376 lines
11 KiB
Nix
376 lines
11 KiB
Nix
{ config, lib, pkgs, ... }:
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with lib;
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let
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cfg = config.services.openssh;
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cfgc = config.programs.ssh;
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nssModulesPath = config.system.nssModules.path;
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userOptions = {
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openssh.authorizedKeys = {
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keys = mkOption {
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type = types.listOf types.str;
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default = [];
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description = ''
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A list of verbatim OpenSSH public keys that should be added to the
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user's authorized keys. The keys are added to a file that the SSH
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daemon reads in addition to the the user's authorized_keys file.
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You can combine the <literal>keys</literal> and
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<literal>keyFiles</literal> options.
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Warning: If you are using <literal>NixOps</literal> then don't use this
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option since it will replace the key required for deployment via ssh.
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'';
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};
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keyFiles = mkOption {
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type = types.listOf types.path;
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default = [];
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description = ''
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A list of files each containing one OpenSSH public key that should be
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added to the user's authorized keys. The contents of the files are
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read at build time and added to a file that the SSH daemon reads in
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addition to the the user's authorized_keys file. You can combine the
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<literal>keyFiles</literal> and <literal>keys</literal> options.
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'';
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};
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};
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};
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authKeysFiles = let
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mkAuthKeyFile = u: nameValuePair "ssh/authorized_keys.d/${u.name}" {
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mode = "0444";
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source = pkgs.writeText "${u.name}-authorized_keys" ''
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${concatStringsSep "\n" u.openssh.authorizedKeys.keys}
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${concatMapStrings (f: readFile f + "\n") u.openssh.authorizedKeys.keyFiles}
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'';
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};
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usersWithKeys = attrValues (flip filterAttrs config.users.extraUsers (n: u:
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length u.openssh.authorizedKeys.keys != 0 || length u.openssh.authorizedKeys.keyFiles != 0
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));
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in listToAttrs (map mkAuthKeyFile usersWithKeys);
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supportOldHostKeys = !versionAtLeast config.system.stateVersion "15.07";
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in
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{
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###### interface
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options = {
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services.openssh = {
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enable = mkOption {
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type = types.bool;
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default = false;
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description = ''
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Whether to enable the OpenSSH secure shell daemon, which
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allows secure remote logins.
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'';
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};
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startWhenNeeded = mkOption {
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type = types.bool;
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default = false;
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description = ''
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If set, <command>sshd</command> is socket-activated; that
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is, instead of having it permanently running as a daemon,
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systemd will start an instance for each incoming connection.
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'';
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};
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forwardX11 = mkOption {
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type = types.bool;
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default = false;
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description = ''
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Whether to allow X11 connections to be forwarded.
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'';
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};
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allowSFTP = mkOption {
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type = types.bool;
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default = true;
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description = ''
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Whether to enable the SFTP subsystem in the SSH daemon. This
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enables the use of commands such as <command>sftp</command> and
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<command>sshfs</command>.
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'';
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};
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permitRootLogin = mkOption {
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default = "prohibit-password";
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type = types.enum ["yes" "without-password" "prohibit-password" "forced-commands-only" "no"];
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description = ''
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Whether the root user can login using ssh.
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'';
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};
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gatewayPorts = mkOption {
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type = types.str;
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default = "no";
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description = ''
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Specifies whether remote hosts are allowed to connect to
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ports forwarded for the client. See
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<citerefentry><refentrytitle>sshd_config</refentrytitle>
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<manvolnum>5</manvolnum></citerefentry>.
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'';
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};
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ports = mkOption {
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type = types.listOf types.int;
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default = [22];
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description = ''
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Specifies on which ports the SSH daemon listens.
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'';
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};
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listenAddresses = mkOption {
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type = with types; listOf (submodule {
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options = {
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addr = mkOption {
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type = types.nullOr types.str;
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default = null;
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description = ''
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Host, IPv4 or IPv6 address to listen to.
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'';
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};
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port = mkOption {
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type = types.nullOr types.int;
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default = null;
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description = ''
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Port to listen to.
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'';
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};
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};
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});
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default = [];
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example = [ { addr = "192.168.3.1"; port = 22; } { addr = "0.0.0.0"; port = 64022; } ];
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description = ''
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List of addresses and ports to listen on (ListenAddress directive
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in config). If port is not specified for address sshd will listen
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on all ports specified by <literal>ports</literal> option.
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NOTE: this will override default listening on all local addresses and port 22.
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NOTE: setting this option won't automatically enable given ports
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in firewall configuration.
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'';
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};
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passwordAuthentication = mkOption {
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type = types.bool;
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default = true;
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description = ''
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Specifies whether password authentication is allowed.
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'';
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};
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challengeResponseAuthentication = mkOption {
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type = types.bool;
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default = true;
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description = ''
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Specifies whether challenge/response authentication is allowed.
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'';
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};
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hostKeys = mkOption {
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type = types.listOf types.attrs;
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default =
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[ { type = "rsa"; bits = 4096; path = "/etc/ssh/ssh_host_rsa_key"; }
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{ type = "ed25519"; path = "/etc/ssh/ssh_host_ed25519_key"; }
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] ++ optionals supportOldHostKeys
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[ { type = "dsa"; path = "/etc/ssh/ssh_host_dsa_key"; }
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{ type = "ecdsa"; bits = 521; path = "/etc/ssh/ssh_host_ecdsa_key"; }
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];
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description = ''
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NixOS can automatically generate SSH host keys. This option
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specifies the path, type and size of each key. See
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<citerefentry><refentrytitle>ssh-keygen</refentrytitle>
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<manvolnum>1</manvolnum></citerefentry> for supported types
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and sizes.
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'';
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};
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authorizedKeysFiles = mkOption {
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type = types.listOf types.str;
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default = [];
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description = "Files from which authorized keys are read.";
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};
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extraConfig = mkOption {
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type = types.lines;
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default = "";
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description = "Verbatim contents of <filename>sshd_config</filename>.";
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};
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moduliFile = mkOption {
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example = "services.openssh.moduliFile = /etc/my-local-ssh-moduli;";
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type = types.path;
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description = ''
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Path to <literal>moduli</literal> file to install in
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<literal>/etc/ssh/moduli</literal>. If this option is unset, then
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the <literal>moduli</literal> file shipped with OpenSSH will be used.
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'';
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};
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};
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users.users = mkOption {
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options = [ userOptions ];
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};
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};
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###### implementation
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config = mkIf cfg.enable {
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users.extraUsers.sshd =
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{ isSystemUser = true;
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description = "SSH privilege separation user";
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};
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services.openssh.moduliFile = mkDefault "${cfgc.package}/etc/ssh/moduli";
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environment.etc = authKeysFiles //
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{ "ssh/moduli".source = cfg.moduliFile; };
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systemd =
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let
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service =
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{ description = "SSH Daemon";
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wantedBy = optional (!cfg.startWhenNeeded) "multi-user.target";
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stopIfChanged = false;
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path = [ cfgc.package pkgs.gawk ];
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environment.LD_LIBRARY_PATH = nssModulesPath;
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preStart =
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''
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# Make sure we don't write to stdout, since in case of
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# socket activation, it goes to the remote side (#19589).
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exec >&2
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mkdir -m 0755 -p /etc/ssh
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${flip concatMapStrings cfg.hostKeys (k: ''
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if ! [ -f "${k.path}" ]; then
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ssh-keygen -t "${k.type}" ${if k ? bits then "-b ${toString k.bits}" else ""} -f "${k.path}" -N ""
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fi
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'')}
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'';
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serviceConfig =
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{ ExecStart =
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(optionalString cfg.startWhenNeeded "-") +
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"${cfgc.package}/bin/sshd " + (optionalString cfg.startWhenNeeded "-i ") +
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"-f ${pkgs.writeText "sshd_config" cfg.extraConfig}";
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KillMode = "process";
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} // (if cfg.startWhenNeeded then {
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StandardInput = "socket";
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StandardError = "journal";
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} else {
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Restart = "always";
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Type = "simple";
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});
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};
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in
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if cfg.startWhenNeeded then {
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sockets.sshd =
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{ description = "SSH Socket";
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wantedBy = [ "sockets.target" ];
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socketConfig.ListenStream = cfg.ports;
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socketConfig.Accept = true;
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};
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services."sshd@" = service;
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} else {
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services.sshd = service;
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};
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networking.firewall.allowedTCPPorts = cfg.ports;
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security.pam.services.sshd =
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{ startSession = true;
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showMotd = true;
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unixAuth = cfg.passwordAuthentication;
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};
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services.openssh.authorizedKeysFiles =
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[ ".ssh/authorized_keys" ".ssh/authorized_keys2" "/etc/ssh/authorized_keys.d/%u" ];
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services.openssh.extraConfig = mkOrder 0
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''
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Protocol 2
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UsePAM yes
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AddressFamily ${if config.networking.enableIPv6 then "any" else "inet"}
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${concatMapStrings (port: ''
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Port ${toString port}
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'') cfg.ports}
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${concatMapStrings ({ port, addr, ... }: ''
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ListenAddress ${addr}${if port != null then ":" + toString port else ""}
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'') cfg.listenAddresses}
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${optionalString cfgc.setXAuthLocation ''
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XAuthLocation ${pkgs.xorg.xauth}/bin/xauth
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''}
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${if cfg.forwardX11 then ''
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X11Forwarding yes
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'' else ''
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X11Forwarding no
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''}
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${optionalString cfg.allowSFTP ''
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Subsystem sftp ${cfgc.package}/libexec/sftp-server
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''}
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PermitRootLogin ${cfg.permitRootLogin}
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GatewayPorts ${cfg.gatewayPorts}
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PasswordAuthentication ${if cfg.passwordAuthentication then "yes" else "no"}
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ChallengeResponseAuthentication ${if cfg.challengeResponseAuthentication then "yes" else "no"}
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PrintMotd no # handled by pam_motd
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AuthorizedKeysFile ${toString cfg.authorizedKeysFiles}
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${flip concatMapStrings cfg.hostKeys (k: ''
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HostKey ${k.path}
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'')}
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# Allow DSA client keys for now. (These were deprecated
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# in OpenSSH 7.0.)
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PubkeyAcceptedKeyTypes +ssh-dss
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# Re-enable DSA host keys for now.
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${optionalString supportOldHostKeys ''
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HostKeyAlgorithms +ssh-dss
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''}
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'';
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assertions = [{ assertion = if cfg.forwardX11 then cfgc.setXAuthLocation else true;
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message = "cannot enable X11 forwarding without setting xauth location";}]
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++ flip map cfg.listenAddresses ({ addr, port, ... }: {
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assertion = addr != null;
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message = "addr must be specified in each listenAddresses entry";
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});
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};
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}
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