting the session.

.Pp

Protocol version 1 allows specification of a single cipher.

The suported values are

.Dq 3des ,

.Dq blowfish

and

.Dq des .

.Ar 3des

is used by default.

It is believed to be secure.

.Ar 3des

(triple-des) is an encrypt-decrypt-encrypt triple with three different keys.

It is believed to be secure.

.Ar blowfish

is a fast block cipher, it appears very secure and is much faster than

is a fast block cipher; it appears very secure and is much faster than

.Ar 3des .

.Ar des

is only supported in the

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.Ar 3des

cipher.

Its use is strongly discouraged due to cryptographic weaknesses.

.It Fl c Ar cipher_spec

The default is

Additionally, for protocol version 2 a comma-separated list of ciphers can

.Dq 3des .

be specified in order of preference.

.Pp

See

For protocol version 2

.Cm Ciphers

.Ar cipher_spec

for more information.

is a comma-separated list of ciphers

.It Fl e Ar ch|^ch|none

listed in order of preference.

The supported ciphers are

.Dq 3des-cbc ,

.Dq aes128-cbc ,

.Dq aes192-cbc ,

.Dq aes256-cbc ,

.Dq aes128-ctr ,

.Dq aes192-ctr ,

.Dq aes256-ctr ,

.Dq arcfour ,

.Dq blowfish-cbc ,

and

.Dq cast128-cbc .

The default is

.Bd -literal

``aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,

aes192-cbc,aes256-cbc''

.Ed

.It Fl D Ar port

Specifies a local

.Dq dynamic

application-level port forwarding.

This works by allocating a socket to listen to

.Ar port

on the local side, and 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

.Nm

will act as a SOCKS server.

Only root can forward privileged ports.

Dynamic port forwardings can also be specified in the configuration file.

.It Fl e Ar ch | ^ch | none

Sets the escape character for sessions with a pty (default:

.Ql ~ ) .

The escape character is only recognized at the beginning of a line.

The escape character followed by a dot

.Pq Ql \&.

closes the connection, followed

closes the connection;

by control-Z suspends the connection, and followed by itself sends the

followed by control-Z suspends the connection;

escape character once.

and followed by itself sends the escape character once.

Setting the character to

.Dq none

disables any escapes and makes the session fully transparent.

.It Fl F Ar configfile

Specifies an alternative per-user configuration file.

If a configuration file is given on the command line,

the system-wide configuration file

.Pq Pa /etc/ssh/ssh_config

will be ignored.

The default for the per-user configuration file is

.Pa $HOME/.ssh/config .

.It Fl f

Requests

.Nm

Line 471

Line 556

.Ic ssh -f host xterm .

.It Fl g

Allows remote hosts to connect to local forwarded ports.

.It Fl I Ar smartcard_device

Specifies which smartcard device to use.

The argument is the device

.Nm

should use to communicate with a smartcard used for storing the user's

private RSA key.

.It Fl i Ar identity_file

Selects a file from which the identity (private key) for

RSA or DSA authentication is read.

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.Fl i

options (and multiple identities specified in

configuration files).

.It Fl I Ar smartcard_device

Specifies which smartcard device to use.

The argument is the device

.Nm

should use to communicate with a smartcard used for storing the user's

private RSA key.

.It Fl k

Disables forwarding of Kerberos tickets.

Disables forwarding (delegation) of GSSAPI credentials to the server.

This may also be specified on a per-host basis in the configuration file.

.It Fl L Xo

.Sm off

.Ar port : host : hostport

.Sm on

.Xc

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

.Ar 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

.Ar host

port

.Ar hostport

from the remote machine.

Port forwardings can also be specified in the configuration file.

Only root can forward privileged ports.

IPv6 addresses can be specified with an alternative syntax:

.Sm off

.Xo

.Ar port No / Ar host No /

.Ar hostport .

.Xc

.Sm on

.It Fl l Ar login_name

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.

.It Fl M

Places the

.Nm

client into

.Dq master

mode for connection sharing.

Refer to the description of

.Cm ControlMaster

.Xr ssh_config 5

for details.

.It Fl m Ar mac_spec

Additionally, for protocol version 2 a comma-separated list of MAC

(message authentication code) algorithms can

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See the

.Cm MACs

keyword for more information.

.It Fl N

Do not execute a remote command.

This is useful for just forwarding ports

(protocol version 2 only).

.It Fl n

Redirects stdin from

.Pa /dev/null

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needs to ask for a password or passphrase; see also the

.Fl f

option.)

.It Fl N

Do not execute a remote command.

This is useful for just forwarding ports

(protocol version 2 only).

.It Fl o Ar option

Can be used to give options in the format used in the configuration 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

.Xr ssh_config 5 .

.Pp

.Bl -tag -width Ds -offset indent -compact

.It AddressFamily

.It BatchMode

.It BindAddress

.It ChallengeResponseAuthentication

.It CheckHostIP

.It Cipher

.It Ciphers

.It ClearAllForwardings

.It Compression

.It CompressionLevel

.It ConnectionAttempts

.It ConnectTimeout

.It ControlMaster

.It ControlPath

.It DynamicForward

.It EscapeChar

.It ForwardAgent

.It ForwardX11

.It ForwardX11Trusted

.It GatewayPorts

.It GlobalKnownHostsFile

.It GSSAPIAuthentication

.It GSSAPIDelegateCredentials

.It Host

.It HostbasedAuthentication

.It HostKeyAlgorithms

.It HostKeyAlias

.It HostName

.It IdentityFile

.It IdentitiesOnly

.It LocalForward

.It LogLevel

.It MACs

.It NoHostAuthenticationForLocalhost

.It NumberOfPasswordPrompts

.It PasswordAuthentication

.It Port

.It PreferredAuthentications

.It Protocol

.It ProxyCommand

.It PubkeyAuthentication

.It RemoteForward

.It RhostsRSAAuthentication

.It RSAAuthentication

.It SendEnv

.It ServerAliveInterval

.It ServerAliveCountMax

.It SmartcardDevice

.It StrictHostKeyChecking

.It TCPKeepAlive

.It UsePrivilegedPort

.It User

.It UserKnownHostsFile

.It VerifyHostKeyDNS

.It XAuthLocation

.El

.It Fl p Ar port

Port to connect to on the remote host.

This can be specified on a

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.It Fl q

Quiet mode.

Causes all warning and diagnostic messages to be suppressed.

.It Fl R Xo

.Sm off

.Ar port : host : hostport

.Sm on

.Xc

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

.Ar 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

.Ar host

port

.Ar 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 with an alternative syntax:

.Sm off

.Xo

.Ar port No / Ar host No /

.Ar hostport .

.Xc

.Sm on

.It Fl S Ar ctl

Specifies the location of a control socket for connection sharing.

Refer to the description of

.Cm ControlPath

and

.Cm ControlMaster

.Xr ssh_config 5

for details.

.It Fl 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 applications (eg. sftp).

of SSH as a secure transport for other applications (eg.\&

.Xr sftp 1 ) .

The subsystem is specified as the remote command.

.It Fl T

Disable pseudo-tty allocation.

.It Fl t

Force pseudo-tty allocation.

This can be used to execute arbitrary

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options force tty allocation, even if

.Nm

has no local tty.

.It Fl T

.It Fl V

Disable pseudo-tty allocation.

Display the version number and exit.

.It Fl v

Verbose mode.

Causes

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.Fl v

options increase the verbosity.

The maximum is 3.

.It Fl V

Display the version number and exit.

.It Fl x

Disables X11 forwarding.

.It Fl X

Enables X11 forwarding.

This can also be specified on a per-host basis in a configuration file.

Line 582

Line 796

(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.

.It Fl C

.It Fl x

Requests compression of all data (including stdin, stdout, stderr, and

Disables X11 forwarding.

data for forwarded X11 and TCP/IP connections).

.It Fl Y

The compression algorithm is the same used by

Enables trusted X11 forwarding.

.Xr gzip 1 ,

and the

.Dq level

can be controlled by the

.Cm 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

.Cm Compression

option.

.It Fl F Ar configfile

Specifies an alternative per-user configuration file.

If a configuration file is given on the command line,

the system-wide configuration file

.Pq Pa /etc/ssh/ssh_config

will be ignored.

The default for the per-user configuration file is

.Pa $HOME/.ssh/config .

.It Fl L Ar 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

.Ar 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

.Ar host

port

.Ar hostport

from the remote machine.

Port forwardings can also be specified in the configuration file.

Only root can forward privileged ports.

IPv6 addresses can be specified with an alternative syntax:

.Ar port/host/hostport

.It Fl R Ar 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

.Ar 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

.Ar host

port

.Ar 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 with an alternative syntax:

.Ar port/host/hostport

.It Fl D Ar port

Specifies a local

.Dq dynamic

application-level port forwarding.

This works by allocating a socket to listen to

.Ar port

on the local side, and 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

.Nm

will act as a SOCKS server.

Only root can forward privileged ports.

Dynamic port forwardings can also be specified in the configuration file.

.It Fl 1

Forces

.Nm

to try protocol version 1 only.

.It Fl 2

Forces

.Nm

to try protocol version 2 only.

.It Fl 4

Forces

.Nm

to use IPv4 addresses only.

.It Fl 6

Forces

.Nm

to use IPv6 addresses only.

.El

.Sh CONFIGURATION FILES

.Nm

Line 680

Line 810

.Sh ENVIRONMENT

.Nm

will normally set the following environment variables:

.Bl -tag -width Ds

.Bl -tag -width LOGNAME

.It Ev DISPLAY

The

.Ev DISPLAY

Line 690

Line 820

to point to a value of the form

.Dq hostname:n

where hostname indicates

the host where the shell runs, and n is an integer >= 1.

the host where the shell runs, and n is an integer \*(Ge 1.

.Nm

uses this special value to forward X11 connections over the secure

channel.

Line 768

Line 898

.Dq VARNAME=value

to the environment if the file exists and if users are allowed to

change their environment.

See the

For more information, see the

.Cm PermitUserEnvironment

option in

.Xr sshd_config 5 .

Line 797

Line 927

identity file in human-readable form).

The contents of the

.Pa $HOME/.ssh/identity.pub

file should be added to

file should be added to the file

.Pa $HOME/.ssh/authorized_keys

on all machines

where the user wishes to log in using protocol version 1 RSA authentication.

Line 818

Line 948

This is the per-user configuration file.

The file format and configuration options are described in

.Xr ssh_config 5 .

Because of the potential for abuse, this file must have strict permissions:

read/write for the user, and not accessible by others.

.It Pa $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

.Xr sshd 8

manual page.

In the simplest form the format is the same as the .pub

In the simplest form the format is the same as the

.Pa .pub

identity files.

This file is not highly sensitive, but the recommended

permissions are read/write for the user, and not accessible by others.

Line 839

Line 972

When different names are used

for the same machine, all such names should be listed, separated by

commas.

The format is described on the

The format is described in the

.Xr sshd 8

manual page.

.Pp

Line 879

Line 1012

is not setuid root.

.It Pa $HOME/.rhosts

This file is used in

.Pa \&.rhosts

.Em rhosts

authentication to list the

host/user pairs that are permitted to log in.

(Note that this file is

Line 901

Line 1034

Note that by default

.Xr sshd 8

will be installed so that it requires successful RSA host

authentication before permitting \s+2.\s0rhosts authentication.

authentication before permitting

.Em rhosts

authentication.

If the server machine does not have the client's host key in

.Pa /etc/ssh/ssh_known_hosts ,

it can be stored in

Line 912

Line 1047

.Pa $HOME/.ssh/known_hosts .

.It Pa $HOME/.shosts

This file is used exactly the same way as

.Pa \&.rhosts .

.Pa .rhosts .

The purpose for

having this file is to be able to use rhosts authentication with

.Nm

without permitting login with

.Nm rlogin

.Xr rlogin

.Xr rsh 1 .

.It Pa /etc/hosts.equiv

This file is used during

.Pa \&.rhosts

.Em rhosts

authentication.

It contains

canonical hosts names, one per line (the full format is described on

canonical hosts names, one per line (the full format is described in the

the

.Xr sshd 8

manual page).

If the client host is found in this file, login is

Line 966

Line 1100

exits with the exit status of the remote command or with 255

if an error occurred.

.Sh SEE ALSO

.Xr gzip 1 ,

.Xr rsh 1 ,

.Xr scp 1 ,

.Xr sftp 1 ,

Line 973

Line 1108

.Xr ssh-agent 1 ,

.Xr ssh-keygen 1 ,

.Xr telnet 1 ,

.Xr hosts.equiv 5 ,

.Xr ssh_config 5 ,

.Xr ssh-keysign 8 ,

.Xr sshd 8