Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!NCS.DND.CA!netcoor
From: netcoor@NCS.DND.CA (DRENET Coordinator)
Newsgroups: comp.protocols.tcp-ip
Subject: Odd FTP Problem
Message-ID: <8902221936.AA10826@ncs.dnd.ca>
Date: 22 Feb 89 19:36:35 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 40


Has anyone seen, or can anyone explain this problem?

We have users on network 128.43 who has reported trouble retreiving
files from several hosts in the Internet. The FTP connection is opened
and the user and password are exchanged and the login completed message
is received. After this, problems occur for any command for which a
data connection is to be opened. Other commands not needing the data
connection (eg cd, ascii, binary) work as expected, but commands like
get and dir fail. The usual message received is:

	< 425 Can't build data connection: Connection timed out

although the message:

	< 425 Can't build data connection: Network is unreachable.

is also common. After this, cd and other commands not needing data
connections still work.

This problem is variable in that sometimes it strikes and sometimes it
doesn't. Sometimes it will interrupt an already started data transfer
(the above messages don't apply in this case).

Network 128.43 is gatewayed onto the ARPANET through a Butterfly gateway
(10.1.0.15). I am on network 192.12.98, which is also gatewayed through
the same Butterfly. I have yet to see the problem affect my host (Ultrix).
The host affected on net 128.43 is a DEC 2065 running TOPS-20. 

What confuses me is that packets are being transferred between the two systems
over the command connection throughout, yet any attempt to establish a
new connection for data fails.

Can anyone explain this? I would sure like to understand what is going on
to create this situation, then I can try to do something about it.

Thanks.

Bob Bradford				netcoor@ncs.dnd.ca
DREnet Coordinator			(613) 998-2520