Provided by: libconfig-model-openssh-perl_1.232-1_all 
NAME
Config::Model::models::Sshd::MatchElement - Configuration class Sshd::MatchElement
DESCRIPTION
Configuration classes used by Config::Model
Configuration class that represents all parameters available inside a Match block of a
sshd configuration.
Elements
AcceptEnv
Specifies what environment variables sent by the client will be copied into the session's
environ(7).Optional. Type list of uniline.
AllowAgentForwarding
Specifies whether ssh-agent(1) forwarding is permitted. 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: '1'.
AllowGroups
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 directives are processed in
the following order: DenyUsers, AllowUsers, DenyGroups, and finally AllowGroups.Optional.
Type list of uniline.
AllowUsers
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. The allow/deny directives are processed in the following
order: DenyUsers, AllowUsers, DenyGroups, and finally AllowGroups.Optional. Type list of
uniline.
AuthenticationMethods - authentication methods that must be successfully completed for a user
to be granted access
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 comma-separated lists of
authentication method names. Successful authentication requires completion of every method
in at least one of these lists.
For example, an argument of "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", "pam",
or "skey", depending on the server configuration. For example,
"keyboard-interactive:bsdauth" would restrict keyboard interactive authentication to the
"bsdauth" device.
This option is only available for SSH protocol 2 and will yield a fatal error if enabled
if protocol 1 is also enabled. Note that each authentication method listed should also be
explicitly enabled in the configuration. The default is not to require multiple
authentication; successful completion of a single authentication method is
sufficient.Optional. Type uniline.
AuthorizedKeysCommand - program to be used to look up the user's public keys
Specifies a program to be used to look up the user's public keys. The program must be
owned by root and not writable by group or others. It will be invoked with a single
argument of the username being authenticated, and should produce on standard output zero
or more lines of authorized_keys output (see AUTHORIZED_KEYS in sshd(8)). If a key
supplied by AuthorizedKeysCommand does not successfully authenticate and authorize the
user then public key authentication continues using the usual AuthorizedKeysFile files. By
default, no AuthorizedKeysCommand is run.Optional. Type uniline.
AuthorizedKeysCommandUser - user under whose account the AuthorizedKeysCommand is run
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.Optional. Type uniline.
AllowTcpForwarding
Specifies whether TCP forwarding is permitted. The default is "yes".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: 'no', 'yes'.
upstream_default: 'yes'.
AuthorizedKeysFile2
Specifies the file that contains the public keys that can be used for user authentication.
AuthorizedKeysFile may contain tokens of the form %T which are substituted during
connection setup.Deprecated Optional. Type list of uniline.
AuthorizedKeysFile
Specifies the file that contains the public keys that can be used for user authentication.
The format is described in the AUTHORIZED_KEYS FILE FORMAT section of sshd(8).
AuthorizedKeysFile may contain tokens of the form %T which are substituted during
connection setup. The following tokens are defined: %% is replaced by a literal '%', %h is
replaced by the home directory of the user being authenticated, and %u is replaced by the
username of that user. 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. The default is ".ssh/authorized_keys .ssh/authorized_keys2".Optional. Type
list of uniline.
Note: AuthorizedKeysFile values are migrated from '- AuthorizedKeysFile2'
AuthorizedPrincipalsFile - file that lists principal names that are accepted for certificate
authentication
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.
AuthorizedPrincipalsFile may contain tokens of the form %T which are substituted during
connection setup. The following tokens are defined: %% is replaced by a literal '%', %h is
replaced by the home directory of the user being authenticated, and %u is replaced by the
username of that user. 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.
Banner
In some jurisdictions, sending a warning message before authentication may be relevant for
getting legal protection. The contents of the specified file are sent to the remote user
before authentication is allowed. This option is only available for protocol version 2. By
default, no banner is displayed.Optional. Type uniline.
ChrootDirectory - pathname of a directory to chroot to after authentication
Specifies the pathname of a directory to chroot(2) to after authentication. All
components of the pathname must be root owned directories that are not writable by any
other user or group. After the chroot, sshd(8) changes the working directory to the
user's home directory.
The pathname may contain the following tokens that are expanded at runtime once the
connecting user has been authenticated: %% is replaced by a literal '%', %h is replaced by
the home directory of the user being authenticated, and %u is replaced by the username of
that user.
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), arandom(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 do require /dev/log inside the chroot directory (see sftp-server(8) for
details).
The default is not to chroot(2).Optional. Type uniline.
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 directives are processed in the following
order: DenyUsers, AllowUsers, DenyGroups, and finally AllowGroups.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. The allow/deny directives are processed
in the following order: DenyUsers, AllowUsers, DenyGroups, and finally
AllowGroups.Optional. Type list of uniline.
ForceCommand
Forces the execution of the command specified by ForceCommand, ignoring any command
supplied by the client. 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.Optional. Type uniline.
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.Optional. Type enum. choice: 'yes', 'clientspecified',
'no'. upstream_default: 'no'.
Here are some explanations on the possible values:
'clientspecified'
allow the client to select the address to which the forwarding is bound
'no'
No port forwarding
'yes'
force remote port forwardings to bind to the wildcard address
GSSAPIAuthentication
Specifies whether user authentication based on GSSAPI is allowed. Note that this option
applies to protocol version 2 only.Optional. Type enum. choice: 'no', 'yes'.
upstream_default: 'no'.
HostbasedAuthentication
Specifies whether rhosts or /etc/hosts.equiv authentication together with successful
public key client host authentication is allowed (host-based authentication). This option
is similar to RhostsRSAAuthentication and applies to protocol version 2 only.Optional.
Type enum. choice: 'no', 'yes'. upstream_default: '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.Optional. Type enum. choice: 'no', 'yes'. upstream_default: 'no'.
Here are some explanations on the possible values:
'no'
sshd(8) attempts to resolve the name from the TCP connection itself.
'yes'
sshd(8) uses the name supplied by the client
KbdInteractiveAuthentication
No doc found in sshd documentation. Optional. Type enum. choice: 'no', 'yes'.
upstream_default: 'no'.
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 enum. choice: 'no', 'yes'. upstream_default: 'no'.
MaxAuthTries
Specifies the maximum number of authentication attempts permitted per connection. Once the
number of failures reaches half this value, additional failures are logged.Optional. Type
integer. upstream_default: '6'.
MaxSessions - Specifies the maximum number of open sessions permitted per network connection
Optional. Type integer. upstream_default: '10'.
PasswordAuthentication
Specifies whether password authentication is allowed.Optional. Type enum. choice: 'no',
'yes'. upstream_default: '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 enum. choice:
'no', 'yes'. upstream_default: 'no'.
Here are some explanations on the possible values:
'yes'
So, you want your machine to be part of a botnet ? ;-)
PermitOpen
Specifies the destinations to which TCP port forwarding is permitted. The forwarding
specification must be one of the following forms: "host:port" or "IPv4_addr:port" or
"[IPv6_addr]:port". An argument of "any" can be used to remove all restrictions and permit
any forwarding requests. By default all port forwarding requests are permitted.Optional.
Type list of uniline.
PermitRootLogin
Specifies whether root can log in using ssh(1).Optional. Type enum. choice: 'yes',
'without-password', 'forced-commands-only', 'no'. upstream_default: 'yes'.
Here are some explanations on the possible values:
'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.
'no'
root is not allowed to log in
'without-password'
password authentication is disabled for root
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".Optional. Type enum. choice: 'yes', 'point-to-point', 'ethernet',
'no'. upstream_default: 'no'.
Here are some explanations on the possible values:
'yes'
permits both "point-to-point" and "ethernet"
PubkeyAuthentication
Specifies whether public key authentication is allowed. The default is "yes". Note that
this option applies to protocol version 2 only.Optional. Type enum. choice: 'no', 'yes'.
upstream_default: 'yes'.
RekeyLimit
Specifies the maximum amount of data that may be transmitted before the session key is
renegotiated, optionally followed 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. This option applies to protocol version 2 only.Optional. Type
uniline. upstream_default: 'default none'.
RhostsRSAAuthentication
Specifies whether rhosts or /etc/hosts.equiv authentication together with successful RSA
host authentication is allowed. The default is "no". This option applies to protocol
version 1 only.Optional. Type enum. choice: 'no', 'yes'. upstream_default: 'no'.
RSAAuthentication
Specifies whether pure RSA authentication is allowed. This option applies to protocol
version 1 only.Optional. Type enum. choice: 'no', 'yes'. upstream_default: 'yes'.
X11DisplayOffset
Specifies the first display number available for sshd(8)'s X11 forwarding. This prevents
sshd from interfering with real X11 servers.Optional. Type integer. upstream_default:
'10'.
X11Forwarding
Specifies whether X11 forwarding is permitted. Note that disabling X11 forwarding does not
prevent users from forwarding X11 traffic, as users can always install their own
forwarders. X11 forwarding is automatically disabled if UseLogin is enabled.Optional. Type
enum. choice: 'yes', 'no'. upstream_default: '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.Optional. Type
enum. choice: 'yes', 'no'. upstream_default: 'yes'.
SEE ALSO
• cme
AUTHOR
Dominique Dumont
COPYRIGHT
2009-2011 Dominique Dumont
LICENSE
LGPL2
perl v5.18.1 2013-12Config::Model::models::Sshd::MatchElement(3pm)