ARP -SCAN for MAC Address Lookup

Summary

This post highlights how the arp (Win) or arp-scan (Linux) commands can be used in conjunction with online MAC address lookup tools, to assist in hardware identification of Ethernet devices.

Predicament
For a software development project a boxed cluster of Single Board Computers (SBC) was provided. The SBC cluster contained systems configured with static and dynamic IP addressing. No issue I mused, each SBC could be powered individually, the SBC that needed to be upgraded could then be identified. The real issue then presented itself, the cluster was boxed hardware and could not be opened and individual boards could not be powered or unpowered. One of the solutions that came to mind was the sometimes overlooked ARP command.

ARP Command (Windows)
Using ARP in the Windows command line may not be the most operator friendly solution, especially if a GUI based application is more your flavour. There are plenty of Windows applications such as the well-known Angry IP Scanner, Nmap or Free IP Scanner which will do a similar task. Some of these applications detail the OEM or hardware manufacturer in the scan results.

For testing with ARP, the SBC box was powered and networked directly to a development computer.

The arp -a command was issued from the Windows command line.

ARP Results

A doctored copy of the results from the arp are shown above. A few dynamic devices were listed. 

The first six characters of the MAC address were used to identify the vendors.


ARP Scan Command (Linux)
The arp-scan command used in Linux terminal produces similar results, usually including the hardware vendor.

ARP Scan Results

MAC Lookup
For this SBC project the AskApache website was utilised for identification of the hardware vendor using the MAC addresses. A Google search will throw up numerous sites with similar search functionality, such as MAC Vendor Lookup.

On the AskApache site, the MAC address starting with b8 yielded the target SBC.

AskApache MAC Address Lookup

Results from the website show the target SBC was a Raspberry Pi.

AskApache MAC Address Lookup Result

Using the command line serves as handy reminder to the tools available in most operating systems.

Recover Mac Files Old SCSI

Summary

This blog demonstrates how a Linux PC and SCSI PCI card can be used to retrieve the files from the SCSI hard disk of a twenty year old Power Mac.

Power Mac
The Power Mac 6100/66 was possibly the third Mac that I had the pleasure of owning back in the day. The 'pizza box' as it was affectionately known, had 24MB of RAM, 16bit colour, a proprietary Ethernet interface and no USB connection or CD burner.

Power Mac 6100/66

Somehow twenty years later, my belief was that the machine had long been retired from use, the old Mac turns out to have a family members five year old files stored on the hard drive. To make life a bit more interesting the floppy drive, similar to most of the plastic in the old Mac, has degraded to the point of failure. 

Inside a Power Mac 6100/66

Fortunately the Mac still booted verifying that the internal SCSI drive was mountable. After removing the cover from the Power Mac the non-Apple drive was easily visible at the bottom left hand corner of the above image.

SCSI Controller
After performing price comparisons between a second hand Apple Network adaptor and a replacement floppy drive, it turned out that there was alternative solution. One of the online stores was selling off some AdvanSys ABP 3922 SCSI Controllers.

AdvanSys PCI SCSI Controller

CNET had a basic specification for the ABP 3922 which indicated this card was suitable for PC or Mac. 

AdvanSys PCI SCSI Controller Rear

The online store price for the card ended up significantly cheaper than purchasing an Apple Network adaptor and also less than a suitable replacement Panasonic 1.44Mb Superdrive.

AdvanSys ABP 3922 SCSI Controller

Linux
Fitting the SCSI Controller into an existing Linux tower running Mint, a quick check of the PCI bus using LSPCI this indicated that the card has been detected.

PCI SCSI Card Identification

With the card detected in Linux the Mac SCSI drive was hot plugged to the 50 way IDC connection and powered.

Mac Formatted SCSI Drive Connection

Under Linux Mint the drive auto mounted and could be located in the usual location under the Computer icon.

Linux Mint Computer Icon

As part of basic troubleshooting, a drive that has not auto mounted could be checked in the Linux 'Disks' tool.

Linux Mint Disks with Mac Drive

Old Mac drives were formatted in HFS or HFS+ both of which Linux will commonly mount without any issues.

File Retrieval

With the SCSI drive mounted the required files could be accessed and copied off the SCSI drive. It should be noted that some specific files relating to preference files for games were not able to be copied.

Summary
Using an older model SCSI PCI card, which suits an existing motherboard together with Linux, was an inexpensive solution to retrieve files from an old Mac drive. The same methodology may even work for some of the single board computers with the addition of a USB to PCI bridge or for other platforms a suitable USB interface such as the discontinued but still available Adaptec USBXchange adaptor.