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Debug Logging and visibility of SSH Connection errors (#99)

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* Debug Logging and visibility of SSH Connection errors

* Updated date in man page
This commit is contained in:
thecliguy 2021-03-02 16:06:40 +00:00 committed by GitHub
parent c483fe1861
commit 83bd049486
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7 changed files with 67 additions and 28 deletions
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3
src/ssh_audit/auditconf.py
View File

@ -57,10 +57,11 @@ class AuditConf:
self.list_policies = False
self.lookup = ''
self.manual = False
self.debug = False
def __setattr__(self, name: str, value: Union[str, int, float, bool, Sequence[int]]) -> None:
valid = False
if name in ['batch', 'client_audit', 'colors', 'json', 'list_policies', 'manual', 'make_policy', 'ssh1', 'ssh2', 'timeout_set', 'verbose']:
if name in ['batch', 'client_audit', 'colors', 'json', 'list_policies', 'manual', 'make_policy', 'ssh1', 'ssh2', 'timeout_set', 'verbose', 'debug']:
valid, value = True, bool(value)
elif name in ['ipv4', 'ipv6']:
valid, value = True, bool(value)

20
src/ssh_audit/gextest.py
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@ -30,6 +30,7 @@ from ssh_audit.kexdh import KexGroupExchange_SHA1, KexGroupExchange_SHA256
from ssh_audit.ssh2_kexdb import SSH2_KexDB
from ssh_audit.ssh2_kex import SSH2_Kex
from ssh_audit.ssh_socket import SSH_Socket
from ssh_audit.outputbuffer import OutputBuffer
# Performs DH group exchanges to find what moduli are supported, and checks
@ -38,22 +39,24 @@ class GEXTest:
# Creates a new connection to the server. Returns True on success, or False.
@staticmethod
def reconnect(s: 'SSH_Socket', kex: 'SSH2_Kex', gex_alg: str) -> bool:
def reconnect(out: 'OutputBuffer', s: 'SSH_Socket', kex: 'SSH2_Kex', gex_alg: str) -> bool:
if s.is_connected():
return True
err = s.connect()
err = s.connect(out)
if err is not None:
out.v(err, write_now=True)
return False
_, _, err = s.get_banner()
_, _, err = s.get_banner(out)
if err is not None:
out.v(err, write_now=True)
s.close()
return False
# Send our KEX using the specified group-exchange and most of the
# server's own values.
s.send_kexinit(key_exchanges=[gex_alg], hostkeys=kex.key_algorithms, ciphers=kex.server.encryption, macs=kex.server.mac, compressions=kex.server.compression, languages=kex.server.languages)
s.send_kexinit(out, key_exchanges=[gex_alg], hostkeys=kex.key_algorithms, ciphers=kex.server.encryption, macs=kex.server.mac, compressions=kex.server.compression, languages=kex.server.languages)
# Parse the server's KEX.
_, payload = s.read_packet(2)
@ -63,7 +66,7 @@ class GEXTest:
# Runs the DH moduli test against the specified target.
@staticmethod
def run(s: 'SSH_Socket', kex: 'SSH2_Kex') -> None:
def run(out: 'OutputBuffer', s: 'SSH_Socket', kex: 'SSH2_Kex') -> None:
GEX_ALGS = {
'diffie-hellman-group-exchange-sha1': KexGroupExchange_SHA1,
'diffie-hellman-group-exchange-sha256': KexGroupExchange_SHA256,
@ -79,8 +82,9 @@ class GEXTest:
# algorithms. If so, test each one.
for gex_alg in GEX_ALGS:
if gex_alg in kex.kex_algorithms:
out.d('Preparing to perform DH group exchange using ' + gex_alg + '...', write_now=True)
if GEXTest.reconnect(s, kex, gex_alg) is False:
if GEXTest.reconnect(out, s, kex, gex_alg) is False:
break
kex_group = GEX_ALGS[gex_alg]()
@ -110,7 +114,9 @@ class GEXTest:
if bits >= smallest_modulus > 0:
break
if GEXTest.reconnect(s, kex, gex_alg) is False:
out.d('Preparing to perform DH group exchange using ' + gex_alg + ' with modulus size ' + str(bits) + '...', write_now=True)
if GEXTest.reconnect(out, s, kex, gex_alg) is False:
reconnect_failed = True
break

19
src/ssh_audit/hostkeytest.py
View File

@ -30,6 +30,7 @@ from ssh_audit.kexdh import KexDH, KexGroup1, KexGroup14_SHA1, KexGroup14_SHA256
from ssh_audit.ssh2_kex import SSH2_Kex
from ssh_audit.ssh2_kexdb import SSH2_KexDB
from ssh_audit.ssh_socket import SSH_Socket
from ssh_audit.outputbuffer import OutputBuffer
# Obtains host keys, checks their size, and derives their fingerprints.
@ -52,7 +53,7 @@ class HostKeyTest:
}
@staticmethod
def run(s: 'SSH_Socket', server_kex: 'SSH2_Kex') -> None:
def run(out: 'OutputBuffer', s: 'SSH_Socket', server_kex: 'SSH2_Kex') -> None:
KEX_TO_DHGROUP = {
'diffie-hellman-group1-sha1': KexGroup1,
'diffie-hellman-group14-sha1': KexGroup14_SHA1,
@ -80,10 +81,10 @@ class HostKeyTest:
break
if kex_str is not None and kex_group is not None:
HostKeyTest.perform_test(s, server_kex, kex_str, kex_group, HostKeyTest.HOST_KEY_TYPES)
HostKeyTest.perform_test(out, s, server_kex, kex_str, kex_group, HostKeyTest.HOST_KEY_TYPES)
@staticmethod
def perform_test(s: 'SSH_Socket', server_kex: 'SSH2_Kex', kex_str: str, kex_group: 'KexDH', host_key_types: Dict[str, Dict[str, bool]]) -> None:
def perform_test(out: 'OutputBuffer', s: 'SSH_Socket', server_kex: 'SSH2_Kex', kex_str: str, kex_group: 'KexDH', host_key_types: Dict[str, Dict[str, bool]]) -> None:
hostkey_modulus_size = 0
ca_modulus_size = 0
@ -101,22 +102,26 @@ class HostKeyTest:
# If this host key type is supported by the server, we test it.
if host_key_type in server_kex.key_algorithms:
out.d('Preparing to obtain ' + host_key_type + ' host key...', write_now=True)
cert = host_key_types[host_key_type]['cert']
variable_key_len = host_key_types[host_key_type]['variable_key_len']
# If the connection is closed, re-open it and get the kex again.
if not s.is_connected():
err = s.connect()
err = s.connect(out)
if err is not None:
out.v(err, write_now=True)
return
_, _, err = s.get_banner()
_, _, err = s.get_banner(out)
if err is not None:
out.v(err, write_now=True)
s.close()
return
# Send our KEX using the specified group-exchange and most of the server's own values.
s.send_kexinit(key_exchanges=[kex_str], hostkeys=[host_key_type], ciphers=server_kex.server.encryption, macs=server_kex.server.mac, compressions=server_kex.server.compression, languages=server_kex.server.languages)
s.send_kexinit(out, key_exchanges=[kex_str], hostkeys=[host_key_type], ciphers=server_kex.server.encryption, macs=server_kex.server.mac, compressions=server_kex.server.compression, languages=server_kex.server.languages)
# Parse the server's KEX.
_, payload = s.read_packet()
@ -125,8 +130,8 @@ class HostKeyTest:
# Do the initial DH exchange. The server responds back
# with the host key and its length. Bingo. We also get back the host key fingerprint.
try:
kex_group.send_init(s)
try:
host_key = kex_group.recv_reply(s, variable_key_len)
if host_key is not None:
server_kex.set_host_key(host_key_type, host_key)

12
src/ssh_audit/outputbuffer.py
View File

@ -47,6 +47,7 @@ class OutputBuffer:
self.section: List[str] = []
self.batch = False
self.verbose = False
self.debug = False
self.use_colors = True
self.json = False
self.__level = 0
@ -167,7 +168,16 @@ class OutputBuffer:
def v(self, s: str, write_now: bool = False) -> 'OutputBuffer':
'''Prints a message if verbose output is enabled.'''
if self.verbose:
if self.verbose or self.debug:
self.info(s)
if write_now:
self.write()
return self
def d(self, s: str, write_now: bool = False) -> 'OutputBuffer':
'''Prints a message if verbose output is enabled.'''
if self.debug:
self.info(s)
if write_now:
self.write()

23
src/ssh_audit/ssh_audit.py
View File

@ -84,6 +84,7 @@ def usage(err: Optional[str] = None) -> None:
uout.info(' -6, --ipv6 enable IPv6 (order of precedence)')
uout.info(' -b, --batch batch output')
uout.info(' -c, --client-audit starts a server on port 2222 to audit client\n software config (use -p to change port;\n use -t to change timeout)')
uout.info(' -d, --debug debug output')
uout.info(' -j, --json JSON output')
uout.info(' -l, --level=<level> minimum output level (info|warn|fail)')
uout.info(' -L, --list-policies list all the official, built-in policies')
@ -575,8 +576,8 @@ def process_commandline(out: OutputBuffer, args: List[str], usage_cb: Callable[.
# pylint: disable=too-many-branches
aconf = AuditConf()
try:
sopts = 'h1246M:p:P:jbcnvl:t:T:Lm'
lopts = ['help', 'ssh1', 'ssh2', 'ipv4', 'ipv6', 'make-policy=', 'port=', 'policy=', 'json', 'batch', 'client-audit', 'no-colors', 'verbose', 'level=', 'timeout=', 'targets=', 'list-policies', 'lookup=', 'threads=', 'manual']
sopts = 'h1246M:p:P:jbcnvl:t:T:Lmd'
lopts = ['help', 'ssh1', 'ssh2', 'ipv4', 'ipv6', 'make-policy=', 'port=', 'policy=', 'json', 'batch', 'client-audit', 'no-colors', 'verbose', 'level=', 'timeout=', 'targets=', 'list-policies', 'lookup=', 'threads=', 'manual', 'debug']
opts, args = getopt.gnu_getopt(args, sopts, lopts)
except getopt.GetoptError as err:
usage_cb(str(err))
@ -632,6 +633,9 @@ def process_commandline(out: OutputBuffer, args: List[str], usage_cb: Callable[.
aconf.lookup = a
elif o in ('-m', '--manual'):
aconf.manual = True
elif o in ('-d', '--debug'):
aconf.debug = True
out.debug = True
if len(args) == 0 and aconf.client_audit is False and aconf.target_file is None and aconf.list_policies is False and aconf.lookup == '' and aconf.manual is False:
usage_cb()
@ -813,15 +817,18 @@ def audit(out: OutputBuffer, aconf: AuditConf, sshv: Optional[int] = None, print
program_retval = exitcodes.GOOD
out.batch = aconf.batch
out.verbose = aconf.verbose
out.debug = aconf.debug
out.level = aconf.level
out.use_colors = aconf.colors
s = SSH_Socket(aconf.host, aconf.port, aconf.ip_version_preference, aconf.timeout, aconf.timeout_set)
if aconf.client_audit:
out.v("Listening for client connection on port %d..." % aconf.port, write_now=True)
s.listen_and_accept()
else:
out.v("Connecting to %s:%d..." % ('[%s]' % aconf.host if Utils.is_ipv6_address(aconf.host) else aconf.host, aconf.port), write_now=True)
err = s.connect()
out.v("Starting audit of %s:%d..." % ('[%s]' % aconf.host if Utils.is_ipv6_address(aconf.host) else aconf.host, aconf.port), write_now=True)
err = s.connect(out)
if err is not None:
out.fail(err)
@ -835,14 +842,14 @@ def audit(out: OutputBuffer, aconf: AuditConf, sshv: Optional[int] = None, print
if sshv is None:
sshv = 2 if aconf.ssh2 else 1
err = None
banner, header, err = s.get_banner(sshv)
banner, header, err = s.get_banner(out, sshv)
if banner is None:
if err is None:
err = '[exception] did not receive banner.'
else:
err = '[exception] did not receive banner: {}'.format(err)
if err is None:
s.send_kexinit() # Send the algorithms we support (except we don't since this isn't a real SSH connection).
s.send_kexinit(out) # Send the algorithms we support (except we don't since this isn't a real SSH connection).
packet_type, payload = s.read_packet(sshv)
if packet_type < 0:
@ -878,8 +885,8 @@ def audit(out: OutputBuffer, aconf: AuditConf, sshv: Optional[int] = None, print
elif sshv == 2:
kex = SSH2_Kex.parse(payload)
if aconf.client_audit is False:
HostKeyTest.run(s, kex)
GEXTest.run(s, kex)
HostKeyTest.run(out, s, kex)
GEXTest.run(out, s, kex)
# This is a standard audit scan.
if (aconf.policy is None) and (aconf.make_policy is False):

11
src/ssh_audit/ssh_socket.py
View File

@ -148,7 +148,7 @@ class SSH_Socket(ReadBuf, WriteBuf):
c.settimeout(self.__timeout)
self.__sock = c
def connect(self) -> Optional[str]:
def connect(self, out: 'OutputBuffer') -> Optional[str]:
'''Returns None on success, or an error string.'''
err = None
for af, addr in self._resolve():
@ -156,6 +156,7 @@ class SSH_Socket(ReadBuf, WriteBuf):
try:
s = socket.socket(af, socket.SOCK_STREAM)
s.settimeout(self.__timeout)
out.d(("Connecting to %s:%d..." % ('[%s]' % addr[0] if Utils.is_ipv6_address(addr[0]) else addr[0], addr[1])), write_now=True)
s.connect(addr)
self.__sock = s
return None
@ -169,7 +170,9 @@ class SSH_Socket(ReadBuf, WriteBuf):
errm = 'cannot connect to {} port {}: {}'.format(*errt)
return '[exception] {}'.format(errm)
def get_banner(self, sshv: int = 2) -> Tuple[Optional['Banner'], List[str], Optional[str]]:
def get_banner(self, out: 'OutputBuffer', sshv: int = 2) -> Tuple[Optional['Banner'], List[str], Optional[str]]:
out.d('Getting banner...', write_now=True)
if self.__sock is None:
return self.__banner, self.__header, 'not connected'
if self.__banner is not None:
@ -226,9 +229,11 @@ class SSH_Socket(ReadBuf, WriteBuf):
return -1, str(e.args[-1])
# Send a KEXINIT with the lists of key exchanges, hostkeys, ciphers, MACs, compressions, and languages that we "support".
def send_kexinit(self, key_exchanges: List[str] = ['curve25519-sha256', 'curve25519-sha256@libssh.org', 'ecdh-sha2-nistp256', 'ecdh-sha2-nistp384', 'ecdh-sha2-nistp521', 'diffie-hellman-group-exchange-sha256', 'diffie-hellman-group16-sha512', 'diffie-hellman-group18-sha512', 'diffie-hellman-group14-sha256'], hostkeys: List[str] = ['rsa-sha2-512', 'rsa-sha2-256', 'ssh-rsa', 'ecdsa-sha2-nistp256', 'ssh-ed25519'], ciphers: List[str] = ['chacha20-poly1305@openssh.com', 'aes128-ctr', 'aes192-ctr', 'aes256-ctr', 'aes128-gcm@openssh.com', 'aes256-gcm@openssh.com'], macs: List[str] = ['umac-64-etm@openssh.com', 'umac-128-etm@openssh.com', 'hmac-sha2-256-etm@openssh.com', 'hmac-sha2-512-etm@openssh.com', 'hmac-sha1-etm@openssh.com', 'umac-64@openssh.com', 'umac-128@openssh.com', 'hmac-sha2-256', 'hmac-sha2-512', 'hmac-sha1'], compressions: List[str] = ['none', 'zlib@openssh.com'], languages: List[str] = ['']) -> None: # pylint: disable=dangerous-default-value
def send_kexinit(self, out: 'OutputBuffer', key_exchanges: List[str] = ['curve25519-sha256', 'curve25519-sha256@libssh.org', 'ecdh-sha2-nistp256', 'ecdh-sha2-nistp384', 'ecdh-sha2-nistp521', 'diffie-hellman-group-exchange-sha256', 'diffie-hellman-group16-sha512', 'diffie-hellman-group18-sha512', 'diffie-hellman-group14-sha256'], hostkeys: List[str] = ['rsa-sha2-512', 'rsa-sha2-256', 'ssh-rsa', 'ecdsa-sha2-nistp256', 'ssh-ed25519'], ciphers: List[str] = ['chacha20-poly1305@openssh.com', 'aes128-ctr', 'aes192-ctr', 'aes256-ctr', 'aes128-gcm@openssh.com', 'aes256-gcm@openssh.com'], macs: List[str] = ['umac-64-etm@openssh.com', 'umac-128-etm@openssh.com', 'hmac-sha2-256-etm@openssh.com', 'hmac-sha2-512-etm@openssh.com', 'hmac-sha1-etm@openssh.com', 'umac-64@openssh.com', 'umac-128@openssh.com', 'hmac-sha2-256', 'hmac-sha2-512', 'hmac-sha1'], compressions: List[str] = ['none', 'zlib@openssh.com'], languages: List[str] = ['']) -> None: # pylint: disable=dangerous-default-value
'''Sends the list of supported host keys, key exchanges, ciphers, and MACs. Emulates OpenSSH v8.2.'''
out.d('KEX initialisation...', write_now=True)
kexparty = SSH2_KexParty(ciphers, macs, compressions, languages)
kex = SSH2_Kex(os.urandom(16), key_exchanges, hostkeys, kexparty, kexparty, False, 0)

7
ssh-audit.1
View File

@ -1,4 +1,4 @@
.TH SSH-AUDIT 1 "February 7, 2021"
.TH SSH-AUDIT 1 "March 2, 2021"
.SH NAME
\fBssh-audit\fP \- SSH server & client configuration auditor
.SH SYNOPSIS
@ -46,6 +46,11 @@ Enables grepable output.
.br
Starts a server on port 2222 to audit client software configuration. Use -p/--port=<port> to change port and -t/--timeout=<secs> to change listen timeout.
.TP
.B -d, \-\-debug
.br
Enable debug output.
.TP
.B -j, \-\-json
.br