Reviving ARPAnet

Frank McConnell fmc at
Wed Jan 17 14:12:15 CST 2018

> On Jan 17, 2018, at 10:18, Warner Losh via cctalk <cctalk at> wrote:
> On Wed, Jan 17, 2018 at 5:40 AM, Noel Chiappa via cctalk <
> cctalk at> wrote:
>> (The latter includes NCP as well as TCP/IP.)
> I'm curious: does it inter-operate with modern TCP/IP implementations?

This is a more serious question than one might think, but I know you (Warner) have been around long enough to have gone to Interop when it was about improving network interoperability.

So here's a real example: I have an HP 3000 Micro GX with MPE G.A3.09 (V-delta-9) which is very 1990.  And it has a LANIC, and V-delta-9 is late enough for it to be able to do IP over Ethernet (vs. V-delta-4 and before which could only do IEEE over 802.3).  And it has an FTP client.

So you might think I'd be able to move files between it and a modern FreeBSD box, right?  I mean, it's all just Ethernet, right?

Where it falls apart is that there's a bug in HP's TCP/IP ("NS Transport") in V-delta-9 and before, such that it tears down the connection with a failure if a packet is received with IP type-of-service not zero.  And the FreeBSD FTP server sets a socket option that gets FreeBSD to send that sort of packet.

At a previous employer, I went round with HP a bit on behalf of a mutual customer and got HP to issue a patch for NS Transport that corrects this behavior on the MPE side.  Clearly, I don't have that patch on this system.

FreeBSD is FreeBSD, and I can build its FTP server from source and change it so it works in this situation; but I think this should give y'all some idea of the hilarity that can ensue when you exhume a 1980s TCP/IP and put it on your network.

-Frank McConnell

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