Puppet Class: ssh::config

Defined in:
manifests/config.pp

Summary

Defines what is in the sshd_config, please note,this is using a restricted cipher, kexalgorithms and macs list and so consequently is less compatible with older ssh clients

Overview

Examples:

Simple class instantiation

class { 'ssh::config':
  allow_agent_forwarding = false,
}

Configuration using Hiera

ssh::config::compression: true
ssh::config::allow_users:
  - fred
  - jiminybob

Parameters:

  • accept_env (Array[String]) (defaults to: $::ssh::params::accept_env) —

    Specifies what environment variables sent by the client will be copied into the session's environ(7). See SendEnv in ssh_config(5) for how to configure the client. The TERM environment variable is always sent 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.

  • address_family (Enum['any','ipv4','ipv6']) (defaults to: $::ssh::params::address_family) —

    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).

  • allow_agent_forwarding (Boolean) (defaults to: $::ssh::params::allow_agent_forwarding) —

    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.

  • allow_groups (Array[String]) (defaults to: []) —

    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 sup‐ plementary 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.

  • allow_stream_local_forwarding (Boolean) (defaults to: $::ssh::params::allow_stream_local_forwarding) —

    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.

  • allow_tcp_forwarding (Boolean) (defaults to: $::ssh::params::allow_tcp_forwarding) —

    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.

  • allow_users (Array[String]) (defaults to: []) —

    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 directives are processed in the following order: DenyUsers, AllowUsers, DenyGroups, and finally AllowGroups.

  • banner (String) (defaults to: $::ssh::params::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.

  • challenge_response_authentication (Boolean) (defaults to: $::ssh::params::challenge_response_authentication) —

    Specifies whether challenge-response authentication is allowed (e.g. via PAM). The default is yes.

  • chroot_directory (String) (defaults to: $::ssh::params::chroot_directory) —

    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.

  • ciphers (Array[String]) (defaults to: $::ssh::params::ciphers) —

    Specifies the ciphers allowed. Multiple ciphers must be comma-separated. If the specified value begins with a ‘+’ character, then the specified ciphers will be appended to the default set instead of replacing them. If the specified value begins with a ‘-’ character, then the specified ciphers (including wildcards) will be removed from the default set instead of replacing them. The list of available ciphers may also be obtained using “ssh -Q cipher”.

  • client_alive_count_max (Numeric) (defaults to: $::ssh::params::client_alive_count_max) —

    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 inactive.

  • client_alive_count_interval (Numeric) (defaults to: $::ssh::params::client_alive_count_interval) —

    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.

  • compression (Boolean) (defaults to: $::ssh::params::compression) —

    Specifies whether compression is enabled after the user has authenticated successfully. The argument must be yes, delayed (a legacy synonym for yes) or no.

  • debian_banner (Boolean) (defaults to: $::ssh::params::debian_banner) —

    Specifies whether the distribution-specified extra version suffix is included during initial protocol handshake.

  • deny_groups (Array[String]) (defaults to: []) —

    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.

  • deny_users (Array[String]) (defaults to: []) —

    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 directives are processed in the following order: DenyUsers, AllowUsers, DenyGroups, and finally AllowGroups.#

  • disable_forwarding (Boolean) (defaults to: $::ssh::params::disable_forwarding) —

    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.

  • fingerprint_hash (Enum['sha256','md5']) (defaults to: $::ssh::params::fingerprint_hash) —

    Specifies the hash algorithm used when logging key fingerprints. Valid options are: md5 and sha256. The default is sha256.

  • ignore_rhosts (Boolean) (defaults to: $::ssh::params::ignore_rhosts) —

    Specifies that .rhosts and .shosts files will not be used in HostbasedAuthentication. /etc/hosts.equiv and /etc/ssh/shosts.equiv are still used.

  • gssapi_authentication (Boolean) (defaults to: $::ssh::params::gssapi_authentication) —

    Specifies whether user authentication based on GSSAPI is allowed.

  • kex_algorithms (Array[String]) (defaults to: $::ssh::params::kex_algorithms) —

    Specifies the available KEX (Key Exchange) algorithms. Multiple algorithms must be comma-separated. Alternately if the specified value begins with a ‘+’ char‐ acter, then the specified methods will be appended to the default set instead of replacing them. If the specified value begins with a ‘-’ character, then the specified methods (including wildcards) will be removed from the default set instead of replacing them. The list of available key exchange algorithms may also be obtained using “ssh -Q kex”.

  • listen_addresses (Array[String]) (defaults to: $::ssh::params::listen_addresses) —

    Specifies the local addresses sshd(8) should listen on. The following forms may be used: ListenAddress host|IPv4_addr|IPv6_addr ListenAddress host|IPv4_addr:port ListenAddress [host|IPv6_addr]: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.

  • login_grace_time (Numeric) (defaults to: $::ssh::params::login_grace_time) —

    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.

  • log_level (Enum['INFO','VERBOSE',"DEBUG',"]) (defaults to: $::ssh::params::log_level) —

    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.

  • macs (Array[String]) (defaults to: $::ssh::params::macs) —

    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 value begins with a ‘+’ character, then the specified algorithms will be appended to the default set instead of replacing them. If the specified value begins with a ‘-’ character, then the specified algorithms (including wildcards) will be removed from the default set instead of replacing them. 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 umac-64@openssh.com umac-128@openssh.com hmac-md5-etm@openssh.com hmac-md5-96-etm@openssh.com hmac-sha1-etm@openssh.com hmac-sha1-96-etm@openssh.com hmac-sha2-256-etm@openssh.com hmac-sha2-512-etm@openssh.com umac-64-etm@openssh.com umac-128-etm@openssh.com The list of available MAC algorithms may also be obtained using “ssh -Q mac”.

  • gssapi_cleanup_credentials (Boolean) (defaults to: $::ssh::params::gssapi_cleanup_credentials) —

    Specifies whether to automatically destroy the user's credentials cache on logout.

  • max_auth_tries (Numeric) (defaults to: $::ssh::params::max_auth_tries) —

    Specifies the maximum number of authentication attempts permitted per connection. Once the number of failures reaches half this value, additional failures are logged.

  • max_sessions (Numeric) (defaults to: $::ssh::params::max_sessions) —

    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.

  • max_startups —

    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 connec‐ tion 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).

  • password_authentication (Boolean) (defaults to: $::ssh::params::password_authentication) —

    Specifies whether password authentication is allowed.

  • permit_empty_passwords (Boolean) (defaults to: $::ssh::params::permit_empty_passwords) —

    When password authentication is allowed, it specifies whether the server allows login to accounts with empty password strings.

  • permit_open (Array[String]) (defaults to: $::ssh::params::permit_open) —

    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. By default all port forwarding requests are permitted.

  • permit_root_login (Enum['yes','no','without-password']) (defaults to: $::ssh::params::permit_root_login) —

    Specifies whether root can log in using ssh(1). The argument must be yes, prohibit-password, without-password, forced-commands-only, or no. The default is prohibit-password. If this option is set to prohibit-password or 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.

  • permit_tty (Boolean) (defaults to: $::ssh::params::permit_tty) —

    Specifies whether pty(4) allocation is permitted. The default is yes.

  • permit_tunnel (Boolean) (defaults to: $::ssh::params::permit_tunnel) —

    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.

  • port (Array[Numeric]) (defaults to: $::ssh::params::port) —

    Specifies the port number that sshd(8) listens on. The default is 22. Multiple options of this type are permitted. See also ListenAddress.

  • print_motd (Boolean) (defaults to: $::ssh::params::print_motd) —

    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 equiva‐ lent.)

  • tcp_keepalive (Boolean) (defaults to: $::ssh::params::tcp_keepalive) —

    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.

  • pubkey_authentication (Boolean) (defaults to: $::ssh::params::pubkey_authentication) —

    Specifies whether public key authentication is allowed.

  • use_dns (Boolean) (defaults to: $::ssh::params::use_dns) —

    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_keys from and sshd_config Match Host direc‐ tives.

  • use_pam (Boolean) (defaults to: $::ssh::params::use_pam) —

    Enables the Pluggable Authentication Module interface. If set to yes this will enable PAM authentication using ChallengeResponseAuthentication and PasswordAuthentication in addition to PAM account and session module processing for all authentication types. Because PAM challenge-response authentication usually serves an equivalent role to password authentication, you should disable either PasswordAuthentication or ChallengeResponseAuthentication. If UsePAM is enabled, you will not be able to run sshd(8) as a non-root user.

  • strict_modes (Boolean) (defaults to: $::ssh::params::strict_modes) —

    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.

  • x11_forwarding (Boolean) (defaults to: $::ssh::params::x11_forwarding) —

    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.

  • x11_use_localhost (Boolean) (defaults to: $::ssh::params::x11_use_localhost) —

    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.

  • protocol (Numeric) (defaults to: $::ssh::params::protocol)
  • host_keys (Array[String]) (defaults to: $::ssh::params::host_keys)
  • syslog_facility (String) (defaults to: $::ssh::params::syslog_facility)
  • rsa_authentication (Boolean) (defaults to: $::ssh::params::rsa_authentication)
  • authorized_keys_file (String) (defaults to: $::ssh::params::authorized_keys_file)
  • ignore_user_known_hosts (Boolean) (defaults to: $::ssh::params::ignore_user_known_hosts)
  • permit_user_environment (Boolean) (defaults to: $::ssh::params::permit_user_environment)
  • authentication_methods (Array[String]) (defaults to: []) 


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# File 'manifests/config.pp', line 220

class ssh::config (
  Array[Numeric] $port = $::ssh::params::port,
  Numeric $protocol = $::ssh::params::protocol,
  Array[String] $host_keys = $::ssh::params::host_keys,
  Array[String] $listen_addresses = $::ssh::params::listen_addresses,
  Enum['any','ipv4','ipv6'] $address_family = $::ssh::params::address_family,
  String $syslog_facility = $::ssh::params::syslog_facility,
  Enum['INFO','VERBOSE',"DEBUG',"] $log_level = $::ssh::params::log_level,
  Numeric $login_grace_time = $::ssh::params::login_grace_time,
  Enum['yes','no','without-password'] $permit_root_login = $::ssh::params::permit_root_login,
  Boolean $strict_modes = $::ssh::params::strict_modes,
  Boolean $pubkey_authentication = $::ssh::params::pubkey_authentication,
  Boolean $rsa_authentication = $::ssh::params::rsa_authentication,
  String $authorized_keys_file = $::ssh::params::authorized_keys_file,
  Boolean $password_authentication = $::ssh::params::password_authentication,
  Boolean $ignore_user_known_hosts = $::ssh::params::ignore_user_known_hosts,
  Boolean $permit_empty_passwords = $::ssh::params::permit_empty_passwords,
  Boolean $permit_tty = $::ssh::params::permit_tty,
  Array[String] $permit_open = $::ssh::params::permit_open,
  Boolean $challenge_response_authentication = $::ssh::params::challenge_response_authentication,
  Boolean $gssapi_authentication = $::ssh::params::gssapi_authentication,
  Boolean $gssapi_cleanup_credentials = $::ssh::params::gssapi_cleanup_credentials,
  Boolean $use_dns = $::ssh::params::use_dns,
  Boolean $use_pam = $::ssh::params::use_pam,
  Boolean $allow_agent_forwarding = $::ssh::params::allow_agent_forwarding,
  Boolean $allow_tcp_forwarding = $::ssh::params::allow_tcp_forwarding,
  Boolean $x11_forwarding = $::ssh::params::x11_forwarding,
  Boolean $x11_use_localhost = $::ssh::params::x11_use_localhost,
  Boolean $permit_user_environment = $::ssh::params::permit_user_environment,
  Boolean $print_motd = $::ssh::params::print_motd,
  Boolean $tcp_keepalive = $::ssh::params::tcp_keepalive,
  Boolean $compression = $::ssh::params::compression,
  Boolean $allow_stream_local_forwarding = $::ssh::params::allow_stream_local_forwarding,
  Numeric $client_alive_count_interval = $::ssh::params::client_alive_count_interval,
  Numeric $client_alive_count_max = $::ssh::params::client_alive_count_max,
  String $chroot_directory = $::ssh::params::chroot_directory,
  Boolean $permit_tunnel = $::ssh::params::permit_tunnel,
  Numeric $max_auth_tries = $::ssh::params::max_auth_tries,
  Numeric $max_sessions = $::ssh::params::max_sessions,
  String $banner = $::ssh::params::banner,
  Array[String] $kex_algorithms = $::ssh::params::kex_algorithms,
  Array[String] $ciphers = $::ssh::params::ciphers,
  Array[String] $macs = $::ssh::params::macs,
  Array[String] $allow_users = [],
  Array[String] $allow_groups = [],
  Array[String] $deny_users = [],
  Array[String] $deny_groups = [],
  Array[String] $authentication_methods = [],
  Array[String] $accept_env = $::ssh::params::accept_env,
  Boolean $debian_banner = $::ssh::params::debian_banner,
  Enum['sha256','md5'] $fingerprint_hash = $::ssh::params::fingerprint_hash,
  Boolean $disable_forwarding = $::ssh::params::disable_forwarding,
  Boolean $ignore_rhosts = $::ssh::params::ignore_rhosts,
){
  file { '/etc/ssh/sshd_config':
    ensure  => present,
    mode    => '0640',
    owner   => 'root',
    group   => 'root',
    notify  => Exec['sshd config test'],
    content => template('ssh/sshd_config.erb'),
  }

  exec { 'sshd config test':
    command => 'sshd -T',
    path    => ['/usr/sbin', '/usr/bin',],
  }
}