Droms R. The DHCP handbook
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option spaces
declaration, 470-471
ISC DHCP server
client parameters, 237-238
site-option-space parameter, 238
option statement, 495-496
options section messages (DHCP), 71-72
DHCP message type option, 72-73
DNS server option, 74
end option, 75
magic cookies , 72
requested IP address option, 75
router option, 74
subnet mask option, 73-74
or operator (Boolean), 480
OSPF (Open Shortest Path First), 54
overlay networks
configuring, 266-269
IP address allocation, 266-267
option scoping, 267
pitfalls
cable modem networks, 270
DHCPNAK message wars, 270
private DHCP server at office, 271-272
routing avoidance, 268-269
overlay segments, delivery of, 50
P
packet operator (data), 482
packets
dropped, troubleshooting, 420-422
traces, 103
pad option (DHCP-specific options), 131
parameter request list option (DHCP-specific
options), 129
parameters statements
allow|deny|ignore statement
booting flag, 486
bootp flag, 486
client-updates flag, 487
declines flag, 487
duplicates flag, 486
always-broadcast statement, 491
always-reply-rfc1048 statement, 490
authoritative statement, 489-490
ddns-domainname statement, 492
ddns-hostname statement, 492
ddns-rev-domainname statement, 492
ddns-ttl statement, 493
ddns-updates statement, 492
default-lease-time statement, 487
dynamic-bootp-lease-cutoff statement, 488
dynamic-bootp-lease-length statement, 489
get-lease-hostnames statement, 489
lease-file-name statement, 492
log-facility statement, 494
max-lease-time statement, 487
min-lease-time statement, 487
min-secs statement, 488
omapi-key statement, 493
omapi-port statement, 493
pid-file-name statement, 492
ping-check statement, 494
server-identifier statement, 490-491
site-option-space statement, 491
stash-agent-options statement, 493
update-optimization statement, 493
update-static-leases statement, 494
option spaces576
038 3273 Index 10/3/02 4:58 PM Page 576
use-lease-addr-for-default-route statement,
490
vendor-option-space statement, 491
PARTNER-DOWN state
failover pair service failure, 315-317
failover protocol operational state, 168-170
path MTU discovery (IPv6), 436
peer address statement, failover peer declara-
tion, 473
peer port statement, failover peer declaration,
474
perform mask discovery option (TCP/IP stack
configuration parameters), 139
perform router discovery option (TCP/IP stack
configuration parameters), 140
performance, DHCP service
secondary server configuration, 295-297
use of long leases, 295
physical layer (TCP/IP), 44
pick operator (data), 481
pid-file-name statement, 492
ping command, network interface cards, trou-
bleshooting, 418-419
ping-check statement, 494
PMTU (path maximum transfer unit), TCP/IP
internet layer, 51
PMTU aging timeout option (TCP/IP stack con-
figuration parameters), 138
PMTU plateau table option (TCP/IP stack config-
uration parameters), 138
Point-to-Point Protocol Over Ethernet (PPPoE),
390
pool balancing, ISC DHCP server failures, 318
pool declaration, 466-467
all clients permit, 467
dynamic bootp clients permit, 467
known clients permit, 467
members of permit, 467
unknown clients permit, 467
pool permit list, IP addresses, 197-198
pool rebalancing, failover protocol, 173-174
pool-based address allocation, 343
pools
access control (Microsoft DHCP server), 448
multiple address allocation (Microsoft DHCP
server), 448
POP (Post Office Protocol), 55, 145
port statement, failover peer declaration, 473
ports (UDP), DHCP messages, transmitting,
83-85
Post Office Protocol (POP), 55, 145
potential lease expiry time, failover protocol,
165
POTENTIAL-CONFLICT state, failover protocol
operational state, 171-172
PPP (Point-to-Point Protocol), 44
PPPoE (Point-to-Point Over Ethernet), 390
PREFERRED DSS option (NetWare Directory
Services), 154
prefixes (IPv6), unicast addresses, 432
PREINIT phase, 386
PRIMARY DSS option (NetWare Directory
Services), 155
primary servers (DHCP), 188-189
failover protocol, 160
primary statement, failover peer declaration,
473
primary/backup relationship (failovers), 301-303
private DHCP office server, shared network pit-
falls, 271-272
private IP addresses (RFC 1918), 433
programming statements
else clause, 476
elseif clause, 476
if statement, 475
log statement, 477
on statement, 477
set statement, 477
programming statements 577
038 3273 Index 10/3/02 4:58 PM Page 577
switch statement, 476
unset statement, 478
proxy ARP (Address Transmission Protocol),
268-269
PTR (pointer) resource record (DNS), 178, 394
threat model updates, 395-396
pump DHCP client, 366
Q - R
quotes server option (NIS service options), 144
range declaration, 464
RARP (Reverse Address Resolution Protocol), 65
REBINDING message, IP addresses, lease exten-
sions, 105, 114-115
reclaiming IP addresses, 6-7, 10
records (DNS)
option definition, 498
removal of, 407-408
Time to Live (TTL), setting, 408-410
RECOVER message, failover peers, 162, 170-171
Red Hat Package Manager (RPM)
ISC DHCP server, installing, 249-252
pump DHCP client, 366
redundant servers
address consistency violations, 298
duplicate responses, 298-299
dynamic allocation pool starvation, 298
loss of address while in use, 298
relay agent information option, 157
AGENT CIRCUIT ID suboption, 158
AGENT REMOTE ID suboption, 158
relay agents, 61
chains (RFC 3046), 89
Cisco DHCP, 262-263
configuring (Microsoft DHCP server), 450-451
connectivity problems, debugging, 419
DHCP messages
client forwarding mechanism, 86-88
implementation requirements, 90
multiple use of, 89
server responses, 88
embedded, 263
as firewalls, 422
forwarding destinations, 88
general purpose type, 259-260
implementation requirements, 90
IP router type, 259-260
ISC DHCP, 261
multiple network segments, configuring, 259
multiple use of, 89
options, 87
release candidates, ISC Web site distributions,
224
release event, ISC DHCP server leases, 352
RELEASED state, IP address binding, 163-164
reliability levels (DHCP service)
effects of loss of service, 289-290
secondary server configuration, 295-297
use of long leases, 295
relocating DHCP clients, DNS dynamic updates,
185-186
removing DNS records (DHCPRELEASE mes-
sage), 407-408
renewing IP address leases (DHCPREQUEST mes-
sage), 196-197
RENEWING message, IP addresses, lease
extensions, 105, 112
lease maintenance (ISC DHCP client),
357-358
renumbering
IP addresses, 10
machine IP addresses, pre-DHCP
development, 6
programming statements578
038 3273 Index 10/3/02 4:58 PM Page 578
requested IP address option (DHCP-specific
options), 75, 127
Reservation Options dialog box, 449
reservations
adding (Microsoft DHCP server), 454-455
scopes, configuring (DHCP servers), 214, 449
RESET state, IP address binding, 163-164
RESOLUTION-INTERRUPTED state, failover
protocol operational state, 172
resource records (RRtypes)
A (address), 178, 394
PTR (pointer), 178, 394-396
resources
books
DNS and Bind, 523
Internetworking with TCP/IP, 523
TCP/IP Illustrated, 524
RFCs listing, 520-523
Web sites
DHCP-Handbook, 519
DHCP.org, 519
IETF, 519
ISC (Internet Software Consortium), 519
RFC Editor, 520
restarting computers, DHCP servers (GSI
Network example), 22-23
retiring computers from service (GSI DHCP
Network example), 25
retransmitting DHCP messages, wait times, 90
Reverse Address Resolution Protocol (RARP), 65
reverse mapping of IP addresses (DNS), 178, 393
reverse operator (data), 482
RFC 790, IP address classes, 48-49
RFC 792, Internet Control Message Protocol
(ICMP), 65
RFC 903, RARP (Reverse Address Resolution
Protocol), 65
RFC 1122/1123/1127, IP Host Requirements
documents, 51
RFC 1256, router discovery mechanism, 49-50
RFC 1350, Trivial File Transfer Protocol (TFTP),
65
RFC 1519, CIDR (classless internet domain
routing), 49
RFC 1534, interoperation of BOOTP and DHCP,
322
RFC 1700, htype field (fixed-format messages),
505
RFC 1918, private IP addresses, 433
RFC 1931, DRARP (Dynamic Reverse Address
Resolution Protocol), 65
RFC 2131
automatic IP address allocation, 286
DHCP specifications, 62
possible revisions to, 62-63
state machines, 104-112
state transition diagram, 104-112
RFC 2132
DHCP client identifiers, 276-278
DHCP options, 123-124
alphabetical listing, 507-515
numerical listing, 516-518
DHCP servers, new configuration options,
219-220
RFC 2165, Service Location Protocol (SLP), 66
RFC 2373, interface identifiers (IPv6), 434
RFC 3046, relay agent chains, 89
RFC 3118, DHCP message authentication, 94
goals, 95
key-hashing, 95-101
plain-text tokens, 95-96
RFC Editor Web site, 520
RFCs (Request for Comments), 520-523
listing of DHCP-related items, 520-521
listing of other-related items, 521-523
RFCs 579
038 3273 Index 10/3/02 4:58 PM Page 579
RIP (Routing Information Protocol), 54
RLP (Resource Location Protocol), 145
rogue servers, troubleshooting, 424
root path option (host configuration parame-
ters), 134
router discovery mechanism (RFC 1256), 49-50
router option (DHCP options section), 74
router option (TCP/IP stack configuration para-
meters), 136
router solicitation address option (TCP/IP stack
configuration parameters), 140
routers, 432
addresses, DHCP server configuration, 32-34
advertisements, IPv6 auto-configuration, 435
configuring (DHCP service), 389
default, 49-50
DHCP configuration, rejected DHCP proposal,
64
self-discovering networks, 64
TCP/IP internet layer, 46
routing tables, TCP/IP internet layer, 49-50
RPM (Red Hat Package Manager)
ISC DHCP server, installing, 249-252
packages
dhcp-client, 250
dhcp-devel, 250
dhcp-relay, 250
dhcp-server, 250
S
Scope Properties dialog box, lease times, 446
scopes
activating (DHCP servers), 221
adding (Microsoft DHCP server), 443
automatic starts (DHCP servers), 221
configuring (Microsoft DHCP server), 446
DHCP servers
available addresses, 208-209
configuration options, 215
configuring, 205-214
creating, 207
default gateways, 210-212
excluded addresses, 208-209
lease durations, 210
naming, 208
reservation configuration, 214
global (Microsoft DHCP server), 449
IPv6
global, 433
link-local, 433
multicast addresses, 434
site-local, 433
ISC DHCP server
configuring, 240-243
specific, 243
manual starts (DHCP servers), 221
maximum lease times (Microsoft DHCP
server), 446
reservation (Microsoft DHCP server), 449
subnet (Microsoft DHCP server), 449
secondary servers (DHCP), 188-189
DHCP service improvement guidelines,
295-297
failover protocol, 160
secondary statement, failover peer declaration,
473
secs field, DHCP fixed-format message section,
71
security, DNS updates
GSS-TSIG, 397-399
IP address restriction, 187
SIG(0)-based public key, 397-399
RIP580
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TKEY shared secret, 397-399
TSIG-based shared secret, 187, 397-400
SELECTING state, 104-105
self-discovering networks, 64
send-and-wait mechanism (TFTP), 53
server identifier option (DHCP-specific options),
126
Server Options dialog box, 447
server selection option, 156
server-identifier statement, 490-491
server-name statement, 495
servers, 459
address assignment strategies, manual config-
uration, 321-322
authoritative configuration, 253-257
authoritative name, 188-189
availability of in DHCP services, 60
caching, 188-189
clients
access, controlling based on identification,
286-288
identifying, 275-280
IP address configuration, 256-257
configuration
errors among cooperating servers, trou-
bleshooting, 424-425
file, operational prerequisites, 233-234
connectivity problems, debugging, 419-426
DHCP messages
broadcast flags, 86
DHCPFORCERENEW type, 94
DHCPLEASEQUERY type, 94
forwarding to clients via relay agents, 88
responses to, 85-86
DHCP service
firewall placement, 388
identifiers, 389
limiting authority, 387
dhcp.conf file, 459
declarations, 460-462
statements, 460-462
DHCPNAK message, 423
failure to deliver, 425-426
inappropriate delivery of, 424
DNS name selection, 182-183
DNS updates, 198
dropped packets, troubleshooting, 420-422
duplicate IP addresses, troubleshooting,
427-428
dynamic address probing, 27
explicit departure messages, 27
failover pairs, 314-318
failover protocol
complex configurations, 174-175
database synchronization, 160-161
overview, 160
incorrect DNS information, debugging, 415
incorrect responses to clients, troubleshoot-
ing, 420-422
intercommunication (DHCP), 62
IP addresses
access control lists, 193
address pools, 193-194
allocating (failover protocol), 159-160
allocating via BOOTREQUEST message,
194-195
allocating via DHCPDISCOVER message,
194-195
allocating via DHCPREQUEST message,
196-197
assigning, 195
backup addresses, 161
dynamic allocation, 193
dynamic pool, 256
fixed-address declarations, 194
free addresses, 161
servers 581
038 3273 Index 10/3/02 4:58 PM Page 581
lease extensions via DHCPREQUEST mes-
sage, 197
lease renewal via DHCPREQUEST message,
196-197
maximum client lead time (MCLT), 161
static allocation, 194
use denial, 197-198
ISC office network, DHCP configuration,
263-265
lack of response
client network segment misconfiguration,
423
IP address availability, 423
non-BOOTP client support, 423
troubleshooting, 422-423
leases
extending, 40
infinite, 34
recovery of abandoned leases, 200-201
load concerns with DHCP implementation,
12-13
logs, viewing for debugging purposes, 417
merging configuration files, 305-309
messages
DHCPDECLINE, 199
DHCPINFORM, 199
DHCPLEASEQUERY, 200
DHCPRELEASE, 199
initiating via DHCWG proposal, 63
monitoring, 332
address pool depletion, 334
address pool usage, 334
traffic statistics, 332-333
verification of server configuration, 333
multiple network segments
interface installations, 258
relay agent configuration, 259
servicing, 258-263
network architecture
specifications, 29-32
subnet address allocation, 31-32
subnet declarations, 30
network device configuration, 321-322
primary, 188-189
redundant
address consistency violations, 298
duplicate responses, 298-299
dynamic allocation pool starvation, 298
loss of address while in use, 298
reserved IP addresses, 255
static allocation, 428
restarting, 22-23
retiring from service, 25
rogue, troubleshooting, 424
secondary, 188-189
spurious traffic, handling, 13
standard option definitions, 498-500
static address allocation
automatic, 286
converting to dynamic address allocation,
284-285
unauthorized, locating, 273
Service Location Protocol (SLP), 65-66
set statement, 477
setting
DNS security policies, 397-400
DNS update policies, 395-397
global options (Microsoft DHCP server), 447
Time to Live (TTL), DNS records, 408-410
shared networks
configuring, 266-269
IP address allocation, 266-267
option scoping, 267
servers582
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pitfalls, 270
cable modem networks, 270
DHCPNAK message wars, 270
private DHCP server at office, 271-272
routing avoidance, 268-269
unauthorized servers, locating, 273
shared segments, delivery of, 50
shared-network declaration, 463
shell scripts, automatic startups (ISC DHCP
server), 248
short-term leases
1-minute example, 327-328
benefits/problems, 328
use in public access network, 329
siaddr field, DHCP fixed-format message section,
71
SIG(0)-based public key, DNS updates, 397-399
Simple Mail Transport Protocol (SMTP), 55
site-local scope (IPv6), 433
site-option-space statement, 491
SLP (Service Location Protocol), 65-66
name service search order, 156
SLP Directory Agent, 155
UAP server, 156
small office environments
architectures
IP address translation, 383-384
network topologies, 382-383
DHCP service, configuring, 381-391
SMTP (Simple Mail Transport Protocol), 55, 145
sname field, DHCP fixed-format message sec-
tion, 71
snoop tool, packet traces, 103, 416
Solaris, ISC DHCP server execution difficulties,
530
spawn with statement, 346, 468
split statement, failover peer declaration, 475
start of authority (SOA) records, DNS zones,
401-402
start time of state (STOS), 169
starting
DHCP servers
automatically, 221
manually, 221
ISC DHCP server
automatic options, 247-249
shell scripts, 248
startup files, 249
startup files, ISC DHCP server, automatic
startups, 249
STARTUP state, failover protocol operational
state, 170
stash-agent-options statement, 493
state machines (RFC 2131), 104-112
state transition diagram (RFC 2131), 104-112
statements (programming), 475-476
dhcp.conf file, 460-462
if, 475
log, 477
on, 477
set, 477
switch, 476
unset, 478
statements of authority (ISC DHCP), 234
static address allocation, 15, 94
automatic, 286
BOOTP devices, assigning, 323-324
clients
assigning, 280-281
mixing with dynamic allocation, 281-282
ISC DHCP server configuration, 244
secondary DHCP servers, 296
static operator (Boolean), 479
static routes option (TCP/IP stack configuration
parameters), 140
static routes option 583
038 3273 Index 10/3/02 4:58 PM Page 583
StreetTalk, 150
string operator (data), 483
subclass declaration, 469
subclass-matching rule (clients), 341-342
subclasses (ISC DHCP server)
automatic generation, 346
similar sets, differentiating, 346-347
subnet declaration, 463
subnet mask option (DHCP options section),
73-74, 138
subnets
address allocation, 31-32
declarations, 254-255
DHCP servers
configuration options, 38-39
global configuration options, 39
individual, configuring, 254-255
IP address allocation, 255
local masks, DHCP server configuration,
32-34
moving between on DHCP servers, 40-41
multiple, configuring on each network seg-
ment, 266-272
recommended lease lengths, 35-37
reserved IP addresses, 255
scopes
adding (Microsoft DHCP server), 443
configuring (Microsoft DHCP server), 446
maximum lease times (Microsoft DHCP
server), 446
TCP/IP internet layer, 48-49
substring operator (data), 481
suffix operator (data), 481
Sun Solaris operating system, snoop tool, 103
superscopes
DHCP servers
configuring, 212-213
scope additions, 214
primary function of, 212-213
supply subnet mask option (TCP/IP stack
configuration parameters), 140
swap server option (host configuration
parameters), 135
switch statement, 339, 476
switches, ISC DHCP server invocation
-d, 245
-f, 245
-lf, 246
-p, 245
-pf, 246
-play, 246
-q, 246
-t, 246
-tf, 246
synchronizing databases, failover protocol,
160-161
system logs, ISC DHCP server distributions, 231
T
T1 client RENEWING state, 114
T2 client REBINDING state, 114-115
tar command, ISC DHCP server distributions,
unpacking, 226-227
TCP (Transmission Control Protocol), 53
configuration parameters options
TCP default TTL, 142
TCP keepalive garbage, 142
TCP keepalive interval, 142
flow control, 53-54
messaging process, 53-54
TCP/IP (Transmission Control Protocol/Internet
Protocol), 43
application
client/server model, 54
DNS (Domain Name System), 54
StreetTalk584
038 3273 Index 10/3/02 4:58 PM Page 584
data link, 44
address translation, 45-46
hubs, 45
link-layer addresses, 45
link-layer framing, 44
switches, 45
diagram, 43-44
internet, 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
physical, 44
protocols
Bootstrap Protocol (BOOTP), 65-67
Dynamic Reverse Address Resolution
Protocol (DRARP), 65
Internet Control Message Protocol (ICMP),
65
Reverse Address Resolution Protocol
(RARP), 65
Service Location Protocol (SLP), 65-66
resources
Internetworking with TCP/IP, 43
TCP/IP Illustrated, 43
stack configuration parameters options
all subnets local, 139
broadcast address, 139
default IP time to live, 136
IP forwarding enable/disable, 137
maximum datagram reassembly size, 137
MTU for the interface, 139
nonlocal source routing, 137
perform mask discovery, 139
perform router discovery, 140
PMTU aging timeout, 138
PMTU plateau table, 138
router, 136
router solicitation address, 140
static routes, 140
subnet mask, 138
supply subnet mask, 140
transport, 53
TCP, 53-54
UDP, 53
TCP/IP Illustrated, 43, 524
tcpdump utility (network analyzer), 416
terminating client IP leases, 120
text operator (data), 483
TFTP (Trivial File Transfer Protocol), send-and-
wait mechanism, 53, 130
time offset option (host configuration parame-
ters), 134
time server option (NIS service options), 143
Time to Live (TTL) records, setting (DNS),
408-410
TIMEOUT state, IP addresses, failure to obtain,
356-357
TKEY shared secret, DNS updates, 397, 399
tokens, DHCP message authentication, 95-96
traffic statistics, monitoring, 332-333
trailer encapsulation option (link layers configu-
ration parameters), 141
transaction IDs on DHCP messages, 91-92
transaction signatures (TSIG), 183
Transmission Control Protocol. See TCP
Transmission Control Protocol/Internet Protocol.
See TCP/IP
Transmission Control Protocol/Internet Protocol 585
038 3273 Index 10/3/02 4:58 PM Page 585