Tag Archive - APC

Making an APC 7900 Console Cable

March 29, 2011 in Blog with 0 Comments

A few weeks back, I posted an article on configuring an APC 7900 PDU without a console cable.  This can be done using some ARP hacks to access the device before it’s been manually configured.

That works… Until someone like me comes along and messes around with the PDU and breaks it.

Something happened during configuration whereby the device was accessible but authentication wasn’t taking place.  This created a scenario where I was forced to use the console port to gain access again.

These are the steps needed to make your own APC 7900 console cable (model: 940-0144A).  Don’t spend $20-50 on eBay to buy one.  Just do it yourself for less than $10.

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Configuring an APC 7900 without a Console Cable

March 8, 2011 in Blog with 1 Comment

APC 7900

I’m building a home lab in my basement. Yes, I openly admit that I’m a nerd.

In order to reduce power consumption, I opted to purchase a network accessible PDU that would allow me to turn on/off devices while away from home.

After reviewing my options, I opted for an APC 7900PDU that I purchased from eBay for a little more than $100.  One PayPal transaction and five days later, my PDU arrived in the mail.  Once I racked the device, however, I ran into a problem: there was no console cable.

The APC console cable used is an RJ-12 to DB9 cable.  The official product code for the item is 940-0144.  To avoid the trouble of purchasing a used cable on eBay, I figured out another way to make it work.  Thank you, Mr. ARP.

Configuring an APC 7900 using ARP

You can use Address resolution protocol (ARP) to configure the rack PDU. The MAC Address of the PDU is needed for this method of configuration. The MAC address is located on the quality assurance slip that shipped with the PDU, and is also located on a white sticker on the PDU itself.

From a computer on the same subnet as the unconfigured PDU, follow these instructions:

Open up a command prompt and type the following (replacing <IP address> and <Mac Address> with actual values):

arp<space>-s<space><IP address><space><Mac Address>

If you’re running a Mac (like me), type the following:

sudo<space>arp<space>-s<space><IP address><space><MAC address>

Note: Mac Address format: xx:xx:xx:xx:xx:xx

Next, use Ping with a size of 113 bytes to assign the IP address defined by the ARP command.

Now, you can Telnet to the card by typing: telnet <IP address>

Use “apc” for username and password.

Log out to save changes.

Clearing the ARP Cache in Mac OSX

After configuring the device, make sure to clear out the ARP cache on your Mac.

The form in Terminal for the Router would be…

sudo arp -d -a