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Results from concurrent scans against multiple hosts are no longer improperly combined (#190).
This commit is contained in:
Joe Testa
parent
521a50a796
commit
639f11a5e5
@ -179,6 +179,7 @@ For convenience, a web front-end on top of the command-line tool is available at
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## ChangeLog
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### v3.0.0-dev (2023-??-??)
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- Results from concurrent scans against multiple hosts are no longer improperly combined; bug discovered by [Adam Russell](https://github.com/thecliguy).
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- Added 1 new key exchange: `curve448-sha512@libssh.org`.
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### v2.9.0 (2023-04-29)
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@ -54,7 +54,7 @@ class Algorithms:
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def ssh1(self) -> Optional['Algorithms.Item']:
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if self.ssh1kex is None:
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return None
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item = Algorithms.Item(1, SSH1_KexDB.ALGORITHMS)
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item = Algorithms.Item(1, SSH1_KexDB.get_db())
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item.add('key', ['ssh-rsa1'])
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item.add('enc', self.ssh1kex.supported_ciphers)
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item.add('aut', self.ssh1kex.supported_authentications)
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@ -64,7 +64,7 @@ class Algorithms:
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def ssh2(self) -> Optional['Algorithms.Item']:
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if self.ssh2kex is None:
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return None
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item = Algorithms.Item(2, SSH2_KexDB.ALGORITHMS)
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item = Algorithms.Item(2, SSH2_KexDB.get_db())
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item.add('kex', self.ssh2kex.kex_algorithms)
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item.add('key', self.ssh2kex.key_algorithms)
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item.add('enc', self.ssh2kex.server.encryption)
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@ -208,7 +208,7 @@ class GEXTest:
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# We flag moduli smaller than 2048 as a failure.
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if smallest_modulus < 2048:
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text = 'using small %d-bit modulus' % smallest_modulus
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lst = SSH2_KexDB.ALGORITHMS['kex'][gex_alg]
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lst = SSH2_KexDB.get_db()['kex'][gex_alg]
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# For 'diffie-hellman-group-exchange-sha256', add
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# a failure reason.
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if len(lst) == 1:
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@ -222,7 +222,7 @@ class GEXTest:
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# Moduli smaller than 3072 get flagged as a warning.
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elif smallest_modulus < 3072:
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lst = SSH2_KexDB.ALGORITHMS['kex'][gex_alg]
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lst = SSH2_KexDB.get_db()['kex'][gex_alg]
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# Ensure that a warning list exists for us to append to, below.
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while len(lst) < 3:
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@ -216,16 +216,18 @@ class HostKeyTest:
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# If the current key is a member of the RSA family, then populate all RSA family members with the same
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# failure and/or warning comments.
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while len(SSH2_KexDB.ALGORITHMS['key'][rsa_type]) < 3:
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SSH2_KexDB.ALGORITHMS['key'][rsa_type].append([])
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db = SSH2_KexDB.get_db()
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while len(db['key'][rsa_type]) < 3:
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db['key'][rsa_type].append([])
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SSH2_KexDB.ALGORITHMS['key'][rsa_type][1].extend(key_fail_comments)
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SSH2_KexDB.ALGORITHMS['key'][rsa_type][2].extend(key_warn_comments)
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db['key'][rsa_type][1].extend(key_fail_comments)
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db['key'][rsa_type][2].extend(key_warn_comments)
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else:
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host_key_types[host_key_type]['parsed'] = True
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while len(SSH2_KexDB.ALGORITHMS['key'][host_key_type]) < 3:
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SSH2_KexDB.ALGORITHMS['key'][host_key_type].append([])
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db = SSH2_KexDB.get_db()
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while len(db['key'][host_key_type]) < 3:
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db['key'][host_key_type].append([])
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SSH2_KexDB.ALGORITHMS['key'][host_key_type][1].extend(key_fail_comments)
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SSH2_KexDB.ALGORITHMS['key'][host_key_type][2].extend(key_warn_comments)
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db['key'][host_key_type][1].extend(key_fail_comments)
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db['key'][host_key_type][2].extend(key_warn_comments)
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@ -22,6 +22,9 @@
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THE SOFTWARE.
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"""
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# pylint: disable=unused-import
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import copy
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import threading
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from typing import Dict, List, Set, Sequence, Tuple, Iterable # noqa: F401
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from typing import Callable, Optional, Union, Any # noqa: F401
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@ -34,7 +37,9 @@ class SSH1_KexDB: # pylint: disable=too-few-public-methods
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FAIL_NA_UNSAFE = 'not implemented in OpenSSH (server), unsafe algorithm'
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TEXT_CIPHER_IDEA = 'cipher used by commercial SSH'
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ALGORITHMS: Dict[str, Dict[str, List[List[Optional[str]]]]] = {
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DB_PER_THREAD: Dict[int, Dict[str, Dict[str, List[List[Optional[str]]]]]] = {}
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MASTER_DB: Dict[str, Dict[str, List[List[Optional[str]]]]] = {
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'key': {
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'ssh-rsa1': [['1.2.2']],
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},
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@ -56,3 +61,24 @@ class SSH1_KexDB: # pylint: disable=too-few-public-methods
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'kerberos': [['1.2.2', '3.6'], [FAIL_OPENSSH37_REMOVE]],
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}
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}
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@staticmethod
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def get_db() -> Dict[str, Dict[str, List[List[Optional[str]]]]]:
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'''Returns a copy of the MASTER_DB that is private to the calling thread. This prevents multiple threads from polluting the results of other threads.'''
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calling_thread_id = threading.get_ident()
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if calling_thread_id not in SSH1_KexDB.DB_PER_THREAD:
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SSH1_KexDB.DB_PER_THREAD[calling_thread_id] = copy.deepcopy(SSH1_KexDB.MASTER_DB)
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return SSH1_KexDB.DB_PER_THREAD[calling_thread_id]
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@staticmethod
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def thread_exit() -> None:
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'''Deletes the calling thread's copy of the MASTER_DB. This is needed because, in rare circumstances, a terminated thread's ID can be re-used by new threads.'''
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calling_thread_id = threading.get_ident()
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if calling_thread_id in SSH1_KexDB.DB_PER_THREAD:
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del SSH1_KexDB.DB_PER_THREAD[calling_thread_id]
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@ -23,6 +23,9 @@
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THE SOFTWARE.
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"""
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# pylint: disable=unused-import
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import copy
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import threading
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from typing import Dict, List, Set, Sequence, Tuple, Iterable # noqa: F401
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from typing import Callable, Optional, Union, Any # noqa: F401
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@ -69,8 +72,10 @@ class SSH2_KexDB: # pylint: disable=too-few-public-methods
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INFO_REMOVED_IN_OPENSSH70 = 'removed in OpenSSH 7.0: https://www.openssh.com/txt/release-7.0'
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INFO_WITHDRAWN_PQ_ALG = 'the sntrup4591761 algorithm was withdrawn, as it may not provide strong post-quantum security'
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# Maintains a dictionary per calling thread that yields its own copy of MASTER_DB. This prevents results from one thread polluting the results of another thread.
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DB_PER_THREAD: Dict[int, Dict[str, Dict[str, List[List[Optional[str]]]]]] = {}
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ALGORITHMS: Dict[str, Dict[str, List[List[Optional[str]]]]] = {
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MASTER_DB: Dict[str, Dict[str, List[List[Optional[str]]]]] = {
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# Format: 'algorithm_name': [['version_first_appeared_in'], [reason_for_failure1, reason_for_failure2, ...], [warning1, warning2, ...], [info1, info2, ...]]
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'kex': {
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'Curve25519SHA256': [[]],
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@ -390,3 +395,24 @@ class SSH2_KexDB: # pylint: disable=too-few-public-methods
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'umac-96@openssh.com': [[], [], [WARN_ENCRYPT_AND_MAC], [INFO_NEVER_IMPLEMENTED_IN_OPENSSH]],
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}
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}
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@staticmethod
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def get_db() -> Dict[str, Dict[str, List[List[Optional[str]]]]]:
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'''Returns a copy of the MASTER_DB that is private to the calling thread. This prevents multiple threads from polluting the results of other threads.'''
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calling_thread_id = threading.get_ident()
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if calling_thread_id not in SSH2_KexDB.DB_PER_THREAD:
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SSH2_KexDB.DB_PER_THREAD[calling_thread_id] = copy.deepcopy(SSH2_KexDB.MASTER_DB)
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return SSH2_KexDB.DB_PER_THREAD[calling_thread_id]
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@staticmethod
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def thread_exit() -> None:
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'''Deletes the calling thread's copy of the MASTER_DB. This is needed because, in rare circumstances, a terminated thread's ID can be re-used by new threads.'''
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calling_thread_id = threading.get_ident()
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if calling_thread_id in SSH2_KexDB.DB_PER_THREAD:
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del SSH2_KexDB.DB_PER_THREAD[calling_thread_id]
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@ -446,10 +446,11 @@ def post_process_findings(banner: Optional[Banner], algs: Algorithms) -> List[st
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if (algs.ssh2kex is not None and 'diffie-hellman-group-exchange-sha256' in algs.ssh2kex.kex_algorithms and 'diffie-hellman-group-exchange-sha256' in algs.ssh2kex.dh_modulus_sizes() and algs.ssh2kex.dh_modulus_sizes()['diffie-hellman-group-exchange-sha256'] == 2048) and (banner is not None and banner.software is not None and banner.software.find('OpenSSH') != -1):
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# Ensure a list for notes exists.
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while len(SSH2_KexDB.ALGORITHMS['kex']['diffie-hellman-group-exchange-sha256']) < 4:
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SSH2_KexDB.ALGORITHMS['kex']['diffie-hellman-group-exchange-sha256'].append([])
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db = SSH2_KexDB.get_db()
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while len(db['kex']['diffie-hellman-group-exchange-sha256']) < 4:
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db['kex']['diffie-hellman-group-exchange-sha256'].append([])
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SSH2_KexDB.ALGORITHMS['kex']['diffie-hellman-group-exchange-sha256'][3].append("A bug in OpenSSH causes it to fall back to a 2048-bit modulus regardless of server configuration (https://bugzilla.mindrot.org/show_bug.cgi?id=2793)")
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db['kex']['diffie-hellman-group-exchange-sha256'][3].append("A bug in OpenSSH causes it to fall back to a 2048-bit modulus regardless of server configuration (https://bugzilla.mindrot.org/show_bug.cgi?id=2793)")
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# Ensure that this algorithm doesn't appear in the recommendations section since the user cannot control this OpenSSH bug.
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algorithm_recommendation_suppress_list.append('diffie-hellman-group-exchange-sha256')
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@ -522,7 +523,7 @@ def output(out: OutputBuffer, aconf: AuditConf, banner: Optional[Banner], header
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# SSHv1
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if pkm is not None:
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adb = SSH1_KexDB.ALGORITHMS
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adb = SSH1_KexDB.get_db()
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ciphers = pkm.supported_ciphers
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auths = pkm.supported_authentications
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title, atype = 'SSH1 host-key algorithms', 'key'
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@ -534,7 +535,7 @@ def output(out: OutputBuffer, aconf: AuditConf, banner: Optional[Banner], header
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# SSHv2
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if kex is not None:
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adb = SSH2_KexDB.ALGORITHMS
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adb = SSH2_KexDB.get_db()
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title, atype = 'key exchange algorithms', 'kex'
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program_retval = output_algorithms(out, title, adb, atype, kex.kex_algorithms, unknown_algorithms, aconf.json, program_retval, maxlen, dh_modulus_sizes=kex.dh_modulus_sizes())
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title, atype = 'host-key algorithms', 'key'
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@ -1124,7 +1125,7 @@ def algorithm_lookup(out: OutputBuffer, alg_names: str) -> int:
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}
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algorithm_names = alg_names.split(",")
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adb = SSH2_KexDB.ALGORITHMS
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adb = SSH2_KexDB.get_db()
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# Use nested dictionary comprehension to iterate an outer dictionary where
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# each key is an alg type that consists of a value (which is itself a
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@ -1376,6 +1377,10 @@ def main() -> int:
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if aconf.json:
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print(']')
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# Send notification that this thread is exiting. This deletes the thread's local copy of the algorithm databases.
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SSH1_KexDB.thread_exit()
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SSH2_KexDB.thread_exit()
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else: # Just a scan against a single target.
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ret = audit(out, aconf)
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out.write()
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@ -7,7 +7,7 @@ class Test_SSH2_KexDB:
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@pytest.fixture(autouse=True)
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def init(self):
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self.db = SSH2_KexDB.ALGORITHMS
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self.db = SSH2_KexDB.get_db()
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def test_ssh2_kexdb(self):
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'''Ensures that the SSH2_KexDB.ALGORITHMS dictionary is in the right format.'''
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