public class KnownHosts extends Object
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
It is a thread safe implementation, therefore, you need only to instantiate one
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).
KnownHosts
for your whole application.
Modifier and Type | Field and Description |
---|---|
static int |
HOSTKEY_HAS_CHANGED |
static int |
HOSTKEY_IS_NEW |
static int |
HOSTKEY_IS_OK |
Constructor and Description |
---|
KnownHosts() |
KnownHosts(char[] knownHostsData) |
KnownHosts(File knownHosts) |
Modifier and Type | Method and Description |
---|---|
void |
addHostkey(String[] hostnames,
String serverHostKeyAlgorithm,
byte[] serverHostKey)
Adds a single public key entry to the database.
|
void |
addHostkeys(char[] knownHostsData)
Parses the given known_hosts data and adds entries to the database.
|
void |
addHostkeys(File knownHosts)
Parses the given known_hosts file and adds entries 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.
|
static String |
createBubblebabbleFingerprint(String keytype,
byte[] publickey)
Convert a ssh2 key-blob into a human readable bubblebabble fingerprint.
|
static String |
createHashedHostname(String hostname)
Generate the hashed representation of the given hostname.
|
static String |
createHexFingerprint(String keytype,
byte[] publickey)
Convert a ssh2 key-blob into a human readable hex fingerprint.
|
String[] |
getPreferredServerHostkeyAlgorithmOrder(String hostname)
Try to find the preferred order of hostkey algorithms for the given hostname.
|
int |
verifyHostkey(String hostname,
String serverHostKeyAlgorithm,
byte[] serverHostKey)
Checks the internal hostkey database for the given hostkey.
|
public static final int HOSTKEY_IS_OK
public static final int HOSTKEY_IS_NEW
public static final int HOSTKEY_HAS_CHANGED
public KnownHosts()
public KnownHosts(char[] knownHostsData) throws IOException
IOException
public KnownHosts(File knownHosts) throws IOException
IOException
public void addHostkey(String[] hostnames, String serverHostKeyAlgorithm, byte[] serverHostKey) throws IOException
addHostkeyToFile()
for that purpose.
This method is designed to be used in a ServerHostKeyVerifier
.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
.IOException
public void addHostkeys(char[] knownHostsData) throws IOException
knownHostsData
- IOException
public void addHostkeys(File knownHosts) throws IOException
knownHosts
- IOException
public static final String createHashedHostname(String hostname)
hostname
- public String[] getPreferredServerHostkeyAlgorithmOrder(String hostname)
ssh-rsa
or ssh-dss
)
an ordered list of hostkey algorithms is returned which can be passed
to Connection.setServerHostKeyAlgorithms
.hostname
- 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).public int verifyHostkey(String hostname, String serverHostKeyAlgorithm, byte[] serverHostKey) throws IOException
hostname
- the server's hostname, will be matched with all hostname patternsserverHostKeyAlgorithm
- type of hostkey, either ssh-rsa
or ssh-dss
serverHostKey
- the key blobHOSTKEY_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?)IOException
- if the supplied key blob cannot be parsed or does not match the given hostkey type.public static final void addHostkeyToFile(File knownHosts, String[] hostnames, String serverHostKeyAlgorithm, byte[] serverHostKey) throws IOException
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
.IOException
public static final String createHexFingerprint(String keytype, byte[] publickey)
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 blobpublic static final String createBubblebabbleFingerprint(String keytype, byte[] publickey)
Example fingerprint: xofoc-bubuz-cazin-zufyl-pivuk-biduk-tacib-pybur-gonar-hotat-lyxux.
keytype
- either "ssh-rsa" or "ssh-dss"publickey
- key dataCopyright © 2023. All rights reserved.