Since our new network configuration made it a challenge to bring in new content via the FTP client, I turned my attention to the FTP server in CMUIP. It responded to a client request but, when the user provided a password, it rejected the connection.
I found an old email thread that mentioned this problem, and also mentioned that someone had rewritten the FTP server to fix it. It seemed likely that patch was contained in a package called CMUIP665K.BCK, which came with a readme stating it was a patch set but not what was in it. It did warn that one should only replace components if you truly had a problem, so it seemed I needed FTP_SERVER.EXE.
Unfortunately, a listing of the save-set (BACKUP/LIST CMUIP665K.BCK/SAVE_SET) produced a torrent of errors. I wondered if the file wasn't truly a save set but rather a tape image. A bit of experimenting with SimH discredited that theory. I went to the Web, looking for someone who might still have this save set available by FTP. I didn't find a new copy, but I did find a reference to "problems with save sets after FTP." It seems the FTP exchange corrupts the block size of the file so that BACKUP does not recognize it. The following sequence repairs it:
$ CREATE/FDL=SYS$INPUT newfile.bck
RECORD
FORMAT FIXED
SIZE nnnn
CARRIAGE_CONTROL NONE
^Z
$ COPY/OVERLAY file.bck newfile.bck
I extracted the patched FTP server, rebooted the machine, and we now have inbound FTP access!
We also have the latest version of CMUIP and its patch, if anyone else is looking for it. -- Ian