Cisco IOS Keyboard Shortcuts

Up Arrow   ~~~>  Allows you to scroll forward through previous commands
Down Arrow ~~~> Allows you to scroll backwards through previous commands
Ctrl+P (or up arrow)   ~~~>  Displays the last command entered
Backspace ~~~> Removes the character to the left of the cursor
Ctrl+A   ~~~>  Moves the cursor to the beginning of the current line
Ctrl+E ~~~> Moves the cursor to the end of the current line
Ctrl+F   ~~~>  Moves forward one character
Ctrl+B ~~~> Moves backwards one character
Esc+F   ~~~>  Moves forward one word
Esc+B ~~~> Moves backwards one word
Ctrl+R   ~~~>  Redisplays a line (starts a new line, with the same command shown)
Ctrl+U ~~~> Erases a line
Ctrl+W   ~~~>  Erases a word
Tab ~~~> Completes a partial command
Ctrl+Z   ~~~>  Exits configuration mode, returning you to privileged EXEC mode

How to spoof a MAC address !

Don’t rely on MAC filtering alone, however. Please, just don’t. It’s a bad idea. People seem to think “Oh, well, sure a determined attacker can get past it, but not anyone else.” It doesn’t take much determination at all to spoof a MAC address. In fact, I’ll tell you how:

  1. “Listen” in on network traffic. Pick out the MAC address. This can be done with a plethora of freely available security tools, including Nmap.
  2. Change your MAC address.

You can spoof a MAC address when using Nmap with nothing more than a –spoof-mac command line option for Nmap itself to hide the true source of Nmap probes. If you give it a MAC address argument of “0″, it will even generate a random MAC address for you.

For more general MAC address spoofing, your MAC address is trivially reset with tools available in default installs of most operating systems. Here are some examples:

  • Linux: ifconfig eth0 hw ether 03:a0:04:d3:00:11
  • FreeBSD: ifconfig bge0 link 03:a0:04:d3:00:11
  • MS Windows: On Microsoft Windows systems, the MAC address is stored in a registry key. The location of that key varies from one MS Windows version to the next, but find that and you can just edit it yourself. There are, of course, numerous free utilities you can download to make this change for you as well (such as Macshift for MS Windows XP).

MTU Ping Test

MTU Ping Test

A series of ping tests using the command, ping -f -l xxxx, where xxxx is the packet size, can be used to determine the optimal MTU for your connection.

  1. Go to Start and select Run.
  2. Type in cmd (Windows 2000/XP) or command (Windows 98/ME) into the Open: field. Hit the enter key or click OK. The DOS prompt should open.
  3. At the DOS prompt, type in ping -f -l 1492 and hit the Enter key.
  4. Note the results above indicate that the packet needs to be fragmented. Lower the size the packet in increments of +/-10 (e.g. 1472, 1462, 1440, 1400) until you have a packet size that does not fragment.
  5. Begin increasing the packet size from this number in small increments until you find the largest size that does not fragment. Add 28 to that number (IP/ICMP headers) to get the optimal MTU setting. For example, if the largest packet size from ping tests is 1462, add 28 to 1462 to get a total of 1490 which is the optimal MTU setting.