diff options
Diffstat (limited to 'crypto/openssh/ssh-keyscan.1')
| -rw-r--r-- | crypto/openssh/ssh-keyscan.1 | 120 |
1 files changed, 85 insertions, 35 deletions
diff --git a/crypto/openssh/ssh-keyscan.1 b/crypto/openssh/ssh-keyscan.1 index 4db8c5f15f9d..2f33ddf2068e 100644 --- a/crypto/openssh/ssh-keyscan.1 +++ b/crypto/openssh/ssh-keyscan.1 @@ -1,11 +1,10 @@ -.\" $OpenBSD: ssh-keyscan.1,v 1.5 2001/04/18 16:21:05 ian Exp $ +.\" $OpenBSD: ssh-keyscan.1,v 1.14 2002/02/13 08:33:47 mpech Exp $ .\" .\" Copyright 1995, 1996 by David Mazieres <dm@lcs.mit.edu>. .\" .\" Modification and redistribution in source and binary forms is .\" permitted provided that due credit is given to the author and the -.\" OpenBSD project (for instance by leaving this copyright notice -.\" intact). +.\" OpenBSD project by leaving this copyright notice intact. .\" .Dd January 1, 1996 .Dt SSH-KEYSCAN 1 @@ -15,9 +14,13 @@ .Nd gather ssh public keys .Sh SYNOPSIS .Nm ssh-keyscan -.Op Fl t Ar timeout -.Op Ar -- | host | addrlist namelist -.Op Fl f Ar files ... +.Op Fl v46 +.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 ... .Sh DESCRIPTION .Nm is a utility for gathering the public ssh host keys of a number of @@ -32,46 +35,76 @@ scripts. 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 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. -.Sh SECURITY -If you make an ssh_known_hosts file using -.Nm -without verifying the keys, you will be vulnerable to -.I man in the middle -attacks. -On the other hand, if your security model allows such a risk, -.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 OPTIONS +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 -.It Fl t -Set the timeout for connection attempts. If +.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 .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. -.It Fl f -Read hosts or +.It Fl t Ar type +Specifies the type of the key to fetch from the scanned hosts. +The possible values are +.Dq rsa1 +for protocol version 1 and +.Dq rsa +or +.Dq dsa +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 +will read hosts or .Pa addrlist namelist pairs from the standard input. +.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 +If a ssh_known_hosts file is constructed using +.Nm +without verifying the keys, users will be vulnerable to +.I man in the middle +attacks. +On the other hand, if the security model allows such a risk, +.Nm +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 EXAMPLES .Pp -Print the host key for machine +Print the +.Pa rsa1 +host key for machine .Pa hostname : .Bd -literal -ssh-keyscan hostname +$ ssh-keyscan hostname .Ed .Pp Find all hosts from the file @@ -79,26 +112,43 @@ Find all hosts from the file which have new or different keys from those in the sorted file .Pa ssh_known_hosts : .Bd -literal -$ ssh-keyscan -f ssh_hosts | sort -u - ssh_known_hosts | \e\ - diff ssh_known_hosts - +$ ssh-keyscan -t rsa,dsa -f ssh_hosts | \e\ + sort -u - ssh_known_hosts | diff ssh_known_hosts - .Ed -.Pp .Sh FILES -.Pp .Pa Input format: +.Bd -literal 1.2.3.4,1.2.4.4 name.my.domain,name,n.my.domain,n,1.2.3.4,1.2.4.4 +.Ed .Pp -.Pa Output format: +.Pa Output format for rsa1 keys: +.Bd -literal host-or-namelist bits exponent modulus +.Ed +.Pp +.Pa Output format for rsa and dsa keys: +.Bd -literal +host-or-namelist keytype base64-encoded-key +.Ed +.Pp +Where +.Pa keytype +is either +.Dq ssh-rsa +or +.Dq ssh-dsa . .Pp -.Pa /etc/ssh_known_hosts +.Pa /etc/ssh/ssh_known_hosts .Sh BUGS It generates "Connection closed by remote host" messages on the consoles -of all the machines it scans. +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. .Sh SEE ALSO .Xr ssh 1 , .Xr sshd 8 -.Sh AUTHOR +.Sh AUTHORS David Mazieres <dm@lcs.mit.edu> +wrote the initial version, and +Wayne Davison <wayned@users.sourceforge.net> +added support for protocol version 2. |