ssh_known_hosts
files.
ssh-keyscan
provides a minimal interface suitable for use by shell and perl
scripts.
ssh-keyscan 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. For scanning, one does not need login access to the machines that are being scanned, nor does the scanning process involve any encryption.
The options are as follows:
addrlist
namelist
pairs from this file, one per line.
If
-
is supplied instead of a filename,
ssh-keyscan
will read hosts or
addrlist
namelist
pairs from the standard input.
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.
Input
format:
1.2.3.4,1.2.4.4 name.my.domain,name,n.my.domain,n,1.2.3.4,1.2.4.4
Output
format
for
rsa1
keys:
host-or-namelist bits exponent modulus
Output
format
for
rsa
and
dsa
keys:
host-or-namelist keytype base64-encoded-key
Where
keytype
is either
``ssh-rsa''
or
``ssh-dss''.
/etc/ssh/ssh_known_hosts
rsa1
host key for machine
hostname
:
$ ssh-keyscan hostname
Find all hosts from the file
ssh_hosts
which have new or different keys from those in the sorted file
ssh_known_hosts
:
$ ssh-keyscan -t rsa,dsa -f ssh_hosts | \
sort -u - ssh_known_hosts | diff ssh_known_hosts -
David Mazieres <dm@lcs.mit.edu> wrote the initial version, and Wayne Davison <wayned@users.sourceforge.net> added support for protocol version 2.