contrib/ssh-copy-id.1 - third_party/openssh-portable - Git at Google

 .ig \"  -*- nroff -*-
 Copyright (c) 1999-2013 hands.com Ltd. <http://hands.com/>

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions
 are met:
 1. Redistributions of source code must retain the above copyright
    notice, this list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright
    notice, this list of conditions and the following disclaimer in the
    documentation and/or other materials provided with the distribution.

 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 ..
 .Dd $Mdocdate: June 17 2010 $
 .Dt SSH-COPY-ID 1
 .Os
 .Sh NAME
 .Nm ssh-copy-id
 .Nd use locally available keys to authorise logins on a remote machine
 .Sh SYNOPSIS
 .Nm
 .Op Fl f
 .Op Fl n
 .Op Fl i Op Ar identity_file
 .Op Fl p Ar port
 .Op Fl o Ar ssh_option
 .Op Ar user Ns @ Ns
 .Ar hostname
 .Nm
 .Fl h | Fl ?
 .br
 .Sh DESCRIPTION
 .Nm
 is a script that uses
 .Xr ssh 1
 to log into a remote machine (presumably using a login password,
 so password authentication should be enabled, unless you've done some
 clever use of multiple identities).  It assembles a list of one or more
 fingerprints (as described below) and tries to log in with each key, to
 see if any of them are already installed (of course, if you are not using
 .Xr ssh-agent 1
 this may result in you being repeatedly prompted for pass-phrases).
 It then assembles a list of those that failed to log in, and using ssh,
 enables logins with those keys on the remote server.  By default it adds
 the keys by appending them to the remote user's
 .Pa ~/.ssh/authorized_keys
 (creating the file, and directory, if necessary).  It is also capable
 of detecting if the remote system is a NetScreen, and using its
 .Ql set ssh pka-dsa key ...
 command instead.
 .Pp
 The options are as follows:
 .Bl -tag -width Ds
 .It Fl i Ar identity_file
 Use only the key(s) contained in
 .Ar identity_file
 (rather than looking for identities via
 .Xr ssh-add 1
 or in the
 .Ic default_ID_file ) .
 If the filename does not end in
 .Pa .pub
 this is added.  If the filename is omitted, the
 .Ic default_ID_file
 is used.
 .Pp
 Note that this can be used to ensure that the keys copied have the
 comment one prefers and/or extra options applied, by ensuring that the
 key file has these set as preferred before the copy is attempted.
 .It Fl f
 Forced mode: doesn't check if the keys are present on the remote server.
 This means that it does not need the private key.  Of course, this can result
 in more than one copy of the key being installed on the remote system.
 .It Fl n
 do a dry-run.  Instead of installing keys on the remote system simply
 prints the key(s) that would have been installed.
 .It Fl h , Fl ?
 Print Usage summary
 .It Fl p Ar port , Fl o Ar ssh_option
 These two options are simply passed through untouched, along with their
 argument, to allow one to set the port or other
 .Xr ssh 1
 options, respectively.
 .Pp
 Rather than specifying these as command line options, it is often better to use (per-host) settings in
 .Xr ssh 1 Ns 's
 configuration file:
 .Xr ssh_config 5 .
 .El
 .Pp
 Default behaviour without
 .Fl i ,
 is to check if
 .Ql ssh-add -L
 provides any output, and if so those keys are used.  Note that this results in
 the comment on the key being the filename that was given to
 .Xr ssh-add 1
 when the key was loaded into your
 .Xr ssh-agent 1
 rather than the comment contained in that file, which is a bit of a shame.
 Otherwise, if
 .Xr ssh-add 1
 provides no keys contents of the
 .Ic default_ID_file
 will be used.
 .Pp
 The
 .Ic default_ID_file
 is the most recent file that matches:
 .Pa ~/.ssh/id*.pub ,
 (excluding those that match
 .Pa ~/.ssh/*-cert.pub )
 so if you create a key that is not the one you want
 .Nm
 to use, just use
 .Xr touch 1
 on your preferred key's
 .Pa .pub
 file to reinstate it as the most recent.
 .Pp
 .Sh EXAMPLES
 If you have already installed keys from one system on a lot of remote
 hosts, and you then create a new key, on a new client machine, say,
 it can be difficult to keep track of which systems on which you've
 installed the new key.  One way of dealing with this is to load both
 the new key and old key(s) into your
 .Xr ssh-agent 1 .
 Load the new key first, without the
 .Fl c
 option, then load one or more old keys into the agent, possibly by
 ssh-ing to the client machine that has that old key, using the
 .Fl A
 option to allow agent forwarding:
 .Pp
 .D1 user@newclient$ ssh-add
 .D1 user@newclient$ ssh -A old.client
 .D1 user@oldl$ ssh-add -c
 .D1 No   ... prompt for pass-phrase ...
 .D1 user@old$ logoff
 .D1 user@newclient$ ssh someserver
 .Pp
 now, if the new key is installed on the server, you'll be allowed in
 unprompted, whereas if you only have the old key(s) enabled, you'll be
 asked for confirmation, which is your cue to log back out and run
 .Pp
 .D1 user@newclient$ ssh-copy-id -i someserver
 .Pp
 The reason you might want to specify the -i option in this case is to
 ensure that the comment on the installed key is the one from the
 .Pa .pub
 file, rather than just the filename that was loaded into you agent.
 It also ensures that only the id you intended is installed, rather than
 all the keys that you have in your
 .Xr ssh-agent 1 .
 Of course, you can specify another id, or use the contents of the
 .Xr ssh-agent 1
 as you prefer.
 .Pp
 Having mentioned
 .Xr ssh-add 1 Ns 's
 .Fl c
 option, you might consider using this whenever using agent forwarding
 to avoid your key being hijacked, but it is much better to instead use
 .Xr ssh 1 Ns 's
 .Ar ProxyCommand
 and
 .Fl W
 option,
 to bounce through remote servers while always doing direct end-to-end
 authentication. This way the middle hop(s) don't get access to your
 .Xr ssh-agent 1 .
 A web search for
 .Ql ssh proxycommand nc
 should prove enlightening (N.B. the modern approach is to use the
 .Fl W
 option, rather than
 .Xr nc 1 ) .
 .Sh "SEE ALSO"
 .Xr ssh 1 ,
 .Xr ssh-agent 1 ,
 .Xr sshd 8
	.ig \" -- nroff --
	Copyright (c) 1999-2013 hands.com Ltd. <http://hands.com/>

	Redistribution and use in source and binary forms, with or without
	modification, are permitted provided that the following conditions
	are met:
	1. Redistributions of source code must retain the above copyright
	notice, this list of conditions and the following disclaimer.
	2. Redistributions in binary form must reproduce the above copyright
	notice, this list of conditions and the following disclaimer in the
	documentation and/or other materials provided with the distribution.

	THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	..
	.Dd $Mdocdate: June 17 2010 $
	.Dt SSH-COPY-ID 1
	.Os
	.Sh NAME
	.Nm ssh-copy-id
	.Nd use locally available keys to authorise logins on a remote machine
	.Sh SYNOPSIS
	.Nm
	.Op Fl f
	.Op Fl n
	.Op Fl i Op Ar identity_file
	.Op Fl p Ar port
	.Op Fl o Ar ssh_option
	.Op Ar user Ns @ Ns
	.Ar hostname
	.Nm
	.Fl h \| Fl ?
	.br
	.Sh DESCRIPTION
	.Nm
	is a script that uses
	.Xr ssh 1
	to log into a remote machine (presumably using a login password,
	so password authentication should be enabled, unless you've done some
	clever use of multiple identities). It assembles a list of one or more
	fingerprints (as described below) and tries to log in with each key, to
	see if any of them are already installed (of course, if you are not using
	.Xr ssh-agent 1
	this may result in you being repeatedly prompted for pass-phrases).
	It then assembles a list of those that failed to log in, and using ssh,
	enables logins with those keys on the remote server. By default it adds
	the keys by appending them to the remote user's
	.Pa ~/.ssh/authorized_keys
	(creating the file, and directory, if necessary). It is also capable
	of detecting if the remote system is a NetScreen, and using its
	.Ql set ssh pka-dsa key ...
	command instead.
	.Pp
	The options are as follows:
	.Bl -tag -width Ds
	.It Fl i Ar identity_file
	Use only the key(s) contained in
	.Ar identity_file
	(rather than looking for identities via
	.Xr ssh-add 1
	or in the
	.Ic default_ID_file ) .
	If the filename does not end in
	.Pa .pub
	this is added. If the filename is omitted, the
	.Ic default_ID_file
	is used.
	.Pp
	Note that this can be used to ensure that the keys copied have the
	comment one prefers and/or extra options applied, by ensuring that the
	key file has these set as preferred before the copy is attempted.
	.It Fl f
	Forced mode: doesn't check if the keys are present on the remote server.
	This means that it does not need the private key. Of course, this can result
	in more than one copy of the key being installed on the remote system.
	.It Fl n
	do a dry-run. Instead of installing keys on the remote system simply
	prints the key(s) that would have been installed.
	.It Fl h , Fl ?
	Print Usage summary
	.It Fl p Ar port , Fl o Ar ssh_option
	These two options are simply passed through untouched, along with their
	argument, to allow one to set the port or other
	.Xr ssh 1
	options, respectively.
	.Pp
	Rather than specifying these as command line options, it is often better to use (per-host) settings in
	.Xr ssh 1 Ns 's
	configuration file:
	.Xr ssh_config 5 .
	.El
	.Pp
	Default behaviour without
	.Fl i ,
	is to check if
	.Ql ssh-add -L
	provides any output, and if so those keys are used. Note that this results in
	the comment on the key being the filename that was given to
	.Xr ssh-add 1
	when the key was loaded into your
	.Xr ssh-agent 1
	rather than the comment contained in that file, which is a bit of a shame.
	Otherwise, if
	.Xr ssh-add 1
	provides no keys contents of the
	.Ic default_ID_file
	will be used.
	.Pp
	The
	.Ic default_ID_file
	is the most recent file that matches:
	.Pa ~/.ssh/id*.pub ,
	(excluding those that match
	.Pa ~/.ssh/*-cert.pub )
	so if you create a key that is not the one you want
	.Nm
	to use, just use
	.Xr touch 1
	on your preferred key's
	.Pa .pub
	file to reinstate it as the most recent.
	.Pp
	.Sh EXAMPLES
	If you have already installed keys from one system on a lot of remote
	hosts, and you then create a new key, on a new client machine, say,
	it can be difficult to keep track of which systems on which you've
	installed the new key. One way of dealing with this is to load both
	the new key and old key(s) into your
	.Xr ssh-agent 1 .
	Load the new key first, without the
	.Fl c
	option, then load one or more old keys into the agent, possibly by
	ssh-ing to the client machine that has that old key, using the
	.Fl A
	option to allow agent forwarding:
	.Pp
	.D1 user@newclient$ ssh-add
	.D1 user@newclient$ ssh -A old.client
	.D1 user@oldl$ ssh-add -c
	.D1 No ... prompt for pass-phrase ...
	.D1 user@old$ logoff
	.D1 user@newclient$ ssh someserver
	.Pp
	now, if the new key is installed on the server, you'll be allowed in
	unprompted, whereas if you only have the old key(s) enabled, you'll be
	asked for confirmation, which is your cue to log back out and run
	.Pp
	.D1 user@newclient$ ssh-copy-id -i someserver
	.Pp
	The reason you might want to specify the -i option in this case is to
	ensure that the comment on the installed key is the one from the
	.Pa .pub
	file, rather than just the filename that was loaded into you agent.
	It also ensures that only the id you intended is installed, rather than
	all the keys that you have in your
	.Xr ssh-agent 1 .
	Of course, you can specify another id, or use the contents of the
	.Xr ssh-agent 1
	as you prefer.
	.Pp
	Having mentioned
	.Xr ssh-add 1 Ns 's
	.Fl c
	option, you might consider using this whenever using agent forwarding
	to avoid your key being hijacked, but it is much better to instead use
	.Xr ssh 1 Ns 's
	.Ar ProxyCommand
	and
	.Fl W
	option,
	to bounce through remote servers while always doing direct end-to-end
	authentication. This way the middle hop(s) don't get access to your
	.Xr ssh-agent 1 .
	A web search for
	.Ql ssh proxycommand nc
	should prove enlightening (N.B. the modern approach is to use the
	.Fl W
	option, rather than
	.Xr nc 1 ) .
	.Sh "SEE ALSO"
	.Xr ssh 1 ,
	.Xr ssh-agent 1 ,
	.Xr sshd 8