com.trilead.ssh2
Class KnownHosts
java.lang.Object
com.trilead.ssh2.KnownHosts
public class KnownHosts
extends java.lang.Object
The
KnownHosts
class is a handy tool to verify received server hostkeys
based on the information in
known_hosts
files (the ones used by OpenSSH).
It offers basically an in-memory database for known_hosts entries, as well as some
helper functions. Entries from a
known_hosts
file can be loaded at construction time.
It is also possible to add more keys later (e.g., one can parse different
known_hosts
files).
It is a thread safe implementation, therefore, you need only to instantiate one
KnownHosts
for your whole application.
void | addHostkey(hostnames[] , String serverHostKeyAlgorithm, byte[] serverHostKey) - Adds a single public key entry to the database.
|
static void | addHostkeyToFile(File knownHosts, String[] hostnames, String serverHostKeyAlgorithm, byte[] serverHostKey) - Adds a single public key entry to the a known_hosts file.
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void | addHostkeys(File knownHosts) - Parses the given known_hosts file and adds entries to the database.
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void | addHostkeys(char[] knownHostsData) - Parses the given known_hosts data and adds entries to the database.
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static String | createBubblebabbleFingerprint(String keytype, byte[] publickey) - Convert a ssh2 key-blob into a human readable bubblebabble fingerprint.
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static String | createHashedHostname(String hostname) - Generate the hashed representation of the given hostname.
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static String | createHexFingerprint(String keytype, byte[] publickey) - Convert a ssh2 key-blob into a human readable hex fingerprint.
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String[] | getPreferredServerHostkeyAlgorithmOrder(String hostname) - Try to find the preferred order of hostkey algorithms for the given hostname.
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int | verifyHostkey(String hostname, String serverHostKeyAlgorithm, byte[] serverHostKey) - Checks the internal hostkey database for the given hostkey.
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HOSTKEY_HAS_CHANGED
public static final int HOSTKEY_HAS_CHANGED
HOSTKEY_IS_NEW
public static final int HOSTKEY_IS_NEW
HOSTKEY_IS_OK
public static final int HOSTKEY_IS_OK
KnownHosts
public KnownHosts()
KnownHosts
public KnownHosts(File knownHosts)
throws IOException
KnownHosts
public KnownHosts(char[] knownHostsData)
throws IOException
addHostkey
public void addHostkey(hostnames[] ,
String serverHostKeyAlgorithm,
byte[] serverHostKey)
throws IOException
Adds a single public key entry to the database. Note: this will NOT add the public key
to any physical file (e.g., "~/.ssh/known_hosts") - use
addHostkeyToFile()
for that purpose.
This method is designed to be used in a
ServerHostKeyVerifier
.
addHostkeyToFile
public static final void addHostkeyToFile(File knownHosts,
String[] hostnames,
String serverHostKeyAlgorithm,
byte[] serverHostKey)
throws IOException
Adds a single public key entry to the a known_hosts file.
This method is designed to be used in a
ServerHostKeyVerifier
.
knownHosts
- the file where the publickey entry will be appended.hostnames
- a list of hostname patterns - at least one most be specified. Check out the
OpenSSH sshd man page for a description of the pattern matching algorithm.serverHostKeyAlgorithm
- as passed to the ServerHostKeyVerifier
.serverHostKey
- as passed to the ServerHostKeyVerifier
.
addHostkeys
public void addHostkeys(File knownHosts)
throws IOException
Parses the given known_hosts file and adds entries to the database.
addHostkeys
public void addHostkeys(char[] knownHostsData)
throws IOException
Parses the given known_hosts data and adds entries to the database.
createBubblebabbleFingerprint
public static final String createBubblebabbleFingerprint(String keytype,
byte[] publickey)
Convert a ssh2 key-blob into a human readable bubblebabble fingerprint.
The used bubblebabble algorithm (taken from OpenSSH) generates fingerprints
that are easier to remember for humans.
Example fingerprint: xofoc-bubuz-cazin-zufyl-pivuk-biduk-tacib-pybur-gonar-hotat-lyxux.
keytype
- either "ssh-rsa" or "ssh-dss"publickey
- key data
createHashedHostname
public static final String createHashedHostname(String hostname)
Generate the hashed representation of the given hostname. Useful for adding entries
with hashed hostnames to a known_hosts file. (see -H option of OpenSSH key-gen).
- the hashed representation, e.g., "|1|cDhrv7zwEUV3k71CEPHnhHZezhA=|Xo+2y6rUXo2OIWRAYhBOIijbJMA="
createHexFingerprint
public static final String createHexFingerprint(String keytype,
byte[] publickey)
Convert a ssh2 key-blob into a human readable hex fingerprint.
Generated fingerprints are identical to those generated by OpenSSH.
Example fingerprint: d0:cb:76:19:99:5a:03:fc:73:10:70:93:f2:44:63:47.
keytype
- either "ssh-rsa" or "ssh-dss"publickey
- key blob
getPreferredServerHostkeyAlgorithmOrder
public String[] getPreferredServerHostkeyAlgorithmOrder(String hostname)
Try to find the preferred order of hostkey algorithms for the given hostname.
Based on the type of hostkey that is present in the internal database
(i.e., either ssh-rsa
or ssh-dss
)
an ordered list of hostkey algorithms is returned which can be passed
to Connection.setServerHostKeyAlgorithms
.
null
if no key for the given hostname is present or
there are keys of multiple types present for the given hostname. Otherwise,
an array with hostkey algorithms is returned (i.e., an array of length 2).
verifyHostkey
public int verifyHostkey(String hostname,
String serverHostKeyAlgorithm,
byte[] serverHostKey)
throws IOException
Checks the internal hostkey database for the given hostkey.
If no matching key can be found, then the hostname is resolved to an IP address
and the search is repeated using that IP address.
hostname
- the server's hostname, will be matched with all hostname patternsserverHostKeyAlgorithm
- type of hostkey, either ssh-rsa
or ssh-dss
serverHostKey
- the key blob
HOSTKEY_IS_OK
: the given hostkey matches an entry for the given hostnameHOSTKEY_IS_NEW
: no entries found for this hostname and this type of hostkeyHOSTKEY_HAS_CHANGED
: hostname is known, but with another key of the same type
(man-in-the-middle attack?)