Cisco IOS

user mode (user exec mode)

privileged mode (privileged exec mode)
must type the "enable" (en) command to enter this mode, Hostname#
most likely a password will be required to enter this mode.
privilged mode can be exited by typing the "disable" command

sub modes of privileged mode
the "end"/Ctrl-Z will bring out of any config mode and back to privileged mode  <--try end command
to go back to global config mode use the "exit" command

configuration mode or global configuration mode
entered by "configure terminal" command (conf t)

interface configuration mode
interface <interface name>

serial = s0, s0/0, serial0
ethernet = e0, fa0/0, ethernet0

line configuration mode
line <line type> <line#>

console, vty, tty, async

router configuration mode
router <routing protocol>

routing protocols:
rip, igrp


? - lists available commands

interface commands:
no shutdown (no shut) - enable interface
ip address <IP address> <subnet mask>
description - set text description
clock rate 56000 - dce end of serial cable requires this
bandwidth <value> - set bandwidth in Kbps

user mode commands:
show version - firmware version and other info
show flash - display flash directory
show ip interface brief
show interfaces or show interfaces <interface>
show running-config (show run) - displays active configuration
show startup-config (show start) - displays saved configuration
show ip route - display routing table
show hosts - display defined hosts?
show history - display command history (up-arrow/Ctrl-P = previous command/down-arrow/Ctrl-N = next command)
show users - displays remote users with active telnet sessions
show sessions - displays open telnet sessions
telnet <hostname/ip address> (Ctrl+Shift+6 then x to suspend session)
disconnect <session #> - disconnects specified telnet session

privileged mode commands:
copy running-config startup-config (copy run start) - save running-config to NVRAM
copy tftp flash - copy from tftp to flash
copy flash tftp - backup flash to tftp
erase start
show protocols
show cdp neighbors
show cdp neighbors detail
show cdp interface - display interfaces where CDP is active

configuration mode:
hostname <name> - set hostname
enable password <password> - set cleartext password
enable secret <password> - set encrypted password (secret password overrules standard password)
ip host <hostname> <ip address> - define a host
banner motd # - set login banner
cdp timer <# of seconds> - sets CDP advertisement interval
cdp holdtime <# of seconds> - sets hold-down interval

line mode commands:
line console 0
password <password>

line vty 0 4     <--telnet sessions                        
password <password>

line vty 0 4
privilege level 15
(after telneting in you're put directly into privileged mode)

show mac-address-table
show mac-address-table dynamic

mac-address-table aging-time <seconds>

show vlan
show vlan brief

conf t
swithport access vlan 2
switchport mode access

switchport port-security
switchport port-security mac-address 1111.1111.1111
switchport port-security mac-address sticky

show port-security int