path: root/contrib/make-ssh-known-hosts.1

.\" -*- nroff -*-
.\" ----------------------------------------------------------------------
.\" make-ssh-known-hosts.1 -- Make ssh-known-hosts file
.\" Copyright (c) 1995 Tero Kivinen
.\" All Rights Reserved.
.\"
.\" Make-ssh-known-hosts is distributed in the hope that it will be
.\" useful, but WITHOUT ANY WARRANTY.  No author or distributor accepts
.\" responsibility to anyone for the consequences of using it or for
.\" whether it serves any particular purpose or works at all, unless he
.\" says so in writing.  Refer to the General Public License for full
.\" details.
.\"
.\" Everyone is granted permission to copy, modify and redistribute
.\" make-ssh-known-hosts, but only under the conditions described in
.\" the General Public License.  A copy of this license is supposed to
.\" have been given to you along with make-ssh-known-hosts so you can
.\" know your rights and responsibilities.  It should be in a file named
.\" COPYING.  Among other things, the copyright notice and this notice
.\" must be preserved on all copies.
.\" ----------------------------------------------------------------------
.\"       Program: make-ssh-known-hosts.1
.\"	  $Source: /var/cvs/openssh/contrib/Attic/make-ssh-known-hosts.1,v $
.\"	  Author : $Author: damien $
.\"
.\"	  (C) Tero Kivinen 1995 <Tero.Kivinen@hut.fi>
.\"
.\"	  Creation          : 03:51 Jun 28 1995 kivinen
.\"	  Last Modification : 03:44 Jun 28 1995 kivinen
.\"	  Last check in     : $Date: 2000/03/15 01:13:03 $
.\"	  Revision number   : $Revision: 1.1 $
.\"	  State             : $State: Exp $
.\"	  Version	    : 1.1
.\"
.\"	  Description       : Manual page for make-ssh-known-hosts.pl
.\"
.\"	  $Log: make-ssh-known-hosts.1,v $
.\"	  Revision 1.1  2000/03/15 01:13:03  damien
.\"	   - Created contrib/ subdirectory. Included helpers from Phil Hands'
.\"	     Debian package, README file and chroot patch from Ricardo Cerqueira
.\"	     <rmcc@clix.pt>
.\"	   - Moved gnome-ssh-askpass.c to contrib directory and reomved config
.\"	     option.
.\"	   - Slight cleanup to doc files
.\"	
.\"	  Revision 1.4  1998/07/08 00:40:14  kivinen
.\"	  	Changed to do similar commercial #ifdef processing than other
.\"	  	files.
.\"
.\"	  Revision 1.3  1998/06/11 00:07:21  kivinen
.\"	  	Fixed comment characters.
.\"
.\" Revision 1.2  1997/04/27  21:48:28  kivinen
.\" 	Added F-SECURE stuff.
.\"
.\"	  Revision 1.1.1.1  1996/02/18 21:38:13  ylo
.\"	  	Imported ssh-1.2.13.
.\"
.\" Revision 1.5  1995/10/02  01:23:23  ylo
.\" 	Make substitutions by configure.
.\"
.\" Revision 1.4  1995/08/31  09:21:35  ylo
.\" 	Minor cleanup.
.\"
.\" Revision 1.3  1995/08/29  22:37:10  ylo
.\" 	Minor cleanup.
.\"
.\" Revision 1.2  1995/07/15  13:26:11  ylo
.\" 	Changes from kivinen.
.\"
.\" Revision 1.1.1.1  1995/07/12  22:41:05  ylo
.\" Imported ssh-1.0.0.
.\"
.\"
.\"
.\" If you have any useful modifications or extensions please send them to
.\" Tero.Kivinen@hut.fi
.\"
.\"
.\"
.\"
.\"
.\" #ifndef F_SECURE_COMMERCIAL
.TH MAKE-SSH-KNOWN-HOSTS 1 "November 8, 1995" "SSH TOOLS" "SSH TOOLS"
.\" #endif F_SECURE_COMMERCIAL
.SH NAME
make-ssh-known-hosts \- make ssh_known_hosts file from DNS data
.SH SYNOPSIS
.na
.TP
.B make-ssh-known-hosts
.RB "[\|" "\-\-initialdns "\c
.I initial_dns\c
\|]
.br
.RB "[\|" "\-\-server "\c
.I domain_name_server\c
\|]
.br
.RB "[\|" "\-\-subdomains "\c
.I comma_separated_list_of_subdomains\c
\|]
.br
.RB "[\|" "\-\-debug "\c
.I debug_level\c
\|]
.br
.RB "[\|" "\-\-timeout "\c
.I ssh_exec_timeout\c
\|]
.br
.RB "[\|" "\-\-pingtimeout "\c
.I ping_timeout\c
\|]
.br
.RB "[\|" "\-\-passwordtimeout "\c
.I timeout_when_asking_password\c
\|]
.br
.RB "[\|" "\-\-notrustdaemon" "\|]"
.br
.RB "[\|" "\-\-norecursive" "\|]"
.br
.RB "[\|" "\-\-domainnamesplit" "\|]"
.br
.RB "[\|" "\-\-silent" "\|]"
.br
.RB "[\|" "\-\-keyscan" "\|]"
.br
.RB "[\|" "\-\-nslookup "\c
.I path_to_nslookup_program\c
\|]
.br
.RB "[\|" "\-\-ssh "\c
.I path_to_ssh_program\c
\|]
.br
.IR "domain_name " "[\|" "take_regexp " "[\|" "remove_regexp"\|]\|]"

.SH DESCRIPTION
.LP
.B make-ssh-known-hosts
is a perl5 script that helps create the
.I /etc/ssh_known_hosts
file, which is used by
.B ssh
to contain the host keys of all publicly known hosts.  
.B Ssh
does not normally permit login using rhosts or /etc/hosts.equiv
authentication unless the server knows the client's host key.  In
addition, the host keys are used to prevent man-in-the-middle attacks.
.LP
In addition to
.IR /etc/ssh_known_hosts ",
.B ssh
also uses the
.I $HOME/.ssh/known_hosts
file.  This file, however, is intended to contain only those hosts
that the particular user needs but are not in the global file.  It is
intended that the
.I /etc/ssh_known_hosts
file be maintained by the system administration, and periodically
updated to contain the host keys for any new hosts.
.LP
The
.B make-ssh-known-hosts
program finds all the hosts in a domain by making a DNS query to the
master domain name server of the domain. The master domain name server
is located by searching for the SOA record of the domain from the initial
domain name server (which can be specified with the
.B \-\-initialdns
option). The master domain name server can also be given directly with
the
.B \-\-server
option.
.LP
After getting the hostname list
.B make-ssh-known-hosts
tries to get the public key from every host in the domain. It first
tries to connect ssh port to check check if the host is alive, and if
so, it tries to run the command
.B cat /etc/ssh_host_key.pub
on the remote machine using
.BR ssh ".
If the command succeeds, it knows the remote machine has
.B ssh
installed properly, and it then extracts the public key from the
output, and prints the
.B /etc/ssh_known_hosts
entry for it to 
.BR STDOUT ". Because
.B make-ssh-known-hosts
is usually run before
remote machines have /etc/ssh_known_hosts file you may have to use
RSA-authentication to allow access to hosts. 
.LP
If the command fails for some reason, it checks if the
.B ssh
client still got the public key from the remote host in the initial dialog,
and if so, it will print a proper entry, and if
.B \-\-notrustdaemon
option is given comment it out.
.LP
.I Domain_name
is the domain name for which the file is to be generated. By default 
.B make-ssh-known-hosts
extracts also all subdomains of domain. Many sites will want to
include several domains in their
.I /etc/ssh_known_hosts
file.  The entries for each domain should be extracted separately by
running
.B make-ssh-known-hosts
once for each domain.  The results should then be combined to create
the final file.
.LP
.I Take_regexp
is a perl regular expression that matches the hosts to be taken from the
domain. The data matched contains all the DNS records in the form "\|\c
.B fieldname=value\c
\|". The fields are separated with newline, and the perl match is made in
multiline mode and it is case insensetive. The multiline mode means
that you can use a regexp like "\|\c
.B ^wks=.*telnet.*$\c
\|" to match all hosts that have WKS (well known services) field that
contains value "telnet".
.LP
.I Remove_regexp
is similar but those hosts that match the regexp are not added (it can
be used for example to filter out PCs and Macs using the hinfo field: "\|\c
.B ^hinfo=.*(mac|pc)\c
\|").

.SH OPTIONS
.TP
.BI "\-\-initialdns " "initial_dns"\c
.TP
.BI "\-i " "initial_dns"\c
\&Set the initial domain name server used to query the SOA record of the
domain.

.TP
.BI "\-\-server " "domain_name_server"\c
.TP
.BI "\-se " "domain_name_server"\c
\&Set the master domain name server of the domain. This host is used
to query the DNS list of the domain.

.TP
.BI "\-\-subdomains " "subdomainlist"\c
.TP
.BI "\-su " "subdomainlist"\c
\&Comma separated list of subdomains that are added to hostnames. For
example, if subdomainlist is "\|\c
.I ,foo, foo.bar, foo.bar.zappa, foo.bar.zappa.hut.fi\c
\|" then when host foobar is added to
.B /etc/ssh_known_hosts
file it has aliases "\|\c
.I foobar, foobar.foo, foobar.foo.bar, foobar.foo.bar.zappa, foobar.foo.bar.zappa.hut.fi\c
\|". The default action is to take all subparts of the host but the
second last on a host by host basis.  (The last element is usually the
country code, and something like 
.I foobar.foo.bar.zappa.hut 
would not make sense.)

.TP
.BI "\-\-debug " "debug_level"\c
.TP
.BI "\-de " "debug_level"\c
\&Set the debug level. Default is 5, bigger values give more output.
Using a big value (like 999) will print lots of debugging output.

.TP
.BI "\-\-timeout " "ssh_exec_timeout"\c
.TP
.BI "\-ti " "ssh_exec_timeout"\c
\&Timeout when executing
.B ssh
command.  The default is 60 seconds.

.TP
.BI "\-\-pingtimeout " "ping_timeout"\c
.TP
.BI "\-pi " "ping_timeout"\c
\&Timeout when trying to ping the ssh port.  The default is 3 seconds.

.TP
.BI "\-\-passwordtimeout " "timeout_when_asking_password"\c
.TP
.BI "\-pa " "timeout_when_asking_password"\c
\&Timeout when asking password for ssh command. Default is that no
passwords are queried. Use value 0 to have no timeout for password queries.

.TP
.BI "\-\-notrustdaemon"\c
.TP
.BI "\-notr"\c
\&If the
.B ssh
command fails, use the public key stored in the local known hosts file
and trust it is the correct key for the host. If this option is not
given such entries are commented out in the generated
.B /etc/ssh_known_hosts
file.

.TP
.BI "\-\-norecursive"\c
.TP
.BI "\-nor"\c
\&Tell
.B make-ssh-known-hosts
that it should only extract keys for the given domain, and not to be
recursive. 

.TP
.BI "\-\-domainnamesplit"\c
.TP
.BI "\-do"\c
\&Split the domainname to get the list of subdomains. Use this option
if you don't want hostname to splitted to pieces automatically.
Default splitting is done host by host basis. If the domain is
zappa.hut.fi, and the host name is foo.bar then default action adds
entries "\|\c
.I foo, foo.bar, foo.bar.zappa, foo.bar.zappa.hut.fi\c
\|" and this options adds entries "\|\c
.I foo.bar, foo.bar.zappa, foo.bar.zappa.hut.fi\c
\|").

.TP
.BI "\-\-silent"\c
.TP
.BI "\-si"\c
\&Be silent.

.TP
.BI "\-\-keyscan"\c
.TP
.BI "\-k"\c
\&Output list of all hosts in format "ipaddr1,ipaddr2,...ipaddrn
hostname.domain.co,hostname,ipaddr1,ipaddr2,all_other_hostname_entries".
The output of this can be feeded to ssh-keyscan to fetch keys.

.TP
.BI "\-\-nslookup " "path_to_nslookup_program"\c
.TP
.BI "\-n " "path_to_nslookup_program"\c
\&Path to the
.B nslookup
program. 

.TP
.BI "\-\-ssh " "path_to_ssh_program"\c
.TP
.BI "\-ss " "path_to_ssh_program"\c
\&Path to the
.B ssh
program, including all options.

.SH EXAMPLES
.LP
The following command:
.IP
.B example# make-ssh-known-hosts cs.hut.fi > \c
.B /etc/ssh_known_hosts
.LP
finds all public keys of the hosts in
.B cs.hut.fi
domain and put them to
.B /etc/ssh_known_hosts
file splitting domain names on a per host basis.
.LP
The command
.IP
.B example% make-ssh-known-hosts hut.fi '^wks=.*ssh' > \c
.B hut-hosts
.LP
finds all hosts in
.B hut.fi
domain, and its subdomains having own name server (cs.hut.fi,
tf.hut.fi, tky.hut.fi) that have ssh service and puts their public key
to hut-hosts file. This would require that the domain name server of
hut.fi would define all hosts running ssh to have entry ssh in their
WKS record. Because nobody yet adds ssh to WKS, it would be better to
use command
.IP
.B example% make-ssh-known-hosts hut.fi '^wks=.*telnet' > \c
.B hut-hosts
.LP
that would take those host having telnet service. This uses default
subdomain list.

.LP
The command:
.IP
.B example% make-ssh-known-hosts hut.fi 'dipoli.hut.fi' '^hinfo=.*(mac|pc)' > \c
.B dipoli-hosts
.LP
finds all hosts in hut.fi domain that are in dipoli.hut.fi subdomain
(note dipoli.hut.fi does not have own name server so its entries are
in hut.fi-server) and that are not Mac or PC.

.SH FILES
.ta 3i
/etc/ssh_known_hosts	Global host public key list

.SH "SEE ALSO"
.BR ssh (1),
.BR sshd (8),
.BR ssh-keygen (1),
.BR ping (8),
.BR nslookup (8),
.BR perl (1),
.BR perlre (1)

.SH AUTHOR
Tero Kivinen <kivinen@hut.fi>

.SH COPYING
.LP
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.
.LP
Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.
.LP
Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that this permission notice may be included in
translations approved by the the author instead of in the original
English.