- dtucker@cvs.openbsd.org 2010/01/14 23:41:49

[openssh.git] / ssh-keyscan.1

diff --git a/ssh-keyscan.1 b/ssh-keyscan.1
index 1a358b3386a48171e3175f847fd59fe1754bfdb2..01f3184621c235be08303a8701c014c95e0bd75f 100644 (file)
--- a/ssh-keyscan.1
+++ b/ssh-keyscan.1
@@ -1,4 +1,4 @@
-.\"    $OpenBSD: ssh-keyscan.1,v 1.11 2001/08/23 18:08:59 stevesk Exp $
+.\"    $OpenBSD: ssh-keyscan.1,v 1.28 2010/01/09 23:04:13 dtucker Exp $

 .\"
 .\" Copyright 1995, 1996 by David Mazieres <dm@lcs.mit.edu>.
 .\"
 .\"
 .\" Copyright 1995, 1996 by David Mazieres <dm@lcs.mit.edu>.
 .\"


@@ -6,7 +6,7 @@
 .\" permitted provided that due credit is given to the author and the
 .\" OpenBSD project by leaving this copyright notice intact.
 .\"
 .\" permitted provided that due credit is given to the author and the
 .\" OpenBSD project by leaving this copyright notice intact.
 .\"

-.Dd January 1, 1996
+.Dd $Mdocdate$

 .Dt SSH-KEYSCAN 1
 .Os
 .Sh NAME
 .Dt SSH-KEYSCAN 1
 .Os
 .Sh NAME


@@ -14,17 +14,20 @@
 .Nd gather ssh public keys
 .Sh SYNOPSIS
 .Nm ssh-keyscan
 .Nd gather ssh public keys
 .Sh SYNOPSIS
 .Nm ssh-keyscan

-.Op Fl v46
+.Bk -words
+.Op Fl 46Hv
+.Op Fl f Ar file

 .Op Fl p Ar port
 .Op Fl T Ar timeout
 .Op Fl t Ar type
 .Op Fl p Ar port
 .Op Fl T Ar timeout
 .Op Fl t Ar type

-.Op Fl f Ar file

 .Op Ar host | addrlist namelist
 .Op Ar host | addrlist namelist

-.Op Ar ...
+.Ar ...
+.Ek

 .Sh DESCRIPTION
 .Nm
 is a utility for gathering the public ssh host keys of a number of
 .Sh DESCRIPTION
 .Nm
 is a utility for gathering the public ssh host keys of a number of

-hosts.  It was designed to aid in building and verifying
+hosts.
+It was designed to aid in building and verifying

 .Pa ssh_known_hosts
 files.
 .Nm
 .Pa ssh_known_hosts
 files.
 .Nm


@@ -33,23 +36,53 @@ scripts.
 .Pp
 .Nm
 uses non-blocking socket I/O to contact as many hosts as possible in
 .Pp
 .Nm
 uses non-blocking socket I/O to contact as many hosts as possible in

-parallel, so it is very efficient.  The keys from a domain of 1,000
+parallel, so it is very efficient.
+The keys from a domain of 1,000

 hosts can be collected in tens of seconds, even when some of those
 hosts can be collected in tens of seconds, even when some of those

-hosts are down or do not run ssh.  You do not need login access to the
-machines you are scanning, nor does the scanning process involve
-any encryption.
+hosts are down or do not run ssh.
+For scanning, one does not need
+login access to the machines that are being scanned, nor does the
+scanning process involve any encryption.

 .Pp
 The options are as follows:
 .Bl -tag -width Ds
 .Pp
 The options are as follows:
 .Bl -tag -width Ds

+.It Fl 4
+Forces
+.Nm
+to use IPv4 addresses only.
+.It Fl 6
+Forces
+.Nm
+to use IPv6 addresses only.
+.It Fl f Ar file
+Read hosts or
+.Pa addrlist namelist
+pairs from this file, one per line.
+If
+.Pa -
+is supplied instead of a filename,
+.Nm
+will read hosts or
+.Pa addrlist namelist
+pairs from the standard input.
+.It Fl H
+Hash all hostnames and addresses in the output.
+Hashed names may be used normally by
+.Nm ssh
+and
+.Nm sshd ,
+but they do not reveal identifying information should the file's contents
+be disclosed.

 .It Fl p Ar port
 Port to connect to on the remote host.
 .It Fl T Ar timeout
 .It Fl p Ar port
 Port to connect to on the remote host.
 .It Fl T Ar timeout

-Set the timeout for connection attempts.  If
+Set the timeout for connection attempts.
+If

 .Pa timeout
 seconds have elapsed since a connection was initiated to a host or since the
 last time anything was read from that host, then the connection is
 .Pa timeout
 seconds have elapsed since a connection was initiated to a host or since the
 last time anything was read from that host, then the connection is

-closed and the host in question considered unavailable.  Default is 5
-seconds.
+closed and the host in question considered unavailable.
+Default is 5 seconds.

 .It Fl t Ar type
 Specifies the type of the key to fetch from the scanned hosts.
 The possible values are
 .It Fl t Ar type
 Specifies the type of the key to fetch from the scanned hosts.
 The possible values are


@@ -61,60 +94,23 @@ or
 for protocol version 2.
 Multiple values may be specified by separating them with commas.
 The default is
 for protocol version 2.
 Multiple values may be specified by separating them with commas.
 The default is

-.Dq rsa1 .
-.It Fl f Ar filename
-Read hosts or
-.Pa addrlist namelist
-pairs from this file, one per line.
-If
-.Pa -
-is supplied instead of a filename,
-.Nm
-will read hosts or
-.Pa addrlist namelist
-pairs from the standard input.
+.Dq rsa .

 .It Fl v
 Verbose mode.
 Causes
 .Nm
 to print debugging messages about its progress.
 .It Fl v
 Verbose mode.
 Causes
 .Nm
 to print debugging messages about its progress.

-.It Fl 4
-Forces
-.Nm
-to use IPv4 addresses only.
-.It Fl 6
-Forces
-.Nm
-to use IPv6 addresses only.

 .El
 .Sh SECURITY
 .El
 .Sh SECURITY

-If you make an ssh_known_hosts file using
+If an ssh_known_hosts file is constructed using

 .Nm
 .Nm

-without verifying the keys, you will be vulnerable to
-.I man in the middle
+without verifying the keys, users will be vulnerable to
+.Em man in the middle

 attacks.
 attacks.

-On the other hand, if your security model allows such a risk,
+On the other hand, if the security model allows such a risk,

 .Nm
 .Nm

-can help you detect tampered keyfiles or man in the middle attacks which
-have begun after you created your ssh_known_hosts file.
-.Sh EXAMPLES
-.Pp
-Print the
-.Pa rsa1
-host key for machine
-.Pa hostname :
-.Bd -literal
-ssh-keyscan hostname
-.Ed
-.Pp
-Find all hosts from the file
-.Pa ssh_hosts
-which have new or different keys from those in the sorted file
-.Pa ssh_known_hosts :
-.Bd -literal
-ssh-keyscan -t rsa,dsa -f ssh_hosts | \e\ 
-       sort -u - ssh_known_hosts | diff ssh_known_hosts -
-.Ed
+can help in the detection of tampered keyfiles or man in the middle
+attacks which have begun after the ssh_known_hosts file was created.

 .Sh FILES
 .Pa Input format:
 .Bd -literal
 .Sh FILES
 .Pa Input format:
 .Bd -literal


@@ -136,19 +132,37 @@ Where
 is either
 .Dq ssh-rsa
 or
 is either
 .Dq ssh-rsa
 or

-.Dq ssh-dsa .
+.Dq ssh-dss .

 .Pp
 .Pp

-.Pa /etc/ssh_known_hosts
-.Sh BUGS
-It generates "Connection closed by remote host" messages on the consoles
-of all the machines it scans if the server is older than version 2.9.
-This is because it opens a connection to the ssh port, reads the public
-key, and drops the connection as soon as it gets the key.
+.Pa /etc/ssh/ssh_known_hosts
+.Sh EXAMPLES
+Print the
+.Pa rsa
+host key for machine
+.Pa hostname :
+.Bd -literal
+$ ssh-keyscan hostname
+.Ed
+.Pp
+Find all hosts from the file
+.Pa ssh_hosts
+which have new or different keys from those in the sorted file
+.Pa ssh_known_hosts :
+.Bd -literal
+$ ssh-keyscan -t rsa,dsa -f ssh_hosts | \e
+       sort -u - ssh_known_hosts | diff ssh_known_hosts -
+.Ed

 .Sh SEE ALSO
 .Xr ssh 1 ,
 .Xr sshd 8
 .Sh AUTHORS
 .Sh SEE ALSO
 .Xr ssh 1 ,
 .Xr sshd 8
 .Sh AUTHORS

-David Mazieres <dm@lcs.mit.edu>
+.An -nosplit
+.An David Mazieres Aq dm@lcs.mit.edu

 wrote the initial version, and
 wrote the initial version, and

-Wayne Davison <wayned@users.sourceforge.net>
+.An Wayne Davison Aq wayned@users.sourceforge.net

 added support for protocol version 2.
 added support for protocol version 2.

+.Sh BUGS
+It generates "Connection closed by remote host" messages on the consoles
+of all the machines it scans if the server is older than version 2.9.
+This is because it opens a connection to the ssh port, reads the public
+key, and drops the connection as soon as it gets the key.