[ih] NCP and TCP implementations

[Bob Hinden]

Geoff,

> On Mar 10, 2020, at 12:12 PM, the keyboard of geoff goodfellow via Internet-history <internet-history at elists.isoc.org> wrote:
> 
> for some reason when the C/70's came along, TIP's were renamed to TAC's
> (Terminal Access Controllers) or some such…

I have a vague memory that the term TAC came from AUTODIN, which had included in its architecture a terminal controller that ran TCP/IP.   I found this that shows that:

https://www.computer.org/csdl/proceedings-article/afips/1978/50860735/12OmNzwHv9M

Bob


> BUT, the Access control (i.e.
> login to use/make a connection) of it was known as TACACS (Access Control
> System).... and it might have come about via a conversation/discussion
> yours truly had with Col. Dave Russell of DARPA:
> 
> we were in North Carolina heading/driving to the Fort Bragg ARMY base there
> to do a Packet Radio Net demo... as we drove along yours truly brought up
> the issue of the lack of security on the TIP's-- i.e. that anyone (i.e.
> "randoms") could call up and then connect to any host without having to
> "login" to do so.
> 
> Col. Russell kinda pushed back saying that without userid on a host there
> was nothing you could do -- and therefore would eventually "go away".
> 
> yours truly countered this allowed for "crackers" to spend their time
> trying to break into systems... which yours truly constantly witnessed on
> our systems at SRI was it was common for people to use easily guessable
> passwords such as their initials (or even summarily detailed in RFC602
> <https://tools.ietf.org/html/rfc602> by Bob Metcalfe of PARC-MAXC "*The
> Stockings Were Hung by the Chimney with Care"
> <https://tools.ietf.org/html/rfc602> *when a cracker guessed their SYSTEM's
> password which was their host name spelled backwards).
> 
> so to abate this, a "dead bolt" on the front door of the ARPANET (i.e. the
> TIPs) was needed to this vehicle of easy/free remote access "penetration"
> attemptages.
> 
> there may have been others in other quarters "preaching" the same issues...
> but Col. Russell then agreed and sometime later, there was TACACS.
> 
> let's not forget that at this time many (most?) of the APRANET systems had
> guest accounts on them... user GUEST, password ARPA... and they were
> "advertised" via the NIC at SRI-ARC (host 2) where after connecting to the
> TIP, you did a @l (for link... the original TIP command to connect to a
> host... later also @o (for open) and once getting the SRI-ARC Tenex exec
> prompt just typed in NIC and you were then automatically logged in (w/o a
> pw) as NICGUEST into an NLS (Doug Engelbart's system) special program that
> allowed you to electronically browse the ARPANET Resource Handbook on line
> that contained all the Good Stuff about each ARPANET host system.
> 
> let's also not forget that the MIT ITS (Incompatible Timesharing System)
> hosts MIT-AI, MIT-ML and MIT-DM did not have passwords (let alone any type
> of "security" at all, as it's "command" interface was DDT... perhaps it's
> where the term Security By/Through Obscurity came about?) and given this
> lack of passwords, it was a favorite hangout for "randoms" (along with
> SU-AI with its NET,GUE login) that dialed into the NO access controlled
> TIP's -- like yours truly did via the AMES-TIP after meeting a summer hire
> at Tymshare who wrote its phone # and a few TIP commands on the back of an
> envelope in the early 70's... :D
> 
> geoff
> 
> On Tue, Mar 10, 2020 at 8:03 AM Steve Crocker via Internet-history <
> internet-history at elists.isoc.org> wrote:
> 
>> Argh.  I echoed Leo's use of "TAC."  I read it as referring to the TIP.  If
>> I recall correctly, the "TAC" was an access control method on the TIPs.
>> "TIP Access Control" I think.
>> 
>> Steve
>> 
>> 
>> On Tue, Mar 10, 2020 at 1:55 PM Bernie Cosell via Internet-history <
>> internet-history at elists.isoc.org> wrote:
>> 
>>> On 10 Mar 2020 at 13:23, Steve Crocker via Internet-hi wrote:
>>> 
>>>> The TAC was an extension of the IMP.  The original IMP was built on
>>>> the
>>>> Honeywell 516 (and later 316) platform, which was a 16 bit twos
>>>> complement
>>>> computer.  I assume Hinden's reference to 15-bit arithmetic reflected
>>>> the
>>>> fact that the arithmetic was signed.
>>> 
>>> I honestly cannot remember what the TAC was!!   Was that the TIP?
>>> Regardless,
>>> yes, the x16s had 16-bit signed arithmetic with 10 bit addressing 9 bits
>>> of page
>>> address, 1 bit of "this page" or the 0 page, 16Kwords of memory.
>>> 
>>> Things got more complicated with the 316 -- it supported 32K words.  What
>>> we
>>> did for the TIP [and maybe the TAC, whatever that was] was to keep the
>> IMP
>>> *unchanged* in the bottom 16K, and then in the upper 16K we wrote a
>>> self-contained "host". There was some [small!] hack to fake interrupts
>> and
>>> input/output to this host but to the IMP it thought it was just another
>>> NCP
>>> connected host.  It'd set up a host output buffer and instead of doing a
>>> hardware
>>> "send" it'd pass control to the upper 16K.  Similarly [at least for the
>>> TIP], when it
>>> got something in from a terminal it'd copy it into a host-input buffer
>> and
>>> then
>>> issue an "interrupt" down to the IMP.   Worked quite well.
>>> 
>>>  /Bernie\
>>>            Bernie Cosell
>>>       bernie at fantasyfarm.com
>>> -- Too many people; too few sheep --
>>> 
>>> 
>>> 
>>> 
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>> 
> 
> --
> Geoff.Goodfellow at iconia.com
> living as The Truth is True
> http://geoff.livejournal.com
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