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author | Colin Watson <cjwatson@debian.org> | 2011-09-07 10:26:29 +0100 |
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committer | Colin Watson <cjwatson@debian.org> | 2011-09-07 10:26:29 +0100 |
commit | 44e6c1376b2048fb52e2b29baa5e6df7c0e87816 (patch) | |
tree | 6003d5fc2cb7c43cf28ed53dc9c880500c9bcd98 /ssh-keyscan.0 | |
parent | 5643cf0fc4d71e783c6aef2574684f07d21945ab (diff) | |
parent | e90790abaf031e037f444a6658e136e48577ea49 (diff) |
Import 5.9p1 tarball (respun)
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1 | SSH-KEYSCAN(1) OpenBSD Reference Manual SSH-KEYSCAN(1) | ||
2 | |||
3 | NAME | ||
4 | ssh-keyscan - gather ssh public keys | ||
5 | |||
6 | SYNOPSIS | ||
7 | ssh-keyscan [-46Hv] [-f file] [-p port] [-T timeout] [-t type] | ||
8 | [host | addrlist namelist] ... | ||
9 | |||
10 | DESCRIPTION | ||
11 | ssh-keyscan is a utility for gathering the public ssh host keys of a | ||
12 | number of hosts. It was designed to aid in building and verifying | ||
13 | ssh_known_hosts files. ssh-keyscan provides a minimal interface suitable | ||
14 | for use by shell and perl scripts. | ||
15 | |||
16 | ssh-keyscan uses non-blocking socket I/O to contact as many hosts as | ||
17 | possible in parallel, so it is very efficient. The keys from a domain of | ||
18 | 1,000 hosts can be collected in tens of seconds, even when some of those | ||
19 | hosts are down or do not run ssh. For scanning, one does not need login | ||
20 | access to the machines that are being scanned, nor does the scanning | ||
21 | process involve any encryption. | ||
22 | |||
23 | The options are as follows: | ||
24 | |||
25 | -4 Forces ssh-keyscan to use IPv4 addresses only. | ||
26 | |||
27 | -6 Forces ssh-keyscan to use IPv6 addresses only. | ||
28 | |||
29 | -f file | ||
30 | Read hosts or addrlist namelist pairs from this file, one per | ||
31 | line. If - is supplied instead of a filename, ssh-keyscan will | ||
32 | read hosts or addrlist namelist pairs from the standard input. | ||
33 | |||
34 | -H Hash all hostnames and addresses in the output. Hashed names may | ||
35 | be used normally by ssh and sshd, but they do not reveal | ||
36 | identifying information should the file's contents be disclosed. | ||
37 | |||
38 | -p port | ||
39 | Port to connect to on the remote host. | ||
40 | |||
41 | -T timeout | ||
42 | Set the timeout for connection attempts. If timeout seconds have | ||
43 | elapsed since a connection was initiated to a host or since the | ||
44 | last time anything was read from that host, then the connection | ||
45 | is closed and the host in question considered unavailable. | ||
46 | Default is 5 seconds. | ||
47 | |||
48 | -t type | ||
49 | Specifies the type of the key to fetch from the scanned hosts. | ||
50 | The possible values are ``rsa1'' for protocol version 1 and | ||
51 | ``dsa'', ``ecdsa'' or ``rsa'' for protocol version 2. Multiple | ||
52 | values may be specified by separating them with commas. The | ||
53 | default is ``rsa''. | ||
54 | |||
55 | -v Verbose mode. Causes ssh-keyscan to print debugging messages | ||
56 | about its progress. | ||
57 | |||
58 | SECURITY | ||
59 | If an ssh_known_hosts file is constructed using ssh-keyscan without | ||
60 | verifying the keys, users will be vulnerable to man in the middle | ||
61 | attacks. On the other hand, if the security model allows such a risk, | ||
62 | ssh-keyscan can help in the detection of tampered keyfiles or man in the | ||
63 | middle attacks which have begun after the ssh_known_hosts file was | ||
64 | created. | ||
65 | |||
66 | FILES | ||
67 | Input format: | ||
68 | |||
69 | 1.2.3.4,1.2.4.4 name.my.domain,name,n.my.domain,n,1.2.3.4,1.2.4.4 | ||
70 | |||
71 | Output format for rsa1 keys: | ||
72 | |||
73 | host-or-namelist bits exponent modulus | ||
74 | |||
75 | Output format for rsa, dsa and ecdsa keys: | ||
76 | |||
77 | host-or-namelist keytype base64-encoded-key | ||
78 | |||
79 | Where keytype is either ``ecdsa-sha2-nistp256'', ``ecdsa-sha2-nistp384'', | ||
80 | ``ecdsa-sha2-nistp521'', ``ssh-dss'' or ``ssh-rsa''. | ||
81 | |||
82 | /etc/ssh/ssh_known_hosts | ||
83 | |||
84 | EXAMPLES | ||
85 | Print the rsa host key for machine hostname: | ||
86 | |||
87 | $ ssh-keyscan hostname | ||
88 | |||
89 | Find all hosts from the file ssh_hosts which have new or different keys | ||
90 | from those in the sorted file ssh_known_hosts: | ||
91 | |||
92 | $ ssh-keyscan -t rsa,dsa,ecdsa -f ssh_hosts | \ | ||
93 | sort -u - ssh_known_hosts | diff ssh_known_hosts - | ||
94 | |||
95 | SEE ALSO | ||
96 | ssh(1), sshd(8) | ||
97 | |||
98 | AUTHORS | ||
99 | David Mazieres <dm@lcs.mit.edu> wrote the initial version, and Wayne | ||
100 | Davison <wayned@users.sourceforge.net> added support for protocol version | ||
101 | 2. | ||
102 | |||
103 | BUGS | ||
104 | It generates "Connection closed by remote host" messages on the consoles | ||
105 | of all the machines it scans if the server is older than version 2.9. | ||
106 | This is because it opens a connection to the ssh port, reads the public | ||
107 | key, and drops the connection as soon as it gets the key. | ||
108 | |||
109 | OpenBSD 5.0 August 31, 2010 OpenBSD 5.0 | ||