HP 6120XG HP ProCurve Series 6120 Blade Switches Access Security Guide - Page 332

ACL ID, ACL Mask, Extended ACL, Implicit Deny

Page 332 highlights

IPv4 Access Control Lists (ACLs) Terminology ACL ID: A number or alphanumeric string used to identify an ACL. A standard ACL ID can have either a number from 1 to 99 or an alphanumeric string. An extended ACL ID can have either a number from 100 to 199 or an alphanumeric string. ACL Mask: Follows an IP address (source or destination) listed in an ACE to specify either a subnet or a group of devices. Defines which bits in a packet's corresponding IP addressing must exactly match the IP address­ ing in the ACE, and which bits need not match (wildcards). For example: Dotted-Decimal and CIDR versions of the same mask. In both cases, zeros in the mask indicate significant digits. Ones in the mask indicate wildcard digits. As shown above, zeros in an ACL mask specify an exact match require­ ment for IP addresses, and ones specify a wildcard. In this example, a matching IP address would be any address in the range 10.10.10.1-255. (See also "How an ACE Uses a Mask To Screen Packets for Matches" on page 9-26.) DA: The acronym for Destination IP Address. In an IP packet, this is the destination IP address carried in the header, and identifies the destination intended by the packet's originator. In an extended ACE, this is the second of two IP addresses required by the ACE to determine whether there is a match between a packet and the ACE. See also "SA". Deny: An ACE configured with this action causes the switch to drop an inbound packet for which there is a match within an applicable ACL. As an option, you can configure the switch to generate a logging output to a Syslog server and a console session.) Extended ACL: This type of Access Control List uses layer-3 IP criteria composed of source and destination IP addresses and (optionally) TCP or UDP port criteria to determine whether there is a match with an IP packet.You can apply an extended ACL to inbound traffic on a port or trunk, including any inbound traffic with a DA belonging to the switch itself. Extended ACLs require an identification number (ID) in the range of 100 - 199 or an alphanumeric name. Implicit Deny: If the switch finds no matches between an inbound packet and the configured criteria in an applicable ACL, then the switch denies (drops) the packet with an implicit "deny IP any" operation. You can preempt the implicit "deny IP any" in a given ACL by configuring permit any (standard) or permit IP any any (extended) as the last explicit ACE in 9-8

  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
  • 13
  • 14
  • 15
  • 16
  • 17
  • 18
  • 19
  • 20
  • 21
  • 22
  • 23
  • 24
  • 25
  • 26
  • 27
  • 28
  • 29
  • 30
  • 31
  • 32
  • 33
  • 34
  • 35
  • 36
  • 37
  • 38
  • 39
  • 40
  • 41
  • 42
  • 43
  • 44
  • 45
  • 46
  • 47
  • 48
  • 49
  • 50
  • 51
  • 52
  • 53
  • 54
  • 55
  • 56
  • 57
  • 58
  • 59
  • 60
  • 61
  • 62
  • 63
  • 64
  • 65
  • 66
  • 67
  • 68
  • 69
  • 70
  • 71
  • 72
  • 73
  • 74
  • 75
  • 76
  • 77
  • 78
  • 79
  • 80
  • 81
  • 82
  • 83
  • 84
  • 85
  • 86
  • 87
  • 88
  • 89
  • 90
  • 91
  • 92
  • 93
  • 94
  • 95
  • 96
  • 97
  • 98
  • 99
  • 100
  • 101
  • 102
  • 103
  • 104
  • 105
  • 106
  • 107
  • 108
  • 109
  • 110
  • 111
  • 112
  • 113
  • 114
  • 115
  • 116
  • 117
  • 118
  • 119
  • 120
  • 121
  • 122
  • 123
  • 124
  • 125
  • 126
  • 127
  • 128
  • 129
  • 130
  • 131
  • 132
  • 133
  • 134
  • 135
  • 136
  • 137
  • 138
  • 139
  • 140
  • 141
  • 142
  • 143
  • 144
  • 145
  • 146
  • 147
  • 148
  • 149
  • 150
  • 151
  • 152
  • 153
  • 154
  • 155
  • 156
  • 157
  • 158
  • 159
  • 160
  • 161
  • 162
  • 163
  • 164
  • 165
  • 166
  • 167
  • 168
  • 169
  • 170
  • 171
  • 172
  • 173
  • 174
  • 175
  • 176
  • 177
  • 178
  • 179
  • 180
  • 181
  • 182
  • 183
  • 184
  • 185
  • 186
  • 187
  • 188
  • 189
  • 190
  • 191
  • 192
  • 193
  • 194
  • 195
  • 196
  • 197
  • 198
  • 199
  • 200
  • 201
  • 202
  • 203
  • 204
  • 205
  • 206
  • 207
  • 208
  • 209
  • 210
  • 211
  • 212
  • 213
  • 214
  • 215
  • 216
  • 217
  • 218
  • 219
  • 220
  • 221
  • 222
  • 223
  • 224
  • 225
  • 226
  • 227
  • 228
  • 229
  • 230
  • 231
  • 232
  • 233
  • 234
  • 235
  • 236
  • 237
  • 238
  • 239
  • 240
  • 241
  • 242
  • 243
  • 244
  • 245
  • 246
  • 247
  • 248
  • 249
  • 250
  • 251
  • 252
  • 253
  • 254
  • 255
  • 256
  • 257
  • 258
  • 259
  • 260
  • 261
  • 262
  • 263
  • 264
  • 265
  • 266
  • 267
  • 268
  • 269
  • 270
  • 271
  • 272
  • 273
  • 274
  • 275
  • 276
  • 277
  • 278
  • 279
  • 280
  • 281
  • 282
  • 283
  • 284
  • 285
  • 286
  • 287
  • 288
  • 289
  • 290
  • 291
  • 292
  • 293
  • 294
  • 295
  • 296
  • 297
  • 298
  • 299
  • 300
  • 301
  • 302
  • 303
  • 304
  • 305
  • 306
  • 307
  • 308
  • 309
  • 310
  • 311
  • 312
  • 313
  • 314
  • 315
  • 316
  • 317
  • 318
  • 319
  • 320
  • 321
  • 322
  • 323
  • 324
  • 325
  • 326
  • 327
  • 328
  • 329
  • 330
  • 331
  • 332
  • 333
  • 334
  • 335
  • 336
  • 337
  • 338
  • 339
  • 340
  • 341
  • 342
  • 343
  • 344
  • 345
  • 346
  • 347
  • 348
  • 349
  • 350
  • 351
  • 352
  • 353
  • 354
  • 355
  • 356
  • 357
  • 358
  • 359
  • 360
  • 361
  • 362
  • 363
  • 364
  • 365
  • 366
  • 367
  • 368
  • 369
  • 370
  • 371
  • 372
  • 373
  • 374
  • 375
  • 376
  • 377
  • 378
  • 379
  • 380
  • 381
  • 382
  • 383
  • 384
  • 385
  • 386
  • 387
  • 388
  • 389
  • 390
  • 391
  • 392
  • 393
  • 394
  • 395
  • 396
  • 397
  • 398
  • 399
  • 400
  • 401
  • 402
  • 403
  • 404
  • 405
  • 406
  • 407
  • 408
  • 409
  • 410
  • 411
  • 412
  • 413
  • 414
  • 415
  • 416
  • 417
  • 418
  • 419
  • 420
  • 421
  • 422
  • 423
  • 424
  • 425
  • 426
  • 427
  • 428
  • 429
  • 430
  • 431
  • 432
  • 433
  • 434
  • 435
  • 436
  • 437
  • 438
  • 439
  • 440
  • 441
  • 442
  • 443
  • 444
  • 445
  • 446
  • 447
  • 448
  • 449
  • 450
  • 451
  • 452
  • 453
  • 454
  • 455
  • 456
  • 457
  • 458
  • 459
  • 460
  • 461
  • 462
  • 463
  • 464
  • 465
  • 466
  • 467
  • 468
  • 469
  • 470
  • 471
  • 472
  • 473
  • 474
  • 475
  • 476
  • 477
  • 478
  • 479
  • 480
  • 481
  • 482
  • 483
  • 484
  • 485
  • 486
  • 487
  • 488
  • 489
  • 490
  • 491
  • 492
  • 493
  • 494
  • 495
  • 496
  • 497
  • 498
  • 499
  • 500
  • 501
  • 502
  • 503
  • 504
  • 505
  • 506
  • 507
  • 508
  • 509
  • 510
  • 511
  • 512
  • 513
  • 514
  • 515
  • 516
  • 517
  • 518
  • 519
  • 520
  • 521
  • 522
  • 523
  • 524
  • 525
  • 526
  • 527
  • 528
  • 529
  • 530
  • 531
  • 532
  • 533
  • 534
  • 535
  • 536
  • 537
  • 538
  • 539
  • 540
  • 541
  • 542
  • 543
  • 544
  • 545
  • 546
  • 547
  • 548
  • 549
  • 550
  • 551
  • 552
  • 553
  • 554
  • 555
  • 556
  • 557
  • 558
  • 559
  • 560
  • 561
  • 562
  • 563
  • 564
  • 565
  • 566
  • 567
  • 568
  • 569
  • 570
  • 571
  • 572
  • 573
  • 574
  • 575
  • 576
  • 577
  • 578
  • 579
  • 580
  • 581
  • 582
  • 583
  • 584
  • 585
  • 586
  • 587
  • 588
  • 589
  • 590
  • 591
  • 592
  • 593
  • 594
  • 595
  • 596
  • 597
  • 598
  • 599
  • 600
  • 601
  • 602
  • 603
  • 604
  • 605
  • 606

IPv4 Access Control Lists (ACLs)
Terminology
ACL ID:
A number or alphanumeric string used to identify an ACL. A
standard
ACL ID can have either a number from 1 to 99 or an alphanumeric string.
An
extended
ACL ID can have either a number from 100 to 199 or an
alphanumeric string.
ACL Mask:
Follows an IP address (source or destination) listed in an ACE to
specify either a subnet or a group of devices. Defines which bits in a
packet’s corresponding IP addressing must exactly match the IP address-
ing in the ACE, and which bits need not match (wildcards). For example:
Dotted-Decimal and CIDR
versions of the same mask. In both
cases, zeros in the mask indicate
significant digits. Ones in the mask
indicate wildcard digits.
As shown above, zeros in an ACL mask specify an exact match require-
ment for IP addresses, and ones specify a wildcard. In this example, a
matching IP address would be any address in the range 10.10.10.1-255.
(See also “How an ACE Uses a Mask To Screen Packets for Matches” on
page 9-26.)
DA:
The acronym for
Destination IP Address
. In an IP packet, this is the
destination IP address carried in the header, and identifies the destination
intended by the packet’s originator. In an extended ACE, this is the second
of two IP addresses required by the ACE to determine whether there is a
match between a packet and the ACE. See also “SA”.
Deny:
An ACE configured with this action causes the switch to drop an
inbound packet for which there is a match within an applicable ACL. As
an option, you can configure the switch to generate a logging output to a
Syslog server and a console session.)
Extended ACL:
This type of Access Control List uses layer-3 IP criteria
composed of source and destination IP addresses and (optionally) TCP
or UDP port criteria to determine whether there is a match with an IP
packet.You can apply an extended ACL to inbound traffic on a port or
trunk, including any inbound traffic with a DA belonging to the switch
itself. Extended ACLs require an identification number (ID) in the range
of 100 - 199 or an alphanumeric name.
Implicit Deny:
If the switch finds no matches between an inbound packet
and the configured criteria in an applicable ACL, then the switch denies
(drops) the packet with an implicit “deny IP any” operation. You can
preempt the implicit “deny IP any” in a given ACL by configuring
permit
any
(standard) or
permit IP any any
(extended) as the last explicit ACE in
9-8