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Renamed open* -> * at request of Theo de Raadt <deraadt@cvs.openbsd.org>

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This commit is contained in:
Damien Miller 1999-10-29 09:18:29 +10:00
parent f1d9a30b4f
commit a37010e466
12 changed files with 68 additions and 2338 deletions
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32
Makefile.in
View File

@ -7,9 +7,9 @@ libdir=@libdir@
CC=@CC@ CC=@CC@
OPT_FLAGS=-g OPT_FLAGS=-g
CFLAGS=$(OPT_FLAGS) -Wall -DETCDIR=\"@sysconfdir@\" @DEFS@ CFLAGS=$(OPT_FLAGS) -Wall -DETCDIR=\"@sysconfdir@\" @DEFS@
TARGETS=bin/libopenssh.a bin/openssh bin/opensshd bin/openssh-add bin/openssh-keygen bin/openssh-agent bin/openscp TARGETS=bin/libssh.a bin/ssh bin/sshd bin/ssh-add bin/ssh-keygen bin/ssh-agent bin/scp
LFLAGS=-L./bin LFLAGS=-L./bin
LIBS=-lopenssh @LIBS@ LIBS=-lssh @LIBS@
AR=@AR@ AR=@AR@
RANLIB=@RANLIB@ RANLIB=@RANLIB@
@ -23,32 +23,32 @@ OBJS= authfd.o authfile.o auth-passwd.o auth-rhosts.o auth-rh-rsa.o \
all: $(OBJS) $(TARGETS) all: $(OBJS) $(TARGETS)
bin/libopenssh.a: authfd.o authfile.o bufaux.o buffer.o canohost.o channels.o cipher.o compat.o compress.o crc32.o deattack.o hostfile.o match.o mpaux.o nchan.o packet.o readpass.o rsa.o tildexpand.o ttymodes.o uidswap.o xmalloc.o helper.o rc4.o mktemp.o strlcpy.o bin/libssh.a: authfd.o authfile.o bufaux.o buffer.o canohost.o channels.o cipher.o compat.o compress.o crc32.o deattack.o hostfile.o match.o mpaux.o nchan.o packet.o readpass.o rsa.o tildexpand.o ttymodes.o uidswap.o xmalloc.o helper.o rc4.o mktemp.o strlcpy.o
[ -d bin ] || mkdir bin [ -d bin ] || mkdir bin
$(AR) rv $@ $^ $(AR) rv $@ $^
$(RANLIB) $@ $(RANLIB) $@
bin/openssh: ssh.o sshconnect.o log-client.o readconf.o clientloop.o bin/ssh: ssh.o sshconnect.o log-client.o readconf.o clientloop.o
[ -d bin ] || mkdir bin [ -d bin ] || mkdir bin
$(CC) -o $@ $^ $(LFLAGS) $(LIBS) $(CC) -o $@ $^ $(LFLAGS) $(LIBS)
bin/opensshd: sshd.o auth-rhosts.o auth-passwd.o auth-rsa.o auth-rh-rsa.o pty.o log-server.o login.o servconf.o serverloop.o bin/sshd: sshd.o auth-rhosts.o auth-passwd.o auth-rsa.o auth-rh-rsa.o pty.o log-server.o login.o servconf.o serverloop.o
[ -d bin ] || mkdir bin [ -d bin ] || mkdir bin
$(CC) -o $@ $^ $(LFLAGS) $(LIBS) $(CC) -o $@ $^ $(LFLAGS) $(LIBS)
bin/openscp: scp.o bin/scp: scp.o
[ -d bin ] || mkdir bin [ -d bin ] || mkdir bin
$(CC) -o $@ $^ $(LFLAGS) $(LIBS) $(CC) -o $@ $^ $(LFLAGS) $(LIBS)
bin/openssh-add: ssh-add.o log-client.o bin/ssh-add: ssh-add.o log-client.o
[ -d bin ] || mkdir bin [ -d bin ] || mkdir bin
$(CC) -o $@ $^ $(LFLAGS) $(LIBS) $(CC) -o $@ $^ $(LFLAGS) $(LIBS)
bin/openssh-agent: ssh-agent.o log-client.o bin/ssh-agent: ssh-agent.o log-client.o
[ -d bin ] || mkdir bin [ -d bin ] || mkdir bin
$(CC) -o $@ $^ $(LFLAGS) $(LIBS) $(CC) -o $@ $^ $(LFLAGS) $(LIBS)
bin/openssh-keygen: ssh-keygen.o log-client.o bin/ssh-keygen: ssh-keygen.o log-client.o
[ -d bin ] || mkdir bin [ -d bin ] || mkdir bin
$(CC) -o $@ $^ $(LFLAGS) $(LIBS) $(CC) -o $@ $^ $(LFLAGS) $(LIBS)
@ -59,13 +59,13 @@ install:
install -d $(bindir) install -d $(bindir)
install -d $(sbindir) install -d $(sbindir)
install -d $(libdir) install -d $(libdir)
install -c bin/openssh $(bindir)/openssh install -c bin/ssh $(bindir)/ssh
install -c bin/openscp $(bindir)/openscp install -c bin/scp $(bindir)/scp
install -c bin/openssh-add $(bindir)/openssh-add install -c bin/ssh-add $(bindir)/ssh-add
install -c bin/openssh-agent $(bindir)/openssh-agent install -c bin/ssh-agent $(bindir)/ssh-agent
install -c bin/openssh-keygen $(bindir)/openssh-keygen install -c bin/ssh-keygen $(bindir)/ssh-keygen
install -c bin/opensshd $(sbindir)/opensshd install -c bin/sshd $(sbindir)/sshd
install -c bin/libopenssh.a $(libdir)/libopenssh.a install -c bin/libssh.a $(libdir)/libssh.a
distclean: clean distclean: clean
rm -f Makefile config.h *~ rm -f Makefile config.h *~

110
openscp.1
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@ -1,110 +0,0 @@
.\" -*- nroff -*-
.\"
.\" scp.1
.\"
.\" Author: Tatu Ylonen <ylo@cs.hut.fi>
.\"
.\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
.\" All rights reserved
.\"
.\" Created: Sun May 7 00:14:37 1995 ylo
.\"
.\" $Id: openscp.1,v 1.1 1999/10/28 04:03:14 damien Exp $
.\"
.Dd September 25, 1999
.Dt SCP 1
.Os
.Sh NAME
.Nm scp
.Nd secure copy (remote file copy program)
.Sh SYNOPSIS
.Nm scp
.Op Fl pqrvC
.Op Fl P Ar port
.Op Fl c Ar cipher
.Op Fl i Ar identity_file
.Sm off
.Oo
.Op Ar user@
.Ar host1 No :
.Oc Ns Ar file1
.Sm on
.Op Ar ...
.Sm off
.Oo
.Op Ar user@
.Ar host2 No :
.Oc Ar file2
.Sm on
.Sh DESCRIPTION
.Nm
copies files between hosts on a network. It uses
.Xr ssh 1
for data transfer, and uses the same authentication and provides the
same security as
.Xr ssh 1 .
Unlike
.Xr rcp 1 ,
.Nm
will ask for passwords or passphrases if they are needed for
authentication.
.Pp
Any file name may contain a host and user specification to indicate
that the file is to be copied to/from that host. Copies between two
remote hosts are permitted.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl c Ar cipher
Selects the cipher to use for encrypting the data transfer. This
option is directly passed to
.Xr ssh 1 .
.It Fl i Ar identity_file
Selects the file from which the identity (private key) for RSA
authentication is read. This option is directly passed to
.Xr ssh 1 .
.It Fl p
Preserves modification times, access times, and modes from the
original file.
.It Fl r
Recursively copy entire directories.
.It Fl v
Verbose mode. Causes
.Nm
and
.Xr ssh 1
to print debugging messages about their progress. This is helpful in
debugging connection, authentication, and configuration problems.
.It Fl B
Selects batch mode (prevents asking for passwords or passphrases).
.It Fl q
Disables the progress meter.
.It Fl C
Compression enable. Passes the
.Fl C
flag to
.Xr ssh 1
to enable compression.
.It Fl P Ar port
Specifies the port to connect to on the remote host. Note that this
option is written with a capital
.Sq P ,
because
.Fl p
is already reserved for preserving the times and modes of the file in
.Xr rcp 1 .
.Sh AUTHORS
Timo Rinne <tri@iki.fi> and Tatu Ylonen <ylo@cs.hut.fi>
.Sh HISTORY
.Nm
is based on the
.Xr rcp 1
program in BSD source code from the Regents of the University of
California.
.Sh SEE ALSO
.Xr rcp 1 ,
.Xr ssh 1 ,
.Xr ssh-add 1 ,
.Xr ssh-agent 1 ,
.Xr ssh-keygen 1 ,
.Xr sshd 8

116
openssh-add.1
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@ -1,116 +0,0 @@
.\" -*- nroff -*-
.\"
.\" ssh-add.1
.\"
.\" Author: Tatu Ylonen <ylo@cs.hut.fi>
.\"
.\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
.\" All rights reserved
.\"
.\" Created: Sat Apr 22 23:55:14 1995 ylo
.\"
.\" $Id: openssh-add.1,v 1.1 1999/10/28 04:03:14 damien Exp $
.\"
.Dd September 25, 1999
.Dt SSH-ADD 1
.Os
.Sh NAME
.Nm ssh-add
.Nd adds identities for the authentication agent
.Sh SYNOPSIS
.Nm ssh-add
.Op Fl ldD
.Op Ar
.Sh DESCRIPTION
.Nm
adds identities to the authentication agent,
.Xr ssh-agent 1 .
When run without arguments, it adds the file
.Pa $HOME/.ssh/identity .
Alternative file names can be given on the
command line. If any file requires a passphrase,
.Nm
asks for the passphrase from the user.
The Passphrase it is read from the user's tty.
.Pp
The authentication agent must be running and must be an ancestor of
the current process for
.Nm
to work.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl l
Lists all identities currently represented by the agent.
.It Fl d
Instead of adding the identity, removes the identity from the agent.
.It Fl D
Deletes all identities from the agent.
.El
.Sh FILES
.Bl -tag -width Ds
.Pa $HOME/.ssh/identity
Contains the RSA authentication identity of the user. This file
should not be readable by anyone but the user.
Note that
.Nm
ignores this file if it is accessible by others.
It is possible to
specify a passphrase when generating the key; that passphrase will be
used to encrypt the private part of this file. This is the
default file added by
.Nm
when no other files have been specified.
.Pp
If
.Nm
needs a passphrase, it will read the passphrase from the current
terminal if it was run from a terminal. If
.Nm
does not have a terminal associated with it but
.Ev DISPLAY
is set, it
will open an X11 window to read the passphrase. This is particularly
useful when calling
.Nm
from a
.Pa .Xsession
or related script. (Note that on some machines it
may be necessary to redirect the input from
.Pa /dev/null
to make this work.)
.Sh AUTHOR
Tatu Ylonen <ylo@cs.hut.fi>
.Pp
OpenSSH
is a derivative of the original (free) ssh 1.2.12 release, but with bugs
removed and newer features re-added. Rapidly after the 1.2.12 release,
newer versions bore successively more restrictive licenses. This version
of OpenSSH
.Bl -bullet
.It
has all components of a restrictive nature (ie. patents, see
.Xr ssl 8 )
directly removed from the source code; any licensed or patented components
are chosen from
external libraries.
.It
has been updated to support ssh protocol 1.5.
.It
contains added support for
.Xr kerberos 8
authentication and ticket passing.
.It
supports one-time password authentication with
.Xr skey 1 .
.El
.Pp
The libraries described in
.Xr ssl 8
are required for proper operation.
.Sh SEE ALSO
.Xr ssh 1 ,
.Xr ssh-agent 1 ,
.Xr ssh-keygen 1 ,
.Xr sshd 8 ,
.Xr ssl 8

124
openssh-agent.1
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@ -1,124 +0,0 @@
.\" -*- nroff -*-
.\"
.\" ssh-agent.1
.\"
.\" Author: Tatu Ylonen <ylo@cs.hut.fi>
.\"
.\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
.\" All rights reserved
.\"
.\" Created: Sat Apr 23 20:10:43 1995 ylo
.\"
.\" $Id: openssh-agent.1,v 1.1 1999/10/28 04:03:14 damien Exp $
.\"
.Dd September 25, 1999
.Dt SSH-AGENT 1
.Os
.Sh NAME
.Nm ssh-agent
.Nd authentication agent
.Sh SYNOPSIS
.Nm ssh-agent
.Ar command
.Sh DESCRIPTION
.Nm
is a program to hold authentication private keys. The
idea is that
.Nm
is started in the beginning of an X-session or a login session, and
all other windows or programs are started as children of the ssh-agent
program (the
.Ar command
normally starts X or is the user shell). Programs started under
the agent inherit a connection to the agent, and the agent is
automatically used for RSA authentication when logging to other
machines using
.Xr ssh 1 .
.Pp
The agent initially does not have any private keys. Keys are added
using
.Xr ssh-add 1 .
When executed without arguments,
.Xr ssh-add 1
adds the
.Pa $HOME/.ssh/identity
file. If the identity has a passphrase,
.Xr ssh-add 1
asks for the passphrase (using a small X11 application if running
under X11, or from the terminal if running without X). It then sends
the identity to the agent. Several identities can be stored in the
agent; the agent can automatically use any of these identities.
.Ic ssh-add -l
displays the identities currently held by the agent.
.Pp
The idea is that the agent is run in the user's local PC, laptop, or
terminal. Authentication data need not be stored on any other
machine, and authentication passphrases never go over the network.
However, the connection to the agent is forwarded over SSH
remote logins, and the user can thus use the privileges given by the
identities anywhere in the network in a secure way.
.Pp
A connection to the agent is inherited by child programs:
A unix-domain socket is created
.Pq Pa /tmp/ssh-XXXX/agent.<pid> ,
and the name of this socket is stored in the
.Ev SSH_AUTH_SOCK
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.
.Pp
The agent exits automatically when the command given on the command
line terminates.
.Sh FILES
.Bl -tag -width Ds
.It Pa $HOME/.ssh/identity
Contains the RSA authentication identity of the user. This file
should not be readable by anyone but the user. It is possible to
specify a passphrase when generating the key; that passphrase will be
used to encrypt the private part of this file. This file
is not used by
.Nm
but is normally added to the agent using
.Xr ssh-add 1
at login time.
.It Pa /tmp/ssh-XXXX/agent.<pid> ,
Unix-domain sockets used to contain the connection to the
authentication agent. These sockets should only be readable by the
owner. The sockets should get automatically removed when the agent
exits.
.Sh AUTHOR
Tatu Ylonen <ylo@cs.hut.fi>
.Pp
OpenSSH
is a derivative of the original (free) ssh 1.2.12 release, but with bugs
removed and newer features re-added. Rapidly after the 1.2.12 release,
newer versions bore successively more restrictive licenses. This version
of OpenSSH
.Bl -bullet
.It
has all components of a restrictive nature (ie. patents, see
.Xr ssl 8 )
directly removed from the source code; any licensed or patented components
are chosen from
external libraries.
.It
has been updated to support ssh protocol 1.5.
.It
contains added support for
.Xr kerberos 8
authentication and ticket passing.
.It
supports one-time password authentication with
.Xr skey 1 .
.El
.Pp
The libraries described in
.Xr ssl 8
are required for proper operation.
.Sh SEE ALSO
.Xr ssh 1 ,
.Xr ssh-add 1 ,
.Xr ssh-keygen 1 ,
.Xr sshd 8 ,
.Xr ssl 8

155
openssh-keygen.1
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@ -1,155 +0,0 @@
.\" -*- nroff -*-
.\"
.\" ssh-keygen.1
.\"
.\" Author: Tatu Ylonen <ylo@cs.hut.fi>
.\"
.\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
.\" All rights reserved
.\"
.\" Created: Sat Apr 22 23:55:14 1995 ylo
.\"
.\" $Id: openssh-keygen.1,v 1.1 1999/10/28 04:03:14 damien Exp $
.\"
.Dd September 25, 1999
.Dt SSH-KEYGEN 1
.Os
.Sh NAME
.Nm ssh-keygen
.Nd authentication key generation
.Sh SYNOPSIS
.Nm ssh-keygen
.Op Fl q
.Op Fl b Ar bits
.Op Fl N Ar new_passphrase
.Op Fl C Ar comment
.Nm ssh-keygen
.Fl p
.Op Fl P Ar old_passphrase
.Op Fl N Ar new_passphrase
.Nm ssh-keygen
.Fl c
.Op Fl P Ar passphrase
.Op Fl C Ar comment
.Sh DESCRIPTION
.Nm
generates and manages authentication keys for
.Xr ssh 1 .
Normally each user wishing to use SSH
with RSA authentication runs this once to create the authentication
key in
.Pa $HOME/.ssh/identity .
Additionally, the system administrator may use this to generate host keys.
.Pp
Normally this program generates the key and asks for a file in which
to store the private key. The public key is stored in a file with the
same name but
.Dq .pub
appended. The program also asks for a
passphrase. The passphrase may be empty to indicate no passphrase
(host keys must have empty passphrase), or it may be a string of
arbitrary length. Good passphrases are 10-30 characters long and are
not simple sentences or otherwise easily guessable (English
prose has only 1-2 bits of entropy per word, and provides very bad
passphrases). The passphrase can be changed later by using the
.Fl p
option.
.Pp
There is no way to recover a lost passphrase. If the passphrase is
lost or forgotten, you will have to generate a new key and copy the
corresponding public key to other machines.
.Pp
There is also a comment field in the key file that is only for
convenience to the user to help identify the key. The comment can
tell what the key is for, or whatever is useful. The comment is
initialized to
.Dq user@host
when the key is created, but can be changed using the
.Fl c
option.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl b Ar bits
Specifies the number of bits in the key to create. Minimum is 512
bits. Generally 1024 bits is considered sufficient, and key sizes
above that no longer improve security but make things slower. The
default is 1024 bits.
.It Fl c
Requests changing the comment in the private and public key files.
The program will prompt for the file containing the private keys, for
passphrase if the key has one, and for the new comment.
.It Fl p
Requests changing the passphrase of a private key file instead of
creating a new private key. The program will prompt for the file
containing the private key, for the old passphrase, and twice for the
new passphrase.
.It Fl q
Silence
.Nm ssh-keygen .
Used by
.Pa /etc/rc
when creating a new key.
.It Fl C Ar comment
Provides the new comment.
.It Fl N Ar new_passphrase
Provides the new passphrase.
.It Fl P Ar passphrase
Provides the (old) passphrase.
.El
.Sh FILES
.Bl -tag -width Ds
.It Pa $HOME/.ssh/random_seed
Used for seeding the random number generator. This file should not be
readable by anyone but the user. This file is created the first time
the program is run, and is updated every time.
.It Pa $HOME/.ssh/identity
Contains the RSA authentication identity of the user. This file
should not be readable by anyone but the user. It is possible to
specify a passphrase when generating the key; that passphrase will be
used to encrypt the private part of this file using 3DES. This file
is not automatically accessed by
.Nm
but it is offered as the default file for the private key.
.It Pa $HOME/.ssh/identity.pub
Contains the public key for authentication. The contents of this file
should be added to
.Pa $HOME/.ssh/authorized_keys
on all machines
where you wish to log in using RSA authentication. There is no
need to keep the contents of this file secret.
.Sh AUTHOR
Tatu Ylonen <ylo@cs.hut.fi>
.Pp
OpenSSH
is a derivative of the original (free) ssh 1.2.12 release, but with bugs
removed and newer features re-added. Rapidly after the 1.2.12 release,
newer versions bore successively more restrictive licenses. This version
of OpenSSH
.Bl -bullet
.It
has all components of a restrictive nature (ie. patents, see
.Xr ssl 8 )
directly removed from the source code; any licensed or patented components
are chosen from
external libraries.
.It
has been updated to support ssh protocol 1.5.
.It
contains added support for
.Xr kerberos 8
authentication and ticket passing.
.It
supports one-time password authentication with
.Xr skey 1 .
.El
.Pp
The libraries described in
.Xr ssl 8
are required for proper operation.
.Sh SEE ALSO
.Xr ssh 1 ,
.Xr ssh-add 1 ,
.Xr ssh-agent 1,
.Xr sshd 8 ,
.Xr ssl 8

966
openssh.1
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@ -1,966 +0,0 @@
.\" -*- nroff -*-
.\"
.\" ssh.1.in
.\"
.\" Author: Tatu Ylonen <ylo@cs.hut.fi>
.\"
.\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
.\" All rights reserved
.\"
.\" Created: Sat Apr 22 21:55:14 1995 ylo
.\"
.\" $Id: openssh.1,v 1.1 1999/10/28 04:03:14 damien Exp $
.\"
.Dd September 25, 1999
.Dt SSH 1
.Os
.Sh NAME
.Nm ssh
.Nd OpenSSH secure shell client (remote login program)
.Sh SYNOPSIS
.Nm ssh
.Op Fl l Ar login_name
.Op Ar hostname | user@hostname
.Op Ar command
.Pp
.Nm ssh
.Op Fl afgknqtvxCPX
.Op Fl c Ar blowfish | 3des
.Op Fl e Ar escape_char
.Op Fl i Ar identity_file
.Op Fl l Ar login_name
.Op Fl o Ar option
.Op Fl p Ar port
.Oo Fl L Xo
.Sm off
.Ar host :
.Ar port :
.Ar hostport
.Sm on
.Xc
.Oc
.Oo Fl R Xo
.Sm off
.Ar host :
.Ar port :
.Ar hostport
.Sm on
.Xc
.Oc
.Op Ar hostname | user@hostname
.Op Ar command
.Sh DESCRIPTION
.Nm
(Secure Shell) 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.
.Pp
.Nm
connects and logs into the specified
.Ar hostname .
The user must prove
his/her identity to the remote machine using one of several methods.
.Pp
First, if the machine the user logs in from is listed in
.Pa /etc/hosts.equiv
or
.Pa /etc/openssh/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
.Pa \&.rhosts
or
.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
permitted to log in. This form of authentication alone is normally not
allowed by the server because it is not secure.
.Pp
The second (and primary) authentication method is the
.Pa rhosts
or
.Pa hosts.equiv
method combined with RSA-based host authentication. It
means that if the login would be permitted by
.Pa \&.rhosts ,
.Pa \&.shosts ,
.Pa /etc/hosts.equiv ,
or
.Pa /etc/openssh/shosts.equiv ,
and if additionally the server can verify the client's
host key (see
.Pa /etc/openssh/ssh_known_hosts
in the
.Sx 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:
.Pa /etc/hosts.equiv ,
.Pa \&.rhosts ,
and the rlogin/rsh protocol in general, are inherently insecure and should be
disabled if security is desired.]
.Pp
As a third authentication method,
.Nm
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
.Pa $HOME/.ssh/authorized_keys
lists the public keys that are permitted for logging
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
so, 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
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.
.Pp
.Nm
implements the RSA authentication protocol automatically. The user
creates his/her RSA key pair by running
.Xr ssh-keygen 1 .
This stores the private key in
.Pa \&.ssh/identity
and the public key in
.Pa \&.ssh/identity.pub
in the user's home directory. The user should then
copy the
.Pa identity.pub
to
.Pa \&.ssh/authorized_keys
in his/her home directory on the remote machine (the
.Pa authorized_keys
file corresponds to the conventional
.Pa \&.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.
.Pp
The most convenient way to use RSA authentication may be with an
authentication agent. See
.Xr ssh-agent 1
for more information.
.Pp
If other authentication methods fail,
.Nm
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.
.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. All communication with
the remote command or shell will be automatically encrypted.
.Pp
If a pseudo-terminal has been allocated (normal login session), the
user can disconnect with
.Ic ~. ,
and suspend
.Nm
with
.Ic ~^Z .
All forwarded connections can be listed with
.Ic ~#
and if
the session blocks waiting for forwarded X11 or TCP/IP
connections to terminate, it can be backgrounded with
.Ic ~&
(this should not be used while the user shell is active, as it can cause the
shell to hang). All available escapes can be listed with
.Ic ~? .
.Pp
A single tilde character can be sent as
.Ic ~~
(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.
.Pp
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
.Dq none
will also make the session transparent even if a tty is used.
.Pp
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
.Nm ssh .
.Pp
If the user is using X11 (the
.Ev 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
.Ev DISPLAY .
Forwarding of X11 connections can be
configured on the command line or in configuration files.
.Pp
The
.Ev DISPLAY
value set by
.Nm
will point to the server machine, but with a display number greater
than zero. This is normal, and happens because
.Nm
creates a
.Dq proxy
X server on the server machine for forwarding the
connections over the encrypted channel.
.Pp
.Nm
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).
.Pp
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.
.Pp
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.
.Pp
.Nm
automatically maintains and checks a database containing RSA-based
identifications for all hosts it has ever been used with. The
database is stored in
.Pa \&.ssh/known_hosts
in the user's home directory. Additionally, the file
.Pa /etc/openssh/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,
.Nm
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
.Cm StrictHostKeyChecking
option (see below) can be used to prevent logins to machines whose
host key is not known or has changed.
.Sh OPTIONS
.Bl -tag -width Ds
.It Fl a
Disables forwarding of the authentication agent connection. This may
also be specified on a per-host basis in the configuration file.
.It Fl c Ar blowfish|3des
Selects the cipher to use for encrypting the session.
.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 presumably more secure than the
.Ar des
cipher which is no longer supported in ssh.
.Ar blowfish
is a fast block cipher, it appears very secure and is much faster than
.Ar 3des .
.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
by control-Z suspends the connection, 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
Requests
.Nm
to go to background after authentication. This is useful
if
.Nm
is going to ask for passwords or passphrases, but the user
wants it in the background. This implies
.Fl n .
The recommended way to start X11 programs at a remote site is with
something like
.Ic ssh -f host xterm .
.It Fl i Ar identity_file
Selects the file from which the identity (private key) for
RSA authentication is read. Default is
.Pa \&.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
.Fl i
options (and multiple identities specified in
configuration files).
.It Fl g
Allows remote hosts to connect to local forwarded ports.
.It Fl k
Disables forwarding of Kerberos tickets and AFS tokens. This may
also be specified on a per-host basis in the configuration file.
.It Fl l Ar 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.
.It Fl n
Redirects stdin from
.Pa /dev/null
(actually, prevents reading from stdin).
This must be used when
.Nm
is run in the background. A common trick is to use this to run X11
programs in a remote machine. For example,
.Ic 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
.Nm
program will be put in the background.
(This does not work if
.Nm
needs to ask for a password or passphrase; see also the
.Fl f
option.)
.It Fl o Ar 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.
.It Fl p Ar port
Port to connect to on the remote host. This can be specified on a
per-host basis in the configuration file.
.It Fl P
Use a non-privileged port for outgoing connections.
This can be used if your firewall does
not permit connections from privileged ports.
Note that this option turns of
.Cm RhostsAuthentication
and
.Cm RhostsRSAAuthentication .
.It Fl q
Quiet mode. Causes all warning and diagnostic messages to be
suppressed. Only fatal errors are displayed.
.It Fl 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.
.It Fl v
Verbose mode. Causes
.Nm
to print debugging messages about its progress. This is helpful in
debugging connection, authentication, and configuration problems.
The verbose mode is also used to display
.Xr skey 1
challenges, if the user entered "s/key" as password.
.It Fl x
Disables X11 forwarding. This can also be specified on a per-host
basis in a configuration file.
.It Fl X
Enables X11 forwarding.
.It Fl 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
.Dq level
can be controlled by the
.Cm 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
.Cm Compress
option below.
.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:hostport
from the remote machine. Port forwardings can also be specified in the
configuration file. Only root can forward privileged ports.
.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: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.
.El
.Sh CONFIGURATION FILES
.Nm
obtains configuration data from the following sources (in this order):
command line options, user's configuration file
.Pq Pa $HOME/.ssh/config ,
and system-wide configuration file
.Pq Pa /etc/openssh/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.
.Pp
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.
.Pp
The configuration file has the following format:
.Pp
Empty lines and lines starting with
.Ql #
are comments.
.Pp
Otherwise a line is of the format
.Dq keyword arguments .
The possible
keywords and their meanings are as follows (note that the
configuration files are case-sensitive):
.Bl -tag -width Ds
.It Cm Host
Restricts the following declarations (up to the next
.Cm Host
keyword) to be only for those hosts that match one of the patterns
given after the keyword.
.Ql \&*
and
.Ql ?
can be used as wildcards in the
patterns. A single
.Ql \&*
as a pattern can be used to provide global
defaults for all hosts. The host is the
.Ar hostname
argument given on the command line (i.e., the name is not converted to
a canonicalized host name before matching).
.It Cm AFSTokenPassing
Specifies whether to pass AFS tokens to remote host. The argument to
this keyword must be
.Dq yes
or
.Dq no .
.It Cm BatchMode
If set to
.Dq 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
.Dq yes
or
.Dq no .
.It Cm Cipher
Specifies the cipher to use for encrypting the session. Currently,
.Dq blowfish ,
and
.Dq 3des
are supported. The default is
.Dq 3des .
.It Cm Compression
Specifies whether to use compression. The argument must be
.Dq yes
or
.Dq no .
.It Cm 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.
.It Cm 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.
.It Cm EscapeChar
Sets the escape character (default:
.Ql ~ ) .
The escape character can also
be set on the command line. The argument should be a single
character,
.Ql ^
followed by a letter, or
.Dq none
to disable the escape
character entirely (making the connection transparent for binary
data).
.It Cm FallBackToRsh
Specifies that if connecting via
.Nm
fails due to a connection refused error (there is no
.Xr sshd 8
listening on the remote host),
.Xr rsh 1
should automatically be used instead (after a suitable warning about
the session being unencrypted). The argument must be
.Dq yes
or
.Dq no .
.It Cm ForwardAgent
Specifies whether the connection to the authentication agent (if any)
will be forwarded to the remote machine. The argument must be
.Dq yes
or
.Dq no .
.It Cm ForwardX11
Specifies whether X11 connections will be automatically redirected
over the secure channel and
.Ev DISPLAY
set. The argument must be
.Dq yes
or
.Dq no .
.It Cm GatewayPorts
Specifies whether remote hosts are allowed to connect to local
forwarded ports.
The argument must be
.Dq yes
or
.Dq no .
The default is
.Dq no .
.It Cm GlobalKnownHostsFile
Specifies a file to use instead of
.Pa /etc/openssh/ssh_known_hosts .
.It Cm 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
.Cm HostName
specifications).
.It Cm IdentityFile
Specifies the file from which the user's RSA authentication identity
is read (default
.Pa .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.
.It Cm 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.
.Pp
The default is
.Dq 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.
.Pp
To disable keepalives, the value should be set to
.Dq no
in both the server and the client configuration files.
.It Cm KerberosAuthentication
Specifies whether Kerberos authentication will be used. The argument to
this keyword must be
.Dq yes
or
.Dq no .
.It Cm 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
.Dq yes
or
.Dq no .
.It Cm 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.
.It Cm PasswordAuthentication
Specifies whether to use password authentication. The argument to
this keyword must be
.Dq yes
or
.Dq no .
.It Cm NumberOfPasswordPrompts
Specifies the number of password prompts before giving up. The
argument to this keyword must be an integer. Default is 3.
.It Cm Port
Specifies the port number to connect on the remote host. Default is
22.
.It Cm 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
.Xr sshd 8
server running on some machine, or execute
.Ic 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).
.Pp
.It Cm 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.
.It Cm 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
.Dq yes
or
.Dq no .
.It Cm 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
.Dq yes
or
.Dq no .
.It Cm RSAAuthentication
Specifies whether to try RSA authentication. The argument to this
keyword must be
.Dq yes
or
.Dq no .
RSA authentication will only be
attempted if the identity file exists, or an authentication agent is
running.
.It Cm CheckHostIP
If this flag is set to
.Dq yes ,
ssh will additionally check the host ip address in the
.Pa known_hosts
file. This allows ssh to detect if a host key changed due to DNS spoofing.
If the option is set to
.Dq no ,
the check will not be executed.
.It Cm StrictHostKeyChecking
If this flag is set to
.Dq yes ,
.Nm
ssh will never automatically add host keys to the
.Pa $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
.Pa /etc/openssh/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
.Dq yes
or
.Dq no .
.It Cm 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.
.It Cm UserKnownHostsFile
Specifies a file to use instead of
.Pa $HOME/.ssh/known_hosts .
.It Cm UsePrivilegedPort
Specifies whether to use a privileged port for outgoing connections.
The argument must be
.Dq yes
or
.Dq no .
The default is
.Dq yes .
Note that setting this option to
.Dq no
turns of
.Cm RhostsAuthentication
and
.Cm RhostsRSAAuthentication .
.It Cm UseRsh
Specifies that rlogin/rsh should be used for this host. It is
possible that the host does not at all support the
.Nm
protocol. This causes
.Nm
to immediately exec
.Xr rsh 1 .
All other options (except
.Cm HostName )
are ignored if this has been specified. The argument must be
.Dq yes
or
.Dq no .
.Sh ENVIRONMENT
.Nm
will normally set the following environment variables:
.Bl -tag -width Ds
.It Ev DISPLAY
The
.Ev DISPLAY
variable indicates the location of the X11 server. It is
automatically set by
.Nm
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. 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).
.It Ev HOME
Set to the path of the user's home directory.
.It Ev LOGNAME
Synonym for
.Ev USER ;
set for compatibility with systems that use this variable.
.It Ev MAIL
Set to point the user's mailbox.
.It Ev PATH
Set to the default
.Ev PATH ,
as specified when compiling
.Nm ssh .
.It Ev SSH_AUTH_SOCK
indicates the path of a unix-domain socket used to communicate with the
agent.
.It Ev 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.
.It Ev 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.
.It Ev 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).
.It Ev USER
Set to the name of the user logging in.
.El
.Pp
Additionally,
.Nm
reads
.Pa $HOME/.ssh/environment ,
and adds lines of the format
.Dq VARNAME=value
to the environment.
.Sh FILES
.Bl -tag -width $HOME/.ssh/known_hosts
.It Pa $HOME/.ssh/known_hosts
Records host keys for all hosts the user has logged into (that are not
in
.Pa /etc/openssh/ssh_known_hosts ) .
See
.Xr sshd 8 .
.It Pa $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.
.It Pa $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 (read/write/execute).
Note that
.Nm
ignores this file if it is 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 3DES.
.It Pa $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
.Pa $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.
.It Pa $HOME/.ssh/config
This is the per-user configuration file. The format of this file is
described above. This file is used by the
.Nm
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.
.It Pa $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
.Xr sshd 8
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.
.It Pa /etc/openssh/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
.Xr sshd 8
manual page.
.Pp
The canonical system name (as returned by name servers) is used by
.Xr sshd 8
to verify the client host when logging in; other names are needed because
.Nm
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.
.It Pa /etc/openssh/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.
.It Pa $HOME/.rhosts
This file is used in
.Pa \&.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. One some machines this file may need to be
world-readable if the user's home directory is on a NFS partition,
because
.Xr 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.
.Pp
Note that by default
.Xr sshd 8
will be installed so that it requires successful RSA host
authentication before permitting \s+2.\s0rhosts authentication. If your
server machine does not have the client's host key in
.Pa /etc/openssh/ssh_known_hosts ,
you can store it in
.Pa $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 inxi
.Pa $HOME/.ssh/known_hosts .
.It Pa $HOME/.shosts
This file is used exactly the same way as
.Pa \&.rhosts .
The purpose for
having this file is to be able to use rhosts authentication with
.Nm
without permitting login with
.Xr rlogin 1
or
.Xr rsh 1 .
.It Pa /etc/hosts.equiv
This file is used during
.Pa \&.rhosts authentication. It contains
canonical hosts names, one per line (the full format is described on
the
.Xr sshd 8
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.
.It Pa /etc/openssh/shosts.equiv
This file is processed exactly as
.Pa /etc/hosts.equiv .
This file may be useful to permit logins using
.Nm
but not using rsh/rlogin.
.It Pa /etc/openssh/sshrc
Commands in this file are executed by
.Nm
when the user logs in just before the user's shell (or command) is started.
See the
.Xr sshd 8
manual page for more information.
.It Pa $HOME/.ssh/rc
Commands in this file are executed by
.Nm
when the user logs in just before the user's shell (or command) is
started.
See the
.Xr sshd 8
manual page for more information.
.It Pa libcrypto.so.X.1
A version of this library which includes support for the RSA algorithm
is required for proper operation.
.Sh AUTHOR
Tatu Ylonen <ylo@cs.hut.fi>
.Pp
Issues can be found from the SSH WWW home page:
.Pp
.Dl http://www.cs.hut.fi/ssh
.Pp
OpenSSH
is a derivative of the original (free) ssh 1.2.12 release, but with bugs
removed and newer features re-added. Rapidly after the 1.2.12 release,
newer versions bore successively more restrictive licenses. This version
of OpenSSH
.Bl -bullet
.It
has all components of a restrictive nature (ie. patents, see
.Xr ssl 8 )
directly removed from the source code; any licensed or patented components
are chosen from
external libraries.
.It
has been updated to support ssh protocol 1.5.
.It
contains added support for
.Xr kerberos 8
authentication and ticket passing.
.It
supports one-time password authentication with
.Xr skey 1 .
.El
.Pp
The libraries described in
.Xr ssl 8
are required for proper operation.
.Sh SEE ALSO
.Xr rlogin 1 ,
.Xr rsh 1 ,
.Xr scp 1 ,
.Xr ssh-add 1 ,
.Xr ssh-agent 1 ,
.Xr ssh-keygen 1 ,
.Xr telnet 1 ,
.Xr sshd 8 ,
.Xr ssl 8

88
openssh.spec
View File

@ -32,7 +32,7 @@ patented algorithms to seperate libraries (OpenSSL).
%build %build
./configure --prefix=/usr --sysconfdir=/etc/openssh ./configure --prefix=/usr --sysconfdir=/etc/ssh
make OPT_FLAGS="$RPM_OPT_FLAGS" make OPT_FLAGS="$RPM_OPT_FLAGS"
%install %install
@ -41,71 +41,53 @@ mkdir -p $RPM_BUILD_ROOT/usr/bin
mkdir -p $RPM_BUILD_ROOT/usr/sbin mkdir -p $RPM_BUILD_ROOT/usr/sbin
mkdir -p $RPM_BUILD_ROOT/etc/rc.d/init.d mkdir -p $RPM_BUILD_ROOT/etc/rc.d/init.d
mkdir -p $RPM_BUILD_ROOT/etc/pam.d mkdir -p $RPM_BUILD_ROOT/etc/pam.d
mkdir -p $RPM_BUILD_ROOT/etc/openssh mkdir -p $RPM_BUILD_ROOT/etc/ssh
mkdir -p $RPM_BUILD_ROOT/usr/man/man1 mkdir -p $RPM_BUILD_ROOT/usr/man/man1
mkdir -p $RPM_BUILD_ROOT/usr/man/man8 mkdir -p $RPM_BUILD_ROOT/usr/man/man8
install -m644 opensshd.pam $RPM_BUILD_ROOT/etc/pam.d/opensshd install -m644 sshd.pam $RPM_BUILD_ROOT/etc/pam.d/sshd
install -m755 opensshd.init $RPM_BUILD_ROOT/etc/rc.d/init.d/opensshd install -m755 sshd.init $RPM_BUILD_ROOT/etc/rc.d/init.d/sshd
install -m600 ssh_config $RPM_BUILD_ROOT/etc/openssh/ssh_config install -m600 ssh_config $RPM_BUILD_ROOT/etc/ssh/ssh_config
install -m600 sshd_config $RPM_BUILD_ROOT/etc/openssh/sshd_config install -m600 sshd_config $RPM_BUILD_ROOT/etc/ssh/sshd_config
install -s -m755 bin/opensshd $RPM_BUILD_ROOT/usr/sbin install -s -m755 bin/sshd $RPM_BUILD_ROOT/usr/sbin
install -s -m755 bin/openssh $RPM_BUILD_ROOT/usr/bin install -s -m755 bin/ssh $RPM_BUILD_ROOT/usr/bin
install -s -m755 bin/openscp $RPM_BUILD_ROOT/usr/bin install -s -m755 bin/scp $RPM_BUILD_ROOT/usr/bin
install -s -m755 bin/openssh-agent $RPM_BUILD_ROOT/usr/bin install -s -m755 bin/ssh-agent $RPM_BUILD_ROOT/usr/bin
install -s -m755 bin/openssh-add $RPM_BUILD_ROOT/usr/bin install -s -m755 bin/ssh-add $RPM_BUILD_ROOT/usr/bin
install -s -m755 bin/openssh-keygen $RPM_BUILD_ROOT/usr/bin install -s -m755 bin/ssh-keygen $RPM_BUILD_ROOT/usr/bin
install -m644 opensshd.8 $RPM_BUILD_ROOT/usr/man/man8 install -m644 sshd.8 $RPM_BUILD_ROOT/usr/man/man8
install -m644 openssh.1 $RPM_BUILD_ROOT/usr/man/man1 install -m644 ssh.1 $RPM_BUILD_ROOT/usr/man/man1
install -m644 openscp.1 $RPM_BUILD_ROOT/usr/man/man1 install -m644 scp.1 $RPM_BUILD_ROOT/usr/man/man1
install -m644 openssh-agent.1 $RPM_BUILD_ROOT/usr/man/man1 install -m644 ssh-agent.1 $RPM_BUILD_ROOT/usr/man/man1
install -m644 openssh-add.1 $RPM_BUILD_ROOT/usr/man/man1 install -m644 ssh-add.1 $RPM_BUILD_ROOT/usr/man/man1
install -m644 openssh-keygen.1 $RPM_BUILD_ROOT/usr/man/man1 install -m644 ssh-keygen.1 $RPM_BUILD_ROOT/usr/man/man1
# Install compatibility symlinks
cd $RPM_BUILD_ROOT/usr/sbin
ln -s opensshd sshd
cd $RPM_BUILD_ROOT/usr/bin
ln -s openssh ssh
ln -s openscp scp
ln -s openssh-agent ssh-agent
ln -s openssh-add ssh-add
ln -s openssh-keygen ssh-keygen
%clean %clean
rm -rf $RPM_BUILD_ROOT rm -rf $RPM_BUILD_ROOT
%post %post
/sbin/chkconfig --add opensshd /sbin/chkconfig --add sshd
if [ ! -f /etc/openssh/ssh_host_key -o ! -s /etc/openssh/ssh_host_key ]; then if [ ! -f /etc/ssh/ssh_host_key -o ! -s /etc/ssh/ssh_host_key ]; then
/usr/bin/openssh-keygen -b 1024 -f /etc/openssh/ssh_host_key -N '' >&2 /usr/bin/ssh-keygen -b 1024 -f /etc/ssh/ssh_host_key -N '' >&2
fi fi
if test -r /var/run/opensshd.pid if test -r /var/run/sshd.pid
then then
/etc/rc.d/init.d/opensshd restart >&2 /etc/rc.d/init.d/sshd restart >&2
fi fi
%preun %preun
if [ "$1" = 0 ] if [ "$1" = 0 ]
then then
/etc/rc.d/init.d/opensshd stop >&2 /etc/rc.d/init.d/sshd stop >&2
/sbin/chkconfig --del opensshd /sbin/chkconfig --del sshd
fi fi
%files %files
%defattr(-,root,root) %defattr(-,root,root)
%doc COPYING.Ylonen ChangeLog ChangeLog.Ylonen OVERVIEW %doc COPYING.Ylonen ChangeLog ChangeLog.Ylonen OVERVIEW
%doc README README.openssh %doc README README.openssh
%attr(0755,root,root) /usr/sbin/opensshd
%attr(0755,root,root) /usr/bin/openssh
%attr(0755,root,root) /usr/bin/openssh-agent
%attr(0755,root,root) /usr/bin/openssh-keygen
%attr(0755,root,root) /usr/bin/openssh-add
%attr(0755,root,root) /usr/bin/openscp
# Symlinks
%attr(0755,root,root) /usr/sbin/sshd %attr(0755,root,root) /usr/sbin/sshd
%attr(0755,root,root) /usr/bin/ssh %attr(0755,root,root) /usr/bin/ssh
%attr(0755,root,root) /usr/bin/ssh-agent %attr(0755,root,root) /usr/bin/ssh-agent
@ -113,15 +95,15 @@ fi
%attr(0755,root,root) /usr/bin/ssh-add %attr(0755,root,root) /usr/bin/ssh-add
%attr(0755,root,root) /usr/bin/scp %attr(0755,root,root) /usr/bin/scp
%attr(0755,root,root) /usr/man/man8/opensshd.8 %attr(0755,root,root) /usr/man/man8/sshd.8
%attr(0755,root,root) /usr/man/man1/openssh.1 %attr(0755,root,root) /usr/man/man1/ssh.1
%attr(0755,root,root) /usr/man/man1/openssh-agent.1 %attr(0755,root,root) /usr/man/man1/ssh-agent.1
%attr(0755,root,root) /usr/man/man1/openssh-keygen.1 %attr(0755,root,root) /usr/man/man1/ssh-keygen.1
%attr(0755,root,root) /usr/man/man1/openssh-add.1 %attr(0755,root,root) /usr/man/man1/ssh-add.1
%attr(0755,root,root) /usr/man/man1/openscp.1 %attr(0755,root,root) /usr/man/man1/scp.1
%attr(0600,root,root) %config /etc/openssh/sshd_config %attr(0600,root,root) %config /etc/ssh/sshd_config
%attr(0600,root,root) %config /etc/pam.d/opensshd %attr(0600,root,root) %config /etc/pam.d/sshd
%attr(0755,root,root) %config /etc/rc.d/init.d/opensshd %attr(0755,root,root) %config /etc/rc.d/init.d/sshd
%attr(0644,root,root) %config /etc/openssh/ssh_config %attr(0644,root,root) %config /etc/ssh/ssh_config

781
opensshd.8
View File

@ -1,781 +0,0 @@
.\" -*- nroff -*-
.\"
.\" sshd.8.in
.\"
.\" Author: Tatu Ylonen <ylo@cs.hut.fi>
.\"
.\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
.\" All rights reserved
.\"
.\" Created: Sat Apr 22 21:55:14 1995 ylo
.\"
.\" $Id: opensshd.8,v 1.1 1999/10/28 04:03:14 damien Exp $
.\"
.Dd September 25, 1999
.Dt SSHD 8
.Os
.Sh NAME
.Nm sshd
.Nd secure shell daemon
.Sh SYNOPSIS
.Nm sshd
.Op Fl diq
.Op Fl b Ar bits
.Op Fl f Ar config_file
.Op Fl g Ar login_grace_time
.Op Fl h Ar host_key_file
.Op Fl k Ar key_gen_time
.Op Fl p Ar port
.Sh DESCRIPTION
.Nm
(Secure Shell Daemon) is the daemon program for
.Xr ssh 1 .
Together these programs replace rlogin and rsh programs, and
provide secure encrypted communications between two untrusted hosts
over an insecure network. The programs are intended to be as easy to
install and use as possible.
.Pp
.Nm
is the daemon that listens for connections from clients. It is
normally started at boot from
.Pa /etc/rc .
It forks a new
daemon for each incoming connection. The forked daemons handle
key exchange, encryption, authentication, command execution,
and data exchange.
.Pp
.Nm
works as follows. Each host has a host-specific RSA key
(normally 1024 bits) used to identify the host. Additionally, when
the daemon starts, it generates a server RSA key (normally 768 bits).
This key is normally regenerated every hour if it has been used, and
is never stored on disk.
.Pp
Whenever a client connects the daemon, the daemon sends its host
and server public keys to the client. The client compares the
host key against its own database to verify that it has not changed.
The client then generates a 256 bit random number. It encrypts this
random number using both the host key and the server key, and sends
the encrypted number to the server. Both sides then start to use this
random number as a session key which is used to encrypt all further
communications in the session. The rest of the session is encrypted
using a conventional cipher, currently Blowfish and 3DES, with 3DES
being is used by default. The client selects the encryption algorithm
to use from those offered by the server.
.Pp
Next, the server and the client enter an authentication dialog. The
client tries to authenticate itself using
.Pa .rhosts
authentication,
.Pa .rhosts
authentication combined with RSA host
authentication, RSA challenge-response authentication, or password
based authentication.
.Pp
Rhosts authentication is normally disabled
because it is fundamentally insecure, but can be enabled in the server
configuration file if desired. System security is not improved unless
.Xr rshd 8 ,
.Xr rlogind 8 ,
.Xr rexecd 8 ,
and
.Xr rexd 8
are disabled (thus completely disabling
.Xr rlogin 1
and
.Xr rsh 1
into that machine).
.Pp
If the client successfully authenticates itself, a dialog for
preparing the session is entered. At this time the client may request
things like allocating a pseudo-tty, forwarding X11 connections,
forwarding TCP/IP connections, or forwarding the authentication agent
connection over the secure channel.
.Pp
Finally, the client either requests a shell or execution of a command.
The sides then enter session mode. In this mode, either side may send
data at any time, and such data is forwarded to/from the shell or
command on the server side, and the user terminal in the client side.
.Pp
When the user program terminates and all forwarded X11 and other
connections have been closed, the server sends command exit status to
the client, and both sides exit.
.Pp
.Nm
can be configured using command-line options or a configuration
file. Command-line options override values specified in the
configuration file.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl b Ar bits
Specifies the number of bits in the server key (default 768).
.Pp
.It Fl d
Debug mode. The server sends verbose debug output to the system
log, and does not put itself in the background. The server also will
not fork and will only process one connection. This option is only
intended for debugging for the server.
.It Fl f Ar configuration_file
Specifies the name of the configuration file. The default is
.Pa /etc/openssh/sshd_config .
.Nm
refuses to start if there is no configuration file.
.It Fl g Ar login_grace_time
Gives the grace time for clients to authenticate themselves (default
300 seconds). If the client fails to authenticate the user within
this many seconds, the server disconnects and exits. A value of zero
indicates no limit.
.It Fl h Ar host_key_file
Specifies the file from which the host key is read (default
.Pa /etc/openssh/ssh_host_key ) .
This option must be given if
.Nm
is not run as root (as the normal
host file is normally not readable by anyone but root).
.It Fl i
Specifies that
.Nm
is being run from inetd.
.Nm
is normally not run
from inetd because it needs to generate the server key before it can
respond to the client, and this may take tens of seconds. Clients
would have to wait too long if the key was regenerated every time.
However, with small key sizes (e.g. 512) using
.Nm
from inetd may
be feasible.
.It Fl k Ar key_gen_time
Specifies how often the server key is regenerated (default 3600
seconds, or one hour). The motivation for regenerating the key fairly
often is that the key is not stored anywhere, and after about an hour,
it becomes impossible to recover the key for decrypting intercepted
communications even if the machine is cracked into or physically
seized. A value of zero indicates that the key will never be regenerated.
.It Fl p Ar port
Specifies the port on which the server listens for connections
(default 22).
.It Fl q
Quiet mode. Nothing is sent to the system log. Normally the beginning,
authentication, and termination of each connection is logged.
.It Fl Q
Do not print an error message if RSA support is missing.
.El
.Sh CONFIGURATION FILE
.Nm
reads configuration data from
.Pa /etc/openssh/sshd_config
(or the file specified with
.Fl f
on the command line). The file
contains keyword-value pairs, one per line. Lines starting with
.Ql #
and empty lines are interpreted as comments.
.Pp
The following keywords are possible.
.Bl -tag -width Ds
.It Cm AFSTokenPassing
Specifies whether an AFS token may be forwarded to the server. Default is
.Dq yes .
.It Cm AllowGroups
This keyword can be followed by a number of group names, separated
by spaces. If specified, login is allowed only for users whose primary
group matches one of the patterns.
.Ql \&*
and
.Ql ?
can be used as
wildcards in the patterns. Only group names are valid, a numerical group
id isn't recognized. By default login is allowed regardless of
the primary group.
.Pp
.It Cm AllowUsers
This keyword can be followed by a number of user names, separated
by spaces. If specified, login is allowed only for users names that
match one of the patterns.
.Ql \&*
and
.Ql ?
can be used as
wildcards in the patterns. Only user names are valid, a numerical user
id isn't recognized. By default login is allowed regardless of
the user name.
.Pp
.It Cm CheckMail
Specifies whether
.Nm
should check for new mail for interactive logins.
The default is
.Dq no .
.It Cm DenyGroups
This keyword can be followed by a number of group names, separated
by spaces. Users whose primary group matches one of the patterns
aren't allowed to log in.
.Ql \&*
and
.Ql ?
can be used as
wildcards in the patterns. Only group names are valid, a numerical group
id isn't recognized. By default login is allowed regardless of
the primary group.
.Pp
.It Cm DenyUsers
This keyword can be followed by a number of user names, separated
by spaces. Login is allowed disallowed for user names that match
one of the patterns.
.Ql \&*
and
.Ql ?
can be used as
wildcards in the patterns. Only user names are valid, a numerical user
id isn't recognized. By default login is allowed regardless of
the user name.
.Pp
.It Cm FascistLogging
Specifies whether to use verbose logging. Verbose logging violates
the privacy of users and is not recommended. The argument must be
.Dq yes
or
.Dq no .
The default is
.Dq no .
.It Cm HostKey
Specifies the file containing the private host key (default
.Pa /etc/openssh/ssh_host_key ) .
Note that
.Nm
does not start if this file is group/world-accessible.
.It Cm IgnoreRhosts
Specifies that rhosts and shosts files will not be used in
authentication.
.Pa /etc/hosts.equiv
and
.Pa /etc/openssh/shosts.equiv
are still used. The default is
.Dq no .
.It Cm 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. On the other hand, if keepalives are not send,
sessions may hang indefinitely on the server, leaving
.Dq ghost
users and consuming server resources.
.Pp
The default is
.Dq yes
(to send keepalives), and the server will notice
if the network goes down or the client host reboots. This avoids
infinitely hanging sessions.
.Pp
To disable keepalives, the value should be set to
.Dq no
in both the server and the client configuration files.
.It Cm KerberosAuthentication
Specifies whether Kerberos authentication is allowed. This can
be in the form of a Kerberos ticket, or if
.Cm PasswordAuthentication
is yes, the password provided by the user will be validated through
the Kerberos KDC. Default is
.Dq yes .
.It Cm KerberosOrLocalPasswd
If set then if password authentication through Kerberos fails then
the password will be validated via any additional local mechanism
such as
.Pa /etc/passwd
or SecurID. Default is
.Dq yes .
.It Cm KerberosTgtPassing
Specifies whether a Kerberos TGT may be forwarded to the server.
Default is
.Dq no ,
as this only works when the Kerberos KDC is actually an AFS kaserver.
.It Cm KerberosTicketCleanup
Specifies whether to automatically destroy the user's ticket cache
file on logout. Default is
.Dq yes .
.It Cm KeyRegenerationInterval
The server key is automatically regenerated after this many seconds
(if it has been used). The purpose of regeneration is to prevent
decrypting captured sessions by later breaking into the machine and
stealing the keys. The key is never stored anywhere. If the value is
0, the key is never regenerated. The default is 3600
(seconds).
.It Cm ListenAddress
Specifies what local address
.Nm
should listen on.
The default is to listen to all local addresses.
.It Cm LoginGraceTime
The server disconnects after this time if the user has not
successfully logged in. If the value is 0, there is no time limit.
The default is 600 (seconds).
.It Cm PasswordAuthentication
Specifies whether password authentication is allowed.
The default is
.Dq yes .
.It Cm PermitEmptyPasswords
When password authentication is allowed, it specifies whether the
server allows login to accounts with empty password strings. The default
is
.Dq yes .
.It Cm PermitRootLogin
Specifies whether the root can log in using
.Xr ssh 1 .
The argument must be
.Dq yes ,
.Dq without-password
or
.Dq no .
The default is
.Dq yes .
If this options is set to
.Dq without-password
only password authentication is disabled for root.
.Pp
Root login with RSA authentication when the
.Ar command
option has been
specified will be allowed regardless of the value of this setting
(which may be useful for taking remote backups even if root login is
normally not allowed).
.It Cm Port
Specifies the port number that
.Nm
listens on. The default is 22.
.It Cm PrintMotd
Specifies whether
.Nm
should print
.Pa /etc/motd
when a user logs in interactively. (On some systems it is also
printed by the shell,
.Pa /etc/profile ,
or equivalent.) The default is
.Dq yes .
.It Cm QuietMode
Specifies whether the system runs in quiet mode. In quiet mode,
nothing is logged in the system log, except fatal errors. The default
is
.Dq no .
.It Cm RandomSeed
Obsolete. Random number generation uses other techniques.
.It Cm RhostsAuthentication
Specifies whether authentication using rhosts or /etc/hosts.equiv
files is sufficient. Normally, this method should not be permitted
because it is insecure.
.Cm RhostsRSAAuthentication
should be used
instead, because it performs RSA-based host authentication in addition
to normal rhosts or /etc/hosts.equiv authentication.
The default is
.Dq no .
.It Cm RhostsRSAAuthentication
Specifies whether rhosts or /etc/hosts.equiv authentication together
with successful RSA host authentication is allowed. The default is
.Dq yes .
.It Cm RSAAuthentication
Specifies whether pure RSA authentication is allowed. The default is
.Dq yes .
.It Cm ServerKeyBits
Defines the number of bits in the server key. The minimum value is
512, and the default is 768.
.It Cm SkeyAuthentication
Specifies whether
.Xr skey 1
authentication is allowed. The default is
.Dq yes .
Note that s/key authentication is enabled only if
.Cm PasswordAuthentication
is allowed, too.
.It Cm StrictModes
Specifies whether
.Nm
should check file modes and ownership of the
user's files and home directory before accepting login. This
is normally desirable because novices sometimes accidentally leave their
directory or files world-writable. The default is
.Dq yes .
.It Cm SyslogFacility
Gives the facility code that is used when logging messages from
.Nm sshd .
The possible values are: DAEMON, USER, AUTH, LOCAL0, LOCAL1, LOCAL2,
LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7. The default is AUTH.
.It Cm UseLogin
Specifies whether
.Xr login 1
is used. The default is
.Dq no .
.It Cm X11Forwarding
Specifies whether X11 forwarding is permitted. The default is
.Dq yes .
Note that disabling X11 forwarding does not improve security in any
way, as users can always install their own forwarders.
.It Cm X11DisplayOffset
Specifies the first display number available for
.Nm sshd Ns 's
X11 forwarding. This prevents
.Nm
from interfering with real X11 servers.
.El
.Sh LOGIN PROCESS
When a user successfully logs in,
.Nm
does the following:
.Bl -enum -offset indent
.It
If the login is on a tty, and no command has been specified,
prints last login time and
.Pa /etc/motd
(unless prevented in the configuration file or by
.Pa $HOME/.hushlogin ;
see the
.Sx FILES
section).
.It
If the login is on a tty, records login time.
.It
Checks
.Pa /etc/nologin ;
if it exists, prints contents and quits
(unless root).
.It
Changes to run with normal user privileges.
.It
Sets up basic environment.
.It
Reads
.Pa $HOME/.ssh/environment
if it exists.
.It
Changes to user's home directory.
.It
If
.Pa $HOME/.ssh/rc
exists, runs it; else if
.Pa /etc/openssh/sshrc
exists, runs
it; otherwise runs xauth. The
.Dq rc
files are given the X11
authentication protocol and cookie in standard input.
.It
Runs user's shell or command.
.El
.Sh AUTHORIZED_KEYS FILE FORMAT
The
.Pa $HOME/.ssh/authorized_keys
file lists the RSA keys that are
permitted for RSA authentication. Each line of the file contains one
key (empty lines and lines starting with a
.Ql #
are ignored as
comments). Each line consists of the following fields, separated by
spaces: options, bits, exponent, modulus, comment. The options field
is optional; its presence is determined by whether the line starts
with a number or not (the option field never starts with a number).
The bits, exponent, modulus and comment fields give the RSA key; the
comment field is not used for anything (but may be convenient for the
user to identify the key).
.Pp
Note that lines in this file are usually several hundred bytes long
(because of the size of the RSA key modulus). You don't want to type
them in; instead, copy the
.Pa identity.pub
file and edit it.
.Pp
The options (if present) consists of comma-separated option
specifications. No spaces are permitted, except within double quotes.
The following option specifications are supported:
.Bl -tag -width Ds
.It Cm from="pattern-list"
Specifies that in addition to RSA authentication, the canonical name
of the remote host must be present in the comma-separated list of
patterns ('*' and '?' serve as wildcards). The list may also contain
patterns negated by prefixing them with '!'; if the canonical host
name matches a negated pattern, the key is not accepted. The purpose
of this option is to optionally increase security: RSA authentication
by itself does not trust the network or name servers or anything (but
the key); however, if somebody somehow steals the key, the key
permits an intruder to log in from anywhere in the world. This
additional option makes using a stolen key more difficult (name
servers and/or routers would have to be compromised in addition to
just the key).
.It Cm command="command"
Specifies that the command is executed whenever this key is used for
authentication. The command supplied by the user (if any) is ignored.
The command is run on a pty if the connection requests a pty;
otherwise it is run without a tty. A quote may be included in the
command by quoting it with a backslash. This option might be useful
to restrict certain RSA keys to perform just a specific operation. An
example might be a key that permits remote backups but nothing
else. Notice that the client may specify TCP/IP and/or X11
forwardings unless they are explicitly prohibited.
.It Cm environment="NAME=value"
Specifies that the string is to be added to the environment when
logging in using this key. Environment variables set this way
override other default environment values. Multiple options of this
type are permitted.
.It Cm no-port-forwarding
Forbids TCP/IP forwarding when this key is used for authentication.
Any port forward requests by the client will return an error. This
might be used, e.g., in connection with the
.Cm command
option.
.It Cm no-X11-forwarding
Forbids X11 forwarding when this key is used for authentication.
Any X11 forward requests by the client will return an error.
.It Cm no-agent-forwarding
Forbids authentication agent forwarding when this key is used for
authentication.
.It Cm no-pty
Prevents tty allocation (a request to allocate a pty will fail).
.El
.Ss Examples
1024 33 12121.\|.\|.\|312314325 ylo@foo.bar
.Pp
from="*.niksula.hut.fi,!pc.niksula.hut.fi" 1024 35 23.\|.\|.\|2334 ylo@niksula
.Pp
command="dump /home",no-pty,no-port-forwarding 1024 33 23.\|.\|.\|2323 backup.hut.fi
.Sh SSH_KNOWN_HOSTS FILE FORMAT
The
.Pa /etc/openssh/ssh_known_hosts
and
.Pa $HOME/.ssh/known_hosts
files contain host public keys for all known hosts. The global file should
be prepared by the admistrator (optional), and the per-user file is
maintained automatically: whenever the user connects an unknown host
its key is added to the per-user file.
.Pp
Each line in these files contains the following fields: hostnames,
bits, exponent, modulus, comment. The fields are separated by spaces.
.Pp
Hostnames is a comma-separated list of patterns ('*' and '?' act as
wildcards); each pattern in turn is matched against the canonical host
name (when authenticating a client) or against the user-supplied
name (when authenticating a server). A pattern may also be preceded
by
.Ql !
to indicate negation: if the host name matches a negated
pattern, it is not accepted (by that line) even if it matched another
pattern on the line.
.Pp
Bits, exponent, and modulus are taken directly from the host key; they
can be obtained, e.g., from
.Pa /etc/openssh/ssh_host_key.pub .
The optional comment field continues to the end of the line, and is not used.
.Pp
Lines starting with
.Ql #
and empty lines are ignored as comments.
.Pp
When performing host authentication, authentication is accepted if any
matching line has the proper key. It is thus permissible (but not
recommended) to have several lines or different host keys for the same
names. This will inevitably happen when short forms of host names
from different domains are put in the file. It is possible
that the files contain conflicting information; authentication is
accepted if valid information can be found from either file.
.Pp
Note that the lines in these files are typically hundreds of characters
long, and you definitely don't want to type in the host keys by hand.
Rather, generate them by a script
or by taking
.Pa /etc/openssh/ssh_host_key.pub
and adding the host names at the front.
.Ss Examples
closenet,closenet.hut.fi,.\|.\|.\|,130.233.208.41 1024 37 159.\|.\|.93 closenet.hut.fi
.Sh FILES
.Bl -tag -width Ds
.It Pa /etc/openssh/sshd_config
Contains configuration data for
.Nm sshd .
This file should be writable by root only, but it is recommended
(though not necessary) that it be world-readable.
.It Pa /etc/openssh/ssh_host_key
Contains the private part of the host key.
This file should only be owned by root, readable only by root, and not
accessible to others.
Note that
.Nm
does not start if this file is group/world-accessible.
.It Pa /etc/openssh/ssh_host_key.pub
Contains the public part of the host key.
This file should be world-readable but writable only by
root. Its contents should match the private part. This file is not
really used for anything; it is only provided for the convenience of
the user so its contents can be copied to known hosts files.
These two files are created using
.Xr ssh-keygen 1 .
.It Pa /var/run/sshd.pid
Contains the process ID of the
.Nm
listening for connections (if there are several daemons running
concurrently for different ports, this contains the pid of the one
started last). The contents of this file are not sensitive; it can be
world-readable.
.It Pa $HOME/.ssh/authorized_keys
Lists the RSA keys that can be used to log into the user's account.
This file must be readable by root (which may on some machines imply
it being world-readable if the user's home directory resides on an NFS
volume). It is recommended that it not be accessible by others. The
format of this file is described above.
.It Pa /etc/openssh/ssh_known_hosts
This file is consulted when using rhosts with RSA host
authentication to check the public key of the host. The key must be
listed in this file to be accepted.
.It Pa $HOME/.ssh/known_hosts
The client uses this file
and
.Pa /etc/openssh/ssh_known_hosts
to verify that the remote host is the one we intended to
connect. These files should be writable only by root/the owner.
.Pa /etc/openssh/ssh_known_hosts
should be world-readable, and
.Pa $HOME/.ssh/known_hosts
can but need not be world-readable.
.It Pa /etc/nologin
If this file exists,
.Nm
refuses to let anyone except root log in. The contents of the file
are displayed to anyone trying to log in, and non-root connections are
refused. The file should be world-readable.
.It Pa /etc/hosts.allow, /etc/hosts.deny
If compiled with
.Sy LIBWRAP
support, tcp-wrappers access controls may be defined here as described in
.Xr hosts_access 5 .
.It Pa $HOME/.rhosts
This file contains host-username pairs, separated by a space, one per
line. The given user on the corresponding host is permitted to log in
without password. The same file is used by rlogind and rshd.
The file must
be writable only by the user; it is recommended that it not be
accessible by others.
.Pp
If is also possible to use netgroups in the file. Either host or user
name may be of the form +@groupname to specify all hosts or all users
in the group.
.It Pa $HOME/.shosts
For ssh,
this file is exactly the same as for
.Pa .rhosts .
However, this file is
not used by rlogin and rshd, so using this permits access using SSH only.
.Pa /etc/hosts.equiv
This file is used during
.Pa .rhosts
authentication. In the
simplest form, this file contains host names, one per line. Users on
those hosts are permitted to log in without a password, provided they
have the same user name on both machines. The host name may also be
followed by a user name; such users are permitted to log in as
.Em any
user on this machine (except root). Additionally, the syntax
.Dq +@group
can be used to specify netgroups. Negated entries start with
.Ql \&- .
.Pp
If the client host/user is successfully matched in this file, login is
automatically permitted provided the client and server user names are the
same. Additionally, successful RSA host authentication is normally
required. This file must be writable only by root; it is recommended
that it be world-readable.
.Pp
.Sy "Warning: It is almost never a good idea to use user names in"
.Pa hosts.equiv .
Beware that it really means that the named user(s) can log in as
.Em anybody ,
which includes bin, daemon, adm, and other accounts that own critical
binaries and directories. Using a user name practically grants the
user root access. The only valid use for user names that I can think
of is in negative entries.
.Pp
Note that this warning also applies to rsh/rlogin.
.It Pa /etc/openssh/shosts.equiv
This is processed exactly as
.Pa /etc/hosts.equiv .
However, this file may be useful in environments that want to run both
rsh/rlogin and ssh.
.It Pa $HOME/.ssh/environment
This file is read into the environment at login (if it exists). It
can only contain empty lines, comment lines (that start with
.Ql # ) ,
and assignment lines of the form name=value. The file should be writable
only by the user; it need not be readable by anyone else.
.It Pa $HOME/.ssh/rc
If this file exists, it is run with /bin/sh after reading the
environment files but before starting the user's shell or command. If
X11 spoofing is in use, this will receive the "proto cookie" pair in
standard input (and
.Ev DISPLAY
in environment). This must call
.Xr xauth 1
in that case.
.Pp
The primary purpose of this file is to run any initialization routines
which may be needed before the user's home directory becomes
accessible; AFS is a particular example of such an environment.
.Pp
This file will probably contain some initialization code followed by
something similar to: "if read proto cookie; then echo add $DISPLAY
$proto $cookie | xauth -q -; fi".
.Pp
If this file does not exist,
.Pa /etc/openssh/sshrc
is run, and if that
does not exist either, xauth is used to store the cookie.
.Pp
This file should be writable only by the user, and need not be
readable by anyone else.
.It Pa /etc/openssh/sshrc
Like
.Pa $HOME/.ssh/rc .
This can be used to specify
machine-specific login-time initializations globally. This file
should be writable only by root, and should be world-readable.
.Sh AUTHOR
Tatu Ylonen <ylo@cs.hut.fi>
.Pp
Information about new releases, mailing lists, and other related
issues can be found from the SSH WWW home page:
.Pp
.Dl http://www.cs.hut.fi/ssh.
.Pp
OpenSSH
is a derivative of the original (free) ssh 1.2.12 release, but with bugs
removed and newer features re-added. Rapidly after the 1.2.12 release,
newer versions bore successively more restrictive licenses. This version
of OpenSSH
.Bl -bullet
.It
has all components of a restrictive nature (ie. patents, see
.Xr ssl 8 )
directly removed from the source code; any licensed or patented components
are chosen from
external libraries.
.It
has been updated to support ssh protocol 1.5.
.It
contains added support for
.Xr kerberos 8
authentication and ticket passing.
.It
supports one-time password authentication with
.Xr skey 1 .
.El
.Pp
The libraries described in
.Xr ssl 8
are required for proper operation.
.Sh SEE ALSO
.Xr rlogin 1 ,
.Xr rsh 1 ,
.Xr scp 1 ,
.Xr ssh 1 ,
.Xr ssh-add 1 ,
.Xr ssh-agent 1 ,
.Xr ssh-keygen 1 ,
.Xr ssl 8

22
opensshd.init
View File

@ -5,12 +5,12 @@
# chkconfig: 2345 55 25 # chkconfig: 2345 55 25
# description: OpenSSH server daemon # description: OpenSSH server daemon
# #
# processname: opensshd # processname: sshd
# config: /etc/openssh/ssh_host_key # config: /etc/ssh/ssh_host_key
# config: /etc/openssh/ssh_host_key.pub # config: /etc/ssh/ssh_host_key.pub
# config: /etc/openssh/ssh_random_seed # config: /etc/ssh/ssh_random_seed
# config: /etc/openssh/sshd_config # config: /etc/ssh/sshd_config
# pidfile: /var/run/opensshd.pid # pidfile: /var/run/sshd.pid
# source function library # source function library
. /etc/rc.d/init.d/functions . /etc/rc.d/init.d/functions
@ -19,14 +19,14 @@ RETVAL=0
case "$1" in case "$1" in
start) start)
echo -n "Starting opensshd: " echo -n "Starting sshd: "
daemon /usr/sbin/opensshd daemon /usr/sbin/sshd
RETVAL=$? RETVAL=$?
[ $RETVAL -eq 0 ] && touch /var/lock/subsys/sshd [ $RETVAL -eq 0 ] && touch /var/lock/subsys/sshd
echo echo
;; ;;
stop) stop)
echo -n "Shutting down opensshd: " echo -n "Shutting down sshd: "
killproc sshd killproc sshd
RETVAL=$? RETVAL=$?
[ $RETVAL -eq 0 ] && rm -f /var/lock/subsys/sshd [ $RETVAL -eq 0 ] && rm -f /var/lock/subsys/sshd
@ -38,11 +38,11 @@ case "$1" in
RETVAL=$? RETVAL=$?
;; ;;
status) status)
status opensshd status sshd
RETVAL=$? RETVAL=$?
;; ;;
*) *)
echo "Usage: opensshd {start|stop|restart|status}" echo "Usage: sshd {start|stop|restart|status}"
exit 1 exit 1
esac esac

4
ssh.h
View File

@ -13,7 +13,7 @@ Generic header file for ssh.
*/ */
/* RCSID("$Id: ssh.h,v 1.3 1999/10/28 04:34:49 damien Exp $"); */ /* RCSID("$Id: ssh.h,v 1.4 1999/10/28 23:18:29 damien Exp $"); */
#ifndef SSH_H #ifndef SSH_H
#define SSH_H #define SSH_H
@ -89,7 +89,7 @@ only by root, whereas ssh_config should be world-readable. */
/* The process id of the daemon listening for connections is saved /* The process id of the daemon listening for connections is saved
here to make it easier to kill the correct daemon when necessary. */ here to make it easier to kill the correct daemon when necessary. */
#define SSH_DAEMON_PID_FILE PIDDIR "/opensshd.pid" #define SSH_DAEMON_PID_FILE PIDDIR "/sshd.pid"
/* The directory in user\'s home directory in which the files reside. /* The directory in user\'s home directory in which the files reside.
The directory should be world-readable (though not all files are). */ The directory should be world-readable (though not all files are). */

4
sshd.c
View File

@ -18,7 +18,7 @@ agent connections.
*/ */
#include "includes.h" #include "includes.h"
RCSID("$Id: sshd.c,v 1.4 1999/10/28 04:03:14 damien Exp $"); RCSID("$Id: sshd.c,v 1.5 1999/10/28 23:18:29 damien Exp $");
#include "xmalloc.h" #include "xmalloc.h"
#include "rsa.h" #include "rsa.h"
@ -1136,7 +1136,7 @@ do_authentication(char *user, int privileged_port)
pw = &pwcopy; pw = &pwcopy;
#ifdef HAVE_LIBPAM #ifdef HAVE_LIBPAM
if (PAM_SUCCESS != pam_start("opensshd", pw->pw_name, &conv, (pam_handle_t**)&pamh)) if (PAM_SUCCESS != pam_start("sshd", pw->pw_name, &conv, (pam_handle_t**)&pamh))
{ {
packet_start(SSH_SMSG_FAILURE); packet_start(SSH_SMSG_FAILURE);
packet_send(); packet_send();

4
sshd_config
View File

@ -2,7 +2,7 @@
Port 22 Port 22
ListenAddress 0.0.0.0 ListenAddress 0.0.0.0
HostKey /etc/openssh/ssh_host_key HostKey /etc/ssh/ssh_host_key
ServerKeyBits 768 ServerKeyBits 768
LoginGraceTime 600 LoginGraceTime 600
KeyRegenerationInterval 3600 KeyRegenerationInterval 3600
@ -20,7 +20,7 @@ KeepAlive yes
SyslogFacility AUTH SyslogFacility AUTH
RhostsAuthentication no RhostsAuthentication no
# #
# For this to work you will also need host keys in /etc/openssh/ssh_known_hosts # For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
RhostsRSAAuthentication no RhostsRSAAuthentication no
# #
RSAAuthentication yes RSAAuthentication yes