Bugs item #1473373, was opened at 2006-04-19 22:04
Message generated for change (Comment added) made by mwtoews
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Category: ftp
Group: bad behaviour
Status: Open
Resolution: Works For Me
Priority: 4
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Daniel Stenberg (bagder)
Summary: DNS reverse name lookup

Initial Comment:
Hi,
cURL fails to download from some FTP sites, such as
ftp://ftp.cdc.noaa.gov/Datasets/ncep.reanalysis/README
or any other file at that domain (this usually gets
"curl: (56) FTP response reading failed", however it
randomly works some times). This is because their FTP
server uses a reverse name look-up (i.e.
http://www.cdc.noaa.gov/PublicData/faq.html#8 ). I've
only had success by using Mozilla Firefox and manually
downloading [hundreds of] files. It does not work with
the stock 'ftp' command (error message is "Connection
closed by remote host."), nor with 'wget'.

My WinXP SP2 computer has an assigned or static IP
address (if this matters).

curl 7.15.1 (i686-pc-cygwin) libcurl/7.15.1
OpenSSL/0.9.8a zlib/1.2.3
Protocols: tftp ftp gopher telnet dict ldap http file
https ftps
Features: Largefile NTLM SSL libz

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Comment By: Michael Toews (mwtoews)
Date: 2006-04-25 09:48

Message:
Logged In: YES
user_id=1458205

Hi, sorry for the delay in my response. Here is the verbose
output:

$ curl -v
ftp://ftp.cdc.noaa.gov/Datasets/ncep.reanalysis.dailyavgs/README
* About to connect() to ftp.cdc.noaa.gov port 21
* Trying 140.172.156.239... connected
* Connected to ftp.cdc.noaa.gov (140.172.156.239) port 21
* FTP response reading failed
* Closing connection #0
curl: (56) FTP response reading failed

I'm pretty sure this is a cygwin/windows specific problem,
since curl on my Debian-sid boot volume works normally (same
static IP and everything else).
Also, no I don't know if this is a "DNS reverse name lookup"
problem, but that was my first guess.
I've had mixed success/failure with cygwin at this site
where either both wget and cURL both work or don't work, so
it might not be related to cURL, and it could just be our
crummy university network. I'll capture this in ethreal
regardless.

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Comment By: Daniel Stenberg (bagder)
Date: 2006-04-24 14:20

Message:
Logged In: YES
user_id=1110

Please note that I close reports that are left with no
responses to requests for further feedback.

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Comment By: Daniel Stenberg (bagder)
Date: 2006-04-19 23:33

Message:
Logged In: YES
user_id=1110

First, how do you know the reverse lookup is the reason? The
"curl: (56) FTP response reading failed" message certainly
indicates something else.

Then, can you show us a curl -v output of a failure?

If you run a network capture program like ethereal you could
compare the FTP traffic firefox does to what curl does and
see what the differences are and you could tell us.

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You can respond by visiting:
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Received on 2006-04-25