Thursday, April 26, 2007

Cisco Tip: HSRP MAC Address

If you use HSRP in your network, you are probably familiar with the concept of a virtual IP address. But, did you know that HSRP also uses a virtual MAC address? Yes, indeed. Each HSRP group (standby group) has a MAC address in the following format: 00-00-0c-07-ac-xx (xx represents the standby group in hexadecimal).

If you have a standby group of 8, for example, your virtual MAC address would be 00-00-0c-07-ac-08. Likewise, if you have a standby group of 16, your virtual MAC address would be 00-00-0c-07-ac-10.

For more information on HSRP, check out RFC 2281!

Monday, April 23, 2007

Cisco Tip: Checking Port Status (CatOS vs. IOS)

If you spend a lot of time working with L2 (Layer 2) switches, perhaps the best command to know - and the one you will probably use the most - is show port status. The show port status command displays port status information (obviously!).

If you work with IOS-based switches, you know that the show port status command does not work. Indeed, IOS-based switches do not have ports, but rather interfaces. So, the command you will want to use on IOS-based switches is show interface status.

More to come on the differences between CatOS and IOS!

Friday, April 20, 2007

How Do I Find My IP Address?

Your IP address is your address (location) on the Internet. Depending on your particular Internet setup, your IP address (IP is an acronym for Internet Protocol) may be static (doesn't change) or dynamic (changes each time you log on). Regardless of which type of IP address you may have, you should know how to find out what it is. Here is how......

Go to IP Chicken (there is a link in the sidebar - look for the chicken!), which displays your outside IP address.

NOTE: If you have a router, and I hope you do after reading my Top 5 Things To Do After You Buy A PC post, then you need to be aware that you will not see your home network's private (inside) IP addresses at IP Chicken.

To find out your IP address, which is usually dynamically assigned and also usually a private address, such as 192.168.1.x, do the following:

On a PC


Go to Start...Run

Type "cmd"

At the cursor prompt, type "ipconfig" and you will see your IP address. If you should happen to see more than one IP address, you will, most likely, want the IP address associated with the Ethernet interface.

On a Mac


Go to Applications...Utilities

Click on "Terminal"

At the cursor prompt, type the following:

ipconfig getifaddr en0 (for an ethernet connection)

ipconfig getifaddr en1 (for a wireless connection)

Now you know your IP address. Congratulations!

1Passwd 2.3.11 Released

A minor update of 1Passwd was just released en route to version 2.4, which will include HTTP Basic Authentication and "a few other treats."

Tuesday, April 17, 2007

Cisco Tip: SPAN Destination port is Up/Down

If you configure SPAN on your switch and notice that your destination port is in an "up/down" state - DON'T PANIC!

This is normal!

You should expect to see your destination port in a down (monitoring) state, so that it is known that this port is to be used for monitoring, not production.

Sunday, April 15, 2007

Cisco Tip: Identifying your UDI

Most Cisco devices leave the factory with an assigned UDI, a Unique Device Identifier. The UDI is printed on a label that is affixed to your Cisco hardware, but it is also stored on the hardware electronically.

The Unique Device Identifier (UDI) consists of 3 components:

  • Serial Number
  • Product Identifier (Part Number)

  • Version Identifier

You can determine your hardware's UDI with the show inventory command.

Apple delays Leopard until October

Apple, in its push to get out the iphone, has delayed Leopard until October.

Apple says it will be worth the wait. I believe them!

Tuesday, April 10, 2007

Cisco Tip: Encrypting Passwords

Worried about someone looking over your shoulder while you view your router configuration? Well, then, perhaps you should encrypt the passwords in your configuration so that they are not visible when viewed on screen or when printed out. To encrypt your passwords, use the global command service password-encryption.

The service password-encryption command uses a Vigenere cipher, which is a weak form of encryption.

If you need to decipher your encrypted passwords, check out Get Pass.

For a stronger level of security, you can use the enable secret command, which uses the MD5 algorithm.

Note: Get Pass will not work on enable secret passwords, only Type 7 passwords.

Cisco Tip: Configuring SPAN on 2950 switches

If you plan on enabling the Switched Port Analyzer (SPAN) feature in your network, there is an important point you should keep in mind if you use 2950 switches: 2950s can't monitor VLANs.

If you are using 2950s, you will have to configure source and destination ports with the monitor session command, as follows:

(config)#monitor session 1 source interface fastethernet 0/1

(config)#monitor session 1 destination interface fastethernet 0/24

Sunday, April 08, 2007

Get Firefox!

This blog is best viewed using Firefox and, if you aren't already using it, I would strongly suggest you download it here.

Cisco Tip: Password required, but none set

How many of you have seen these dreaded words?

Password required, but none set

If you have a console connection, you are in good shape. If not, here is what you should have done and what you need to do going forward: PUT A PASSWORD ON YOUR VTY LINES!

Router(config)#line vty 0 4
% Login disabled on line 1, until 'password' is set
% Login disabled on line 2, until 'password' is set
% Login disabled on line 3, until 'password' is set
% Login disabled on line 4, until 'password' is set
% Login disabled on line 5, until 'password' is set
Router(config-line)#password 1Passwd

Next time, I will tell you what you need to do if you want to encrypt your passwords so they are not visible in your configuration.

Windows TIp: What's in your Startup?

The surest way to free up memory for your PC is to remove whatever is truly unnecessary from your Startup Configuration. No matter how much RAM you have in your PC, you can burn up a great deal of it before you even start to use it if you have a lot of programs and services loading into memory.

Take a look at how much Physical Memory you have.....

Right click on the Taskbar

Select Task Manager

Choose the Performance tab

Look at the Available memory in the Physical Memory box

If the Available memory is below 300K, your PC is probably running pretty slow. But, you can do something about this!

To understand what services you should keep or get rid of, you should start with the Black Viper. No, not the snake, but the single best resource on the web for understanding all of the Windows services running on your PC. This is the place to start to understand what is running on your PC.

Once you know what to keep and what to lose, you will need a handy, easy way to do this. Of course, there is always msconfig. However, I prefer WinPatrol, as it automatically notifies you when a program tries to add itself to your Startup Configuration and gives you the chance to permit or deny this.

With Black Viper and WinPatrol, you should be well on your way to more free memory and happier times!

Wednesday, April 04, 2007

Cisco Tip: whichboot command

A quick way to see which file was used to boot your switch is with the whichboot command.

Monday, April 02, 2007

RoboForm for the Mac

Yes, this is a repeat post. But, there are so many people searching for a "RoboForm-like" product on the Mac that I felt another post was required to "set the record straight."

If you are searching for a Mac version of RoboForm, your search ends here: 1Password

1Password works with multiple browsers (Safari, Firefox, Camino and more) and allows you to import all of your RoboForm passcards. If you are a current PC/RoboForm user looking to switch to the Mac, look no further than 1Password.

Windows Updates

If you recently bought a new PC, and you followed my Top 5 Things To Do After You Buy A PC, there is still more work to be done! Remember, you bought a PC, not a Mac! :) But, don't despair; instead, make sure you have Automatic Updates turned on. In order to ensure your PC is protected, you need to keep it patched with the latest software updates from Microsoft. With Automatic Updates, you can be sure your PC will be up-to-date at all times.

Sunday, April 01, 2007

Cisco Tip: Saving Configuration Changes (CatOS vs IOS)

If you are going to be spending a lot of time working with routers and switches, probably the most important thing you need to know is - HOW TO SAVE WHAT YOU ARE DOING!

Let's take a look at how you save your work on routers (and/or switches running IOS) and switches (CatOS):



If make a change on a router or a switch running IOS, you need to enter the copy run start or write memory command in order for the configuration to be saved to NVRAM.



If you make a change on a switch running CatOS, however, it is immediately written to NVRAM.

This is an important distinction and one about which you should be aware when working with these devices.