gnu/services/ssh.scm

   1 ;;; GNU Guix --- Functional package management for GNU
   2 ;;; Copyright © 2014, 2015, 2016, 2017, 2018 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=" #$lsh "/sbin/sftp-server")
 153             "-p" (number->string (lsh-configuration-port-number config))
 154             (if (lsh-configuration-password-authentication? config)
 155                 "--password" "--no-password")
 156             (if (lsh-configuration-public-key-authentication? config)
 157                 "--publickey" "--no-publickey")
 158             (if (lsh-configuration-root-login? config)
 159                 "--root-login" "--no-root-login")
 160             (if (lsh-configuration-x11-forwarding? config)
 161                 "--x11-forward" "--no-x11-forward")
 162             (if (lsh-configuration-tcp/ip-forwarding? config)
 163                 "--tcpip-forward" "--no-tcpip-forward")
 164             (if (null? interfaces)
 165                 '()
 166                 (map (cut string-append "--interface=" <>)
 167                      interfaces)))))
 168
 169   (define requires
 170     (if (and daemonic? (lsh-configuration-syslog-output? config))
 171         '(networking syslogd)
 172         '(networking)))
 173
 174   (list (shepherd-service
 175          (documentation "GNU lsh SSH server")
 176          (provision '(ssh-daemon))
 177          (requirement requires)
 178          (start #~(make-forkexec-constructor (list #$@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          #:allow-empty-passwords?
 186          (lsh-configuration-allow-empty-passwords? config))))
 187
 188 (define lsh-service-type
 189   (service-type (name 'lsh)
 190                 (description
 191                  "Run the GNU@tie{}lsh secure shell (SSH) daemon,
 192 @command{lshd}.")
 193                 (extensions
 194                  (list (service-extension shepherd-root-service-type
 195                                           lsh-shepherd-service)
 196                        (service-extension pam-root-service-type
 197                                           lsh-pam-services)
 198                        (service-extension activation-service-type
 199                                           lsh-activation)))))
 200
 201 (define* (lsh-service #:key
 202                       (lsh lsh)
 203                       (daemonic? #t)
 204                       (host-key "/etc/lsh/host-key")
 205                       (interfaces '())
 206                       (port-number 22)
 207                       (allow-empty-passwords? #f)
 208                       (root-login? #f)
 209                       (syslog-output? #t)
 210                       (pid-file? #f)
 211                       (pid-file "/var/run/lshd.pid")
 212                       (x11-forwarding? #t)
 213                       (tcp/ip-forwarding? #t)
 214                       (password-authentication? #t)
 215                       (public-key-authentication? #t)
 216                       (initialize? #t))
 217   "Run the @command{lshd} program from @var{lsh} to listen on port @var{port-number}.
 218 @var{host-key} must designate a file containing the host key, and readable
 219 only by root.
 220
 221 When @var{daemonic?} is true, @command{lshd} will detach from the
 222 controlling terminal and log its output to syslogd, unless one sets
 223 @var{syslog-output?} to false.  Obviously, it also makes lsh-service
 224 depend on existence of syslogd service.  When @var{pid-file?} is true,
 225 @command{lshd} writes its PID to the file called @var{pid-file}.
 226
 227 When @var{initialize?} is true, automatically create the seed and host key
 228 upon service activation if they do not exist yet.  This may take long and
 229 require interaction.
 230
 231 When @var{initialize?} is false, it is up to the user to initialize the
 232 randomness generator (@pxref{lsh-make-seed,,, lsh, LSH Manual}), and to create
 233 a key pair with the private key stored in file @var{host-key} (@pxref{lshd
 234 basics,,, lsh, LSH Manual}).
 235
 236 When @var{interfaces} is empty, lshd listens for connections on all the
 237 network interfaces; otherwise, @var{interfaces} must be a list of host names
 238 or addresses.
 239
 240 @var{allow-empty-passwords?} specifies whether to accept log-ins with empty
 241 passwords, and @var{root-login?} specifies whether to accept log-ins as
 242 root.
 243
 244 The other options should be self-descriptive."
 245   (service lsh-service-type
 246            (lsh-configuration (lsh lsh) (daemonic? daemonic?)
 247                               (host-key host-key) (interfaces interfaces)
 248                               (port-number port-number)
 249                               (allow-empty-passwords? allow-empty-passwords?)
 250                               (root-login? root-login?)
 251                               (syslog-output? syslog-output?)
 252                               (pid-file? pid-file?) (pid-file pid-file)
 253                               (x11-forwarding? x11-forwarding?)
 254                               (tcp/ip-forwarding? tcp/ip-forwarding?)
 255                               (password-authentication?
 256                                password-authentication?)
 257                               (public-key-authentication?
 258                                public-key-authentication?)
 259                               (initialize? initialize?))))
 260
 261 \f
 262 ;;;
 263 ;;; OpenSSH.
 264 ;;;
 265
 266 (define-record-type* <openssh-configuration>
 267   openssh-configuration make-openssh-configuration
 268   openssh-configuration?
 269   ;; <package>
 270   (openssh               openssh-configuration-openssh
 271                          (default openssh))
 272   ;; string
 273   (pid-file              openssh-configuration-pid-file
 274                          (default "/var/run/sshd.pid"))
 275   ;; integer
 276   (port-number           openssh-configuration-port-number
 277                          (default 22))
 278   ;; Boolean | 'without-password
 279   (permit-root-login     openssh-configuration-permit-root-login
 280                          (default #f))
 281   ;; Boolean
 282   (allow-empty-passwords? openssh-configuration-allow-empty-passwords?
 283                           (default #f))
 284   ;; Boolean
 285   (password-authentication? openssh-configuration-password-authentication?
 286                             (default #t))
 287   ;; Boolean
 288   (public-key-authentication? openssh-configuration-public-key-authentication?
 289                               (default #t))
 290   ;; Boolean
 291   (x11-forwarding?       openssh-configuration-x11-forwarding?
 292                          (default #f))
 293
 294   ;; Boolean
 295   (allow-agent-forwarding? openssh-configuration-allow-agent-forwarding?
 296                            (default #t))
 297
 298   ;; Boolean
 299   (allow-tcp-forwarding? openssh-configuration-allow-tcp-forwarding?
 300                          (default #t))
 301
 302   ;; Boolean
 303   (gateway-ports? openssh-configuration-gateway-ports?
 304                          (default #f))
 305
 306   ;; Boolean
 307   (challenge-response-authentication? openssh-challenge-response-authentication?
 308                                       (default #f))
 309   ;; Boolean
 310   (use-pam?              openssh-configuration-use-pam?
 311                          (default #t))
 312   ;; Boolean
 313   (print-last-log?       openssh-configuration-print-last-log?
 314                          (default #t))
 315   ;; list of two-element lists
 316   (subsystems            openssh-configuration-subsystems
 317                          (default '(("sftp" "internal-sftp"))))
 318
 319   ;; list of strings
 320   (accepted-environment  openssh-configuration-accepted-environment
 321                          (default '()))
 322
 323   ;; symbol
 324   (log-level             openssh-configuration-log-level
 325                          (default 'info))
 326
 327   ;; String
 328   ;; This is an "escape hatch" to provide configuration that isn't yet
 329   ;; supported by this configuration record.
 330   (extra-content         openssh-configuration-extra-content
 331                          (default ""))
 332
 333   ;; list of user-name/file-like tuples
 334   (authorized-keys       openssh-authorized-keys
 335                          (default '()))
 336
 337   ;; Boolean
 338   ;; XXX: This should really be handled in an orthogonal way, for instance as
 339   ;; proposed in <https://bugs.gnu.org/27155>.  Keep it internal/undocumented
 340   ;; for now.
 341   (%auto-start?          openssh-auto-start?
 342                          (default #t)))
 343
 344 (define %openssh-accounts
 345   (list (user-group (name "sshd") (system? #t))
 346         (user-account
 347           (name "sshd")
 348           (group "sshd")
 349           (system? #t)
 350           (comment "sshd privilege separation user")
 351           (home-directory "/var/run/sshd")
 352           (shell #~(string-append #$shadow "/sbin/nologin")))))
 353
 354 (define (openssh-activation config)
 355   "Return the activation GEXP for CONFIG."
 356   (with-imported-modules '((guix build utils))
 357     #~(begin
 358         (use-modules (guix build utils))
 359
 360         (define (touch file-name)
 361           (call-with-output-file file-name (const #t)))
 362
 363         ;; Make sure /etc/ssh can be read by the 'sshd' user.
 364         (mkdir-p "/etc/ssh")
 365         (chmod "/etc/ssh" #o755)
 366         (mkdir-p (dirname #$(openssh-configuration-pid-file config)))
 367
 368         ;; 'sshd' complains if the authorized-key directory and its parents
 369         ;; are group-writable, which rules out /gnu/store.  Thus we copy the
 370         ;; authorized-key directory to /etc.
 371         (catch 'system-error
 372           (lambda ()
 373             (delete-file-recursively "/etc/authorized_keys.d"))
 374           (lambda args
 375             (unless (= ENOENT (system-error-errno args))
 376               (apply throw args))))
 377         (copy-recursively #$(authorized-key-directory
 378                              (openssh-authorized-keys config))
 379                           "/etc/ssh/authorized_keys.d")
 380
 381         (chmod "/etc/ssh/authorized_keys.d" #o555)
 382
 383         (let ((lastlog "/var/log/lastlog"))
 384           (when #$(openssh-configuration-print-last-log? config)
 385             (unless (file-exists? lastlog)
 386               (touch lastlog))))
 387
 388         ;; Generate missing host keys.
 389         (system* (string-append #$(openssh-configuration-openssh config)
 390                                 "/bin/ssh-keygen") "-A"))))
 391
 392 (define (authorized-key-directory keys)
 393   "Return a directory containing the authorized keys specified in KEYS, a list
 394 of user-name/file-like tuples."
 395   (define build
 396     (with-imported-modules (source-module-closure '((guix build utils)))
 397       #~(begin
 398           (use-modules (ice-9 match) (srfi srfi-26)
 399                        (guix build utils))
 400
 401           (mkdir #$output)
 402           (for-each (match-lambda
 403                       ((user keys ...)
 404                        (let ((file (string-append #$output "/" user)))
 405                          (call-with-output-file file
 406                            (lambda (port)
 407                              (for-each (lambda (key)
 408                                          (call-with-input-file key
 409                                            (cut dump-port <> port)))
 410                                        keys))))))
 411                     '#$keys))))
 412
 413   (computed-file "openssh-authorized-keys" build))
 414
 415 (define (openssh-config-file config)
 416   "Return the sshd configuration file corresponding to CONFIG."
 417   (computed-file
 418    "sshd_config"
 419    #~(begin
 420        (use-modules (ice-9 match))
 421        (call-with-output-file #$output
 422          (lambda (port)
 423            (display "# Generated by 'openssh-service'.\n" port)
 424            (format port "Port ~a\n"
 425                    #$(number->string
 426                       (openssh-configuration-port-number config)))
 427            (format port "PermitRootLogin ~a\n"
 428                    #$(match (openssh-configuration-permit-root-login config)
 429                        (#t "yes")
 430                        (#f "no")
 431                        ('without-password "without-password")))
 432            (format port "PermitEmptyPasswords ~a\n"
 433                    #$(if (openssh-configuration-allow-empty-passwords? config)
 434                          "yes" "no"))
 435            (format port "PasswordAuthentication ~a\n"
 436                    #$(if (openssh-configuration-password-authentication? config)
 437                          "yes" "no"))
 438            (format port "PubkeyAuthentication ~a\n"
 439                    #$(if (openssh-configuration-public-key-authentication?
 440                           config)
 441                          "yes" "no"))
 442            (format port "X11Forwarding ~a\n"
 443                    #$(if (openssh-configuration-x11-forwarding? config)
 444                          "yes" "no"))
 445            (format port "AllowAgentForwarding ~a\n"
 446                    #$(if (openssh-configuration-allow-agent-forwarding? config)
 447                          "yes" "no"))
 448            (format port "AllowTcpForwarding ~a\n"
 449                    #$(if (openssh-configuration-allow-tcp-forwarding? config)
 450                          "yes" "no"))
 451            (format port "GatewayPorts ~a\n"
 452                    #$(if (openssh-configuration-gateway-ports? config)
 453                          "yes" "no"))
 454            (format port "PidFile ~a\n"
 455                    #$(openssh-configuration-pid-file config))
 456            (format port "ChallengeResponseAuthentication ~a\n"
 457                    #$(if (openssh-challenge-response-authentication? config)
 458                          "yes" "no"))
 459            (format port "UsePAM ~a\n"
 460                    #$(if (openssh-configuration-use-pam? config)
 461                          "yes" "no"))
 462            (format port "PrintLastLog ~a\n"
 463                    #$(if (openssh-configuration-print-last-log? config)
 464                          "yes" "no"))
 465            (format port "LogLevel ~a\n"
 466                    #$(string-upcase
 467                       (symbol->string
 468                        (openssh-configuration-log-level config))))
 469
 470            ;; Add '/etc/authorized_keys.d/%u', which we populate.
 471            (format port "AuthorizedKeysFile \
 472  .ssh/authorized_keys .ssh/authorized_keys2 /etc/ssh/authorized_keys.d/%u\n")
 473
 474            (for-each (lambda (s) (format port "AcceptEnv ~a\n" s))
 475                      '#$(openssh-configuration-accepted-environment config))
 476
 477            (for-each
 478             (match-lambda
 479               ((name command) (format port "Subsystem\t~a\t~a\n" name command)))
 480             '#$(openssh-configuration-subsystems config))
 481
 482            (format port "~a\n"
 483                    #$(openssh-configuration-extra-content config))
 484            #t)))))
 485
 486 (define (openssh-shepherd-service config)
 487   "Return a <shepherd-service> for openssh with CONFIG."
 488
 489   (define pid-file
 490     (openssh-configuration-pid-file config))
 491
 492   (define openssh-command
 493     #~(list (string-append #$(openssh-configuration-openssh config) "/sbin/sshd")
 494             "-D" "-f" #$(openssh-config-file config)))
 495
 496   (list (shepherd-service
 497          (documentation "OpenSSH server.")
 498          (requirement '(syslogd loopback))
 499          (provision '(ssh-daemon))
 500          (start #~(make-forkexec-constructor #$openssh-command
 501                                              #:pid-file #$pid-file))
 502          (stop #~(make-kill-destructor))
 503          (auto-start? (openssh-auto-start? config)))))
 504
 505 (define (openssh-pam-services config)
 506   "Return a list of <pam-services> for sshd with CONFIG."
 507   (list (unix-pam-service
 508          "sshd"
 509          #:allow-empty-passwords?
 510          (openssh-configuration-allow-empty-passwords? config))))
 511
 512 (define (extend-openssh-authorized-keys config keys)
 513   "Extend CONFIG with the extra authorized keys listed in KEYS."
 514   (openssh-configuration
 515    (inherit config)
 516    (authorized-keys
 517     (append (openssh-authorized-keys config) keys))))
 518
 519 (define openssh-service-type
 520   (service-type (name 'openssh)
 521                 (description
 522                  "Run the OpenSSH secure shell (SSH) server, @command{sshd}.")
 523                 (extensions
 524                  (list (service-extension shepherd-root-service-type
 525                                           openssh-shepherd-service)
 526                        (service-extension pam-root-service-type
 527                                           openssh-pam-services)
 528                        (service-extension activation-service-type
 529                                           openssh-activation)
 530                        (service-extension account-service-type
 531                                           (const %openssh-accounts))
 532
 533                        ;; Install OpenSSH in the system profile.  That way,
 534                        ;; 'scp' is found when someone tries to copy to or from
 535                        ;; this machine.
 536                        (service-extension profile-service-type
 537                                           (lambda (config)
 538                                             (list (openssh-configuration-openssh
 539                                                    config))))))
 540                 (compose concatenate)
 541                 (extend extend-openssh-authorized-keys)
 542                 (default-value (openssh-configuration))))
 543
 544 \f
 545 ;;;
 546 ;;; Dropbear.
 547 ;;;
 548
 549 (define-record-type* <dropbear-configuration>
 550   dropbear-configuration make-dropbear-configuration
 551   dropbear-configuration?
 552   (dropbear               dropbear-configuration-dropbear
 553                           (default dropbear))
 554   (port-number            dropbear-configuration-port-number
 555                           (default 22))
 556   (syslog-output?         dropbear-configuration-syslog-output?
 557                           (default #t))
 558   (pid-file               dropbear-configuration-pid-file
 559                           (default "/var/run/dropbear.pid"))
 560   (root-login?            dropbear-configuration-root-login?
 561                           (default #f))
 562   (allow-empty-passwords? dropbear-configuration-allow-empty-passwords?
 563                           (default #f))
 564   (password-authentication? dropbear-configuration-password-authentication?
 565                             (default #t)))
 566
 567 (define (dropbear-activation config)
 568   "Return the activation gexp for CONFIG."
 569   #~(begin
 570       (use-modules (guix build utils))
 571       (mkdir-p "/etc/dropbear")))
 572
 573 (define (dropbear-shepherd-service config)
 574   "Return a <shepherd-service> for dropbear with CONFIG."
 575   (define dropbear
 576     (dropbear-configuration-dropbear config))
 577
 578   (define pid-file
 579     (dropbear-configuration-pid-file config))
 580
 581   (define dropbear-command
 582     #~(list (string-append #$dropbear "/sbin/dropbear")
 583
 584             ;; '-R' allows host keys to be automatically generated upon first
 585             ;; connection, at a time when /dev/urandom is more likely securely
 586             ;; seeded.
 587             "-F" "-R"
 588
 589             "-p" #$(number->string (dropbear-configuration-port-number config))
 590             "-P" #$pid-file
 591             #$@(if (dropbear-configuration-syslog-output? config) '() '("-E"))
 592             #$@(if (dropbear-configuration-root-login? config) '() '("-w"))
 593             #$@(if (dropbear-configuration-password-authentication? config)
 594                    '()
 595                    '("-s" "-g"))
 596             #$@(if (dropbear-configuration-allow-empty-passwords? config)
 597                    '("-B")
 598                    '())))
 599
 600   (define requires
 601     (if (dropbear-configuration-syslog-output? config)
 602         '(networking syslogd) '(networking)))
 603
 604   (list (shepherd-service
 605          (documentation "Dropbear SSH server.")
 606          (requirement requires)
 607          (provision '(ssh-daemon))
 608          (start #~(make-forkexec-constructor #$dropbear-command
 609                                              #:pid-file #$pid-file))
 610          (stop #~(make-kill-destructor)))))
 611
 612 (define dropbear-service-type
 613   (service-type (name 'dropbear)
 614                 (description
 615                  "Run the Dropbear secure shell (SSH) server.")
 616                 (extensions
 617                  (list (service-extension shepherd-root-service-type
 618                                           dropbear-shepherd-service)
 619                        (service-extension activation-service-type
 620                                           dropbear-activation)))))
 621
 622 (define* (dropbear-service #:optional (config (dropbear-configuration)))
 623   "Run the @uref{https://matt.ucc.asn.au/dropbear/dropbear.html,Dropbear SSH
 624 daemon} with the given @var{config}, a @code{<dropbear-configuration>}
 625 object."
 626   (service dropbear-service-type config))
 627
 628 ;;; ssh.scm ends here