* * * * *

                   MacGyver, with the obligatory paper clip

I fixed a communication problem with some scissors, a bit of wire and a paper
clip.

No, really.

I got two pieces of equipment communicating by using stuff I was able to find
around the office (because that's all I had to work with).

Yesterday, Smirk drops a BayTech DS9 [1] with one DS72 [2] network interface
and eight DS30 modules (which control 12 electrical outlets). I was told to
test it and configure the device.

So I plug the device into the office network, started up the DHCP (Dynamic
Host Configuration Protocol) server, and powered the DS9. Sure enough, I see
the DHCP request come through, it gets an IP address and I try connecting to
it.

Nothing.

I scan the device with nmap [3] and yes, it is studiously ignoring all
attempts to connect to port TCP (Transmission Control Protocol) port 23
(standard telnet) and UDP (User Datagram Protocol) port 161 (SNMP (Simple
Network Management Protocol)). Since it's studiously ignoring the network, my
only recourse is to get at it through the serial port.

It's an RJ-45 connector on the DS9, and I have a DE-9 (commonly referred to
as DB-9 but DE-9 is the proper designation for the connector) on my
workstation. I just so happen to have an RJ-45 to DE-9 adaptor (for the Cisco
routers). I may or may not need the NULL modem adaptor, but that's easy
enough to figure out.

Only it doesn't work. Straight through, or with the NULL modem adaptor.

I have to reach for the heavy guns. I hunker down and read the manual [4].
It's a good manual, and it gives the exact layout for the cabling between the
RJ-45 and the DE-9 that I need to communicate with the DS9. So I go hunting
for a continuity tester to see if the Cisco-specific adaptor I have is wired
such that I can use it.

Only we don't have a continuity tester. A $5,000 network cable analyzer [5]
sure. But something to test the continuity of a single wire? Nada. Not even
Dan the Network Engineer has one.

So I carefully break open the Cisco-specific RJ-45 to DE-9 adaptor and lo—
it's not wired according to the DS72 manual, so it's useless. So are the
other RJ-45 to DE-9 adaptors we have lying around.

So I have to make one.

Only we don't have any spare DE-9 connectors (male or female) lying around,
but plenty of RJ-45 connectors. Hmmm …

I grab about a foot length of network cable, crimp an RJ-45 connector on one
end, and (carefully) use scisors (since we lacked actual wire strippers) to
strip the insulation off the wires at the other end. I then carefully wrapped
the exposed wire around a paper clip to make a small coil, and then slipped
that coil around the pins of a male-to-male DE-9 adaptor, and plugged that
into the serial cable at the back of my workstation. The RJ-45 end of the
jury-rigged cable went into the DS9.

The fragile kludge [6] made from scisors, wires and a paper clip (oh, and a
crimping tool) worked beautifully and I was able to configure the DS9 (and I
kept cursing myself for not having my camera around to document such an
engineering feat).

I did find out one thing about the device, and I don't think it's mentioned
in the manual (although I was more concerned about the serial connection than
anything else) but the device simply drops packets unless they come from a
configured SNMP trap host. Good thing to know.

[1] http://www.baytech.net/products/showprod.php?prod=DS9IPS
[2] http://www.baytech.net/products/showprod.php?prod=DS72
[3] http://www.insecure.org/nmap/
[4] http://www.baytech.net/downloads/manuals/ds72.pdf
[5] gopher://gopher.conman.org/0Phlog:2006/01/10.1
[6] http://www.catb.org/jargon/html/K/kludge.html

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