Index
Note to the reader: Throughout this index boldfaced page numbers indicate primary discussions of a topic. Italicized page numbers indicate illustrations.
Symbols and Numbers
* (asterisk)
in show session results, 273
in show user results, 274
? (question mark), for help, 173
2.4GHz/5GHz (802.11n), 416–417
2.4GHz bands (802.11b), 409, 412–413
2.4GHz bands (802.11g), 413–414, 414
10Base-5, 39
10Base-FX, 42
10GBase-ER, 42
10GBase-EW, 43
10GBase-Extended Range (ER), 41
10GBase-Extra Long Wavelength (EW), 41
10GBase-Long Range (LR), 41
10GBase-Long Wavelength (LW), 41
10GBase-LR, 42
10GBase-LW, 43
10GBase-Short Range (SR), 41
10GBase-Short Wavelength (SW), 41
10GBase-SR, 42
10GBase-SW, 43
40MHz channels, for 802.11n, 416–417
100Base-FX (IEEE 802.3u), 40, 42
100Base-TX (IEEE 802.3u), 40, 42
900MHz bands, 409
1000Base-CX (IEEE 802.3z), 40, 42
1000Base-LX (IEEE 802.3z), 40, 42
1000Base-SX (IEEE 802.3z), 40, 42
1000Base-T (IEEE 802.3ab), 40, 42
A
access points, 417
Acknowledgment Number field, in TCP header, 77
acknowledgments, 21
active console, listing all, 273
active hub, 27
active processes, list of, 284
AD. See administrative distance (AD)
ad hoc service set (IBSS), 417
address learning, by layer 2 switches, 387, 388–389, 389
Address Resolution Protocol (ARP), 51, 92, 92–93
broadcast message from, 103
viewing, 306
administrative distance (AD), 329, 342–343
default, 342
for directly connected routes, 340
advertising
default route using RIP, 365–367
RIP network, limiting, 354
agencies, governing use of wireless technology, 409
agents, 71
AirSnort, 421
anonymous username, for FTP, 69
antennas, 416
anti-x, 435
Application layer (OSI), 15
common attack profiles, 432
application-specific integrated circuit (ASIC), 25
arp -a command, 142
ARP (Address Resolution Protocol), 51, 92, 92–93
broadcast message from, 103
viewing, 306
ARP request, 312
ARPAnet, 79
asterisk (*)
in show session results, 273
in show user results, 274
asynchronous transfer mode (ATM), 454
attenuation, 39
in PPP, 461
TACACS server for, 183
authentication login, in FTP, 69
Authentication phase, in PPP session, 461
autodetect mechanism, 32
Automatic Private IP Addressing (APIPA), 74
autonomous system (AS), 341
autorooters, 433
aux parameter, for line command, 183
auxiliary password, 184
auxiliary port, for Cisco router connection, 164
B
back doors, 433
back up
Cisco Internetwork Operating System (IOS), 245–246
Cisco router configuration, 252–254
backbone, collapsed, 382
backoff, 31
bandwidth, 456
layer 2 switching and, 386
baseline, for SNMP, 71
basic service set (BSS), 418, 418
beaconing, 420
IP address format, 96
memorization chart for converting to decimal, 34
binding, 12
in configuration register, 234–236
block acknowledgment, 417
boot field, 236
boot process, for router, 166
boot sequence
bootloader, 233
bootstrap, 234
in Cisco router, 232
Bootstrap Protocol (BootP), 73
Border Gateway Protocol (BGP), 341
bottlenecks, 18
routers and switches as, 10
Bridge-Group Virtual Interface (BVI), 326
for connecting to mainframe, 382–385
vs. LAN switching, 387
in OSI model, 14
bridging, 7
broadcast address, 95, 102–103, 144
for Class C subnet, 121, 124, 128
for MAC address, 4
routers for breaking up, 6, 23
size, and performance, 386
broadcasting routing updates, 345
brute-force attack, 434
BSS (basic service set), 418, 418
buffer, 18
Buffer Full/Source Quench event, 89
BVI (Bridge-Group Virtual Interface), 326
byte-oriented protocols, 458
C
cabling
for wide area network, 455–457
cache
Address Resolution Protocol (ARP), 304
viewing, 306
of host table information, 278
call setup, 17
call termination, 17
Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA), 412–413, 413
Carrier Sense Multiple Access with Collision Detection (CSMA/CD), 29–31, 30
cd command, 249
CDP. See Cisco Discovery Protocol (CDP)
CDP holdtime, 258
CDP timer, 258
central office (CO), 451
Challenge Handshake Authentication Protocol (CHAP), 461
channel service unit/data service unit (CSU/DSU), 27, 451, 456
channels, non-overlapping, 414
CHAP (Challenge Handshake Authentication Protocol), 461
character
in command-line interface, deleting, 176
delimiting, for banner, 181–182
Checksum field
in TCP header, 77
in UDP segment, 80
circuit-switched WAN connection type, 452, 452
Cisco 1841 router, 165, 165, 314
Cisco 2500 router, 193
changing configuration register on, 240–241
Cisco 2600 series modular router, 164, 164
Cisco 2800/2900 series modular router, 164, 165
Cisco 2811 router, 314
Cisco 2950 switch, and connection, 392
Cisco 2960 switch, 392
Cisco 3550 switch, and connection, 392
Cisco 3560 switch, 392
Cisco Adaptive Security Appliance (ASA), 435, 441
Cisco Catalyst switches, 392–398, 393
Core switch configuration, 396–398
verifying port security, 439
Cisco Discovery Protocol (CDP), 258–270
documenting network topology using, 267, 267–269, 269
Cisco Hot Standby Router Protocol (HSRP), 95
Cisco Internetwork Operating System (IOS), 162
back up and restoring, 243–252
restoring or upgrading, 246–247
seeing size, 250
Cisco IOS file system (Cisco IFS), 247–252
for managing router configuration, 256–257
automatic configuration of clock rate, 322
command to change bit value, 240
default username and password, 163
erase start command and, 319
interface configuration, 194
Cisco routers, 5
Cisco IFS for managing, 256–257
erasing, 255
restoring, 254
verifying current, 252
editing and help features, 173–178
power-on self-test (POST), 165
PPP configuration on, 462
proprietary 60-pin serial connector, 456
reloading to run new IOS, 251
as TFTP server for another router, 247
web resources, 165
Cisco Unified Wireless Solution, 408
Cisco way of troubleshooting IP addressing, 140
Class A network, 97
valid host IDs, 100
addresses, 100
in your head, 136
fast way, 121
in your head, 128
Class D network, 98
Class E network, 98
Cisco routers as, 339
in RIP version 1, 347
RIPv2 and, 356
Classless Inter-Domain Routing (CIDR), 118–120
classless routing, 116, 127, 347
RIPv2 as, 356
clear counters command, 209–210
clear-text passwords, 436
client, 71
access point support for multiple, 412
verifying with ipconfig command, 326
client MAC addresses, 421
clock rate, setting, 322
closing Telnet sessions, 274
CO (central office), 451
Code Bits/Flags field, in TCP header, 77
code formatting, in Presentation layer, 15
collapsed backbone, 382
collision domains, 7, 10, 28–29, 382
breaking up, 5
bridge to increase number of, 8
switch to break up, 9
collision, on Ethernet LAN, 30
command-line interface (CLI), 162, 169–179
entering, 169
interfaces, 171
line commands, 172
subinterfaces, 172
for troubleshooting, 140
command.com, viruses attached to, 434
commands
listing available, 173
listing parameters for, 174
negating, 178
communications port, for router or switch, 45
company network, before Internet, 384
confidentiality, encryption and, 442
config net command, 257
config-register command, 237, 240
configuration
hostnames, 180
copying to TFTP server, 254
restoring, 254
verifying current, 252
in NVRAM, 253
viewing and changing, 241
configuration mode, viewing configuration and statistics from within, 192
configuration register, 234–243
checking current value, 236
configure terminal command, 170
confreg command, 240
congestion, 18
connection-oriented communication, 16, 17–19, 18, 76
characteristics of service, 19
in Transport layer, 50
connectionless communication, 16
connectionless protocol, 79
connections
wide area network (WAN) types, 452–453
console connection, HyperTerminal for, 45–46
console EXEC session, timeout for, 185
console parameter, for line command, 183, 184
for Catalyst switch, 392
copy flash tftp command, 244, 245–246
copy running-config startup-config command, 201–202
copy running-config tftp command, 252, 254
copy startup-config running-config command, 254
copy startup-config tftp command, 252
copy tftp flash command, 246
copy tftp running-config command, 254–255
copying
running-config file to NVRAM, 201
startup-config to running-config file, 241
Corp router configuration
Counter Mode Cipher Block Chaining-Message Authentication Code (CBC-MAC) Protocol (CCMP), 422
counters on interfaces, clearing, 209–210
counting to infinity issue, 346
CPE (customer premises equipment), 451
CPU (central processing unit), utilization output, 284
CRC (Cyclic Redundancy Check), 38, 51, 305, 306
between switches, 393
crosstalk, 39
CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance), 412–413, 413
CSMA/CD (Carrier Sense Multiple Access with Collision Detection), 29–31, 30
CSU/DSU (channel service unit/data service unit), 27, 451, 456
cursor movement, in command-line interface, 175–176
customer premises equipment (CPE), 451
cyclic redundancy check (CRC), 38, 51, 305, 306
D
data communication equipment (DCE), 27, 456–457, 457
serial interface for, 322
data encapsulation, 47–51, 48, 457–458
PPP, 462
Data field, in UDP segment, 80
data frame, 24
data link connections, 459
Data Link layer (OSI), 24, 24–27, 304, 306, 307
802.11b and, 412
data links, leasing, 450
data packets, 22
data terminal equipment (DTE), 27, 456–457, 457
Cisco routers' serial interfaces as, 198–199, 199
data transfer, outer layers to define, 14
data translation, in Presentation layer, 15
datagrams, 48
DCE (data communication equipment), 27, 456–457, 457
serial interface for, 322
de-encapsulation, 48
debug all command, 282
debug ip rip command, 283–284, 360–363
decimal numbering, memorization chart for converting binary to, 34
dedicated WAN connection type, 452
default administrative distance (AD), 342
default answer, for configuration question, 202
default gateway, 141, 144, 304, 307
on switches, 398
misconfiguring, 340
default subnet mask, 118
default variables for ping, changing, 204
deleting
character in command-line interface, 176
startup-config file, 255
delimiting character, for banner, 181–182
demilitarized network (DMZ), 431
Denial-of-Service (DoS) attacks, 433
Department of Defense (DoD), 66. See also DoD model
Destination Address (DA) field, in Ethernet frames, 37
destination hardware address, 50
destination IP address, 304, 309
Destination IP Address field, in IP header, 88
destination MAC address, of frames, 309
Destination Port field
in TCP header, 77
in UDP segment, 80
destination port number, 50
destination unreachable message, 89, 308
DHCP (Dynamic Host Configuration Protocol), 73–74
address conflicts, 75
configuration on router, 326–327
connection, 74
verifying pool, 326
dial-up modems, 452
digital subscriber line access multiplexer (DSLAM), 454
digital subscriber line (DSL), 454
direct connection for network, C indicator for, 318
Direct Sequence Spread Spectrum (DSSS), 413
directories, changing, 249
disable command, 169
disabling
debugging, on router, 283
interfaces, 195
disconnect command, 274
discontiguous networks
RIPv1 and, 352
Discover message (DHCP), 73
distance-vector routing
internetwork with, 344
protocols, 343–347. See also Routing Information Protocol (RIP)
Distributed Denial-of-Service (DDoS) attacks, 433
DMZ (demilitarized network), 431
do command, 192
documentation, of network topology using CDP, 267, 267–269, 269
Host-to-Host layer protocols, 75–85
Internet layer protocols, 85–95
vs. OSI model, 67
Process/Application layer protocols, 68–75
domain name, for SSH, 186
Domain Name Service (DNS), 3, 72
ping to test server, 278
DoS (Denial-of-Service) attacks, 433
dotted-decimal format for IP address, 96
DSL (digital subscriber line), 454
DSLAM (digital subscriber line access multiplexer), 454
DSSS (Direct Sequence Spread Spectrum), 413
DTE (data terminal equipment), 27, 456–457, 457
Cisco routers' serial interfaces as, 198–199, 199
Dynamic Host Configuration Protocol (DHCP), 73–74
address conflicts, 75
configuration on router, 326–327
connection, 74
verifying pool, 326
dynamic NAT, 149
E
echo request payload, 303
editing
negating command, 178
EEPROM (electronically erasable programmable read-only memory), 165, 233
EGPs (exterior gateway protocols), 341
EIA/TIA-232-C, in PPP, 460
EIGRP (Enhanced Interior Gateway Routing Protocol), 22, 343
default administrative distance (AD), 342
Electronic Industries Association, 39
electronically erasable programmable read-only memory (EEPROM), 233
employees, as security risk, 432
enable command, 169
enable secret password, 182
Encapsulating Security Payload (ESP), 442
encapsulation, 47–51, 48, 457–458
PPP, 462
encapsulation ? command, 453
encryption
confidentiality and, 442
encryption keys, for SSH, 187
Enhanced Interior Gateway Routing Protocol (EIGRP), 22, 343
default administrative distance (AD), 342
erase command, 249
erase start command, ISR routers and, 319
erase startup-config command, 202, 255, 316
erasing
Cisco router configuration, 255
line in command-line interface, 176
error messages
destination unreachable, 89, 308
Invalid input detected, 175
request timed out, 308
Serial0/0 is up, line protocol is down, 464
ESP (Encapsulating Security Payload), 442
ESS (extended service set), 417, 419, 419
Ether-Type field, 305
Ethernet II frame format, 37
broadcast domains, 29
half-duplex and full-duplex, 31–32
ETSI (European Telecommunications Standards Institute), 409
European Telecommunications Standards Institute (ETSI), 409
exclusions, for DHCP server, 326
exec banner, 182
exec process creation banner, 181
EXEC session, 163
exec-timeout command, 185
exit interface, 22, 49, 334–335
expiration of passwords, 436
exponent, 117
extended ping, 204
extended service set (ESS), 417, 419, 419
exterior gateway protocols (EGPs), 341
external EIGRP, default administrative distance (AD), 342
extranet VPNs, 441
F
Fast Ethernet, 384
FCS (Frame Check Sequence) field, 305
in Ethernet frames, 38
FDDI (Fiber Distributed Data Interface), 33
Federal Communications Commission (FCC), 409
file prompt command, 248
file systems, Cisco IFS, 247–252
File Transfer Protocol (FTP), 69, 205
as attack risk, 432
real world scenario, 70
filter table, 26
firewall, 431
Flags field, in IP header, 87
flash cards, for ISR routers, 252
flash memory, 165
in Cisco router, 233
loading Cisco IOS from, 234
flow control
transmitting segments with, 19
Transport layer for, 17
format command, 249
forward/filter decisions, 389–391
forward/filter table, 387, 388
FQDN (fully qualified domain name), 72, 277
Fragment Offset field, in IP header, 87
Frame Check Sequence (FCS) field, 305
in Ethernet frames, 38
frame filtering, 390
at Data Link layer, 36
destination MAC address of, 309
frequency bands, unlicensed, for public use, 409–410, 410
FTP (File Transfer Protocol), 69, 205
as attack risk, 432
real world scenario, 70
full-duplex mode for communication, 16, 31–32
fully qualified domain name (FQDN), 72, 277
G
G/L bit (global/local bit), 33
gateway of the last resort, 338, 339
configuration, 339
GETBULK, 71
Gigabit Ethernet, 40
Gigabit Media Independent Interface (GMII), 40
global command, 172
global configuration mode, 170, 173
global/local bit (G/L bit), 33
global NAT addresses, 150
GMII (Gigabit Media Independent Interface), 40
graphical user interface (GUI), X Window for, 71
gratuitous ARP, 75
guest-mode line, 326
H
half-duplex mode for communication, 16, 31–32, 408
hardware address, 3–4, 25, 32, 86. See also MAC (Media Access Control) addresses
hardware broadcasts, 103
HDLC (High-Level Data-Link Control), 454, 457–459
frame format, 458
in PPP, 460
Header Checksum field, in IP header, 88
Header Length field
in IP header, 87
in TCP header, 77
help, global configuration mode for, 186
hertz, 456
hexadecimal addressing, 35–36, 96, 235
High-Level Data-Link Control (HDLC), 454, 457–459
frame format, 458
in PPP, 460
HMAC-SHA-1 algorithm, 442
holddown, 347
holddown timer, 348
hop, 343
incrementing, 353
maximum, 346
RIP use of, 347
Hops/Time Exceeded event, 90
host address, 96
vs. DNS server, 279
removing hostname from, 277
Host-to-Host layer (DoD), 67
Transmission Control Protocol (TCP), 76–78
User Datagram Protocol (UDP), 78–79
hostname command, 180, 186, 462
hostname resolution, 72, 274–278
hostnames
removing from host table, 277
show sessions for displaying, 276
for SSH, 186
Hot Standby Router Protocol (HSRP), 95
HTTP (Hypertext Transfer Protocol), 205
as attack risk, 432
HTTPS server, sending data to, 310
hub network, 382
as layer 2 switches, 388
in OSI model, 14
vs. switches, 27
hybrid protocols, 343
HyperTerminal
Ctrl+Break to interrupt boot sequence, 239
IBSS (independent basic service set), 417, 418, 418
ICMP. See Internet Control Message Protocol (ICMP)
Identification field, in IP header, 87
IDSs (intrusion detection systems), 435
IEEE (Institute of Electrical and Electronics Engineers), 409
802.1AB for Station and Media Access Control Connectivity Discovery, 270
specifications, 24
IEEE 802.1AB for Station and Media Access Control Connectivity Discovery (IEEE), 270
IEEE 802.3 Ethernet, 31
frame format, 37
IEEE 802.3u (Fast Ethernet), 40
IEEE 802.11
committees and subcommittees, 411–412
comparing 802.11a, b, and g, 415
product certification for interoperability, 410
IEEE 802.11a standard, 414
IEEE 802.11b standard, 412
disabling, 416
IEEE 802.11g standard, 412, 413–414, 414
IEEE 802.11i standard, 422
IEEE 802.11n standard, 416–417
IGRP (Interior Gateway Routing Protocol), default administrative distance (AD), 342
IMAP, 71
in-band, 164
incoming terminal line banner, 181, 182
independent basic service set (IBSS), 417, 418, 418
Industrial, Scientific, and Medical (ISM) bands, 409
inside global address, 150
int serial command, 193
Integrated Services Router (ISR), 164, 165
automatic configuration of clock rate, 322
command to change bit value, 240
default username and password, 163
erase start command and, 319
interface configuration, 194
interface command, 171
interface configuration mode, 171
interface ethernet command, 193
interfaces, 171
checking status, 195
configuration on router, 320
configuring IP address on, 196–197
disabling, 195
enabling, with no shutdown command, 255
gathering traffic information, 264
output modifier (|; pipe), 197–198
in routing table, 22
verifying statistics, 205
interference, 802.11a/g immunity to, 414
interior gateway protocols (IGPs), 341
Interior Gateway Routing Protocol (IGRP), default administrative distance (AD), 342
International Organization for Standardization (ISO), 11
Internet
company network before, 384
router processing of packets, 365–367
and security, 432
Internet Control Message Protocol (ICMP), 89, 89–92, 91, 303, 306, 310–311
error example, 310
Internet layer (DoD), 67
Internet layer (DoD) protocols, 85–95
Address Resolution Protocol (ARP), 51, 92, 92–93
broadcast message from, 103
Internet Control Message Protocol (ICMP), 89, 89–92, 91
Proxy Address Resolution Protocol (Proxy ARP), 94
Reverse Address Resolution Protocol (RARP), 93–94, 94
Internet Protocol (IP), 22, 86–87, 303–304
internetwork, 7
devices, 8
with distance-vector routing, 344
router in, 23
routers for creating, 6
Internetwork Operating System (IOS), 162
back up and restoring, 243–252
restoring or upgrading, 246–247
seeing size, 250
Internetwork Packet Exchange (IPX), 22
intranet VPNs, 441
intrusion detection systems (IDSs), 435
intrusion prevention systems (IPSs), 435, 436
“Invalid input detected” error message, 175
invalid timer, 348
IOS. See Internetwork Operating System (IOS)
IP, 22
ip address command, 196
IP addressing, 86
assigning to hosts, 73
basic IP routing using, 311
configuring on interface, 196–197
domain name and, 72
terminology, 95
problem determination, 143–148
ip classless command, 338, 339
ip default-gateway command, for managing switches, 398
ip default-network command, 339, 340, 341, 367
ip domain-lookup command, 277
ip domain-name command, 72, 186, 277
ip host command, 275
IP (Internet Protocol), 22, 86–87, 303–304
ip name-server command, 277
ip route command, syntax, 328
configuration
interfaces for Corp router, 316–318
network addresses, 315
R1 router configuration, 318–322
R2 router configuration, 322–324
R3 router configuration, 325–326
configuration in network, 327–343
Corp router static routes, 330–331
R1 router static routes, 331–332
R2 router static routes, 332–333
R3 router static routes, 334–335
testing understanding of, 309–313
IP spoofing, 433
IP stack failure, 140
ip subnet-zero command, 115–116
ipconfig /all command, 142
ipconfig command, 337
verifying client with, 326
IPsec, 442
IPSs (intrusion prevention systems), 435, 436
IPv6, 22
IPX (Internetwork Packet Exchange), 22
ISDN, 452
in PPP, 460
ISM (Industrial, Scientific, and Medical) bands, 409
ISO (International Organization for Standardization), 11
automatic configuration of clock rate, 322
command to change bit value, 240
default username and password, 163
erase start command and, 319
interface configuration, 194
K
keepalives, 208
kernel, 163
keystroke loggers, 434
L
LAN. See local area network (LAN)
laptop, Ethernet port directly connected to router interface, 244
large files, FTP for sending, 70
last-resort parameter, for enable password, 183
latency, 25
Layer 2 broadcasts, 103
address learning by, 388–389, 389
features, 386
Layer 3 broadcasts, 103
layer 3 switches, routers as, 7
layered approach to internetworking models, 11–12
layers, seeing status of each interface, 211
LCP (Link Control Protocol), 459
in PPP, 460
leased lines, 452
leasing data links, 450
Length field
in Ethernet frames, 38
in UDP segment, 80
line-activation (exec) banner, 182
line console command, 172
line in command-line interface, erasing, 176
Line Printer Daemon (LPD), 71
line vty command, 185
Link Control Protocol (LCP), 459
in PPP, 460
Link Establishment phase, in PPP session, 461
Link Layer Discovery Protocol (LLDP), 270
link-state protocols, 343
local area network (LAN), 3. See also virtual LANs (VLANs)
assign server and router IP addresses, 145
bridging vs. switching, 387
first switched, 384
open access mode for wireless products, 420
switching vs. hub-centered implementations, 27
local device, ending session from, 274
local loop, 451
DSL connections in, 454
local NAT addresses, 150
logging synchronous command, 185
logical addressing, 48, 50, 86
logical interfaces, 206
Logical Link Control (LLC) 802.2 sublayer, 25
login command, 184
login, disabling accounts after unsuccessful attempts, 436
logout command, 169
loop avoidance, 387
loopback address, 140
loops, default routing on, 338
M
MAC database, 387
MAC frame format, 37
MAC (Media Access Control) addresses
assigning to switch port, 391
basic IP routing using, 311
client, 421
in filtering table, 388
MAC (Media Access Control) authentication, 420
mainframes, bridges for connecting to, 382–385
major command, 172
man-in-the-middle WLAN attacks, 421, 434
management interface, 395
maximum hop count, 346
maximum transmission time (MTU), 207
MD5 hash function, 461
Media Access Control (MAC) 802.3 sublayer, 25
Ethernet addressing using, 32
Media Access Control (MAC) address, 3–4
Media Access Control (MAC) authentication, 420
Media Independent Interface (MII), 40
memorization, slash notation (/), 129–130
message of the day (MOTD) banner, 181
metric, in routing table, 22
microsegmentation, 385
MII (Media Independent Interface), 40
MIMO (multiple-input multiple-output), 416
mini-IOS, in Cisco router, 233
mkdir command, 249
mobile devices, as security risk, 432
modems, dial-up, 452
more command, 248
MOTD (message of the day) banner, 181
MTU (maximum transmission time), 207
multicast address, 98, 103, 104
multilayer switches, security features, 431
multiple-input multiple-output (MIMO), 416, 417
multiplexing, spatial, 417
multiport bridges, 7
layer 2 switch as, 385
N
name, for routers, 180
name resolution, 3
troubleshooting, 142
native VLAN, 395
NCP (Network Control Protocol), 459, 461
in PPP, 460
negating command, 178
neighbor
gathering information, 259–264
IOS version of, 262
Network layer address, 203
neighbor routers, 301
NetWare servers, 383
Network Access layer (DoD), 68
Network Address Translation (NAT), 101, 148, 148–152
advantages and disadvantages, 149
global addresses, 150
types of, 149
in routing table, 22
network analyzer, output for name resolution process, 4
network command, 348
Network Control Protocol (NCP), 459, 461
in PPP, 460
Network File System (NFS), 70
network interface card (NIC), troubleshooting, 141
Network layer (OSI), 22–24, 48, 306
address of neighbor, 203
logical addressing, 50
Network Layer Protocol phase, in PPP session, 461
network loops, and redundancy, 387
network reconnaissance, 434
networks
best design, 10
documenting topology using CDP, 267, 267–269, 269
before layer 2 switching, 382–385, 383
segmentation, 4
switched design, 385
troubleshooting connectivity, 279–285
with ping command, 280
with show processes command, 284–285
with traceroute command, 280–282
next-hop router, 338
NFS (Network File System), 70
NIC (network interface card), troubleshooting, 141
no auto-summary command, 358
no cdp enable command, 265
no debug all command, 283
no ip domain-lookup command, 277
no ip host command, 277
no shutdown command, 195–196, 208, 315
to enable port, 392
for enabling interface, 255
node address, 96
non-ISR router, bringing up, 167–169
non-overlapping channels, 414
“not ready” indicator, 19
Novell, 383
numbering system, conversion, 35–36
NVRAM (nonvolatile RAM), 165, 233
in Cisco router, 233
seeing contents, 256
verifying configuration, 253
O
o/r command, 240
OFDM (Orthogonal Frequency Division Multiplexing) modulation, 413
open access mode, for wireless LAN products, 420
open authentication, 421
Open Shortest Path First (OSPF), 22, 356
default administrative distance (AD), 342
Open Systems Internconnection (OSI) reference model, 11–28
advantages, 12
Application layer, 15
vs. DoD model, 67
layer functions, 14
lower layers, 14
PPP stack vs., 460
Session layer, 16
upper layers, 13
Options field
in IP header, 88
in TCP header, 78
organizationally unique identifier (OUI), 32–33
Orthogonal Frequency Division Multiplexing (OFDM) modulation, 413
OSI. See Open Systems Internconnection (OSI) reference model
OSPF (Open Shortest Path First), 22, 356
default administrative distance (AD), 342
out-of-band, 164
output modifier (|; pipe), 197–198
overhead, 17
P
packet filtering, 7
Packet Internet Grouper (Ping). See ping (Packet Internet Grouper)
packet sniffers, 434
packet-switched WAN connection type, 452
destination IP address of, 309
PAP (Password Authentication Protocol), 461
parallel transmission, 455
passive-interface command, 354
passphrase, 421
password attacks, 434
Password Authentication Protocol (PAP), 461
auxiliary, 184
clear-text, 436
mitigating security threats, 436–437
in plain-text configuration file, 437
strong, 436
user-mode, for Telnet, 185
performance
broadcast domain size and, 386
of routers, debug all command and, 282, 284
physical interfaces, 206
displaying information about, 211
Physical layer (OSI), 27–28, 51, 305
Ethernet networking at, 38–43, 39
output from problem, 208
physical star network, 28
ping of death attacks, 433
ping (Packet Internet Grouper), 72, 90, 91, 396
for DHCP conflicts, 75
extended, 204
to test connectivity, 279, 280
to test DNS server, 278
TFTP device from router console, 245
for troubleshooting, 140
unreachable network and, 362
to verify configuration, 203, 336
PoE (Power over Ethernet), 392
point of presence (POP), 451
point-to-point connection, 452
Point-to-Point Protocol (PPP), 454, 458, 459–464
authentication, 461
configuration on Cisco router, 462
configuring authentication, 462–463
session establishment, 460–461, 461
stack vs. OSI layer, 460
verifying encapsulation, 463–464
poison reverse, 347
populating forward/filter table, 389, 390
Port Address Translation (PAT), 149, 150, 151
port numbers, for TCP and UDP, 81–85, 82
port redirection attacks, 434
port security, 391–392, 437–438
ports
gathering information, 264–266
numbers at Transport layer, 50
security for unused, 440
setting for rolled cable connection, 46
positive acknowledgment with retransmission, 21
Post Office Protocol version 3 (POP3), 71
POST (power-on self-test), 232
in boot sequence, 233
power-on self-test (POST), 232
for Cisco switch, 392
Power over Ethernet (PoE), 392
Powers of 2, 117
PPP (Point-to-Point Protocol), 454, 458, 459–464
authentication, 461
configuration on Cisco router, 462
configuring authentication, 462–463
session establishment, 460–461, 461
verifying encapsulation, 463–464
Pre-Shared Key (PSK), 421
Preamble field, in Ethernet frames, 37
prefix routing, 347
Presentation layer (OSI), 15–16
printer sharing, Line Printer Daemon for, 71
printing, working directory, 249
Priority field, in IP header, 87
privileged EXEC mode, 172
entering, 241
for ping, 280
Telnet and, 272
Process/Application layer (DoD), 67
Process/Application layer (DoD) protocols, 68–75
Automatic Private IP Addressing (APIPA), 74
Domain Name Service (DNS), 3, 72
Dynamic Host Configuration Protocol (DHCP), 73–74
address conflicts, 75
configuration on router, 326–327
connection, 74
verifying pool, 326
File Transfer Protocol (FTP), 69, 205
as attack risk, 432
real world scenario, 70
Line Printer Daemon (LPD), 71
Network File System (NFS), 70
Secure Shell (SSH), 72
Simple Mail Transfer Protocol (SMTP), 70–71
Simple Network Management Protocol, 71
Simple Network Management Protocol (SNMP), 79
checking connections, 273
for Cisco router connection, 164
closing sessions, 274
ending connection, 272
into multiple devices simultaneously, 272
user-mode passwords for, 185
Trivial File Transfer Protocol (TFTP), 69–70
routers booting from host, 242
X Window, 71
promiscuous mode, 434
propagation, holding down RIP, 354–355
proprietary HDLC implementation, 458
Protocol Data Units (PDUs), 47
and layer addressing, 49
Protocol field, in IP header, 87, 88
Proxy Address Resolution Protocol (Proxy ARP), 94
public IP addresses, NAT to decrease, 148
public use, unlicensed frequency bands for, 409–410, 410
pwd command, 249
Q
question mark (?), for help, 173
R
RAM (random access memory)
in Cisco router, 233
seeing contents, 256
range command, 440
rate shifting, 412
read-only memory (ROM), in Cisco router, 233
recovery, of passwords, 235, 238–239
redistribution, 355
redundancy, and network loops, 387
reference model, 11
software developers use of, 12
registered jack (RJ) connector, 39
Registry (Windows), 307
reliable networking, 16
remote access VPNs, 441
remote device
ending session from, 274
telnet into, 272
remote network, computing distance for, 22
removing hostname, from host table, 277
repeaters, 27
in OSI model, 14
Request for Comments (RFC), 79
768, on UDP, 79
791, on IP, 86
1661, on PPP, 458
request timed out message, 308
request to send, clear to send (RTS/CTS), 413
reserved IP addresses, 98–99, 101
resolving hostnames. See hostname resolution
restoring
Cisco router configuration, 254
retransmission delay, after collision, 31
retransmission, positive acknowledgment with, 21
Reverse Address Resolution Protocol (RARP), 93–94, 94
reverse Telnet, banner for terminals connected to, 182
RF spectrum, unlicensed bands in, 410
RIP version 2 (RIPv2), 22
RJ-45 connector, 163
rmdir command, 249
port setting for connection, 46
ROM monitor, in Cisco router, 233
ROM monitor mode, 240
ROM (read-only memory), in Cisco router, 233
rootkit, 433
route flush timer, 348
route poisoning, 347
route update packets, 22
router-command history, reviewing, 176–177
Router (config-if)# prompt, 171
Router (config-line)# prompt, 172
Router (config-subif)# prompt, 172
router console, pinging TFTP device from, 245
router modes, overview, 170
Router# prompt, 169
Router> prompt, 169
router prompt, 248
router rip command, 348
router rip global command, 360
administrative configurations, 179–182
hostnames, 180
advantages, 6
mitigating security threats, 436–437
need for inter-VLAN communication, 9
network locations and, 25
routing
gathering basic information, 178–179, 301
routing by rumor, 343
Routing Information Protocol (RIP), 22, 341, 347–357
advertising default route using, 365–367
default administrative distance (AD), 342
and discontiguous networks, 352
holding down propagation, 354–355
timers, 348
verifying routing tables, 351–353
v1 vs., 356
administrative distance (AD), 329, 340, 342–343
classes, 343
and dynamic routing, 341
routing table, 7, 23, 301, 311
codes for, 318
converged, 345
manually adding routes, 327
viewing, 318
RSA algorithm, 442
copying startup-config to, 241
copying to NVRAM, 201
RXBOOT, 233
S
scalability, RIP v1 vs. v2, 356
scrolling, in command-line interface, 176
SDLC (Synchronous Data Link Control), 454
secondary parameter, for ip address command, 196
secret parameter, for enable password, 183
Secure Shell (SSH), 72
SecureCRT, 239
security
common attack profiles, 432–435
for unused ports, 440
for wireless technology, 419–422
segment, 47
segmentation, 384
sendmail, as attack risk, 432
Sequence Number field, in TCP header, 77
serial interface
indication of problem, 208
for WAN connections, 6
serial transmission, for WAN connections, 455–456
Serial0/0 is up, line protocol is down message, 464
service password-encryption command, 188–189, 190, 437, 462
Service Set ID (SSID), 417, 420
setting access points to same, 419
Session layer (OSI), 16
setup command, 168
for router configuration, 168
shared-key authentication, 421
shortest-path-first protocols, 343
show cdp entry * command, 262–264
show cdp entry * protocol command, 203, 263
show cdp entry * version command, 263
show cdp interface command, 264–266
show cdp neighbor command, 259, 269
show cdp neighbor detail command, 260–262, 267
show cdp traffic command, 264
show controllers command, 200, 211–213, 212
displaying clock rate, 322
show file command, 248, 250, 251, 256
show flash command, 238, 244, 250
show history command, 176
show hosts command, 275–276, 278
show interface command, 179, 190, 196, 205–210, 459
for verifying PPP configuration, 463–464
show interface fastethernet command, 206–207
show interfaces command, 195
show ip dhcp binding command, 326
show ip interface brief command, 179, 210–211, 360
to verify switch configuration, 398
show ip interface command, 210, 212
show ip protocols command, 358–360, 364–365
show ip route command, 302–303, 311, 318, 321, 330–331
output, 323
for troubleshooting, 279
show mac address-table command, 390–391
show port-security command, 439
show processes command, 284–285
show protocols command, 211
show run command, 462
show running-config command, 190, 195, 196, 202
for documenting network topology, 267–268
password visibility, 188
to verify configuration, 252, 398
for viewing interface description, 190
show sessions command, 273, 276
show startup-config command, 202
show terminal command, 177
show users command, 273
show version command, 178–179, 236, 237–238, 245
Simple Mail Transfer Protocol (SMTP), 70–71
Simple Network Management Protocol (SNMP), 71, 79
simplex mode for communication, 16
site-to-site VPNs, 441
sniffer, 434
software address, 86
software, configuration meanings, 235
Source Address (SA) field, in Ethernet frames, 37
Source IP Address field, in IP header, 88
Source Port field
in TCP header, 77
in UDP segment, 80
source port, numbers for multiple hosts communicating to server, 309
spanning-tree, 392
Spanning Tree Protocol (STP), 387
spatial multiplexing, 417
special purpose IP address, 98–99
specific configuration mode, 173
split horizon, to solve routing loop problem, 346–347
squeeze command, 249
SSID (Service Set ID), 417
configuration, 326
Stacheldraht attack, 433
Start Frame Delimiter (SFD/)Sync field, in Ethernet frames, 37
startup-config file, 167, 168, 201, 234
copying to running-config file, 241
deleting, 202
state transitions, 27
static IP addressing, 75
static NAT, 149
benefits, 327
configuration
default administrative distance (AD), 342
disadvantages, 328
sticky command, 392
straight-through cable, 43, 43–44
strong passwords, 436
stub networks, default routing on, 338
stub routers, 335
subinterfaces, 172
as starting point in troubleshooting, 147
subnets
benefits, 115
in your head, 136
fast way, 121
in your head, 128
creating, 116
routing protocol and, 349
switch card configuration, 316
switch port, setup to allow only one host per port, 391
switched network, 393
switched network design, 385
switches, 4, 5, 8. See also Cisco Catalyst switches
administrative configurations, 179–182
hostnames, 180
crossover cable between, 393
vs. hubs, 27
mitigating security threats, 436–437
multilayer, security features, 431
in OSI model, 14
and routing, 310
troubleshooting port LED alternating green and amber, 392
switchport port-security command, 391, 438
syn packet, 84
synchronization, for connection-oriented communication, 17
Synchronous Data Link Control (SDLC), 454
T
TACACS server, for authentication, 183
TCP SYN flood attacks, 433
Telecommunications Industry Alliance (EIA/TIA), 39
telecommuters, 441
checking connections, 273
for Cisco router connection, 164
closing sessions, 274
ending connection, 272
into multiple devices simultaneously, 272
user-mode passwords for, 185
terminal emulation, 69
terminal history size command, 177, 178
terminal monitor command, 284, 360
TFTP (Trivial File Transfer Protocol), 69–70
routers booting from host, 242
TFTP host
copying IOS to, 243
router search for, 319
routers booting from, 242
TFTP server
back up Cisco IOS to, 245
copying configuration to, 254
tftp-server flash:ios_name command, 247
thicknet, 39
thin protocol, 78
thinnet, 39
threats to security, recognizing, 431–432
three-way handshake, 17, 18, 18
Time to Live field, in IP header, 87
timers, RIP, 348
Token Ring (TR), 33
toll network, 451
Total Length field, in IP header, 87
trace command, 280
traceroute command, 90, 142, 204, 279, 280–282
tracert command, 142, 281–282, 337
Transmission Control Layer (TCP), 16
Transmission Control Protocol (TCP), 76–78
key features, 81
syn packet acknowledgment, 84–85
Transmission Control Protocol/Internet Protocol (TCP/IP), 66, 68
transparent bridging, 26
header, 47
port numbers at, 50
reliable delivery, 21
trap, 71
tribe flood network 2000 (TFN2K), 433
tribe flood network (TFN), 433
Trivial File Transfer Protocol (TFTP), 69–70. See also TFTP (Trivial File Transfer Protocol)
troubleshooting
with debug ip rip command, 361–363
description command and, 191
with ping command, 280
with show processes command, 284–285
with traceroute command, 280–282
with show ip protocols command, 359–360
switch port LED alternating green and amber, 392
trust exploitation attacks, 435
trusted network, 431
trustworthiness of routing information, 342
tunneling protocols, 442
Type of Service field, in IP header, 87
U
U/L bit (universal/local bit), 33
UDP. See User Datagram Protocol (UDP)
undebug all command, 283
universal/local bit (U/L bit), 33
Unlicensed National Information Infrastructure (UNII) band, 409–410
unreachable network, ping and, 362
unreliable protocol, 79
unshielded twisted-pair (UTP) cabling, 39
untrusted network, 431
unused ports, security for, 440
update timer, 348
Urgent field, in TCP header, 78
URLs, for file system, 248
use-tacacs parameter, for enable password, 183
user accounts, disabling after unsuccessful login attempts, 436
User Datagram Protocol (UDP), 16, 78–79
DHCP use of, 73
key features, 81
for ping, 280
user interface, for IOS, 163–169
for Telnet, 185
users for Telnet, checking, 273–274
V
V.24 standard, in PPP, 460
V.35 standard, in PPP, 460
valid host IDs
in Class A network, 100
in Class B network, 100
in Class C network, 101
verifying
Cisco router configuration, 252
IP routing configuration, 336–337, 358–367
version 2 command, 358
Version field, in IP header, 87
video over IP, 76
virtual circuit, 76
virtual LANs (VLANs), 9, 385, 386, 431
native, 395
router for connections between, 10
virtual private networks (VPNs), 440–442, 441
viruses, 434
voice over IP (VOIP), 76
vty parameter, for line command, 183
VTY ports, 270
listing all, 273
W
well-known port numbers, 81, 82
Wi-Fi Protected Access (WPA), 421–422
wide area network (WAN)
router for connections to, 6
subnet masks, 127
wildcards, for configuring default route, 338
Window field, in TCP header, 77
Wired Equivalency Protocol (WEP), 420
wireless LANs (WLANs)
radio frequencies, 408
as security risk, 432
wireless technology
agencies governing use, 409
connection for WAN services, 455
interface configuration, 326
witless user ignorance (WUI), 432
WLAN Association (WLANA), 409
working directory, printing, 249
workstation, Ethernet port directly connected to router interface, 244
WPA (Wi-Fi Protected Access), 421–422
WUI (witless user ignorance), 432
X
X Window, 71
X.25 protocol, 453
Y
Yeager, William, 163
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