Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!orion.oac.uci.edu!cedman From: cedman@lynx.ps.uci.edu (Carl Edman) Newsgroups: comp.unix.internals Subject: Re: Duplicating ASCII bel in the tty driver (was Re: Changing tty drivers) Message-ID: Date: 23 Oct 90 15:36:44 GMT References: <24752@adm.BRL.MIL> <1990Oct16.173128.7280@onion.pdx.com> <11552:Oct1721:36:1390@kramden.acf.nyu.edu> <1884@necisa.ho.necisa.oz> Organization: non serviam Lines: 47 Nntp-Posting-Host: lynx.ps.uci.edu In-reply-to: boyd@necisa.ho.necisa.oz's message of 23 Oct 90 04:55:11 GMT In article <1884@necisa.ho.necisa.oz> boyd@necisa.ho.necisa.oz (Boyd Roberts) writes: In article cedman@lynx.ps.uci.edu (Carl Edman) writes: > >Summary: I think it is a good and simple idea, which (in contrast >to almost all other suggestions made in this group) actually >would work. > No, no, no, no! It may be simple, but it's just not _right_. When you write ASCII bel to some file/tty/whatever you expect to get _one_ ASCII bel. Not two. Just one. It's just a YANDS (Yet Another Nickel and Dime Solution). A proposal to break the tty driver for no good reason, except that it's cheap. Consider a communications protocol that runs across RS-232 via the tty driver. This protocol uses full 7 bit ASCII (or 8 bits if you like). Every once in a while it is _possible_ that an ASCII bel may appear in the byte stream of this protocol (maybe a real bel, maybe ASCII 7 makes up part of a CRC checksum). And at this point another bel is inserted, corrupting the protocol which will result in circuit shutdown. No, no , no, no ! You didn't read what I wrote I explicitly stated that this would only apply to fixed hardwired "dumb" terminals in public access areas. There it is that the problem of spoofs is the greatest and where this feature would be most effective. On this kind of terminal NO compilcated file transfer protocoll is going to run and the system managers will know the kind of terminals they have well enough to always install the right bell character. On the other hand, for dialup lines on which most file transfer protocolls are run there is little (altough not no) chance of spoofs. So this would NOT apply to them. It's O.K. , but I would be grateful if people READ the post they replied to first, BEFORE replying. The argument in the preceeding 2 paragraphs is exactly the one made in my original post and (I think you will agree after having read it) largly invalidates your complaint. Carl Edman Theorectial Physicist,N.:A physicist whose | Send mail existence is postulated, to make the numbers | to balance but who is never actually observed | cedman@golem.ps.uci.edu in the laboratory. | edmanc@uciph0.ps.uci.edu