Re: IBMPC-based implementations


Barry Shein (bzs%bostonu.csnet@CSNET-RELAY.ARPA)
Fri, 17 Jan 86 21:58:18 est


>I have used the MIT PC/IP package with some degree of success. I have
>largely quit using it, however, in favor of serial protocols like Kermit
>because of various problems like:
>
> 1. Can't upload a file unless it already exists.
> 2. Can't upload a file unless it is accessible by everyone.
> 3. Occasional bit errors.
>
>What I would really like is rcp, rsh, and rlogin on a PC. Let me
>know if you find such.
>Thomas N. Anderson ...uw-beaver!teltone!tna

Obviously your problem is not really PC/IP but the way TFTP works. A while
back I modified our 4.2bsd TFTP to add the following capability:

        On a WRQ or a RRQ if there are strings past the mode
        they are assumed to be a login-name/password to be used,
        the fork from the server changes to that person's home
        directory and sets itself to be that user (setuid/setgid
        in UNIX.) Otherwise the default rules apply.

For example:

        RRQ thesis/chapter1\0netascii\0bzs\0passwd\0
(where \0 means a null byte)

I needed this because we had lisp machines and my own IP/UDP/TFTP
implementations for the 3B2 and the mentioned restrictions would be,
well, too restrictive for use, they didn't have TCP. It's all
backwards compatible, if I were you I would consider this with your
administration (there are security problems but they are worse in my
opinion the old way, in fact my server currently *demands* a legal
login/password, I just wouldn't run it at all without the addition.)

It requires a few minor changes to server and client, I would suggest it
(is this too far out of spec to be accepted? I think TFTP is almost
useless w/o it for the user these days. The TFTP RFC also mentions that
extensions are appreciated, here's one...[I realize diskless nodes are
using TFTP to boot, that's a slightly different issue but manageable.])

        -Barry Shein, Boston University



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