Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!pasteur!ucbvax!ICASE.EDU!doug
From: doug@ICASE.EDU (Doug Peterson)
Newsgroups: comp.protocols.tcp-ip
Subject: ftp problem
Message-ID: <8810201901.AA00182@work1.icase.edu>
Date: 20 Oct 88 19:01:24 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 40

My ftp problem is fixed. Here's the sequence of events that led to
is conception.

I changed my workstation net to a new Class C address, updated
/etc/hosts on my server, and rebult my YP database. I made all the other
required changes (I thought). However, I overlooked the /etc/hosts on all
my diskless clients. (After all, they boted, rlogin, rsh, et. al. worked)
No user here initiated an ftp session FROM THEIR WORKSTATION until
yesterday. A few days after installing the new IP address, someone
noticed that /etc/hosts on their workstation still had the old IP
addresses in it. I replaced those tables with the current ones just
for consistency's sake, but didn't reboot the workstations. (I use
an rcp script for such things.)

It turns out that ypserv (and related daemons) use an image of the
YP database (on the clients, anyway), that they get when they first
start up. If any of the files are changed, they don't update their
image. The bizarre thing here is that the daemons on the clients
get their image from the client copy of the host tables, not the
YP database, but only when they start up. Thus, ftp would use the
nameserver to get a connection to a remote host, but the ftp sub-command
(e.g. ls) would use the CLIENT version of the data, which was apparently
obtained from a different source than the ftp command itself. Is this
a bug in the ftp-YP interface???

Restarting the daemons (read rebooting the workstations) fixed everything!

The credit for this discovery goes to Sharon Beskenis (sdo@csab.larc.nasa.gov)
a long-time friend and colleague. She talked me into trying a reboot.
Thanks, Sharon!!

Doug Peterson
Systems Manager
ICASE
Mail Stop 132C
NASA Langley Research Center
Hampton, VA 23665-5225
(804) 865-4090
FTS: 928-4090
doug@icase.edu