Michael Ossman brings us the handiest little set of network
administrator tools you can fit in
your mini-screwdriver set. With one standard Ethernet cable, a
straight-through coupler, and a few homebrew adapters, you will have:
straight-through ethernet cable:
crossover ethernet cable:
ethernet - coupler - crossover
DB9/RJ45 - ethernet - DB9/RJ45
null modem cable:
DB9/RJ45 - ethernet - coupler - crossover - DB9/RJ45
Cisco console cable:
DB9/RJ45 - ethernet - coupler - Cisco adapter
This set is easily expandable with a loopback (which will work on both
Ethernet and RS-232, also useful for testing distant connectors) and
Read the rest of the story.
After cloning a working Debian virtual machine, the new system
would not bring up its Ethernet interface. This is because I checked
VirtualBox's dialog, "Reset MAC address for network card" and got a new
hardware Ethernet address.
Trying "ifup eth0" didn't work. I did an "ip addr" and saw that the
only configured interface was now called eth1.
This is simple to solve. Edit the file
/etc/udev/rules.d/70-persistent-net.rules and move the new MAC address
(like "00-0F-35-01..." and so on) from the eth1 line back to eth0,
erasing the previous address in the eth0 line. Then delete the
remainder of the eth1 line, save, and reboot.
You should now have your eth0 back.
For setup of the Zonet ZPS2102:
The default IP is 192.168.0.10 ... in the Add Printer dialogs, choose
Network Printer, then enter the IP address, the queue (default is:
and choose the model.
The Device URI, when you are done, looks like: