Droms R. The DHCP handbook
Подождите немного. Документ загружается.
DHCP Relay Agent dialog box, 450-451
DHCP server port (UDP port 67), 83
DHCP servers
BOOTP devices
automatic IP address assignments for
clients, 324-325
eliminating, 322-323
static IP address assignments for clients,
323-324
clients, configuration options, 217-218
configuration parameters
DNS server address, 32-34
Impress server option, 37-38
local subnet masks, 32-34
router addresses, 32-34
interoperation with BOOTP devices (RFC
1534), 322
IP address allocation
agent, 9
automatic method, 15
dynamic method, 15
hybrid methods, 15-16
static method, 15
IP addresses
assigning, 321-322
lease assignments, 10
manual configuration, 321-322
lease lengths, 325
1-minute example, 327-328
1-year example, 326
adjustments, 331
compromising, 331
configuring, 331-332
customizing durations, 331-332
DDNS updates, 330
effect on server load/reliability, 329
long-term benefits/problems, 326-327
renewal time, 330
short-term benefits/problems, 328
short-term use on public access network,
329
versus number of clients, 328-329
leases
default length, 35
extending, 40
infinite, 34
length configuration, 36-37
maximum length, 35
minimum length, 35
subnet lengths, 35-37
monitoring, 332
address pool depletion, 334
address pool usage, 334
traffic statistics, 332-333
verification of server configuration, 333
network architecture
specifications, 29-32
subnet address allocation, 31-32
subnet declarations, 30
network devices, configuring, 321-322
reservations, configuring, 214
scopes
activating, 221
automatic starts, 221
available addresses, 208-209
configuration options, 215
configuring, 205-214
default gateways, 210-212
excluded addresses, 208-209
lease durations, 210
manual starts, 221
naming, 208
DHCP Relay Agent dialog box556
038 3273 Index 10/3/02 4:58 PM Page 556
subnets
configuration options, 38-39
global configuration options, 39
moving between, 40-41
superscopes
adding to existing scopes, 214
configuring, 212-213
user classes, configuration options, 218
vendor-specific configuration options, 217
DHCP service
clients, alias configuration, 387
DSL router problems, avoiding, 389
failure scenarios
failed relay agents, 295
hardware failures, 293
limited power failures, 291
major power outages, 291-292
misconfigured relay agents, 295
network hardware failure, 294-295
planned outages, 293
resource starvation, 293
server failures, 291
installing, 203-205
integrated router/server, configuring, 389
LAN ports, configuring, 390-391
managing, 205
PREINIT problem, avoiding, 386
reliability levels
effects of loss of service, 289-290
secondary server configuration, 295-297
use of long leases, 295
running server and client on same and
different interfaces, 384-386
servers
firewall filters, 388
firewall placement, 388
identifiers, 389
limiting authority, 387
small office environment, configuring,
381-391
uninstalling, 221
WAN ports, configuring, 390
dhcp-client package (RPM), 250
dhcp-client-identifier option statement, 465
dhcp-devel package (RPM), 250
DHCP Handbook Web site, 519
dhcp-relay package (RPM), 250
dhcp-server package (RPM), 250
dhcp.conf file, 459
declarations, 460-462
class declaration, 468-469
dhcp-client-identifier option statement,
465
failover peer declaration, 472-475
fixed-address declaration, 466
hardware declaration, 465
host declaration, 464-465
pool declaration, 466-471
range declaration, 464
shared-network declaration, 463
subnet declaration, 463
zone declaration, 472
include directive, 471
statements, 460-462
DHCP.org Web site, 432, 519
DHCPACK message
fields, 77-79
hexadecimal format example, 79
IP addresses
confirming, 110-112
lease extensions, 113-114
obtaining, 108-109
DHCPACK message 557
038 3273 Index 10/3/02 4:58 PM Page 557
dhcpcd DHCP client, 365-366
DHCPDECLINE message
denial of service attacks, 199
duplicate IP addresses, 427-428
DHCPDISCOVER message, 90
delayed authentication method, 97-98
IP addresses
allocation of, 194-195
obtaining, 105-106, 117-118
ISC DHCP client, 356
DHCPFORCERENEW message, 90, 94
DHCPINFORM message, 93, 199, 365
DHCPKNOWN message, 91
DHCPLEASEQUERY message, 94, 200
DHCPNAK message
failure to deliver to client, 425-426
inappropriate delivery to client, 424
IP addresses, obtaining, 118
wars on shared networks, 270
DHCPOFFER message
IP addresses, obtaining, 106-107
keyed-hashing authentication, 97-98
DHCPPLEASEQUERY message, 91
DHCPRELEASE message, 90, 94
DNS record removal, 407-408
lease terminations, 120, 199
DHCPREQUEST message, 92-93
fields, 76-77
hexadecimal format example, 77
IP addresses
allocation of, 196-197
lease extensions, 197
lease extensions, broadcasting, 118
lease renewal, 196-197
moving to new network, 115-116
obtaining, 107-108
restarting, 118
ISC DHCP client, 356
recovery of abandoned leases, 200-201
DHCPUNKNOWN message, 91
DHCPv4 (version 4)
client identifiers, 438
lifetime address management, 437
link-local addresses, 437
message formats, 438
multicast addresses, 437
multiple addresses for interfaces, 436-437
versus DHCPv6, 436
virtual hosting, 437
DHCPv6 (version 6)
client/server transactions
client configuration without address
assignment, 439
client reconfiguration, 439
duplicate addresses, 439
initial address assignment, 438
interaction with IPv6 auto-configuration,
440
lease extensions, 439
obtaining additional addresses, 438
releasing addresses, 439
current status as standard, 432
IPv6 development, 431
latest specification information, 440
motivations for development, 436
versus DHCPv4, 436
client identifiers, 438
lifetime address management, 437
link-local addresses, 437
message formats, 438
multicast addresses, 437
multiple addresses for interfaces, 436-437
virtual hosting, 437
dhcpcd DHCP client558
038 3273 Index 10/3/02 4:58 PM Page 558
dialog boxes
BOOTP Table, 448
DHCP Relay Agent, 450-451
Reservation Options, 449
Scope Properties, 446
Server Options, 447
differentiating clients on ISC DHCP server,
338-342
DISCONNECT message, failover peers, 162
disjointed servers (DHCP), configuration files,
merging, 305-309
distributions (ISC DHCP server)
building, 227-228
configuring, 227
installing, 229-230
system log configuration, 231
unpacking, 226-227
vendor-supplied versions, 230
DNS (Domain Name System), 54, 177
A (address) resource record, 394
automatic updates via DHCP, 63
dangling A (address) records, 408
databases, dynamic updates, 179-189
domain name management, 178-179
function of, 177
incorrect DHCP server information, debug-
ging, 415
IP addresses
forward mapping, 393
reverse mapping, 178, 393
ISC DHCP server updates, configuring, 239
namespaces, 177
PTR (pointer) resource record, 394
threat model, 395-396
records, removal of, 407-408
resource records (RRtypes), 178
A (address), 178
PTR (pointer), 178
server updates, 198
TCP/IP application layer, 54
Time to Live (TTL) records, setting, 408-410
updates
client-supplied hostnames, 396
debugging, 410-411
dual booting issues, 397
name clashes, 397
no supplied hostnames, 397
policies, setting, 395-397
security, 397-400
zones, start of authority (SOA) records,
401-402
DNS and Bind, 523
DNS operators
add, 485
delete, 485
exists, 485
not exists, 485
DNS servers
addresses, DHCP server configuration, 32-34
updates, configuring, 402-407
domain name option (host configuration para-
meters), 132
Domain Name System. See DNS
domain server option (NIS service options), 143
downloading ISC DHCP server, 223-224
DRARP (Dynamic Reverse Address Resolution
Protocol), 65
DSL routers, problems, avoiding (DHCP service),
389
dual booting, DNS updates, 397
dual-boot client systems, troubleshooting, 427
DUIDs (DHCP unique identifiers), 438
duplicate IP addresses, troubleshooting, 427-428
dynamic address allocation
clients
mixing with static allocation, 281-282
moving to static allocation, 282-284
dynamic address allocation 559
038 3273 Index 10/3/02 4:58 PM Page 559
secondary DHCP servers, 296
servers, converting from static allocation,
284-285
dynamic address probing as alternative to IP
address leases, 27
dynamic allocation, IP addresses, 15, 193
subnets, 255
dynamic bootp clients permit, pool declaration,
467
Dynamic Host Configuration Protocol. See DHCP
Dynamic Host Configuration Working Group
(DHCWG)
failover protocol resources, 160
Web site, current projects, 62-63
dynamic IP address pools, assigning (DHCP), 60,
256
Dynamic Reverse Address Resolution Protocol
(DRARP), 65
dynamic updates to DNS databases, 179
DHCP clients, 180-187
DHCP servers, 182-183, 188-189
security issues, 187
dynamic-bootp-lease-cutoff statement, 488
dynamic-bootp-lease-length statement, 489
E
eliminating BOOTP devices, 322-323
else clause, 476
conditional statements, 338
elsif clause, 476
embedded relay agents, 263
enabling Microsoft DHCP client, 359-362
encode-int operator (data), 483
end option (DHCP-specific options), 75, 131
etherfind utility (network analyzer), 416
Ethernet encapsulation option (link layers con-
figuration parameters), 141
Ethernet framing, 44
excluded addresses, DHCP servers, 208-209
exists operator (Boolean), 480, 485
expired leases, client IP addresses, 115
EXPIRED state, IP address binding, 163-164
expiry event, ISC DHCP server leases, 352
explicit departure messages as alternative to IP
address leases, 27
explicit rule, class-matching rules for clients, 341
expressions, 478
Boolean operators
=, 479
and, 480
defined, 480
exists, 480
known, 480
not, 480
or, 480
static, 479
data operators
binary-to-ascii, 481
concat, 483
config-option, 482
encode-int, 483
hardware, 482
host-decl-name, 483
leased-address, 483
option, 482
packet, 482
pick, 481
reverse, 482
string, 483
substring, 481
suffix, 481
text, 483
dynamic address allocation560
038 3273 Index 10/3/02 4:58 PM Page 560
DNS operators
add, 485
delete, 485
exists, 485
not exists, 485
indeterminate operators
null, 479
variable, 479
numeric operators
client-state, 484
extract-int, 484
lease-time, 484
ns-update, 484
number, 484
extending leases, 40
client IP addresses, 112-115, 118
DHCPREQUEST message, 197
extensions path option (host configuration para-
meters), 135
extract-int operator (numeric), 484
F
failover peer declaration, 472-473
address statement, 473
hba statement, 475
load-balance-max secs statement, 475
max-response-delay statement, 474
max-unpacked-updates statement, 474
mclt statement, 474
peer address statement, 473
peer port statement, 474
port statement, 473
primary statement, 473
secondary statement, 473
split statement, 475
failover protocol
binding update conflicts, 173
complex configurations, 174-175
database synchronization, 160-161
function of, 159-160
IETF Web site resources, 160
IP addresses
allocation rules, 161
pool rebalancing, 173-174
lazy updates, 160-161
lease handling, 163-164
desired lease time, 165
durations, 165-166
potential lease expiry time, 165
operational states
COMMUNICATIONS-INTERRUPTED, 168
CONFLICT-DONE, 172
NORMAL, 166-168
PARTNER-DOWN, 168-170
POTENTIAL-CONFLICT, 171-172
RECOVER, 170-171
RESOLUTION-INTERRUPTED, 172
STARTUP, 170
original purpose of, 160
peers, communication between, 162
resource starvation, 293
failovers, 14
configuring (ISC DHCP server), 305-314
installation scenarios, 304-305
ISC DHCP server
contact ports, setting, 310
contact timeout, setting, 310
free address balance, setting, 311
load balance override, setting, 312
load balance split, setting, 312
maximum number of pending updates,
310
failovers 561
038 3273 Index 10/3/02 4:58 PM Page 561
MCLT, setting, 311
partner addresses, setting, 310
server roles, setting, 309
ISC DHCP servers
implementation issues, 319-320
troubleshooting issues, 319-320
pairs
executing, 314-318
normal operations, 315
operational problems, 315-318
peer declaration information, 309
relationships
backing store, 301-303
cooperating partners, 301-302, 309-314
primary/backup, 301-303
scenarios
failed relay agents, 295
hardware failures, 293
limited power failures, 291
major power outages, 291-292
misconfigured relay agents, 295
network hardware failure, 294-295
planned outages, 293
resource starvation, 293
server failures, 291
servers, configuring, 239
filename statement, 495
finger server option (NIS service options), 146
firewalls
DHCP servers
filtering rules, 388
placing, 388
relay agent configuration, 422
fixed-address declarations
host declaration, 466
IP addresses, 194
fixed-format messages (DHCP), 69-70
fields, 71, 503-505
htype field, 505-506
flags field, DHCP fixed-format message section,
71
flow control (TCP), 53-54
forward mapping of IP addresses (DNS), 393
forwarding
client DHCP messages, relay agent destina-
tions, 88
server DHCP messages, relay agent destina-
tions, 88
fragmentation in IPv6 datagrams, 436
free IP addresses, 161
FREE state, IP address binding, 163-164
G
generating
subclasses in ISC DHCP server, 346
TSIG key for DNS updates, 399-400
get-lease-hostnames statement, 489
giaddr field, DHCP fixed-format message sec-
tion, 71
global options, setting (Microsoft DHCP server),
447
global scope (IPv6)
addresses, 433
Microsoft DHCP server, 449
group declaration, 470
GSI Network (Generic Startup Inc. Network),
configuring, 19-27
GSS-TSIG
DNS databases, 183
security, DNS updates, 397-399
failovers562
038 3273 Index 10/3/02 4:58 PM Page 562
H
hardware addresses, TCP/IP data link layer, 45
hardware declaration, 465
hardware operator (data), 482
Hashed Message Authentication Code (HMAC),
95-96
hba statement, failover peer declaration, 475
hlen field, DHCP fixed-format message section,
71
hops field, DHCP fixed-format message section,
71
host declaration, 464-465
dhcp-client-identifier option statement, 465
fixed-address declaration, 466
hardware declaration, 465
host identifiers, IP addresses, 46-47
host name option (host configuration parame-
ters), 131
host-decl-name operator (data), 483
host-name option (Microsoft DHCP client)
configuring, 363-365
NBNS name protocol, 364-365
hosts
configuration parameters options
bootfile size, 134
client FQDN, 132-133
domain name, 132
extensions path, 135
host name, 131
merit dump file, 135
root path, 134
swap server, 135
time offset, 134
user class, 136
TCP/IP internet layer, 46
hosts (IPv6), 432
hoteling (lease lengths), 36
htype field, DHCP fixed-format message section,
71
hubs, TCP/IP data link layer, 45
hybrid address allocation, 15-16
secondary DHCP servers, 297
I - J - K
IANA (Internet Assigned Number Authority)
Web site, 505
ICMP (Internet Control Message Protocol), 65
identifiers (clients)
dual-boot client systems, potential problems,
427
uniqueness of, 426
identifiers (servers), 389
identifying clients (DHCP), 62, 275
collision avoidance, 280
dhcp-client-identifier option, 276-279
link-layer address implementation, 276-277
non-standard options, 279
identity associations (IAs), 437
IEEE 802.3 framing, 44
IETF (Internet Engineering Task Force)
DHCPv6 specification information, 440
IPv6 development, 431
Web site, 519
if statement, 475
Impress server option, DHCP server configura-
tion, 37-38, 144
include directive, 471
indeterminate operators
null, 479
variable, 479
individual subnets, configuring, 254-255
infinite leases, 34
infinite leases 563
038 3273 Index 10/3/02 4:58 PM Page 563
INIT state, 104-112
IP addresses, lease expiration, 115
INIT-REBOOT DHCPREQUEST message, 109-110
INIT-REBOOT state, 104-105
installing
DHCP service, 203-205
failover scenarios, 304-305
ISC DHCP client, 367-368
ISC DHCP server distributions, 229-230
Microsoft DHCP client, 359-362
RPM (Red Hat Package Manager), 249-252
integrated routers/servers, configuring (DHCP
service), 389
interface identifiers (IPv6), 434
interfaces
ISC DHCP server, specifying, 247
multiple addresses, managing (DHCPv6),
436-437
multiple network segments, installing, 258
interfaces (IPv6), 432
Internet Control Message Protocol (ICMP), 65
Internet Engineering Task Force (IETF)
failover protocol resources, 160
IPv6 development, 431
internet layer (TCP/IP), 46
datagram delivery, 49-50
hosts, 46
IP addresses, 46-47
IP software parameters, 51-52
MTU (maximum transfer unit), 51
multicast, 50
PMTU (path maximum transfer unit), 51
routers, 46
shared segments, 50
subnetting, 48-49
TTL (time to live field), 51
Internet Protocol. See IP or IPv6
Internet Software Consortium DHCP server. See
ISC DHCP server
Internetworking with TCP/IP, 43, 523
invoking ISC DHCP server, command-line argu-
ments, 244-246
IP (Internet Protocol), 46, 431
datagrams, 46
previous versions, 431
software parameters, RFC specifications,
51-52
IP addresses
access control lists, 193
controlling based on client identification,
286-288
allocation
BOOTREQUEST message, 194-195
DHCPDISCOVER message, 194-195
DHCPREQUEST message, 196-197
pre-DHCP development, 4-5
allocation policies
automatic, 15
dynamic, 15
hybrid, 15-16
static, 15
allocation rules (failover protocol)
acknowledged potential lease expiry time,
161
maximum client lead time (MCLT), 161
assigning, 9-10
dynamically (DHCP), 60
assignments, ICMP echo requests, 195
autoconfiguration addresses, 357
Automated Private IP Addressing (APIPA), 356
binding states
ABANDONED, 163-164
ACTIVE, 163-164
BACKUP, 163-164
INIT state564
038 3273 Index 10/3/02 4:58 PM Page 564
EXPIRED, 163-164
FREE, 163-164
RELEASED, 163-164
RESET, 163-164
broadcast messages from clients (DHCP), 84
classes (RFC 790), 48-49
clients
failure to reserve, troubleshooting, 428
initial configuration, obtaining, 105-109,
117-118
initial configuration, obtaining through
non-DHCP protocol, 119
initial configuration, updating, 120
lease expiration, 115
lease extensions, 112-115, 118
lease renewal times, 114
lease terminations, 120
moving to new network, 115-116
restart confirmations, 109-112, 118
confirming (Delayed Authentication
Protocol), 100
default routers, 49-50
DHCP servers, obtaining, 21-22
DNS, function of, 177
duplicate, troubleshooting, 427-428
dynamic allocation, 193, 428
mixing with static allocation, 281-282
secondary DHCP servers, 296
dynamic pools, assigning, 256
failover protocol, function of, 159-160
fixed-address declarations, 194
forward mapping (DNS), 393
functions, 46-47
host identifiers, 46-47
hybrid allocation, secondary DHCP servers,
297
incorrect option values on leases, trou-
bleshooting, 426
ISC DHCP client
BOUND state, 357
failure to obtain, 356-357
lease expirations, 358
lease maintenance, 357-358
multiple network interfaces, 358
obtaining, 355-356
ISC DHCP server, assigning, 244
leases, 10
alternatives (DHCP GSI Network server),
26-27
assigning durations (failover protocol),
165-166
benefits (DHCP GSI Network server), 27
DHCP GSI Network server, 25-26
extensions, 101, 197
handling (failover protocol), 163-166
recovery of abandoned leases, 200-201
renewals, 196-197
machine renumbering, pre-DHCP develop-
ment, 6
multiple servers, obtaining, 117-118
network numbers, 46-47
obtaining (Delayed Authentication Protocol),
99-100
packet transmission (ARP), 268-269
pools
declarations, 244
depletion monitors, 334
rebalancing (failover protocol), 173-174
usage monitors, 334
private (RFC 1918), 433
reclamation of, 6-7, 10
redundant servers
address consistency rule violations, 298
duplicate responses, 298-299
dynamic allocation pool starvation, 298
loss of address while in use, 298
IP addresses 565
038 3273 Index 10/3/02 4:58 PM Page 565