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Monday, August 6, 2012

Tangling with MacTCP back in the '90s

Was I just incredibly unlucky, or did everyone have to suffer nutty Mac TCP/IP extensions in the '90s? The ones I had to use demanded a setup using the integer form of a network number. I've been trying to sort out some random memories from the days when I was expected to set up all of the new machines on my school's network, and this one popped up.

Back in those days, I used to carry around a little binder with some cheat sheets (and a get out of jail free card or two, for running around in the halls during classes), and one of my notes was a large number for the school's IP network. That is, instead of (say) 192.168.30.x, you actually had to enter 12625950 or something like that.

Who ever thought of IP networks as integers? Maybe this was some Appletalk mentality sneaking in. At any rate, having remembered this much, I went digging tonight, and this time I got lucky. I turned up a setup help page and it has screenshots of this monster. Just look at this mess.

MacTCP setup

So, okay, I wasn't imagining things! Look at that! We actually did have to type in these integers and try to make sense of it. It took a fair bit of trial and error to realize what was going on at first.

Further digging reveals there was an actual IP address input field at the top level, but I seem to recall that it would be greyed out for some unknown reason. That left me with no choice but to do battle with this thing the hard way.

There's one final parting shot here. Notice that it shows 192.0.0.0 and a corresponding network number of 12582912. If you tried to calculate that, you'd quickly discover that it's offset by 8 bits. That number in hex is 0xc00000, not the 0xc0000000 you might expect for a 32 bit IPv4 address. Tricky.

I imagine there may have been documentation for this sort of thing, but at the time, all I had was a floppy disk with a couple of OS extensions: MacTCP itself plus some random dialup stuff. With nothing else to go on and no other alternatives, I put up with this to get those teachers online. I'm sure they appreciated it.