FTPWebRequest Fails on Some FTP Sites

microsoft.public.dotnet.framework

14 Feb 2006 2:34 PM

Frank Walker

While using FTPWebRequest, I have found at least one FTP site where this
function fails.
The URI I am using is ftp://nssdca.gsfc.nasa.gov/md_doc/app_a.doc

This NASA ftp site is available through anonymous log in, and other FTP
clients, including Internet Explorer using FTP protocols,
download the file just fine.

As the capture below shows, when FTPWebRequest sends PWD, it receives
ANON_DIR:[000000] from the ftp site.
Then when FTPWEbRequest sends CWD ANON_DIR:[000000]/md_doc/ it receives an
error of 550, then it gives up and
closes the connection.

Any advice on this would be helpful.

Thanks,

Frank Walker

No.     Time        Source                Destination           Protocol
Info
    656 127.450368 130.14.60.135         128.183.241.14        TCP
2888 > ftp [SYN] Seq=0 Ack=0 Win=65535 Len=0 MSS=1460
    659 127.454361 130.14.60.135         128.183.241.14        TCP
2888 > ftp [ACK] Seq=1 Ack=1 Win=65535 Len=0
    660 127.459681 128.183.241.14        130.14.60.135         FTP
Response: 220 ndadsb.gsfc.nasa.gov MultiNet FTP Server Process V4.2(16) at
Tue 14-Feb-2006 9:10AM-EST
    661 127.459876 130.14.60.135         128.183.241.14        FTP
Request: USER anonymous
    662 127.527600 128.183.241.14        130.14.60.135         FTP
Response: 331 anonymous user ok. Send real ident as password.
    663 127.527751 130.14.60.135         128.183.241.14        FTP
Request: PASS MYUSER@
    670 128.539245 128.183.241.14        130.14.60.135         FTP
Response: 230-Guest User MYUSER@ logged into ANON_DIR:[000000] at Tue
14-Feb-2006 9:10AM-EST, job 4280ad34.
    674 128.690469 128.183.241.14        130.14.60.135         FTP
Response: 230 Directory and access restrictions apply
    675 128.690726 130.14.60.135         128.183.241.14        FTP
Request: PWD
    676 128.695622 128.183.241.14        130.14.60.135         FTP
Response: 257 "ANON_DIR:[000000]" is current directory.
    677 128.695731 130.14.60.135         128.183.241.14        FTP
Request: CWD ANON_DIR:[000000]/md_doc/
    678 128.702017 128.183.241.14        130.14.60.135         FTP
Response: 550 %RMS-F-SYN, file specification syntax error:
ANON_DIR:[000000]/md_doc/
    679 128.705557 130.14.60.135         128.183.241.14        TCP
2888 > ftp [FIN, ACK] Seq=67 Ack=414 Win=65122 Len=0