Config::Model::models::Sshd - Configuration class Sshd
Configuration classes used by Config::Model
This configuration class was generated from sshd_system documentation. by
parse-man.pl
<
https://github.com/dod38fr/config-model-openssh/contrib/parse-man.pl>
Specifies what environment variables sent by the client will be copied into the
session's
environ(7). See
SendEnv and
SetEnv in
ssh_config(5) for how to configure the client. The TERM environment
variable is always accepted whenever the client requests a pseudo-terminal as
it is required by the protocol. Variables are specified by name, which may
contain the wildcard characters '*' and '?'. Multiple environment variables
may be separated by whitespace or spread across multiple
AcceptEnv
directives. Be warned that some environment variables could be used to bypass
restricted user environments. For this reason, care should be taken in the use
of this directive. The default is not to accept any environment variables.
Optional. Type list of uniline.
Specifies whether
ssh-agent(1) forwarding is permitted. The default is
yes. Note that disabling agent forwarding does not improve security
unless users are also denied shell access, as they can always install their
own forwarders.
Optional. Type boolean.
- upstream_default value :
- yes
This keyword can be followed by a list of group name patterns, separated by
spaces. If specified, login is allowed only for users whose primary group or
supplementary group list matches one of the patterns. Only group names are
valid; a numerical group ID is not recognized. By default, login is allowed
for all groups. The allow/deny groups directives are processed in the
following order:
DenyGroups,
AllowGroups.
See PATTERNS in
ssh_config(5) for more information on patterns.
Optional. Type list of uniline.
Specifies whether StreamLocal (Unix-domain socket) forwarding is permitted. The
available options are
yes (the default) or
all to allow
StreamLocal forwarding,
no to prevent all StreamLocal forwarding,
local to allow local (from the perspective of
ssh(1)) forwarding
only or
remote to allow remote forwarding only. Note that disabling
StreamLocal forwarding does not improve security unless users are also denied
shell access, as they can always install their own forwarders.
Optional.
Type enum. choice: 'yes', 'all', 'no', 'local', 'remote'.
- upstream_default value :
- yes
Specifies whether TCP forwarding is permitted. The available options are
yes (the default) or
all to allow TCP forwarding,
no to
prevent all TCP forwarding,
local to allow local (from the perspective
of
ssh(1)) forwarding only or
remote to allow remote forwarding
only. Note that disabling TCP forwarding does not improve security unless
users are also denied shell access, as they can always install their own
forwarders.
Optional. Type enum. choice: 'yes', 'all', 'no', 'local',
'remote'.
- upstream_default value :
- yes
This keyword can be followed by a list of user name patterns, separated by
spaces. If specified, login is allowed only for user names that match one of
the patterns. Only user names are valid; a numerical user ID is not
recognized. By default, login is allowed for all users. If the pattern takes
the form USER@HOST then USER and HOST are separately checked, restricting
logins to particular users from particular hosts. HOST criteria may
additionally contain addresses to match in CIDR address/masklen format. The
allow/deny users directives are processed in the following order:
DenyUsers,
AllowUsers.
See PATTERNS in
ssh_config(5) for more information on patterns.
Optional. Type list of uniline.
Specifies the authentication methods that must be successfully completed for a
user to be granted access. This option must be followed by one or more lists
of comma-separated authentication method names, or by the single string
any to indicate the default behaviour of accepting any single
authentication method. If the default is overridden, then successful
authentication requires completion of every method in at least one of these
lists.
For example, "publickey, password publickey, keyboard-interactive"
would require the user to complete public key authentication, followed by
either password or keyboard interactive authentication. Only methods that are
next in one or more lists are offered at each stage, so for this example it
would not be possible to attempt password or keyboard-interactive
authentication before public key.
For keyboard interactive authentication it is also possible to restrict
authentication to a specific device by appending a colon followed by the
device identifier
bsdauth or
pam. depending on the server
configuration. For example, "keyboard-interactive:bsdauth" would
restrict keyboard interactive authentication to the
bsdauth device.
If the publickey method is listed more than once,
sshd(8) verifies that
keys that have been used successfully are not reused for subsequent
authentications. For example, "publickey, publickey" requires
successful authentication using two different public keys.
Note that each authentication method listed should also be explicitly enabled in
the configuration.
The available authentication methods are: "gssapi-with-mic",
"hostbased", "keyboard-interactive", "none"
(used for access to password-less accounts when
PermitEmptyPasswords is
enabled), "password" and "publickey".
Optional. Type
uniline.
Specifies a program to be used to look up the user's public keys. The program
must be owned by root, not writable by group or others and specified by an
absolute path. Arguments to
AuthorizedKeysCommand accept the tokens
described in the
TOKENS section. If no arguments are specified then the
username of the target user is used.
The program should produce on standard output zero or more lines of
authorized_keys output (see
AUTHORIZED_KEYS in
sshd(8)).
AuthorizedKeysCommand is tried after the usual
AuthorizedKeysFile files and will not be executed if a matching key is
found there. By default, no
AuthorizedKeysCommand is run.
Optional.
Type uniline.
Specifies the user under whose account the
AuthorizedKeysCommand is run.
It is recommended to use a dedicated user that has no other role on the host
than running authorized keys commands. If
AuthorizedKeysCommand is
specified but
AuthorizedKeysCommandUser is not, then
sshd(8)
will refuse to start.
Optional. Type uniline.
Specifies the file that contains the public keys used for user authentication.
The format is described in the AUTHORIZED_KEYS FILE FORMAT section of
sshd(8). Arguments to
AuthorizedKeysFile accept the tokens
described in the
TOKENS section. After expansion,
AuthorizedKeysFile is taken to be an absolute path or one relative to
the user's home directory. Multiple files may be listed, separated by
whitespace. Alternately this option may be set to
none to skip checking
for user keys in files. The default is ".ssh/authorized_keys
.ssh/authorized_keys2".
Optional. Type list of uniline.
Note: AuthorizedKeysFile values are migrated from '- AuthorizedKeysFile2'
Specifies a program to be used to generate the list of allowed certificate
principals as per
AuthorizedPrincipalsFile. The program must be owned
by root, not writable by group or others and specified by an absolute path.
Arguments to
AuthorizedPrincipalsCommand accept the tokens described in
the
TOKENS section. If no arguments are specified then the username of
the target user is used.
The program should produce on standard output zero or more lines of
AuthorizedPrincipalsFile output. If either
AuthorizedPrincipalsCommand or
AuthorizedPrincipalsFile is
specified, then certificates offered by the client for authentication must
contain a principal that is listed. By default, no
AuthorizedPrincipalsCommand is run.
Optional. Type uniline.
Specifies the user under whose account the
AuthorizedPrincipalsCommand is
run. It is recommended to use a dedicated user that has no other role on the
host than running authorized principals commands. If
AuthorizedPrincipalsCommand is specified but
AuthorizedPrincipalsCommandUser is not, then
sshd(8) will refuse
to start.
Optional. Type uniline.
Specifies a file that lists principal names that are accepted for certificate
authentication. When using certificates signed by a key listed in
TrustedUserCAKeys, this file lists names, one of which must appear in
the certificate for it to be accepted for authentication. Names are listed one
per line preceded by key options (as described in
AUTHORIZED_KEYS
FILE FORMAT in
sshd(8)). Empty lines and comments starting with
'#' are ignored.
Arguments to
AuthorizedPrincipalsFile accept the tokens described in the
TOKENS section. After expansion,
AuthorizedPrincipalsFile is
taken to be an absolute path or one relative to the user's home directory. The
default is
none, i.e. not to use a principals file X in this case, the
username of the user must appear in a certificate's principals list for it to
be accepted.
Note that
AuthorizedPrincipalsFile is only used when authentication
proceeds using a CA listed in
TrustedUserCAKeys and is not consulted
for certification authorities trusted via
~/.ssh/authorized_keys,
though the
principals= key option offers a similar facility (see
sshd(8) for details).
Optional. Type uniline.
- upstream_default value :
- none
The contents of the specified file are sent to the remote user before
authentication is allowed. If the argument is
none then no banner is
displayed. By default, no banner is displayed.
Optional. Type uniline.
Specifies which algorithms are allowed for signing of certificates by
certificate authorities (CAs). The default is:
ssh-ed25519, ecdsa-sha2-nistp256, ecdsa-sha2-nistp384, ecdsa-sha2-nistp521,
[email protected],
[email protected], rsa-sha2-512,
rsa-sha2-256
If the specified list begins with a '+' character, then the specified algorithms
will be appended to the default set instead of replacing them. If the
specified list begins with a '-' character, then the specified algorithms
(including wildcards) will be removed from the default set instead of
replacing them.
Certificates signed using other algorithms will not be accepted for public key
or host-based authentication.
Optional. Type uniline.
Specifies the pathname of a directory to
chroot(2) to after
authentication. At session startup
sshd(8) checks that all components
of the pathname are root-owned directories which are not writable by any other
user or group. After the chroot,
sshd(8) changes the working directory
to the user's home directory. Arguments to
ChrootDirectory accept the
tokens described in the
TOKENS section.
The
ChrootDirectory must contain the necessary files and directories to
support the user's session. For an interactive session this requires at least
a shell, typically
sh(1), and basic
/dev nodes such as
null(4),
zero(4),
stdin(4),
stdout(4),
stderr(4), and
tty(4) devices. For file transfer sessions using
SFTP no additional configuration of the environment is necessary if the
in-process sftp-server is used, though sessions which use logging may require
/dev/log inside the chroot directory on some operating systems (see
sftp-server(8) for details).
For safety, it is very important that the directory hierarchy be prevented from
modification by other processes on the system (especially those outside the
jail). Misconfiguration can lead to unsafe environments which
sshd(8)
cannot detect.
The default is
none, indicating not to
chroot(2).
Optional.
Type uniline.
- upstream_default value :
- none
Sets the number of client alive messages which may be sent without
sshd(8) receiving any messages back from the client. If this threshold
is reached while client alive messages are being sent, sshd will disconnect
the client, terminating the session. It is important to note that the use of
client alive messages is very different from
TCPKeepAlive. The client
alive messages are sent through the encrypted channel and therefore will not
be spoofable. The TCP keepalive option enabled by
TCPKeepAlive is
spoofable. The client alive mechanism is valuable when the client or server
depend on knowing when a connection has become unresponsive.
The default value is 3. If
ClientAliveInterval is set to 15, and
ClientAliveCountMax is left at the default, unresponsive SSH clients
will be disconnected after approximately 45 seconds. Setting a zero
ClientAliveCountMax disables connection termination.
Optional. Type
integer.
- upstream_default value :
- 3
Sets a timeout interval in seconds after which if no data has been received from
the client,
sshd(8) will send a message through the encrypted channel
to request a response from the client. The default is 0, indicating that these
messages will not be sent to the client.
Optional. Type integer.
- upstream_default value :
- 0
This keyword can be followed by a list of group name patterns, separated by
spaces. Login is disallowed for users whose primary group or supplementary
group list matches one of the patterns. Only group names are valid; a
numerical group ID is not recognized. By default, login is allowed for all
groups. The allow/deny groups directives are processed in the following order:
DenyGroups,
AllowGroups.
See PATTERNS in
ssh_config(5) for more information on patterns.
Optional. Type list of uniline.
This keyword can be followed by a list of user name patterns, separated by
spaces. Login is disallowed for user names that match one of the patterns.
Only user names are valid; a numerical user ID is not recognized. By default,
login is allowed for all users. If the pattern takes the form USER@HOST then
USER and HOST are separately checked, restricting logins to particular users
from particular hosts. HOST criteria may additionally contain addresses to
match in CIDR address/masklen format. The allow/deny users directives are
processed in the following order:
DenyUsers,
AllowUsers.
See PATTERNS in
ssh_config(5) for more information on patterns.
Optional. Type list of uniline.
Disables all forwarding features, including X11,
ssh-agent(1), TCP and
StreamLocal. This option overrides all other forwarding-related options and
may simplify restricted configurations.
Optional. Type uniline.
Writes a temporary file containing a list of authentication methods and public
credentials (e.g. keys) used to authenticate the user. The location of the
file is exposed to the user session through the SSH_USER_AUTH environment
variable. The default is
no.
Optional. Type boolean.
- upstream_default value :
- no
Forces the execution of the command specified by
ForceCommand, ignoring
any command supplied by the client and
~/.ssh/rc if present. The
command is invoked by using the user's login shell with the -c option. This
applies to shell, command, or subsystem execution. It is most useful inside a
Match block. The command originally supplied by the client is available
in the SSH_ORIGINAL_COMMAND environment variable. Specifying a command of
internal-sftp will force the use of an in-process SFTP server that
requires no support files when used with
ChrootDirectory. The default
is
none.
Optional. Type uniline.
- upstream_default value :
- none
Specifies whether remote hosts are allowed to connect to ports forwarded for the
client. By default,
sshd(8) binds remote port forwardings to the
loopback address. This prevents other remote hosts from connecting to
forwarded ports.
GatewayPorts can be used to specify that sshd should
allow remote port forwardings to bind to non-loopback addresses, thus allowing
other hosts to connect. The argument may be
no to force remote port
forwardings to be available to the local host only,
yes to force remote
port forwardings to bind to the wildcard address, or
clientspecified to
allow the client to select the address to which the forwarding is bound. The
default is
no.
Optional. Type enum. choice: 'no', 'yes',
'clientspecified'.
- upstream_default value :
- no
Specifies whether user authentication based on GSSAPI is allowed. The default is
no.
Optional. Type boolean.
- upstream_default value :
- no
Specifies the signature algorithms that will be accepted for hostbased
authentication as a list of comma-separated patterns. Alternately if the
specified list begins with a '+' character, then the specified signature
algorithms will be appended to the default set instead of replacing them. If
the specified list begins with a '-' character, then the specified signature
algorithms (including wildcards) will be removed from the default set instead
of replacing them. If the specified list begins with a '^' character, then the
specified signature algorithms will be placed at the head of the default set.
The default for this option is:
[email protected],
[email protected],
[email protected],
[email protected],
[email protected],
[email protected],
[email protected],
[email protected],
ssh-ed25519, ecdsa-sha2-nistp256, ecdsa-sha2-nistp384, ecdsa-sha2-nistp521,
[email protected],
[email protected], rsa-sha2-512,
rsa-sha2-256
The list of available signature algorithms may also be obtained using "ssh
-Q HostbasedAcceptedAlgorithms". This was formerly named
HostbasedAcceptedKeyTypes.
Optional. Type uniline.
Specifies whether rhosts or /etc/hosts.equiv authentication together with
successful public key client host authentication is allowed (host-based
authentication). The default is
no.
Optional. Type boolean.
- upstream_default value :
- no
Specifies whether or not the server will attempt to perform a reverse name
lookup when matching the name in the
~/.shosts,
~/.rhosts, and
/etc/hosts.equiv files during
HostbasedAuthentication. A setting
of
yes means that
sshd(8) uses the name supplied by the client
rather than attempting to resolve the name from the TCP connection itself. The
default is
no.
Optional. Type boolean.
- upstream_default value :
- no
Specifies whether to ignore per-user
.rhosts and
.shosts files
during
HostbasedAuthentication. The system-wide
/etc/hosts.equiv
and
/etc/ssh/shosts.equiv are still used regardless of this setting.
Accepted values are
yes (the default) to ignore all per-user files,
shosts-only to allow the use of
.shosts but to ignore
.rhosts or
no to allow both
.shosts and
rhosts.
Optional. Type boolean.
- upstream_default value :
- yes
Include the specified configuration file(s). Multiple pathnames may be specified
and each pathname may contain
glob(7) wildcards that will be expanded
and processed in lexical order. Files without absolute paths are assumed to be
in
/etc/ssh. An
Include directive may appear inside a
Match block to perform conditional inclusion.
Optional. Type list
of uniline.
Specifies the IPv4 type-of-service or DSCP class for the connection. Accepted
values are
af11,
af12,
af13,
af21,
af22,
af23,
af31,
af32,
af33,
af41,
af42,
af43,
cs0,
cs1,
cs2,
cs3,
cs4,
cs5,
cs6,
cs7,
ef,
le,
lowdelay,
throughput,
reliability, a numeric value, or
none to use
the operating system default. This option may take one or two arguments,
separated by whitespace. If one argument is specified, it is used as the
packet class unconditionally. If two values are specified, the first is
automatically selected for interactive sessions and the second for
non-interactive sessions. The default is
lowdelay for interactive
sessions and
throughput for non-interactive sessions.
Optional.
Type uniline.
- upstream_default value :
- af21 cs1
Specifies whether to allow keyboard-interactive authentication. The default is
yes. The argument to this keyword must be
yes or
no.
ChallengeResponseAuthentication is a deprecated alias for this.
Optional. Type boolean.
- upstream_default value :
- yes
Note: KbdInteractiveAuthentication is migrated with '$old' and with:
- •
- $old => "-
ChallengeResponseAuthentication"
Specifies whether the password provided by the user for
PasswordAuthentication will be validated through the Kerberos KDC. To
use this option, the server needs a Kerberos servtab which allows the
verification of the KDC's identity. The default is
no.
Optional.
Type boolean.
- upstream_default value :
- no
Gives the verbosity level that is used when logging messages from
sshd(8). The possible values are: QUIET, FATAL, ERROR, INFO, VERBOSE,
DEBUG, DEBUG1, DEBUG2, and DEBUG3. The default is INFO. DEBUG and DEBUG1 are
equivalent. DEBUG2 and DEBUG3 each specify higher levels of debugging output.
Logging with a DEBUG level violates the privacy of users and is not
recommended.
Optional. Type enum. choice: 'QUIET', 'FATAL', 'ERROR',
'INFO', 'VERBOSE', 'DEBUG', 'DEBUG1', 'DEBUG2', 'DEBUG3'.
- upstream_default value :
- INFO
Specifies the maximum number of authentication attempts permitted per
connection. Once the number of failures reaches half this value, additional
failures are logged. The default is 6.
Optional. Type integer.
- upstream_default value :
- 6
Specifies the maximum number of open shell, login or subsystem (e.g. sftp)
sessions permitted per network connection. Multiple sessions may be
established by clients that support connection multiplexing. Setting
MaxSessions to 1 will effectively disable session multiplexing, whereas
setting it to 0 will prevent all shell, login and subsystem sessions while
still permitting forwarding. The default is 10.
Optional. Type integer.
- upstream_default value :
- 10
Specifies whether password authentication is allowed. The default is
yes.
Optional. Type boolean.
- upstream_default value :
- yes
When password authentication is allowed, it specifies whether the server allows
login to accounts with empty password strings. The default is
no.
Optional. Type boolean.
- upstream_default value :
- no
Specifies the addresses/ports on which a remote TCP port forwarding may listen.
The listen specification must be one of the following forms:
PermitListenport PermitListen
host:
port
Multiple permissions may be specified by separating them with whitespace. An
argument of
any can be used to remove all restrictions and permit any
listen requests. An argument of
none can be used to prohibit all listen
requests. The host name may contain wildcards as described in the PATTERNS
section in
ssh_config(5). The wildcard '*' can also be used in place of
a port number to allow all ports. By default all port forwarding listen
requests are permitted. Note that the
GatewayPorts option may further
restrict which addresses may be listened on. Note also that
ssh(1) will
request a listen host of
localhost if no listen host was specifically
requested, and this name is treated differently to explicit localhost
addresses of X127.0.0.1X and X::1X.
Optional. Type list of uniline.
Specifies the destinations to which TCP port forwarding is permitted. The
forwarding specification must be one of the following forms:
PermitOpenhost:
port PermitOpen
IPv4_addr:
port PermitOpen
[IPv6_addr]:
port
Multiple forwards may be specified by separating them with whitespace. An
argument of
any can be used to remove all restrictions and permit any
forwarding requests. An argument of
none can be used to prohibit all
forwarding requests. The wildcard '*' can be used for host or port to allow
all hosts or ports respectively. Otherwise, no pattern matching or address
lookups are performed on supplied names. By default all port forwarding
requests are permitted.
Optional. Type list of uniline.
Specifies whether root can log in using
ssh(1). The argument must be
yes,
prohibit-password,
forced-commands-only, or
no. The default is
prohibit-password.
If this option is set to
prohibit-password (or its deprecated alias,
without-password), password and keyboard-interactive authentication are
disabled for root.
If this option is set to
forced-commands-only, root login with public key
authentication will be allowed, but only if the
command option has been
specified (which may be useful for taking remote backups even if root login is
normally not allowed). All other authentication methods are disabled for root.
If this option is set to
no, root is not allowed to log in.
Optional.
Type enum. choice: 'yes', 'prohibit-password', 'forced-commands-only', 'no'.
Specifies whether
pty(4) allocation is permitted. The default is
yes.
Optional. Type boolean.
- upstream_default value :
- yes
Specifies whether
tun(4) device forwarding is allowed. The argument must
be
yes,
point-to-point (layer 3),
ethernet (layer 2), or
no. Specifying
yes permits both
point-to-point and
ethernet. The default is
no.
Independent of this setting, the permissions of the selected
tun(4)
device must allow access to the user.
Optional. Type enum. choice: 'yes',
'point-to-point', 'ethernet', 'no'.
- upstream_default value :
- no
Specifies whether any
~/.ssh/rc file is executed. The default is
yes.
Optional. Type boolean.
- upstream_default value :
- yes
Specifies the signature algorithms that will be accepted for public key
authentication as a list of comma-separated patterns. Alternately if the
specified list begins with a '+' character, then the specified algorithms will
be appended to the default set instead of replacing them. If the specified
list begins with a '-' character, then the specified algorithms (including
wildcards) will be removed from the default set instead of replacing them. If
the specified list begins with a '^' character, then the specified algorithms
will be placed at the head of the default set. The default for this option is:
[email protected],
[email protected],
[email protected],
[email protected],
[email protected],
[email protected],
[email protected],
[email protected],
ssh-ed25519, ecdsa-sha2-nistp256, ecdsa-sha2-nistp384, ecdsa-sha2-nistp521,
[email protected],
[email protected], rsa-sha2-512,
rsa-sha2-256
The list of available signature algorithms may also be obtained using "ssh
-Q PubkeyAcceptedAlgorithms".
Optional. Type uniline.
Sets one or more public key authentication options. The supported keywords are:
none (the default; indicating no additional options are enabled),
touch-required and
verify-required.
The
touch-required option causes public key authentication using a FIDO
authenticator algorithm (i.e.
ecdsa-sk or
ed25519-sk) to always
require the signature to attest that a physically present user explicitly
confirmed the authentication (usually by touching the authenticator). By
default,
sshd(8) requires user presence unless overridden with an
authorized_keys option. The
touch-required flag disables this override.
The
verify-required option requires a FIDO key signature attest that the
user was verified, e.g. via a PIN.
Neither the
touch-required or
verify-required options have any
effect for other, non-FIDO, public key types.
Optional. Type enum. choice:
'none', 'touch-required', 'verify-required'.
Specifies whether public key authentication is allowed. The default is
yes.
Optional. Type boolean.
- upstream_default value :
- yes
Specifies the maximum amount of data that may be transmitted before the session
key is renegotiated, optionally followed by a maximum amount of time that may
pass before the session key is renegotiated. The first argument is specified
in bytes and may have a suffix of 'K', 'M', or 'G' to indicate Kilobytes,
Megabytes, or Gigabytes, respectively. The default is between '1G' and '4G',
depending on the cipher. The optional second value is specified in seconds and
may use any of the units documented in the
TIME FORMATS section.
The default value for
RekeyLimit is
default none, which means
that rekeying is performed after the cipher's default amount of data has been
sent or received and no time based rekeying is done.
Optional. Type
uniline.
Specifies revoked public keys file, or
none to not use one. Keys listed
in this file will be refused for public key authentication. Note that if this
file is not readable, then public key authentication will be refused for all
users. Keys may be specified as a text file, listing one public key per line,
or as an OpenSSH Key Revocation List (KRL) as generated by
ssh-keygen(1). For more information on KRLs, see the KEY REVOCATION
LISTS section in
ssh-keygen(1).
Optional. Type uniline.
Specifies one or more environment variables to set in child sessions started by
sshd(8) as XNAME=VALUEX. The environment value may be quoted (e.g. if
it contains whitespace characters). Environment variables set by
SetEnv
override the default environment and any variables specified by the user via
AcceptEnv or
PermitUserEnvironment.
Optional. Type uniline.
Sets the octal file creation mode mask (umask) used when creating a Unix-domain
socket file for local or remote port forwarding. This option is only used for
port forwarding to a Unix-domain socket file.
The default value is 0177, which creates a Unix-domain socket file that is
readable and writable only by the owner. Note that not all operating systems
honor the file mode on Unix-domain socket files.
Optional. Type uniline.
Specifies whether to remove an existing Unix-domain socket file for local or
remote port forwarding before creating a new one. If the socket file already
exists and
StreamLocalBindUnlink is not enabled,
sshd will be
unable to forward the port to the Unix-domain socket file. This option is only
used for port forwarding to a Unix-domain socket file.
The argument must be
yes or
no. The default is
no.
Optional. Type boolean.
- upstream_default value :
- no
Specifies a file containing public keys of certificate authorities that are
trusted to sign user certificates for authentication, or
none to not
use one. Keys are listed one per line; empty lines and comments starting with
'#' are allowed. If a certificate is presented for authentication and has its
signing CA key listed in this file, then it may be used for authentication for
any user listed in the certificate's principals list. Note that certificates
that lack a list of principals will not be permitted for authentication using
TrustedUserCAKeys. For more details on certificates, see the
CERTIFICATES section in
ssh-keygen(1).
Optional. Type uniline.
Specifies the first display number available for
sshd(8)'s X11
forwarding. This prevents sshd from interfering with real X11 servers. The
default is 10.
Optional. Type uniline.
Specifies whether X11 forwarding is permitted. The argument must be
yes
or
no. The default is
no.
When X11 forwarding is enabled, there may be additional exposure to the server
and to client displays if the
sshd(8) proxy display is configured to
listen on the wildcard address (see
X11UseLocalhost), though this is
not the default. Additionally, the authentication spoofing and authentication
data verification and substitution occur on the client side. The security risk
of using X11 forwarding is that the client's X11 display server may be exposed
to attack when the SSH client requests forwarding (see the warnings for
ForwardX11 in
ssh_config(5)). A system administrator may have a
stance in which they want to protect clients that may expose themselves to
attack by unwittingly requesting X11 forwarding, which can warrant a
no
setting.
Note that disabling X11 forwarding does not prevent users from forwarding X11
traffic, as users can always install their own forwarders.
Optional. Type
boolean.
- upstream_default value :
- no
Specifies whether
sshd(8) should bind the X11 forwarding server to the
loopback address or to the wildcard address. By default, sshd binds the
forwarding server to the loopback address and sets the hostname part of the
DISPLAY environment variable to
localhost. This prevents remote hosts
from connecting to the proxy display. However, some older X11 clients may not
function with this configuration.
X11UseLocalhost may be set to
no to specify that the forwarding server should be bound to the
wildcard address. The argument must be
yes or
no. The default is
yes.
Optional. Type boolean.
- upstream_default value :
- yes
This parameter is now ignored by Ssh.
Deprecated Optional. Type list
of uniline.
Deprecated Optional. Type boolean.
Deprecated Optional. Type uniline.
Deprecated Optional. Type uniline.
Deprecated Optional. Type uniline.
Deprecated Optional. Type uniline.
Deprecated Optional. Type uniline.
Deprecated Optional. Type uniline.
Specifies which address family should be used by
sshd(8). Valid arguments
are
any (the default),
inet (use IPv4 only), or
inet6
(use IPv6 only).
Optional. Type enum. choice: 'any', 'inet', 'inet6'.
- upstream_default value :
- any
Specifies the ciphers allowed. Multiple ciphers must be comma-separated. If the
specified list begins with a '+' character, then the specified ciphers will be
appended to the default set instead of replacing them. If the specified list
begins with a '-' character, then the specified ciphers (including wildcards)
will be removed from the default set instead of replacing them. If the
specified list begins with a '^' character, then the specified ciphers will be
placed at the head of the default set.
The supported ciphers are:
3des-cbc aes128-cbc aes192-cbc aes256-cbc aes128-ctr aes192-ctr aes256-ctr
[email protected] [email protected] [email protected]
The default is:
[email protected], aes128-ctr, aes192-ctr, aes256-ctr,
[email protected],
[email protected]
The list of available ciphers may also be obtained using "ssh -Q
cipher".
Optional. Type uniline.
Specifies whether compression is enabled after the user has authenticated
successfully. The argument must be
yes,
delayed (a legacy
synonym for
yes) or
no. The default is
yes.
Optional.
Type enum. choice: 'yes', 'delayed', 'no'.
- upstream_default value :
- yes
Specifies whether the distribution-specified extra version suffix is included
during initial protocol handshake. The default is
yes.
Optional.
Type boolean.
- upstream_default value :
- yes
Specifies the hash algorithm used when logging key fingerprints. Valid options
are:
md5 and
sha256. The default is
sha256.
Optional.
Type enum. choice: 'md5', 'sha256'.
- upstream_default value :
- sha256
Specifies whether to automatically destroy the user's credentials cache on
logout. The default is
yes.
Optional. Type boolean.
- upstream_default value :
- yes
Specifies whether key exchange based on GSSAPI is allowed. GSSAPI key exchange
doesn't rely on ssh keys to verify host identity. The default is
no.
Optional. Type boolean.
- upstream_default value :
- no
Determines whether to be strict about the identity of the GSSAPI acceptor a
client authenticates against. If set to
yes then the client must
authenticate against the host service on the current hostname. If set to
no then the client may authenticate against any service key stored in
the machine's default store. This facility is provided to assist with
operation on multi homed machines. The default is
yes.
Optional.
Type boolean.
- upstream_default value :
- yes
Controls whether the user's GSSAPI credentials should be updated following a
successful connection rekeying. This option can be used to accepted renewed or
updated credentials from a compatible client. The default is
no.
For this to work
GSSAPIKeyExchange needs to be enabled in the server and
also used by the client.
Optional. Type boolean.
- upstream_default value :
- no
The list of key exchange algorithms that are accepted by GSSAPI key exchange.
Possible values are
gss-gex-sha1-, gss-group1-sha1-, gss-group14-sha1-, gss-group14-sha256-,
gss-group16-sha512-, gss-nistp256-sha256-, gss-curve25519-sha256-
The default is Xgss-group14-sha256-, gss-group16-sha512-, gss-nistp256-sha256-,
gss-curve25519-sha256-, gss-gex-sha1-, gss-group14-sha1-X. This option only
applies to connections using GSSAPI.
Optional. Type uniline.
Specifies a file containing a public host certificate. The certificate's public
key must match a private host key already specified by
HostKey. The
default behaviour of
sshd(8) is not to load any certificates.
Optional. Type uniline.
Specifies a file containing a private host key used by SSH. The defaults are
/etc/ssh/ssh_host_ecdsa_key,
/etc/ssh/ssh_host_ed25519_key and
/etc/ssh/ssh_host_rsa_key.
Note that
sshd(8) will refuse to use a file if it is
group/world-accessible and that the
HostKeyAlgorithms option restricts
which of the keys are actually used by
sshd(8).
It is possible to have multiple host key files. It is also possible to specify
public host key files instead. In this case operations on the private key will
be delegated to an
ssh-agent(1).
Optional. Type uniline.
Identifies the UNIX-domain socket used to communicate with an agent that has
access to the private host keys. If the string "SSH_AUTH_SOCK" is
specified, the location of the socket will be read from the SSH_AUTH_SOCK
environment variable.
Optional. Type uniline.
Specifies the host key signature algorithms that the server offers. The default
for this option is:
[email protected],
[email protected],
[email protected],
[email protected],
[email protected],
[email protected],
[email protected],
[email protected],
ssh-ed25519, ecdsa-sha2-nistp256, ecdsa-sha2-nistp384, ecdsa-sha2-nistp521,
[email protected],
[email protected], rsa-sha2-512,
rsa-sha2-256
The list of available signature algorithms may also be obtained using "ssh
-Q HostKeyAlgorithms".
Optional. Type uniline.
Specifies whether
sshd(8) should ignore the user's
~/.ssh/known_hosts during
HostbasedAuthentication and use only
the system-wide known hosts file
/etc/ssh/known_hosts. The default is
no.
Optional. Type boolean.
- upstream_default value :
- no
If AFS is active and the user has a Kerberos 5 TGT, attempt to acquire an AFS
token before accessing the user's home directory. The default is
no.
Optional. Type boolean.
- upstream_default value :
- no
If password authentication through Kerberos fails then the password will be
validated via any additional local mechanism such as
/etc/passwd. The
default is
yes.
Optional. Type boolean.
- upstream_default value :
- yes
Specifies whether to automatically destroy the user's ticket cache file on
logout. The default is
yes.
Optional. Type boolean.
- upstream_default value :
- yes
Specifies the available KEX (Key Exchange) algorithms. Multiple algorithms must
be comma-separated. Alternately if the specified list begins with a '+'
character, then the specified algorithms will be appended to the default set
instead of replacing them. If the specified list begins with a '-' character,
then the specified algorithms (including wildcards) will be removed from the
default set instead of replacing them. If the specified list begins with a '^'
character, then the specified algorithms will be placed at the head of the
default set. The supported algorithms are:
curve25519-sha256
[email protected] diffie-hellman-group1-sha1
diffie-hellman-group14-sha1 diffie-hellman-group14-sha256
diffie-hellman-group16-sha512 diffie-hellman-group18-sha512
diffie-hellman-group-exchange-sha1 diffie-hellman-group-exchange-sha256
ecdh-sha2-nistp256 ecdh-sha2-nistp384 ecdh-sha2-nistp521
[email protected]
The default is:
[email protected], curve25519-sha256,
[email protected], 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
The list of available key exchange algorithms may also be obtained using
"ssh -Q KexAlgorithms".
Optional. Type uniline.
Specifies the local addresses
sshd(8) should listen on. The following
forms may be used:
ListenAddresshostname|
address ListenAddress
hostname:
port ListenAddress
IPv4_address:
port ListenAddress [
hostname|
address ]:
port
If
port is not specified, sshd will listen on the address and all
Port options specified. The default is to listen on all local
addresses. Multiple
ListenAddress options are permitted.
Optional.
Type uniline.
The server disconnects after this time if the user has not successfully logged
in. If the value is 0, there is no time limit. The default is 120 seconds.
Optional. Type uniline.
Specify one or more overrides to LogLevel. An override consists of a pattern
lists that matches the source file, function and line number to force detailed
logging for. For example, an override pattern of:
kex.c:*:1000,*:
kex_exchange_identification():*, packet.c:*
would enable detailed logging for line 1000 of
kex.c, everything in the
kex_exchange_identification() function, and all code in the
packet.c file. This option is intended for debugging and no overrides
are enabled by default.
Optional. Type uniline.
Specifies the available MAC (message authentication code) algorithms. The MAC
algorithm is used for data integrity protection. Multiple algorithms must be
comma-separated. If the specified list begins with a '+' character, then the
specified algorithms will be appended to the default set instead of replacing
them. If the specified list begins with a '-' character, then the specified
algorithms (including wildcards) will be removed from the default set instead
of replacing them. If the specified list begins with a '^' character, then the
specified algorithms will be placed at the head of the default set.
The algorithms that contain "-etm" calculate the MAC after encryption
(encrypt-then-mac). These are considered safer and their use recommended. The
supported MACs are:
hmac-md5 hmac-md5-96 hmac-sha1 hmac-sha1-96 hmac-sha2-256 hmac-sha2-512
[email protected] [email protected] [email protected]
[email protected] [email protected]
[email protected] [email protected]
[email protected] [email protected] [email protected]
The default is:
[email protected],
[email protected],
[email protected],
[email protected],
[email protected],
[email protected],
[email protected],
hmac-sha2-256, hmac-sha2-512, hmac-sha1
The list of available MAC algorithms may also be obtained using "ssh -Q
mac".
Optional. Type uniline.
Introduces a conditional block. If all of the criteria on the
Match line
are satisfied, the keywords on the following lines override those set in the
global section of the config file, until either another
Match line or
the end of the file. If a keyword appears in multiple
Match blocks that
are satisfied, only the first instance of the keyword is applied.
The arguments to
Match are one or more criteria-pattern pairs or the
single token
All which matches all criteria. The available criteria are
User,
Group,
Host,
LocalAddress,
LocalPort,
and
Address.
The match patterns may consist of single entries or comma-separated lists and
may use the wildcard and negation operators described in the
PATTERNS
section of
ssh_config(5).
The patterns in an
Address criteria may additionally contain addresses to
match in CIDR address/masklen format, such as 192.0.2.0/24 or 2001:db8::/32.
Note that the mask length provided must be consistent with the address - it is
an error to specify a mask length that is too long for the address or one with
bits set in this host portion of the address. For example, 192.0.2.0/33 and
192.0.2.0/8, respectively.
Only a subset of keywords may be used on the lines following a
Match
keyword. Available keywords are
AcceptEnv,
AllowAgentForwarding,
AllowGroups,
AllowStreamLocalForwarding,
AllowTcpForwarding,
AllowUsers,
AuthenticationMethods,
AuthorizedKeysCommand,
AuthorizedKeysCommandUser,
AuthorizedKeysFile,
AuthorizedPrincipalsCommand,
AuthorizedPrincipalsCommandUser,
AuthorizedPrincipalsFile,
Banner,
CASignatureAlgorithms,
ChrootDirectory,
ClientAliveCountMax,
ClientAliveInterval,
DenyGroups,
DenyUsers,
DisableForwarding,
ExposeAuthInfo,
ForceCommand,
GatewayPorts,
GSSAPIAuthentication,
HostbasedAcceptedAlgorithms,
HostbasedAuthentication,
HostbasedUsesNameFromPacketOnly,
IgnoreRhosts,
Include,
IPQoS,
KbdInteractiveAuthentication,
KerberosAuthentication,
LogLevel,
MaxAuthTries,
MaxSessions,
PasswordAuthentication,
PermitEmptyPasswords,
PermitListen,
PermitOpen,
PermitRootLogin,
PermitTTY,
PermitTunnel,
PermitUserRC,
PubkeyAcceptedAlgorithms,
PubkeyAuthentication,
PubkeyAuthOptions,
RekeyLimit,
RevokedKeys,
SetEnv,
StreamLocalBindMask,
StreamLocalBindUnlink,
TrustedUserCAKeys,
X11DisplayOffset,
X11Forwarding and
X11UseLocalhost.
Optional. Type list of node of class Sshd::MatchBlock .
Specifies the maximum number of concurrent unauthenticated connections to the
SSH daemon. Additional connections will be dropped until authentication
succeeds or the
LoginGraceTime expires for a connection. The default is
10:30:100.
Alternatively, random early drop can be enabled by specifying the three colon
separated values start:rate:full (e.g. "10:30:60").
sshd(8)
will refuse connection attempts with a probability of rate/100 (30%) if there
are currently start (10) unauthenticated connections. The probability
increases linearly and all connection attempts are refused if the number of
unauthenticated connections reaches full (60).
Optional. Type uniline.
- upstream_default value :
- 10
Specifies the
moduli(5) file that contains the Diffie-Hellman groups used
for the Xdiffie-hellman-group-exchange-sha1X and
Xdiffie-hellman-group-exchange-sha256X key exchange methods. The default is
/etc/ssh/moduli.
Optional. Type uniline.
- upstream_default value :
- /etc/ssh/moduli
Specifies whether
~/.ssh/environment and
environment= options in
~/.ssh/authorized_keys are processed by
sshd(8). Valid options
are
yes,
no or a pattern-list specifying which environment
variable names to accept (for example "LANG, LC_*"). The default is
no. Enabling environment processing may enable users to bypass access
restrictions in some configurations using mechanisms such as LD_PRELOAD.
Optional. Type boolean.
- upstream_default value :
- no
Specifies the number of unauthenticated connections allowed from a given source
address, or
none if there is no limit. This limit is applied in
addition to
MaxStartups, whichever is lower. The default is
none.
Optional. Type uniline.
- upstream_default value :
- none
Specifies the number of bits of source address that are grouped together for the
purposes of applying PerSourceMaxStartups limits. Values for IPv4 and
optionally IPv6 may be specified, separated by a colon. The default is
32:128, which means each address is considered individually.
Optional. Type uniline.
- upstream_default value :
- 32:128
Specifies the file that contains the process ID of the SSH daemon, or
none to not write one. The default is
/run/sshd.pid.
Optional. Type uniline.
Specifies the port number that
sshd(8) listens on. The default is 22.
Multiple options of this type are permitted. See also
ListenAddress.
Optional. Type uniline.
Specifies whether
sshd(8) should print the date and time of the last user
login when a user logs in interactively. The default is
yes.
Optional. Type boolean.
- upstream_default value :
- yes
Specifies whether
sshd(8) should print
/etc/motd when a user logs
in interactively. (On some systems it is also printed by the shell,
/etc/profile, or equivalent.) The default is
yes.
Optional.
Type boolean.
- upstream_default value :
- yes
Specifies a path to a library that will be used when loading FIDO
authenticator-hosted keys, overriding the default of using the built-in USB
HID support.
Optional. Type uniline.
Specifies whether
sshd(8) should check file modes and ownership of the
user's files and home directory before accepting login. This is normally
desirable because novices sometimes accidentally leave their directory or
files world-writable. The default is
yes. Note that this does not apply
to
ChrootDirectory, whose permissions and ownership are checked
unconditionally.
Optional. Type boolean.
- upstream_default value :
- yes
Configures an external subsystem (e.g. file transfer daemon). Arguments should
be a subsystem name and a command (with optional arguments) to execute upon
subsystem request.
The command
sftp-server implements the SFTP file transfer subsystem.
Alternately the name
internal-sftp implements an in-process SFTP server.
This may simplify configurations using
ChrootDirectory to force a
different filesystem root on clients.
By default no subsystems are defined.
Optional. Type hash of uniline.
Gives the facility code that is used when logging messages from
sshd(8).
The possible values are: DAEMON, USER, AUTH, LOCAL0, LOCAL1, LOCAL2, LOCAL3,
LOCAL4, LOCAL5, LOCAL6, LOCAL7. The default is AUTH.
Optional. Type enum.
choice: 'DAEMON', 'USER', 'AUTH', 'LOCAL0', 'LOCAL1', 'LOCAL2', 'LOCAL3',
'LOCAL4', 'LOCAL5', 'LOCAL6', 'LOCAL7'.
- upstream_default value :
- AUTH
Specifies whether the system should send TCP keepalive messages to the other
side. If they are sent, death of the connection or crash of one of the
machines will be properly noticed. However, this means that connections will
die if the route is down temporarily, and some people find it annoying. On the
other hand, if TCP keepalives are not sent, sessions may hang indefinitely on
the server, leaving "ghost" users and consuming server resources.
The default is
yes (to send TCP keepalive messages), and the server will
notice if the network goes down or the client host crashes. This avoids
infinitely hanging sessions.
To disable TCP keepalive messages, the value should be set to
no.
This option was formerly called
KeepAlive.
Optional. Type boolean.
- upstream_default value :
- yes
Specifies whether
sshd(8) should look up the remote host name, and to
check that the resolved host name for the remote IP address maps back to the
very same IP address.
If this option is set to
no (the default) then only addresses and not
host names may be used in
~/.ssh/authorized_keysfrom and
sshd_config Match Host directives.
Optional. Type boolean.
- upstream_default value :
- no
Enables the Pluggable Authentication Module interface. If set to
yes this
will enable PAM authentication using
KbdInteractiveAuthentication and
PasswordAuthentication in addition to PAM account and session module
processing for all authentication types.
Because PAM keyboard-interactive authentication usually serves an equivalent
role to password authentication, you should disable either
PasswordAuthentication or
KbdInteractiveAuthentication.
If
UsePAM is enabled, you will not be able to run
sshd(8) as a
non-root user. The default is
no.
Optional. Type boolean.
- upstream_default value :
- no
Optionally specifies additional text to append to the SSH protocol banner sent
by the server upon connection. The default is
none.
Optional. Type
uniline.
Specifies the full pathname of the
xauth(1) program, or
none to
not use one. The default is
/usr/bin/xauth.
Optional. Type uniline.
- upstream_default value :
- /usr/bin/xauth
- •
- cme
- •
- Config::Model::models::Sshd::MatchBlock
- LGPL2