Provided by: libconfig-model-openssh-perl_2.9.4.1-1_all 
NAME
Config::Model::models::Sshd::MatchElement - Configuration class Sshd::MatchElement
DESCRIPTION
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>
Elements
AcceptEnv
Specifies what environment variables sent by the client will be copied into the session's
environ(7). See SendEnv and SetEnv in ssh_config5 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.
AllowAgentForwarding
Specifies whether ssh-agent1 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
AllowGroups
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_config5 for more information on patterns. This keyword may appear
multiple times in sshd_config with each instance appending to the list. Optional. Type
list of uniline.
AllowStreamLocalForwarding
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: 'all', 'local', 'no',
'remote', 'yes'.
upstream_default value :
yes
AllowTcpForwarding
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: 'all', 'local', 'no', 'remote', 'yes'.
upstream_default value :
yes
AllowUsers
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_config5 for more information on patterns. This keyword may appear
multiple times in sshd_config with each instance appending to the list. Optional. Type
list of uniline.
AuthenticationMethods
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, Qq 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, Qq 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, Qq
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: Qq gssapi-with-mic , Qq hostbased , Qq keyboard-
interactive , Qq none (used for access to password-less accounts when PermitEmptyPasswords
is enabled), Qq password and Qq publickey . Optional. Type uniline.
AuthorizedKeysCommand
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.
AuthorizedKeysCommandUser
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.
AuthorizedKeysFile
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 Qq
.ssh/authorized_keys .ssh/authorized_keys2 . Optional. Type list of uniline.
Note: AuthorizedKeysFile values are migrated from '- AuthorizedKeysFile2'
AuthorizedPrincipalsCommand
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.
AuthorizedPrincipalsCommandUser
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.
AuthorizedPrincipalsFile
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 - 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
Banner
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.
CASignatureAlgorithms
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, sk-ssh-ed25519@openssh.com, sk-ecdsa-sha2-nistp256@openssh.com,
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.
ChannelTimeout
Specifies whether and how quickly sshd(8) should close inactive channels. Timeouts are
specified as one or more ''type=interval'' pairs separated by whitespace, where the
''type'' must be a channel type name (as described in the table below), optionally
containing wildcard characters.
The timeout value ''interval'' is specified in seconds or may use any of the units
documented in the TIME FORMATS section. For example, ''session:*=5m'' would cause all
sessions to terminate after five minutes of inactivity. Specifying a zero value disables
the inactivity timeout.
The available channel types include:
agent-connection Open connections to ssh-agent1. direct-tcpip ,
direct-streamlocal@openssh.com Open TCP or Unix socket (respectively) connections that
have been established from a ssh(1) local forwarding, i.e. LocalForward or DynamicForward
forwarded-tcpip , forwarded-streamlocal@openssh.com Open TCP or Unix socket (respectively)
connections that have been established to a sshd(8) listening on behalf of a ssh(1) remote
forwarding, i.e. RemoteForward session:command Command execution sessions. session:shell
Interactive shell sessions. session:subsystem:... Subsystem sessions, e.g. for sftp(1),
which could be identified as session:subsystem:sftp x11-connection Open X11 forwarding
sessions.
Note that in all the above cases, terminating an inactive session does not guarantee to
remove all resources associated with the session, e.g. shell processes or X11 clients
relating to the session may continue to execute.
Moreover, terminating an inactive channel or session does not necessarily close the SSH
connection, nor does it prevent a client from requesting another channel of the same type.
In particular, expiring an inactive forwarding session does not prevent another identical
forwarding from being subsequently created. See also UnusedConnectionTimeout which may be
used in conjunction with this option.
The default is not to expire channels of any type for inactivity. Optional. Type uniline.
ChrootDirectory
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-server8 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
ClientAliveCountMax
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
ClientAliveInterval
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
DenyGroups
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_config5 for more information on patterns. This keyword may appear
multiple times in sshd_config with each instance appending to the list. Optional. Type
list of uniline.
DenyUsers
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_config5 for more information on patterns. This keyword may appear
multiple times in sshd_config with each instance appending to the list. Optional. Type
list of uniline.
DisableForwarding
Disables all forwarding features, including X11, ssh-agent1, TCP and StreamLocal. This
option overrides all other forwarding-related options and may simplify restricted
configurations. Optional. Type uniline.
ExposeAuthInfo
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
ForceCommand
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
GatewayPorts
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:
'clientspecified', 'no', 'yes'.
upstream_default value :
no
GSSAPIAuthentication
Specifies whether user authentication based on GSSAPI is allowed. The default is no
Optional. Type boolean.
upstream_default value :
no
HostbasedAcceptedAlgorithms
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: ssh-ed25519-cert-v01@openssh.com,
ecdsa-sha2-nistp256-cert-v01@openssh.com, ecdsa-sha2-nistp384-cert-v01@openssh.com,
ecdsa-sha2-nistp521-cert-v01@openssh.com, sk-ssh-ed25519-cert-v01@openssh.com,
sk-ecdsa-sha2-nistp256-cert-v01@openssh.com, rsa-sha2-512-cert-v01@openssh.com,
rsa-sha2-256-cert-v01@openssh.com, ssh-ed25519, ecdsa-sha2-nistp256, ecdsa-sha2-nistp384,
ecdsa-sha2-nistp521, sk-ssh-ed25519@openssh.com, sk-ecdsa-sha2-nistp256@openssh.com,
rsa-sha2-512, rsa-sha2-256
The list of available signature algorithms may also be obtained using Qq ssh -Q
HostbasedAcceptedAlgorithms . This was formerly named HostbasedAcceptedKeyTypes.
Optional. Type uniline.
HostbasedAuthentication
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
HostbasedUsesNameFromPacketOnly
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
IgnoreRhosts
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
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.
IPQoS
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
KbdInteractiveAuthentication
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"
KerberosAuthentication
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
LogLevel
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: 'DEBUG', 'DEBUG1', 'DEBUG2', 'DEBUG3',
'ERROR', 'FATAL', 'INFO', 'QUIET', 'VERBOSE'.
upstream_default value :
INFO
MaxAuthTries
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
MaxSessions
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
PasswordAuthentication
Specifies whether password authentication is allowed. The default is yes Optional. Type
boolean.
upstream_default value :
yes
PermitEmptyPasswords
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
PermitListen
Specifies the addresses/ports on which a remote TCP port forwarding may listen. The
listen specification must be one of the following forms:
PermitListen port 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_config5. 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 ''127.0.0.1'' and ''::1'' Optional. Type list of uniline.
PermitOpen
Specifies the destinations to which TCP port forwarding is permitted. The forwarding
specification must be one of the following forms:
PermitOpen host : 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.
PermitRootLogin
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:
'forced-commands-only', 'no', 'prohibit-password', 'yes'.
PermitTTY
Specifies whether pty(4) allocation is permitted. The default is yes Optional. Type
boolean.
upstream_default value :
yes
PermitTunnel
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: 'ethernet', 'no', 'point-to-point',
'yes'.
upstream_default value :
no
PermitUserRC
Specifies whether any ~/.ssh/rc file is executed. The default is yes Optional. Type
boolean.
upstream_default value :
yes
PubkeyAcceptedAlgorithms
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:
ssh-ed25519-cert-v01@openssh.com, ecdsa-sha2-nistp256-cert-v01@openssh.com,
ecdsa-sha2-nistp384-cert-v01@openssh.com, ecdsa-sha2-nistp521-cert-v01@openssh.com,
sk-ssh-ed25519-cert-v01@openssh.com, sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,
rsa-sha2-512-cert-v01@openssh.com, rsa-sha2-256-cert-v01@openssh.com, ssh-ed25519,
ecdsa-sha2-nistp256, ecdsa-sha2-nistp384, ecdsa-sha2-nistp521, sk-ssh-ed25519@openssh.com,
sk-ecdsa-sha2-nistp256@openssh.com, rsa-sha2-512, rsa-sha2-256
The list of available signature algorithms may also be obtained using Qq ssh -Q
PubkeyAcceptedAlgorithms . Optional. Type uniline.
PubkeyAuthOptions
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'.
PubkeyAuthentication
Specifies whether public key authentication is allowed. The default is yes Optional. Type
boolean.
upstream_default value :
yes
RekeyLimit
Specifies the maximum amount of data that may be transmitted or received 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.
RevokedKeys
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-keygen1. For more information on KRLs, see the KEY REVOCATION LISTS
section in ssh-keygen1. Optional. Type uniline.
SetEnv
Specifies one or more environment variables to set in child sessions started by sshd(8) as
''NAME=VALUE'' 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.
StreamLocalBindMask
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.
StreamLocalBindUnlink
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
TrustedUserCAKeys
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-keygen1. Optional. Type uniline.
UnusedConnectionTimeout
Specifies whether and how quickly sshd(8) should close client connections with no open
channels. Open channels include active shell, command execution or subsystem sessions,
connected network, socket, agent or X11 forwardings. Forwarding listeners, such as those
from the ssh(1) -R flag, are not considered as open channels and do not prevent the
timeout. The timeout value is specified in seconds or may use any of the units documented
in the TIME FORMATS section.
Note that this timeout starts when the client connection completes user authentication but
before the client has an opportunity to open any channels. Caution should be used when
using short timeout values, as they may not provide sufficient time for the client to
request and open its channels before terminating the connection.
The default none is to never expire connections for having no open channels. This option
may be useful in conjunction with ChannelTimeout Optional. Type uniline.
X11DisplayOffset
Specifies the first display number available for sshd(8)Ns's X11 forwarding. This
prevents sshd from interfering with real X11 servers. The default is 10. Optional. Type
uniline.
X11Forwarding
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_config5). 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
X11UseLocalhost
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
AuthorizedKeysFile2
This parameter is now ignored by Ssh. Deprecated Optional. Type list of uniline.
ChallengeResponseAuthentication
Deprecated Optional. Type boolean.
KeyRegenerationInterval
Deprecated Optional. Type uniline.
Protocol
Deprecated Optional. Type uniline.
RDomain
Deprecated Optional. Type uniline.
RSAAuthentication
Deprecated Optional. Type uniline.
RhostsRSAAuthentication
Deprecated Optional. Type uniline.
UsePrivilegeSeparation
Deprecated Optional. Type uniline.
SEE ALSO
• cme
LICENSE
LGPL2
perl v5.36.0 2023-10Config::Model::models::Sshd::MatchElement(3pm)