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3c0ef626 | 1 | /* |
2 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
3 | * All rights reserved | |
4 | * | |
5 | * As far as I am concerned, the code I have written for this software | |
6 | * can be used freely for any purpose. Any derived versions of this | |
7 | * software must be clearly marked as such, and if the derived work is | |
8 | * incompatible with the protocol description in the RFC file, it must be | |
9 | * called by a name other than "ssh" or "Secure Shell". | |
10 | */ | |
11 | ||
12 | #include "includes.h" | |
510132b6 | 13 | RCSID("$OpenBSD: auth1.c,v 1.40 2002/04/10 08:21:47 markus Exp $"); |
3c0ef626 | 14 | |
15 | #include "xmalloc.h" | |
16 | #include "rsa.h" | |
17 | #include "ssh1.h" | |
099f4607 | 18 | #include "dispatch.h" |
3c0ef626 | 19 | #include "packet.h" |
20 | #include "buffer.h" | |
21 | #include "mpaux.h" | |
22 | #include "log.h" | |
23 | #include "servconf.h" | |
24 | #include "compat.h" | |
25 | #include "auth.h" | |
1e608e42 | 26 | #include "channels.h" |
3c0ef626 | 27 | #include "session.h" |
3c0ef626 | 28 | #include "uidswap.h" |
510132b6 | 29 | #include "monitor_wrap.h" |
3c0ef626 | 30 | |
31 | /* import */ | |
32 | extern ServerOptions options; | |
33 | ||
099f4607 | 34 | #ifdef GSSAPI |
feefe038 | 35 | #ifdef GSI |
36 | #include "globus_gss_assist.h" | |
37 | #endif | |
38 | ||
755621a1 | 39 | int userauth_gssapi(Authctxt *authctxt); |
40 | ||
099f4607 | 41 | void |
42 | auth1_gss_protocol_error(int type, u_int32_t plen, void *ctxt) | |
43 | { | |
44 | Authctxt *authctxt = ctxt; | |
45 | /* Other side told us to abort, dont need to tell him */ | |
46 | /* maybe we can us some other method. */ | |
47 | if (type == SSH_MSG_AUTH_GSSAPI_ABORT) { | |
48 | log("auth1: GSSAPI aborting"); | |
49 | dispatch_set(SSH_MSG_AUTH_GSSAPI_TOKEN, NULL); | |
50 | authctxt->success = 1; /* get out of loop*/ | |
51 | return; | |
52 | } | |
53 | ||
54 | log("auth1: protocol error: type %d plen %d", type, plen); | |
55 | packet_disconnect("Protocol error during GSSAPI authentication: " | |
56 | "Unknown packet type %d", type); | |
57 | } | |
755621a1 | 58 | |
59 | /* | |
60 | * SSH1 GSSAPI clients may send us a user name of the form: | |
61 | * | |
62 | * (1) username:x:SSL Subject Name | |
63 | * or | |
64 | * (2) username:i:SSL Subject Name | |
65 | * or | |
66 | * (3) username | |
67 | * | |
68 | * if case 1, then uname is an explicit name (ssh -l uname). Keep this | |
69 | * name always, rewrite the user parameter to be just uname. We'll pull | |
70 | * the GSSAPI idenity out and deal with (or skip it) later. | |
71 | * | |
72 | * if case 2, then uname is implicit (user didn't use the -l option), so | |
73 | * use the default gridmap mapping and replace uname with whatever | |
74 | * the gridmap maps to. If the gridmap mapping fails, drop down | |
75 | * to just uname | |
76 | * | |
77 | * if case 3, then leave it be. | |
78 | * | |
79 | * This function may return the original pointer to the orginal string, | |
80 | * the original pointer to a modified string, or a completely new pointer. | |
81 | */ | |
82 | static char * | |
83 | ssh1_gssapi_parse_userstring(char *userstring) | |
84 | { | |
85 | char name_type = '\0'; /* explicit 'x' or implicit 'i' */ | |
86 | char *ssl_subject_name = NULL; | |
87 | char *delim = NULL; | |
88 | ||
89 | debug("Looking at username '%s' for gssapi-ssleay type name", userstring); | |
90 | if((delim = strchr(userstring, ':')) != NULL) { | |
91 | /* Parse and split into components */ | |
92 | ssl_subject_name = strchr(delim + 1, ':'); | |
93 | ||
94 | if (ssl_subject_name) { | |
95 | /* Successful parse, split into components */ | |
96 | *delim = '\0'; | |
97 | name_type = *(delim + 1); | |
98 | *ssl_subject_name = '\0'; | |
99 | ssl_subject_name++; | |
100 | ||
101 | debug("Name parsed. type = '%c'. ssl subject name is \"%s\"", | |
102 | name_type, ssl_subject_name); | |
103 | ||
104 | } else { | |
105 | ||
106 | debug("Don't understand name format. Letting it pass."); | |
107 | } | |
108 | } | |
109 | ||
110 | #ifdef GSI | |
111 | if(ssl_subject_name) { | |
112 | char *gridmapped_name = NULL; | |
113 | switch (name_type) { | |
114 | case 'x': | |
115 | debug("explicit name given, using %s as username", userstring); | |
116 | break; | |
117 | ||
118 | case 'i': | |
119 | /* gridmap check */ | |
120 | debug("implicit name given. gridmapping '%s'", ssl_subject_name); | |
121 | ||
122 | if(globus_gss_assist_gridmap(ssl_subject_name, | |
123 | &gridmapped_name) == 0) { | |
124 | userstring = gridmapped_name; | |
125 | debug("I gridmapped and got %s", userstring); | |
126 | ||
127 | } else { | |
128 | debug("I gridmapped and got null, reverting to %s", userstring); | |
129 | } | |
130 | break; | |
131 | ||
132 | default: | |
133 | debug("Unknown name type '%c'. Ignoring.", name_type); | |
134 | break; | |
135 | } | |
136 | } else { | |
137 | debug("didn't find any :'s so I assume it's just a user name"); | |
138 | } | |
139 | #endif /* GSI */ | |
140 | ||
141 | return userstring; | |
142 | } | |
099f4607 | 143 | #endif |
144 | ||
3c0ef626 | 145 | /* |
146 | * convert ssh auth msg type into description | |
147 | */ | |
148 | static char * | |
149 | get_authname(int type) | |
150 | { | |
151 | static char buf[1024]; | |
152 | switch (type) { | |
153 | case SSH_CMSG_AUTH_PASSWORD: | |
154 | return "password"; | |
155 | case SSH_CMSG_AUTH_RSA: | |
156 | return "rsa"; | |
157 | case SSH_CMSG_AUTH_RHOSTS_RSA: | |
158 | return "rhosts-rsa"; | |
159 | case SSH_CMSG_AUTH_RHOSTS: | |
160 | return "rhosts"; | |
161 | case SSH_CMSG_AUTH_TIS: | |
162 | case SSH_CMSG_AUTH_TIS_RESPONSE: | |
163 | return "challenge-response"; | |
164 | #if defined(KRB4) || defined(KRB5) | |
165 | case SSH_CMSG_AUTH_KERBEROS: | |
166 | return "kerberos"; | |
099f4607 | 167 | #endif |
168 | #if defined(GSSAPI) | |
169 | case SSH_CMSG_AUTH_GSSAPI: | |
170 | return "gssapi"; | |
3c0ef626 | 171 | #endif |
172 | } | |
173 | snprintf(buf, sizeof buf, "bad-auth-msg-%d", type); | |
174 | return buf; | |
175 | } | |
176 | ||
177 | /* | |
178 | * read packets, try to authenticate the user and | |
179 | * return only if authentication is successful | |
180 | */ | |
181 | static void | |
182 | do_authloop(Authctxt *authctxt) | |
183 | { | |
184 | int authenticated = 0; | |
185 | u_int bits; | |
1e608e42 | 186 | Key *client_host_key; |
3c0ef626 | 187 | BIGNUM *n; |
188 | char *client_user, *password; | |
189 | char info[1024]; | |
190 | u_int dlen; | |
3c0ef626 | 191 | u_int ulen; |
192 | int type = 0; | |
193 | struct passwd *pw = authctxt->pw; | |
194 | ||
195 | debug("Attempting authentication for %s%.100s.", | |
1e608e42 | 196 | authctxt->valid ? "" : "illegal user ", authctxt->user); |
3c0ef626 | 197 | |
198 | /* If the user has no password, accept authentication immediately. */ | |
199 | if (options.password_authentication && | |
200 | #if defined(KRB4) || defined(KRB5) | |
201 | (!options.kerberos_authentication || options.kerberos_or_local_passwd) && | |
202 | #endif | |
510132b6 | 203 | PRIVSEP(auth_password(authctxt, ""))) { |
3c0ef626 | 204 | auth_log(authctxt, 1, "without authentication", ""); |
205 | return; | |
206 | } | |
207 | ||
208 | /* Indicate that authentication is needed. */ | |
209 | packet_start(SSH_SMSG_FAILURE); | |
210 | packet_send(); | |
211 | packet_write_wait(); | |
212 | ||
213 | client_user = NULL; | |
214 | ||
215 | for (;;) { | |
216 | /* default to fail */ | |
217 | authenticated = 0; | |
218 | ||
219 | info[0] = '\0'; | |
220 | ||
221 | /* Get a packet from the client. */ | |
1e608e42 | 222 | type = packet_read(); |
3c0ef626 | 223 | |
224 | /* Process the packet. */ | |
225 | switch (type) { | |
226 | ||
227 | #if defined(KRB4) || defined(KRB5) | |
228 | case SSH_CMSG_AUTH_KERBEROS: | |
229 | if (!options.kerberos_authentication) { | |
230 | verbose("Kerberos authentication disabled."); | |
231 | } else { | |
232 | char *kdata = packet_get_string(&dlen); | |
1e608e42 | 233 | packet_check_eom(); |
234 | ||
3c0ef626 | 235 | if (kdata[0] == 4) { /* KRB_PROT_VERSION */ |
236 | #ifdef KRB4 | |
237 | KTEXT_ST tkt; | |
1e608e42 | 238 | |
3c0ef626 | 239 | tkt.length = dlen; |
240 | if (tkt.length < MAX_KTXT_LEN) | |
241 | memcpy(tkt.dat, kdata, tkt.length); | |
1e608e42 | 242 | |
3c0ef626 | 243 | if (auth_krb4(authctxt, &tkt, &client_user)) { |
244 | authenticated = 1; | |
245 | snprintf(info, sizeof(info), | |
246 | " tktuser %.100s", | |
247 | client_user); | |
248 | } | |
249 | #endif /* KRB4 */ | |
250 | } else { | |
251 | #ifdef KRB5 | |
252 | krb5_data tkt; | |
253 | tkt.length = dlen; | |
254 | tkt.data = kdata; | |
1e608e42 | 255 | |
3c0ef626 | 256 | if (auth_krb5(authctxt, &tkt, &client_user)) { |
257 | authenticated = 1; | |
258 | snprintf(info, sizeof(info), | |
259 | " tktuser %.100s", | |
260 | client_user); | |
261 | } | |
262 | #endif /* KRB5 */ | |
263 | } | |
264 | xfree(kdata); | |
265 | } | |
266 | break; | |
267 | #endif /* KRB4 || KRB5 */ | |
0b582e46 | 268 | |
0b582e46 | 269 | #ifdef GSSAPI |
099f4607 | 270 | case SSH_CMSG_AUTH_GSSAPI: |
271 | if (!options.gss_authentication) { | |
272 | verbose("GSSAPI authentication disabled."); | |
273 | break; | |
274 | } | |
275 | /* | |
276 | * GSSAPI was first added to ssh1 in ssh-1.2.27, and | |
277 | * was added to the SecurtCRT product. In order | |
278 | * to continue operating with these, we will add | |
279 | * the equivelent GSSAPI support to SSH1. | |
280 | * Will use the gssapi routines from the ssh2 as | |
281 | * they are almost identical. But they use dispatch | |
282 | * so we need to setup the dispatch tables here | |
283 | * auth1.c for use only by the gssapi code. | |
284 | * Since we already have the packet, we will call | |
285 | * userauth_gssapi then start the dispatch loop. | |
286 | */ | |
287 | if (!authctxt->valid) { | |
288 | packet_disconnect("Authentication rejected for invalid user"); | |
289 | } | |
290 | dispatch_init(&auth1_gss_protocol_error); | |
291 | userauth_gssapi(authctxt); | |
292 | dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt); | |
293 | if (authctxt->postponed) { /* failed, try other methods */ | |
294 | authctxt->success = 0; | |
295 | authctxt->postponed = 0; | |
296 | break; | |
297 | } | |
298 | do_authenticated(authctxt); | |
299 | /* will only return if authenticated */ | |
300 | authenticated = 1; | |
301 | break; | |
0b582e46 | 302 | #endif /* GSSAPI */ |
3c0ef626 | 303 | |
304 | #if defined(AFS) || defined(KRB5) | |
305 | /* XXX - punt on backward compatibility here. */ | |
306 | case SSH_CMSG_HAVE_KERBEROS_TGT: | |
307 | packet_send_debug("Kerberos TGT passing disabled before authentication."); | |
308 | break; | |
309 | #ifdef AFS | |
310 | case SSH_CMSG_HAVE_AFS_TOKEN: | |
311 | packet_send_debug("AFS token passing disabled before authentication."); | |
312 | break; | |
313 | #endif /* AFS */ | |
314 | #endif /* AFS || KRB5 */ | |
1e608e42 | 315 | |
3c0ef626 | 316 | case SSH_CMSG_AUTH_RHOSTS: |
317 | if (!options.rhosts_authentication) { | |
318 | verbose("Rhosts authentication disabled."); | |
319 | break; | |
320 | } | |
321 | /* | |
322 | * Get client user name. Note that we just have to | |
323 | * trust the client; this is one reason why rhosts | |
324 | * authentication is insecure. (Another is | |
325 | * IP-spoofing on a local network.) | |
326 | */ | |
327 | client_user = packet_get_string(&ulen); | |
1e608e42 | 328 | packet_check_eom(); |
3c0ef626 | 329 | |
330 | /* Try to authenticate using /etc/hosts.equiv and .rhosts. */ | |
331 | authenticated = auth_rhosts(pw, client_user); | |
332 | ||
333 | snprintf(info, sizeof info, " ruser %.100s", client_user); | |
334 | break; | |
335 | ||
336 | case SSH_CMSG_AUTH_RHOSTS_RSA: | |
337 | if (!options.rhosts_rsa_authentication) { | |
338 | verbose("Rhosts with RSA authentication disabled."); | |
339 | break; | |
340 | } | |
341 | /* | |
342 | * Get client user name. Note that we just have to | |
343 | * trust the client; root on the client machine can | |
344 | * claim to be any user. | |
345 | */ | |
346 | client_user = packet_get_string(&ulen); | |
347 | ||
348 | /* Get the client host key. */ | |
1e608e42 | 349 | client_host_key = key_new(KEY_RSA1); |
3c0ef626 | 350 | bits = packet_get_int(); |
1e608e42 | 351 | packet_get_bignum(client_host_key->rsa->e); |
352 | packet_get_bignum(client_host_key->rsa->n); | |
3c0ef626 | 353 | |
1e608e42 | 354 | if (bits != BN_num_bits(client_host_key->rsa->n)) |
3c0ef626 | 355 | verbose("Warning: keysize mismatch for client_host_key: " |
1e608e42 | 356 | "actual %d, announced %d", |
357 | BN_num_bits(client_host_key->rsa->n), bits); | |
358 | packet_check_eom(); | |
3c0ef626 | 359 | |
1e608e42 | 360 | authenticated = auth_rhosts_rsa(pw, client_user, |
361 | client_host_key); | |
362 | key_free(client_host_key); | |
3c0ef626 | 363 | |
364 | snprintf(info, sizeof info, " ruser %.100s", client_user); | |
365 | break; | |
366 | ||
367 | case SSH_CMSG_AUTH_RSA: | |
368 | if (!options.rsa_authentication) { | |
369 | verbose("RSA authentication disabled."); | |
370 | break; | |
371 | } | |
372 | /* RSA authentication requested. */ | |
1e608e42 | 373 | if ((n = BN_new()) == NULL) |
374 | fatal("do_authloop: BN_new failed"); | |
375 | packet_get_bignum(n); | |
376 | packet_check_eom(); | |
3c0ef626 | 377 | authenticated = auth_rsa(pw, n); |
378 | BN_clear_free(n); | |
379 | break; | |
380 | ||
381 | case SSH_CMSG_AUTH_PASSWORD: | |
382 | if (!options.password_authentication) { | |
383 | verbose("Password authentication disabled."); | |
384 | break; | |
385 | } | |
386 | /* | |
387 | * Read user password. It is in plain text, but was | |
388 | * transmitted over the encrypted channel so it is | |
389 | * not visible to an outside observer. | |
390 | */ | |
391 | password = packet_get_string(&dlen); | |
1e608e42 | 392 | packet_check_eom(); |
3c0ef626 | 393 | |
3c0ef626 | 394 | /* Try authentication with the password. */ |
510132b6 | 395 | authenticated = PRIVSEP(auth_password(authctxt, password)); |
3c0ef626 | 396 | |
397 | memset(password, 0, strlen(password)); | |
398 | xfree(password); | |
399 | break; | |
400 | ||
401 | case SSH_CMSG_AUTH_TIS: | |
402 | debug("rcvd SSH_CMSG_AUTH_TIS"); | |
403 | if (options.challenge_response_authentication == 1) { | |
404 | char *challenge = get_challenge(authctxt); | |
405 | if (challenge != NULL) { | |
406 | debug("sending challenge '%s'", challenge); | |
407 | packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE); | |
408 | packet_put_cstring(challenge); | |
409 | xfree(challenge); | |
410 | packet_send(); | |
411 | packet_write_wait(); | |
412 | continue; | |
413 | } | |
414 | } | |
415 | break; | |
416 | case SSH_CMSG_AUTH_TIS_RESPONSE: | |
417 | debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE"); | |
418 | if (options.challenge_response_authentication == 1) { | |
419 | char *response = packet_get_string(&dlen); | |
420 | debug("got response '%s'", response); | |
1e608e42 | 421 | packet_check_eom(); |
3c0ef626 | 422 | authenticated = verify_response(authctxt, response); |
423 | memset(response, 'r', dlen); | |
424 | xfree(response); | |
425 | } | |
426 | break; | |
427 | ||
428 | default: | |
429 | /* | |
430 | * Any unknown messages will be ignored (and failure | |
431 | * returned) during authentication. | |
432 | */ | |
433 | log("Unknown message during authentication: type %d", type); | |
434 | break; | |
435 | } | |
436 | #ifdef BSD_AUTH | |
437 | if (authctxt->as) { | |
438 | auth_close(authctxt->as); | |
439 | authctxt->as = NULL; | |
440 | } | |
441 | #endif | |
442 | if (!authctxt->valid && authenticated) | |
443 | fatal("INTERNAL ERROR: authenticated invalid user %s", | |
444 | authctxt->user); | |
445 | ||
446 | #ifdef HAVE_CYGWIN | |
447 | if (authenticated && | |
1e608e42 | 448 | !check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD, pw)) { |
3c0ef626 | 449 | packet_disconnect("Authentication rejected for uid %d.", |
1e608e42 | 450 | pw == NULL ? -1 : pw->pw_uid); |
3c0ef626 | 451 | authenticated = 0; |
452 | } | |
453 | #else | |
454 | /* Special handling for root */ | |
455 | if (authenticated && authctxt->pw->pw_uid == 0 && | |
456 | !auth_root_allowed(get_authname(type))) | |
457 | authenticated = 0; | |
458 | #endif | |
459 | #ifdef USE_PAM | |
510132b6 | 460 | if (!use_privsep && authenticated && |
461 | !do_pam_account(pw->pw_name, client_user)) | |
3c0ef626 | 462 | authenticated = 0; |
463 | #endif | |
464 | ||
465 | /* Log before sending the reply */ | |
466 | auth_log(authctxt, authenticated, get_authname(type), info); | |
467 | ||
468 | if (client_user != NULL) { | |
469 | xfree(client_user); | |
470 | client_user = NULL; | |
471 | } | |
472 | ||
473 | if (authenticated) | |
474 | return; | |
475 | ||
476 | if (authctxt->failures++ > AUTH_FAIL_MAX) { | |
477 | #ifdef WITH_AIXAUTHENTICATE | |
478 | loginfailed(authctxt->user, | |
1e608e42 | 479 | get_canonical_hostname(options.verify_reverse_mapping), |
3c0ef626 | 480 | "ssh"); |
481 | #endif /* WITH_AIXAUTHENTICATE */ | |
482 | packet_disconnect(AUTH_FAIL_MSG, authctxt->user); | |
483 | } | |
484 | ||
485 | packet_start(SSH_SMSG_FAILURE); | |
486 | packet_send(); | |
487 | packet_write_wait(); | |
488 | } | |
489 | } | |
490 | ||
491 | /* | |
492 | * Performs authentication of an incoming connection. Session key has already | |
493 | * been exchanged and encryption is enabled. | |
494 | */ | |
510132b6 | 495 | Authctxt * |
1e608e42 | 496 | do_authentication(void) |
3c0ef626 | 497 | { |
498 | Authctxt *authctxt; | |
3c0ef626 | 499 | u_int ulen; |
510132b6 | 500 | char *user, *style = NULL; |
3c0ef626 | 501 | |
502 | /* Get the name of the user that we wish to log in as. */ | |
1e608e42 | 503 | packet_read_expect(SSH_CMSG_USER); |
3c0ef626 | 504 | |
505 | /* Get the user name. */ | |
506 | user = packet_get_string(&ulen); | |
1e608e42 | 507 | packet_check_eom(); |
3c0ef626 | 508 | |
755621a1 | 509 | #ifdef GSSAPI |
96c41595 | 510 | /* Parse GSSAPI identity from userstring */ |
511 | user = ssh1_gssapi_parse_userstring(user); | |
0b582e46 | 512 | #endif /* GSSAPI */ |
3c0ef626 | 513 | |
514 | if ((style = strchr(user, ':')) != NULL) | |
515 | *style++ = '\0'; | |
516 | ||
510132b6 | 517 | #ifdef KRB5 |
3c0ef626 | 518 | /* XXX - SSH.com Kerberos v5 braindeath. */ |
510132b6 | 519 | if ((datafellows & SSH_BUG_K5USER) && |
520 | options.kerberos_authentication) { | |
521 | char *p; | |
522 | if ((p = strchr(user, '@')) != NULL) | |
523 | *p = '\0'; | |
524 | } | |
525 | #endif | |
1e608e42 | 526 | |
3c0ef626 | 527 | authctxt = authctxt_new(); |
528 | authctxt->user = user; | |
529 | authctxt->style = style; | |
530 | ||
531 | /* Verify that the user is a valid user. */ | |
510132b6 | 532 | if ((authctxt->pw = PRIVSEP(getpwnamallow(user))) != NULL) |
3c0ef626 | 533 | authctxt->valid = 1; |
510132b6 | 534 | else |
3c0ef626 | 535 | debug("do_authentication: illegal user %s", user); |
3c0ef626 | 536 | |
510132b6 | 537 | setproctitle("%s%s", authctxt->pw ? user : "unknown", |
538 | use_privsep ? " [net]" : ""); | |
3c0ef626 | 539 | |
540 | #ifdef USE_PAM | |
510132b6 | 541 | PRIVSEP(start_pam(authctxt->pw == NULL ? "NOUSER" : user)); |
3c0ef626 | 542 | #endif |
543 | ||
544 | /* | |
545 | * If we are not running as root, the user must have the same uid as | |
546 | * the server. (Unless you are running Windows) | |
547 | */ | |
548 | #ifndef HAVE_CYGWIN | |
510132b6 | 549 | if (!use_privsep && getuid() != 0 && authctxt->pw && |
550 | authctxt->pw->pw_uid != getuid()) | |
3c0ef626 | 551 | packet_disconnect("Cannot change user when server not running as root."); |
552 | #endif | |
553 | ||
554 | /* | |
555 | * Loop until the user has been authenticated or the connection is | |
556 | * closed, do_authloop() returns only if authentication is successful | |
557 | */ | |
558 | do_authloop(authctxt); | |
559 | ||
560 | /* The user has been authenticated and accepted. */ | |
561 | packet_start(SSH_SMSG_SUCCESS); | |
562 | packet_send(); | |
563 | packet_write_wait(); | |
564 | ||
510132b6 | 565 | return (authctxt); |
3c0ef626 | 566 | } |