Droms R. The DHCP handbook
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renumbering, 10
reserved, 255
reverse mapping (DNS), 178, 393
routing tables, 49-50
server configuration file (ISC DHCP), 233
single address per interface
rejected DHCP proposal, 63-64
static allocation, 194, 428
assigning to clients, 280-281
mixing with dynamic allocation, 281-282
moving from dynamic allocation, 282-285
secondary DHCP servers, 296
subnet address allocation, 31-32, 48-49
dynamic, 255
TCP/IP internet layer, 46-47
translation on DHCP service, 383-384
unicast messages from clients (DHCP), 85
use denial, 197-198
IP forwarding enable/disable option (TCP/IP
stack configuration parameters), 137
IP layer parameter 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
IPv6 (Internet Protocol version 6), 431
addresses, 432
colon hexadecimal, 432
global scope, 433
identity associations (IAs), 437
interface identifiers, 434
link-local scope, 433
loopback, 433
prefix length, 432
site-local scope, 433
unicast, 432
auto-configuration
link-local addresses, 435
router advertisements, 435
datagram fragmentation, 436
development of, 431
DHCPv6 development, 431
duplicate address detection mechanism, 439
hosts, 432
interfaces, 432
links, 432
motivations for development, 431
nodes, 432
path MTU discovery, 436
prefixes, 432
routers, 432
scopes, multicast addresses, 434
IRC (Internet Relay Chat) server option, 146
ISC (Internet Software Consortium) Web site,
519
ISC DHCP server downloads, 224
release candidates, 224
requests for help, 225-226
ISC DHCP client, 367
-d switch (background), 367
-g switch (silent startup), 367
IP addresses566
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additional options, requesting, 368
addresses, allocating by pools, 343
configuring, 368-369
controlling (OMAPI interface), 372-374
debugging, 370-372
DHCPDISCOVER message, 356
DHCPREQUEST message, 356
installing, 367-368
IP addresses
BOUND state, 357
failure to obtain, 356-357
lease expirations, 358
lease maintenance, 357-358
multiple network interfaces, 358
obtaining, 355-356
network interface customizations, 369
network setup script customization, 370
operational overview, 355
overriding options sent by DHCP server, 368
unacceptable offers, rejecting, 368
updates, configuring, 404-405
ISC DHCP relay agent, 261
ISC DHCP server, 223
ad hoc DNS updates, 319
addresses
allocating by class, 344-346
allocating by class membership, 343-344
automatic startups
configuring, 247-249
shell scripts, 248
startup files, 249
client classes
user class option, 347-348
vendor class identifier option, 348-350
vendor-specific information option,
350-351
clients, differentiating, 338-342
Concurrent Versioning System (CVS), 309
configuration file
client options, 235-238
DHCP failover servers, 239
DNS updates, 239
function of, 234-235
IP address assignments, 244
network settings, 240
OMAPI protocol settings, 239
option spaces, 237-238
parameters, 235
scopes, 240-243
specific scopes, 243
user-defined options, 236-237
configuration files, updating, 249
cost of, 224
distributions
building, 227-228
configuring, 227
installing, 229-230
system log configuration, 231
unpacking, 226-227
vendor-supplied versions, 230
downloading, 223-224
failover pairs
executing, 314-318
implementation issues, 319-320
normal operations, 315
operational problems, 315-318
failovers, troubleshooting issues, 319-320
FAQ site, 225
interfaces, specifying, 247
interim DNS updates, 319
invoking via command-line arguments,
244-246
lease database, modifying, 249
ISC DHCP server 567
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lease events
commit, 352
expiry, 352
release, 352
lease variables, 352-353
leases, limiting, 346
mailing list subscriptions, 224-225
network settings
shared-network declaration, 240
subnet declaration, 240
obtaining, 223-224
operating system dependencies
255.255.255.255 broadcast address prob-
lems, 528
HP-UX difficulties, 530
Linux difficulties, 528-530
Solaris difficulties, 530
operational prerequisites
lease database creation, 231-232
server configuration file, 233-234
requests for help, required information,
225-226
RPM (Red Hat Package Manager) package
installation, 249-252
software versions, 319
subclasses
automatic generation, 346
similar sets, differentiating, 346-347
technical support, 224-225
versus Microsoft DHCP server
BOOTP client support, 527
database formats, 527
operating system platforms, 525-526
selection criteria, 525-527
user interface, 526
key declaration, 471
key-hashing method, DHCP message authentica-
tion, 95-101
known clients permit, pool declaration, 467
known operator (Boolean), 480
L
LAN ports, configuring (DHCP service), 390-391
launching DHCP Manager, 205
layers (TCP/IP)
application
client/server model, 54
DNS (Domain Name System), 54
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
stack, 43-44
ISC DHCP server568
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transport
TCP, 53-54
UDP, 53
lazy updates, failover protocol, 160-161
lease time renewal (T1) option (DHCP-specific
options), 127
lease time renewal (T2) option (DHCP-specific
options), 128
lease-file-name statement, 492
lease-time operator (numeric), 484
leased-address operator (data), 483
leases
allocation, ISC DHCP server failures, 318
client IP addresses
broadcasting extensions, 118
expiration of, 115
extending, 112-115
terminating, 120
clients, locating (Microsoft DHCP server), 455
databases
modifying, 249
operational prerequisites, 231-232
DHCP service
1-minute length, 327-328
1-year length, 326
compromising, 331
customizing duration of, 331-332
duration, compromising, 331
duration, customizing, 331-332
duration, modifying, 331
effect of length on DDNS updates, 330
effect of length on renewal times, 330
effect of length on server load, 329
effect of length on server reliability, 329
length and DDNS updates, 330
length and renewal times, 330
length of versus number of clients,
328-329
length versus server load, 329
length versus server reliability, 329
length, configuring, 331-332
lengths of, 325
long-term benefits/problems, 326-327
modifying duration, 331
number per client, 328-329
short-term benefits/problems, 328
short-term use on public access network,
329
DHCPREQUEST messages, 92-93
DNS expiration, 184-185
durations of, 210
events
commit, 352
expiry, 352
release, 352
extending, 40
extensions, obtaining (Delayed
Authentication Protocol), 101
failure to acquire, debugging, 414-415
failure to renew, debugging, 414-415
incorrect option values, troubleshooting, 426
infinite, 34
IP addresses, 10
alternatives (GSI DHCP Network exam-
ple), 26-27
assigning durations (failover protocol),
165-166
benefits (GSI DHCP Network example), 27
expired (ISC DHCP client), 358
handling (failover protocol), 163-166
maintaining (ISC DHCP client), 357-358
recovery of abandoned leases, 200-201
IP addresses (GSI DHCP Network example),
25-26
leases 569
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lengths
default, 35
hoteling, 36
maximum, 35
minimum, 35
subnet configuration, 36-37
subnet recommendations, 35-37
lost, ISC DHCP server failures, 317-318
prolonged, 295
renewal times, 114
scopes, maximum lease times (Microsoft
DHCP server), 446
variables, 352-353
legacy BOOTP devices
automatic address assignments for clients,
324-325
eliminating, 322-323
managing, 322
static address assignments for clients, 323-324
support strategies, separating BOOTP server
and DHCP server, 325
limiting leases on ISC DHCP server, 346
link layers, configuration parameters options
ARP cache timeout, 141
Ethernet encapsulation, 141
trailer encapsulation, 141
link-layer addresses, 45, 276-277
link-layer framing, TCP/IP data link layer, 44
link-local addresses
DHCPv6 versus DHCPv4, 437
IPv6 auto-configuration, 435
link-local scope (IPv6), 432-433
Linux, ISC DHCP server, execution difficulties,
528-530
load-balance-max secs statement, failover peer
declaration, 475
load-sharing, resource starvation, 293
locating
client leases on Microsoft DHCP server, 455
unauthorized servers, 273
log server option (NIS service options), 144
log statement, 477
log-facility statement, 494
logs of servers, viewing for debugging purposes,
417
long-term leases
1-year example, 326
benefits/problems, 326-327
loopback addresses (IPv6), 433
lost leases, ISC DHCP server failures, 317-318
LPR (Line Printer Protocol) server option, 144
M
MAC addresses
DHCP client identification method, 62
TCP/IP data link layer, 45
magic cookies, options section (DHCP mes-
sages), 72
make command, ISC DHCP server distributions,
227-228
make install command, ISC DHCP server distrib-
utions, 229-230
managing DHCP service, 205
match if statement, class declaration, 468
match statement, class declaration, 468
max-lease-time statement, 487
max-response-delay statement, failover peer
declaration, 474
max-unpacked-updates statement, failover peer
declaration, 474
maximum client lead time (MCLT), IP address
leases, 161
leases570
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maximum datagram reassembly size option
(TCP/IP stack configuration parameters), 137
maximum DHCP message size option (DHCP-
specific options), 130
maximum lease length, 35
mclt statement, failover peer declaration, 474
merging configuration files (DHCP servers),
305-309
merit dump file option (host configuration para-
meters), 135
message authentication code (MAC), DHCP mes-
sages, 98-99
message exchanges, packet traces, 103
message option (DHCP-specific options), 129
messages
clients
DHCPDECLINE, 199
DHCPINFORM, 199
DHCPLEASEQUERY, 200
DHCPRELEASE, 199
DHCP
authentication, 94-101
collision avoidance, 91
design constraints, 80-81
DHCPACK, 77-79
DHCPDISCOVER, 90, 97-98
DHCPFORCERENEW, 90, 94
DHCPINFORM, 93
DHCPKNOWN, 91
DHCPLEASEQUERY, 91, 94
DHCPRELEASE, 90, 94
DHCPREQUEST, 76-77, 92-93
DHCPUNKNOWN, 91
fixed-format section, 69-71
number option codes, 80-81
options section, 71-75
relay agents, 86-90
reliable delivery of, 90-91
retransmitting frequency, 90
special case considerations, 79-80
transaction IDs, 91-92
transmitting via UDP ports, 83-86
validating, 99
variable-format section, 69-70
fixed-format section
fields, 503-505
htype field, 505-506
IP address configuration, 105
DHCFORCERENEW, 120
DHCINFORM, 119
DHCPACK, 108-109
DHCPDISCOVER, 105-106, 117-118
DHCPNAK, 118
DHCPOFFER, 106-107
DHCPREQUEST, 107-108
IP address confirmation
DHCPACK, 110, 112
DHCPREQUEST, 118
INIT-REBOOT DHCPREQUEST, 109-110
IP address lease expirations
DHCPREQUEST, 115-116
INIT state, 115
IP address lease extensions
broadcasting, 118
DHCPACK, 113-114
REBINDING, 114-115
RENEWING, 112
IP address lease terminations, DHCPRELEASE,
120
options
authentication, 157
RFC 2132, 123-124
three-part format, 123
variable-format section fields, 506
messages 571
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MIB (management information base), 332-334
address pool depletion, 334
address pool usage, 334
monitoring information, 332-333
verification of server configuration, 333
Microsoft DHCP client
client identifier option, 365
DHCPINFORM message, 365
emulation, 369-370
enabling, 359-362
host-name option, 363-365
installing, 359-362
Microsoft Web site resources, 359
user interface, configuring (winipcfg),
362-363
Microsoft DHCP server
BOOTP file, configuring, 448
client identifiers, entering, 453
client leases, locating, 455
global options, setting, 447
option declarations, 445
pools
access control, 448
multiple address allocation, 448
relay agents, configuring, 450-451
reservations, adding, 454-455
scopes
adding, 443
configuring, 446
global, 449
maximum lease times, 446
reservation, 449
subnet, 449
versus ISC DHCP server
BOOTP client support, 527
database formats, 527
operating system platforms, 525-526
selection criteria, 525-527
user interface, 526
Microsoft Web site, DHCP client resources, 359
min-lease-time statement, 487
min-secs statement, 488
minimum lease length, 35
mixing dynamic and static address allocation
(clients), 281-282
monitoring DHCP servers, 332
address pool depletion, 334
address pool usage, 334
traffic statistics, 332-333
verification of server configuration, 333
moving
between subnets (DHCP servers), 40-41
computers to new network segment (GSI
DHCP Network example), 23-25
dynamic address allocation to static alloca-
tion, 282-284
network devices (pre-DHCP development), 5
networks, new IP addresses, seeking, 115-116
MTU (maximum transfer unit), TCP/IP internet
layer, 51, 139
multicast addresses
datagram delivery, 50
DHCPv6 versus DHCPv4, 437
scopes, 434
multicast traffic, resource starvation, 294
multiple IP subnets, configuring on each net-
work segment, 266-272
multiple network interfaces, ISC DHCP client,
358
multiple network segments
relay agent configuration, 259
servicing, 258-263
multiple relay agents, 89
MIB572
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multiple servers, IP addresses
initial configuration, obtaining, 117-118
restarting, 118
N
name clashes and DNS updates, 397
name server option (NIS service options), 143
name service search order option (Service
Location Protocol), 156
namespaces (DNS), 177
naming scopes (DHCP servers), 208
NBNS name protocol, 364-365
NDS context option (NetWare Directory
Services), 151
NDS servers option (NetWare Directory
Services), 150
NDS TreeName option (NetWare Directory
Services), 151
NEAREST NWIP SERVER option (NetWare
Directory Services), 154
Neighbor Discovery Protocol (RFC 2461), 439
nesting conditional statements, 339
NetBIOS over TCP/IP options, 149
netstat-r command, routing table, displaying,
415
NetWare Directory Services (NDS) options
NDS context, 151
NDS servers, 150
NDS Tree Name, 151
NetWare/IP options
AUTORETRIES, 154
AUTORETRY SECS, 154
NEAREST NWIP SERVER, 154
NetWare/IP Domain Name, 152
NetWare/IP Information, 152
NSQ BROADCAST, 154
NWIP 1.1, 155
NWIP DOES NOT EXIST, 152
NWIP EXIST BUT TOO BIG, 153
NWIP EXIST IN OPTIONS AREA, 153
NWIP EXIST IN SNAME FILE, 153
PREFERRED DSS, 154
PRIMARY DSS, 155
network analyzers (debuggers)
etherfind utility, 416
snoop utility, 416
tcpdump utility, 416
network devices
configuring prior to DHCP, 3-7
configuring with BOOTP, 7
IPv6 auto-configuration
link-local addresses, 435
router advertisements, 435
Network Information Service (NIS), service
parameters options
domain server, 143
finger server, 146
Impress server, 144
IRC server, 146
log server, 144
LPR server, 144
name server, 143
NIS domain, 148
NIS server addresses, 148
NIS+ domain, 148
NIS+ server addresses, 148
NNTP server, 146
NTP server, 145
POP server, 145
quotes server, 144
RLP server, 145
SMTP server, 145
Network Information Service 573
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time server, 143
WWW server, 146
network interface cards, connectivity problems,
417-419
network interfaces, ISC DHCP client customiza-
tions, 369
Network News Transport Protocol (NNTP), 55
network numbers for IP addresses, 46-47
network segments
declarations in server configuration file (ISC
DHCP), 233
multiple
relay agent configuration, 259
servicing, 258-263
subnets, configuring, 266-272
network services
adding
pre-DHCP development, 6
via DHCP, 11
describing via DHCP, 10
Network Time Protocol (NTP), 55
networks
architecture, specifying to DHCP servers,
29-32
devices, when not to use DHCP, 14
infrastructure failure, 294-295
failed relay agents, 295
misconfigured relay agents, 295
ISC DHCP server, configuring, 240
large configurations, DHCP benefits, 8
new IP addresses, moving, 115-116
self-discovering, 64
small configurations, DHCP benefits, 9
topologies, small office architectures, 382-383
IP address translation, 383-384
New Scope Wizard, lease times, 446
next-server statement, 495
NIS domain option (NIS service options), 148
NIS server addresses option (NIS service
options), 148
NIS+ domain option (NIS service options), 148
NIS+ server addresses option (NIS+ service
options), 148
NNTP (Network News Transport Protocol), 55
nodes (IPv6), 432
nonlocal source routing option (TCP/IP stack
configuration parameters), 137
NORMAL state, failover protocol operational
state, 166-168
not exists operator (DNS), 485
not operator (Boolean), 480
ns-update operator (numeric), 484
NSQ BROADCAST option (NetWare Directory
Services), 154
NTP (Network Time Protocol), 55, 145
NTTP (Network News Transport Protocol) server
option (NIS service options), 146
null operator (indeterminate), 479
numeric operators, 484
NWIP 1.1 option (NetWare Directory Services),
155
NWIP DOES NOT EXIST option (NetWare
Directory Services), 152
NWIP EXIST BUT TOO BIG option (NetWare
Directory Services), 153
NWIP EXIST IN OPTIONS option (NetWare
Directory Services), 153
NWIP EXIST IN SNAME FILE option (NetWare
Directory Services), 153
O
obtaining
IP addresses for ISC DHCP client, 355-356
ISC DHCP server, 223-224
Network Information Service574
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OMAPI protocol
ISC DHCP client, controlling via interface,
372-374
ISC DHCP server
configuring, 239
PARTNER-DOWN state (failover problems),
316
omapi-key statement, 493
omapi-port statement, 493
on statement, 477
op field, DHCP fixed-format message section, 71
Open Shortest Path First (OSPF), 54
operational states, failover protocol
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
operators
Boolean
and, 480
defined, 480
exists, 480
known, 480
not, 480
or, 480
static, 479
data
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
DNS
add, 485
delete, 485
exists, 485
not exists, 485
indeterminate
null, 479
variable, 479
numeric
client-state, 484
extract-int, 484
lease-time, 484
ns-update, 484
number, 484
option definition, 496
arrays, 498
boolean type, 497
integer type, 497
ip-address type, 497
records, 498
string type, 497
text type, 497
option operator (data), 482
option overload option (DHCP-specific options),
130
option scoping
overlay networks, 267
shared networks, 267
option scoping 575
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