gnu/services/ssh.scm

   1 ;;; GNU Guix --- Functional package management for GNU
   2 ;;; Copyright © 2014, 2015, 2016, 2017, 2018, 2019 Ludovic Courtès <ludo@gnu.org>
   3 ;;; Copyright © 2016 David Craven <david@craven.ch>
   4 ;;; Copyright © 2016 Julien Lepiller <julien@lepiller.eu>
   5 ;;; Copyright © 2017 Clément Lassieur <clement@lassieur.org>
   6 ;;; Copyright © 2019 Ricardo Wurmus <rekado@elephly.net>
   7 ;;;
   8 ;;; This file is part of GNU Guix.
   9 ;;;
  10 ;;; GNU Guix is free software; you can redistribute it and/or modify it
  11 ;;; under the terms of the GNU General Public License as published by
  12 ;;; the Free Software Foundation; either version 3 of the License, or (at
  13 ;;; your option) any later version.
  14 ;;;
  15 ;;; GNU Guix is distributed in the hope that it will be useful, but
  16 ;;; WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;;; GNU General Public License for more details.
  19 ;;;
  20 ;;; You should have received a copy of the GNU General Public License
  21 ;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
  22
  23 (define-module (gnu services ssh)
  24   #:use-module (gnu packages ssh)
  25   #:use-module (gnu packages admin)
  26   #:use-module (gnu services)
  27   #:use-module (gnu services shepherd)
  28   #:use-module (gnu system pam)
  29   #:use-module (gnu system shadow)
  30   #:use-module (guix gexp)
  31   #:use-module (guix records)
  32   #:use-module (guix modules)
  33   #:use-module (srfi srfi-1)
  34   #:use-module (srfi srfi-26)
  35   #:use-module (ice-9 match)
  36   #:export (lsh-configuration
  37             lsh-configuration?
  38             lsh-service
  39             lsh-service-type
  40
  41             openssh-configuration
  42             openssh-configuration?
  43             openssh-service-type
  44
  45             dropbear-configuration
  46             dropbear-configuration?
  47             dropbear-service-type
  48             dropbear-service))
  49
  50 ;;; Commentary:
  51 ;;;
  52 ;;; This module implements secure shell (SSH) services.
  53 ;;;
  54 ;;; Code:
  55
  56 (define-record-type* <lsh-configuration>
  57   lsh-configuration make-lsh-configuration
  58   lsh-configuration?
  59   (lsh lsh-configuration-lsh
  60        (default lsh))
  61   (daemonic? lsh-configuration-daemonic?)
  62   (host-key lsh-configuration-host-key)
  63   (interfaces lsh-configuration-interfaces)
  64   (port-number lsh-configuration-port-number)
  65   (allow-empty-passwords? lsh-configuration-allow-empty-passwords?)
  66   (root-login? lsh-configuration-root-login?)
  67   (syslog-output? lsh-configuration-syslog-output?)
  68   (pid-file? lsh-configuration-pid-file?)
  69   (pid-file lsh-configuration-pid-file)
  70   (x11-forwarding? lsh-configuration-x11-forwarding?)
  71   (tcp/ip-forwarding? lsh-configuration-tcp/ip-forwarding?)
  72   (password-authentication? lsh-configuration-password-authentication?)
  73   (public-key-authentication? lsh-configuration-public-key-authentication?)
  74   (initialize? lsh-configuration-initialize?))
  75
  76 (define %yarrow-seed
  77   "/var/spool/lsh/yarrow-seed-file")
  78
  79 (define (lsh-initialization lsh host-key)
  80   "Return the gexp to initialize the LSH service for HOST-KEY."
  81   #~(begin
  82       (unless (file-exists? #$%yarrow-seed)
  83         (system* (string-append #$lsh "/bin/lsh-make-seed")
  84                  "--sloppy" "-o" #$%yarrow-seed))
  85
  86       (unless (file-exists? #$host-key)
  87         (mkdir-p (dirname #$host-key))
  88         (format #t "creating SSH host key '~a'...~%" #$host-key)
  89
  90         ;; FIXME: We're just doing a simple pipeline, but 'system' cannot be
  91         ;; used yet because /bin/sh might be dangling; factorize this somehow.
  92         (let* ((in+out (pipe))
  93                (keygen (primitive-fork)))
  94           (case keygen
  95             ((0)
  96              (close-port (car in+out))
  97              (close-fdes 1)
  98              (dup2 (fileno (cdr in+out)) 1)
  99              (execl (string-append #$lsh "/bin/lsh-keygen")
 100                     "lsh-keygen" "--server"))
 101             (else
 102              (let ((write-key (primitive-fork)))
 103                (case write-key
 104                  ((0)
 105                   (close-port (cdr in+out))
 106                   (close-fdes 0)
 107                   (dup2 (fileno (car in+out)) 0)
 108                   (execl (string-append #$lsh "/bin/lsh-writekey")
 109                          "lsh-writekey" "--server" "-o" #$host-key))
 110                  (else
 111                   (close-port (car in+out))
 112                   (close-port (cdr in+out))
 113                   (waitpid keygen)
 114                   (waitpid write-key))))))))))
 115
 116 (define (lsh-activation config)
 117   "Return the activation gexp for CONFIG."
 118   #~(begin
 119       (use-modules (guix build utils))
 120       (mkdir-p "/var/spool/lsh")
 121       #$(if (lsh-configuration-initialize? config)
 122             (lsh-initialization (lsh-configuration-lsh config)
 123                                 (lsh-configuration-host-key config))
 124             #t)))
 125
 126 (define (lsh-shepherd-service config)
 127   "Return a <shepherd-service> for lsh with CONFIG."
 128   (define lsh (lsh-configuration-lsh config))
 129   (define pid-file (lsh-configuration-pid-file config))
 130   (define pid-file? (lsh-configuration-pid-file? config))
 131   (define daemonic? (lsh-configuration-daemonic? config))
 132   (define interfaces (lsh-configuration-interfaces config))
 133
 134   (define lsh-command
 135     (append
 136      (cons (file-append lsh "/sbin/lshd")
 137            (if daemonic?
 138                (let ((syslog (if (lsh-configuration-syslog-output? config)
 139                                  '()
 140                                  (list "--no-syslog"))))
 141                  (cons "--daemonic"
 142                        (if pid-file?
 143                            (cons #~(string-append "--pid-file=" #$pid-file)
 144                                  syslog)
 145                            (cons "--no-pid-file" syslog))))
 146                (if pid-file?
 147                    (list #~(string-append "--pid-file=" #$pid-file))
 148                    '())))
 149      (cons* #~(string-append "--host-key="
 150                              #$(lsh-configuration-host-key config))
 151             #~(string-append "--password-helper=" #$lsh "/sbin/lsh-pam-checkpw")
 152             #~(string-append "--subsystems=sftp=" #$lsh "/sbin/sftp-server")
 153             "-p" (number->string (lsh-configuration-port-number config))
 154             (if (lsh-configuration-password-authentication? config)
 155                 "--password" "--no-password")
 156             (if (lsh-configuration-public-key-authentication? config)
 157                 "--publickey" "--no-publickey")
 158             (if (lsh-configuration-root-login? config)
 159                 "--root-login" "--no-root-login")
 160             (if (lsh-configuration-x11-forwarding? config)
 161                 "--x11-forward" "--no-x11-forward")
 162             (if (lsh-configuration-tcp/ip-forwarding? config)
 163                 "--tcpip-forward" "--no-tcpip-forward")
 164             (if (null? interfaces)
 165                 '()
 166                 (map (cut string-append "--interface=" <>)
 167                      interfaces)))))
 168
 169   (define requires
 170     (if (and daemonic? (lsh-configuration-syslog-output? config))
 171         '(networking syslogd)
 172         '(networking)))
 173
 174   (list (shepherd-service
 175          (documentation "GNU lsh SSH server")
 176          (provision '(ssh-daemon ssh sshd))
 177          (requirement requires)
 178          (start #~(make-forkexec-constructor (list #$@lsh-command)))
 179          (stop  #~(make-kill-destructor)))))
 180
 181 (define (lsh-pam-services config)
 182   "Return a list of <pam-services> for lshd with CONFIG."
 183   (list (unix-pam-service
 184          "lshd"
 185          #:login-uid? #t
 186          #:allow-empty-passwords?
 187          (lsh-configuration-allow-empty-passwords? config))))
 188
 189 (define lsh-service-type
 190   (service-type (name 'lsh)
 191                 (description
 192                  "Run the GNU@tie{}lsh secure shell (SSH) daemon,
 193 @command{lshd}.")
 194                 (extensions
 195                  (list (service-extension shepherd-root-service-type
 196                                           lsh-shepherd-service)
 197                        (service-extension pam-root-service-type
 198                                           lsh-pam-services)
 199                        (service-extension activation-service-type
 200                                           lsh-activation)))))
 201
 202 (define* (lsh-service #:key
 203                       (lsh lsh)
 204                       (daemonic? #t)
 205                       (host-key "/etc/lsh/host-key")
 206                       (interfaces '())
 207                       (port-number 22)
 208                       (allow-empty-passwords? #f)
 209                       (root-login? #f)
 210                       (syslog-output? #t)
 211                       (pid-file? #f)
 212                       (pid-file "/var/run/lshd.pid")
 213                       (x11-forwarding? #t)
 214                       (tcp/ip-forwarding? #t)
 215                       (password-authentication? #t)
 216                       (public-key-authentication? #t)
 217                       (initialize? #t))
 218   "Run the @command{lshd} program from @var{lsh} to listen on port @var{port-number}.
 219 @var{host-key} must designate a file containing the host key, and readable
 220 only by root.
 221
 222 When @var{daemonic?} is true, @command{lshd} will detach from the
 223 controlling terminal and log its output to syslogd, unless one sets
 224 @var{syslog-output?} to false.  Obviously, it also makes lsh-service
 225 depend on existence of syslogd service.  When @var{pid-file?} is true,
 226 @command{lshd} writes its PID to the file called @var{pid-file}.
 227
 228 When @var{initialize?} is true, automatically create the seed and host key
 229 upon service activation if they do not exist yet.  This may take long and
 230 require interaction.
 231
 232 When @var{initialize?} is false, it is up to the user to initialize the
 233 randomness generator (@pxref{lsh-make-seed,,, lsh, LSH Manual}), and to create
 234 a key pair with the private key stored in file @var{host-key} (@pxref{lshd
 235 basics,,, lsh, LSH Manual}).
 236
 237 When @var{interfaces} is empty, lshd listens for connections on all the
 238 network interfaces; otherwise, @var{interfaces} must be a list of host names
 239 or addresses.
 240
 241 @var{allow-empty-passwords?} specifies whether to accept log-ins with empty
 242 passwords, and @var{root-login?} specifies whether to accept log-ins as
 243 root.
 244
 245 The other options should be self-descriptive."
 246   (service lsh-service-type
 247            (lsh-configuration (lsh lsh) (daemonic? daemonic?)
 248                               (host-key host-key) (interfaces interfaces)
 249                               (port-number port-number)
 250                               (allow-empty-passwords? allow-empty-passwords?)
 251                               (root-login? root-login?)
 252                               (syslog-output? syslog-output?)
 253                               (pid-file? pid-file?) (pid-file pid-file)
 254                               (x11-forwarding? x11-forwarding?)
 255                               (tcp/ip-forwarding? tcp/ip-forwarding?)
 256                               (password-authentication?
 257                                password-authentication?)
 258                               (public-key-authentication?
 259                                public-key-authentication?)
 260                               (initialize? initialize?))))
 261
 262 \f
 263 ;;;
 264 ;;; OpenSSH.
 265 ;;;
 266
 267 (define-record-type* <openssh-configuration>
 268   openssh-configuration make-openssh-configuration
 269   openssh-configuration?
 270   ;; <package>
 271   (openssh               openssh-configuration-openssh
 272                          (default openssh))
 273   ;; string
 274   (pid-file              openssh-configuration-pid-file
 275                          (default "/var/run/sshd.pid"))
 276   ;; integer
 277   (port-number           openssh-configuration-port-number
 278                          (default 22))
 279   ;; Boolean | 'without-password
 280   (permit-root-login     openssh-configuration-permit-root-login
 281                          (default #f))
 282   ;; Boolean
 283   (allow-empty-passwords? openssh-configuration-allow-empty-passwords?
 284                           (default #f))
 285   ;; Boolean
 286   (password-authentication? openssh-configuration-password-authentication?
 287                             (default #t))
 288   ;; Boolean
 289   (public-key-authentication? openssh-configuration-public-key-authentication?
 290                               (default #t))
 291   ;; Boolean
 292   (x11-forwarding?       openssh-configuration-x11-forwarding?
 293                          (default #f))
 294
 295   ;; Boolean
 296   (allow-agent-forwarding? openssh-configuration-allow-agent-forwarding?
 297                            (default #t))
 298
 299   ;; Boolean
 300   (allow-tcp-forwarding? openssh-configuration-allow-tcp-forwarding?
 301                          (default #t))
 302
 303   ;; Boolean
 304   (gateway-ports? openssh-configuration-gateway-ports?
 305                          (default #f))
 306
 307   ;; Boolean
 308   (challenge-response-authentication? openssh-challenge-response-authentication?
 309                                       (default #f))
 310   ;; Boolean
 311   (use-pam?              openssh-configuration-use-pam?
 312                          (default #t))
 313   ;; Boolean
 314   (print-last-log?       openssh-configuration-print-last-log?
 315                          (default #t))
 316   ;; list of two-element lists
 317   (subsystems            openssh-configuration-subsystems
 318                          (default '(("sftp" "internal-sftp"))))
 319
 320   ;; list of strings
 321   (accepted-environment  openssh-configuration-accepted-environment
 322                          (default '()))
 323
 324   ;; symbol
 325   (log-level             openssh-configuration-log-level
 326                          (default 'info))
 327
 328   ;; String
 329   ;; This is an "escape hatch" to provide configuration that isn't yet
 330   ;; supported by this configuration record.
 331   (extra-content         openssh-configuration-extra-content
 332                          (default ""))
 333
 334   ;; list of user-name/file-like tuples
 335   (authorized-keys       openssh-authorized-keys
 336                          (default '()))
 337
 338   ;; Boolean
 339   ;; XXX: This should really be handled in an orthogonal way, for instance as
 340   ;; proposed in <https://bugs.gnu.org/27155>.  Keep it internal/undocumented
 341   ;; for now.
 342   (%auto-start?          openssh-auto-start?
 343                          (default #t)))
 344
 345 (define %openssh-accounts
 346   (list (user-group (name "sshd") (system? #t))
 347         (user-account
 348           (name "sshd")
 349           (group "sshd")
 350           (system? #t)
 351           (comment "sshd privilege separation user")
 352           (home-directory "/var/run/sshd")
 353           (shell (file-append shadow "/sbin/nologin")))))
 354
 355 (define (openssh-activation config)
 356   "Return the activation GEXP for CONFIG."
 357   (with-imported-modules '((guix build utils))
 358     #~(begin
 359         (use-modules (guix build utils))
 360
 361         (define (touch file-name)
 362           (call-with-output-file file-name (const #t)))
 363
 364         ;; Make sure /etc/ssh can be read by the 'sshd' user.
 365         (mkdir-p "/etc/ssh")
 366         (chmod "/etc/ssh" #o755)
 367         (mkdir-p (dirname #$(openssh-configuration-pid-file config)))
 368
 369         ;; 'sshd' complains if the authorized-key directory and its parents
 370         ;; are group-writable, which rules out /gnu/store.  Thus we copy the
 371         ;; authorized-key directory to /etc.
 372         (catch 'system-error
 373           (lambda ()
 374             (delete-file-recursively "/etc/authorized_keys.d"))
 375           (lambda args
 376             (unless (= ENOENT (system-error-errno args))
 377               (apply throw args))))
 378         (copy-recursively #$(authorized-key-directory
 379                              (openssh-authorized-keys config))
 380                           "/etc/ssh/authorized_keys.d")
 381
 382         (chmod "/etc/ssh/authorized_keys.d" #o555)
 383
 384         (let ((lastlog "/var/log/lastlog"))
 385           (when #$(openssh-configuration-print-last-log? config)
 386             (unless (file-exists? lastlog)
 387               (touch lastlog))))
 388
 389         ;; Generate missing host keys.
 390         (system* (string-append #$(openssh-configuration-openssh config)
 391                                 "/bin/ssh-keygen") "-A"))))
 392
 393 (define (authorized-key-directory keys)
 394   "Return a directory containing the authorized keys specified in KEYS, a list
 395 of user-name/file-like tuples."
 396   (define build
 397     (with-imported-modules (source-module-closure '((guix build utils)))
 398       #~(begin
 399           (use-modules (ice-9 match) (srfi srfi-26)
 400                        (guix build utils))
 401
 402           (mkdir #$output)
 403           (for-each (match-lambda
 404                       ((user keys ...)
 405                        (let ((file (string-append #$output "/" user)))
 406                          (call-with-output-file file
 407                            (lambda (port)
 408                              (for-each (lambda (key)
 409                                          (call-with-input-file key
 410                                            (cut dump-port <> port)))
 411                                        keys))))))
 412                     '#$keys))))
 413
 414   (computed-file "openssh-authorized-keys" build))
 415
 416 (define (openssh-config-file config)
 417   "Return the sshd configuration file corresponding to CONFIG."
 418   (computed-file
 419    "sshd_config"
 420    #~(begin
 421        (use-modules (ice-9 match))
 422        (call-with-output-file #$output
 423          (lambda (port)
 424            (display "# Generated by 'openssh-service'.\n" port)
 425            (format port "Port ~a\n"
 426                    #$(number->string
 427                       (openssh-configuration-port-number config)))
 428            (format port "PermitRootLogin ~a\n"
 429                    #$(match (openssh-configuration-permit-root-login config)
 430                        (#t "yes")
 431                        (#f "no")
 432                        ('without-password "without-password")))
 433            (format port "PermitEmptyPasswords ~a\n"
 434                    #$(if (openssh-configuration-allow-empty-passwords? config)
 435                          "yes" "no"))
 436            (format port "PasswordAuthentication ~a\n"
 437                    #$(if (openssh-configuration-password-authentication? config)
 438                          "yes" "no"))
 439            (format port "PubkeyAuthentication ~a\n"
 440                    #$(if (openssh-configuration-public-key-authentication?
 441                           config)
 442                          "yes" "no"))
 443            (format port "X11Forwarding ~a\n"
 444                    #$(if (openssh-configuration-x11-forwarding? config)
 445                          "yes" "no"))
 446            (format port "AllowAgentForwarding ~a\n"
 447                    #$(if (openssh-configuration-allow-agent-forwarding? config)
 448                          "yes" "no"))
 449            (format port "AllowTcpForwarding ~a\n"
 450                    #$(if (openssh-configuration-allow-tcp-forwarding? config)
 451                          "yes" "no"))
 452            (format port "GatewayPorts ~a\n"
 453                    #$(if (openssh-configuration-gateway-ports? config)
 454                          "yes" "no"))
 455            (format port "PidFile ~a\n"
 456                    #$(openssh-configuration-pid-file config))
 457            (format port "ChallengeResponseAuthentication ~a\n"
 458                    #$(if (openssh-challenge-response-authentication? config)
 459                          "yes" "no"))
 460            (format port "UsePAM ~a\n"
 461                    #$(if (openssh-configuration-use-pam? config)
 462                          "yes" "no"))
 463            (format port "PrintLastLog ~a\n"
 464                    #$(if (openssh-configuration-print-last-log? config)
 465                          "yes" "no"))
 466            (format port "LogLevel ~a\n"
 467                    #$(string-upcase
 468                       (symbol->string
 469                        (openssh-configuration-log-level config))))
 470
 471            ;; Add '/etc/authorized_keys.d/%u', which we populate.
 472            (format port "AuthorizedKeysFile \
 473  .ssh/authorized_keys .ssh/authorized_keys2 /etc/ssh/authorized_keys.d/%u\n")
 474
 475            (for-each (lambda (s) (format port "AcceptEnv ~a\n" s))
 476                      '#$(openssh-configuration-accepted-environment config))
 477
 478            (for-each
 479             (match-lambda
 480               ((name command) (format port "Subsystem\t~a\t~a\n" name command)))
 481             '#$(openssh-configuration-subsystems config))
 482
 483            (format port "~a\n"
 484                    #$(openssh-configuration-extra-content config))
 485            #t)))))
 486
 487 (define (openssh-shepherd-service config)
 488   "Return a <shepherd-service> for openssh with CONFIG."
 489
 490   (define pid-file
 491     (openssh-configuration-pid-file config))
 492
 493   (define openssh-command
 494     #~(list (string-append #$(openssh-configuration-openssh config) "/sbin/sshd")
 495             "-D" "-f" #$(openssh-config-file config)))
 496
 497   (list (shepherd-service
 498          (documentation "OpenSSH server.")
 499          (requirement '(syslogd loopback))
 500          (provision '(ssh-daemon ssh sshd))
 501          (start #~(make-forkexec-constructor #$openssh-command
 502                                              #:pid-file #$pid-file))
 503          (stop #~(make-kill-destructor))
 504          (auto-start? (openssh-auto-start? config)))))
 505
 506 (define (openssh-pam-services config)
 507   "Return a list of <pam-services> for sshd with CONFIG."
 508   (list (unix-pam-service
 509          "sshd"
 510          #:login-uid? #t
 511          #:allow-empty-passwords?
 512          (openssh-configuration-allow-empty-passwords? config))))
 513
 514 (define (extend-openssh-authorized-keys config keys)
 515   "Extend CONFIG with the extra authorized keys listed in KEYS."
 516   (openssh-configuration
 517    (inherit config)
 518    (authorized-keys
 519     (append (openssh-authorized-keys config) keys))))
 520
 521 (define openssh-service-type
 522   (service-type (name 'openssh)
 523                 (description
 524                  "Run the OpenSSH secure shell (SSH) server, @command{sshd}.")
 525                 (extensions
 526                  (list (service-extension shepherd-root-service-type
 527                                           openssh-shepherd-service)
 528                        (service-extension pam-root-service-type
 529                                           openssh-pam-services)
 530                        (service-extension activation-service-type
 531                                           openssh-activation)
 532                        (service-extension account-service-type
 533                                           (const %openssh-accounts))
 534
 535                        ;; Install OpenSSH in the system profile.  That way,
 536                        ;; 'scp' is found when someone tries to copy to or from
 537                        ;; this machine.
 538                        (service-extension profile-service-type
 539                                           (lambda (config)
 540                                             (list (openssh-configuration-openssh
 541                                                    config))))))
 542                 (compose concatenate)
 543                 (extend extend-openssh-authorized-keys)
 544                 (default-value (openssh-configuration))))
 545
 546 \f
 547 ;;;
 548 ;;; Dropbear.
 549 ;;;
 550
 551 (define-record-type* <dropbear-configuration>
 552   dropbear-configuration make-dropbear-configuration
 553   dropbear-configuration?
 554   (dropbear               dropbear-configuration-dropbear
 555                           (default dropbear))
 556   (port-number            dropbear-configuration-port-number
 557                           (default 22))
 558   (syslog-output?         dropbear-configuration-syslog-output?
 559                           (default #t))
 560   (pid-file               dropbear-configuration-pid-file
 561                           (default "/var/run/dropbear.pid"))
 562   (root-login?            dropbear-configuration-root-login?
 563                           (default #f))
 564   (allow-empty-passwords? dropbear-configuration-allow-empty-passwords?
 565                           (default #f))
 566   (password-authentication? dropbear-configuration-password-authentication?
 567                             (default #t)))
 568
 569 (define (dropbear-activation config)
 570   "Return the activation gexp for CONFIG."
 571   #~(begin
 572       (use-modules (guix build utils))
 573       (mkdir-p "/etc/dropbear")))
 574
 575 (define (dropbear-shepherd-service config)
 576   "Return a <shepherd-service> for dropbear with CONFIG."
 577   (define dropbear
 578     (dropbear-configuration-dropbear config))
 579
 580   (define pid-file
 581     (dropbear-configuration-pid-file config))
 582
 583   (define dropbear-command
 584     #~(list (string-append #$dropbear "/sbin/dropbear")
 585
 586             ;; '-R' allows host keys to be automatically generated upon first
 587             ;; connection, at a time when /dev/urandom is more likely securely
 588             ;; seeded.
 589             "-F" "-R"
 590
 591             "-p" #$(number->string (dropbear-configuration-port-number config))
 592             "-P" #$pid-file
 593             #$@(if (dropbear-configuration-syslog-output? config) '() '("-E"))
 594             #$@(if (dropbear-configuration-root-login? config) '() '("-w"))
 595             #$@(if (dropbear-configuration-password-authentication? config)
 596                    '()
 597                    '("-s" "-g"))
 598             #$@(if (dropbear-configuration-allow-empty-passwords? config)
 599                    '("-B")
 600                    '())))
 601
 602   (define requires
 603     (if (dropbear-configuration-syslog-output? config)
 604         '(networking syslogd) '(networking)))
 605
 606   (list (shepherd-service
 607          (documentation "Dropbear SSH server.")
 608          (requirement requires)
 609          (provision '(ssh-daemon ssh sshd))
 610          (start #~(make-forkexec-constructor #$dropbear-command
 611                                              #:pid-file #$pid-file))
 612          (stop #~(make-kill-destructor)))))
 613
 614 (define dropbear-service-type
 615   (service-type (name 'dropbear)
 616                 (description
 617                  "Run the Dropbear secure shell (SSH) server.")
 618                 (extensions
 619                  (list (service-extension shepherd-root-service-type
 620                                           dropbear-shepherd-service)
 621                        (service-extension activation-service-type
 622                                           dropbear-activation)))
 623                 (default-value (dropbear-configuration))))
 624
 625 (define* (dropbear-service #:optional (config (dropbear-configuration)))
 626   "Run the @uref{https://matt.ucc.asn.au/dropbear/dropbear.html,Dropbear SSH
 627 daemon} with the given @var{config}, a @code{<dropbear-configuration>}
 628 object."
 629   (service dropbear-service-type config))
 630
 631 ;;; ssh.scm ends here