version 1, including all changes.
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perry |
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__NAME__ |
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ssh-keyscan - gather ssh public keys |
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__SYNOPSIS__ |
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ssh-keyscan [[-v46] [[-p port] [[-T timeout] [[-t type] [[-f |
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file] [[host | addrlist namelist] [[...] |
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__DESCRIPTION__ |
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ssh-keyscan is a utility for gathering the public ssh host |
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keys of a number of hosts. It was designed to aid in build- |
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ing and verifying ssh_known_hosts files. |
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ssh-keyscan pro- vides a minimal interface suitable for use |
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by shell and perl scripts. |
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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. |
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The options are as follows: |
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-p port |
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Port to connect to on the remote host.-T timeoutSet the timeout for connection attempts. If 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. |
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-t type |
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Specifies the type of the key to fetch from the scanned |
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hosts. The possible values are ``rsa1'' for protocol version |
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1 and ``rsa'' or ``dsa'' for proto- col version 2. Multiple |
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values may be specified by separating them with commas. The |
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default is ``rsa1''. |
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-f filename |
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Read hosts or addrlist namelist pairs from this |
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file, one per line. If - is supplied instead of a |
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file- name, ssh-keyscan will read hosts or addrlist |
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namelist pairs from the standard input. |
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-v |
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Verbose mode. Causes ssh-keyscan to print debugging messages |
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about its progress. |
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-4 |
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Forces ssh-keyscan to use IPv4 addresses only. |
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-6 |
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Forces ssh-keyscan to use IPv6 addresses only. |
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__SECURITY__ |
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If a ssh_known_hosts file is constructed using ssh-keyscan |
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without verifying the keys, users will be vulnerable to |
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attacks. On the other hand, if the security model allows |
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such a risk, ssh-keyscan can help in the detection of tam- |
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pered keyfiles or man in the middle attacks which have begun |
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after the ssh_known_hosts file was created. |
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__EXAMPLES__ |
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Print the rsa1 host key for machine hostname: |
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ssh-keyscan hostname |
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Find all hosts from the file ssh_hosts which have new or different keys from those in the sorted file ssh_known_hosts: |
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ssh-keyscan -t rsa,dsa -f ssh_hosts | \ |
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sort -u - ssh_known_hosts | diff ssh_known_hosts - |
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__FILES__ |
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Input format: |
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1.2.3.4,1.2.4.4 name.my.domain,name,n.my.domain,n,1.2.3.4,1.2.4.4 |
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Output format for rsa1 keys: |
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host-or-namelist bits exponent modulus |
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Output format for rsa and dsa keys: |
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host-or-namelist keytype base64-encoded-key |
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Where keytype is either ``ssh-rsa'' or ``ssh-dsa''. |
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/etc/ssh/ssh_known_hosts |
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__BUGS__ |
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It generates |
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__SEE ALSO__ |
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ssh(1), sshd(8) |
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__AUTHORS__ |
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David Mazieres |
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BSD January 1, 1996 1 |
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---- |