edtFTPnetPRO 5.0.5 SFTP download issue

Question

This is for edtFTPnetPRO.
I upgraded from version 3.0.0 to 5.0.5 about a week ago.

I get a "MAC Error" exception when downloading a file that is more than 35,000 bytes.
works fine if filesize is less than 32,000 bytes.

this happens only for one particular SFTP server (win2003).
works fine with another SFTP server (win2000)
I do not have access to a different win2003 SFTP server to test on.

the error does not occur when using version 3.0.0.

let me know if you meed more info/tests.

DEBUG [SFTPMessageStore] 13 Jun 2008 12:44:32.547 : Set timeout=200000
INFO [LicenseProperties] 13 Jun 2008 12:44:32.562 : Licence expiry date: 12/31/9999
INFO [LicenseProperties] 13 Jun 2008 12:44:32.562 : Production license
DEBUG [FTPConnection] 13 Jun 2008 12:44:32.562 : Set LocalDirectory='xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx'
INFO [LicenseProperties] 13 Jun 2008 12:44:32.562 : Licence expiry date: 12/31/9999
INFO [LicenseProperties] 13 Jun 2008 12:44:32.562 : Production license
DEBUG [SSHFTPClient] 13 Jun 2008 12:44:32.562 : Setting up fallback kbi prompt based on supplied password
DEBUG [HostNameResolver] 13 Jun 2008 12:44:32.578 : xxxxxxxxxxxxxxxx resolved to xxxxxxxxxxxxx
DEBUG [SSHFTPClient] 13 Jun 2008 12:44:32.578 : Connecting directly to SFTP server xxxxxxxxxxxxxx:22
DEBUG [SSHFTPClient] 13 Jun 2008 12:44:32.593 : Connected successfully to SFTP server xxxxxxxxxxxxxxx:22
DEBUG [SSHConnection] 13 Jun 2008 12:44:32.593 : Beginning protocol negotiation
DEBUG [PlainSocket] 13 Jun 2008 12:44:32.625 : RepeatCallback received 24 bytes
DEBUG [ProtocolNegotiationHandler] 13 Jun 2008 12:44:32.640 : offset=0,length=24
DEBUG [ProtocolNegotiationHandler] 13 Jun 2008 12:44:32.640 : pos=23
DEBUG [SSHConnection] 13 Jun 2008 12:44:32.640 : Server version=SSH-2.0-WS_FTP-SSH_1.0
DEBUG [SSH2Connection] 13 Jun 2008 12:44:32.640 : Timeout=200000
DEBUG [SSHConnection] 13 Jun 2008 12:44:32.640 : Sending client version=SSH-2.0-edtFTPnet/PRO-5.0.5.0
DEBUG [SSH2Connection] 13 Jun 2008 12:44:32.640 : Starting key exchange

[snipped for clarity]

DEBUG [SSH2PacketBuilder] 13 Jun 2008 12:44:34.187 : Writeoffset=44144,Readoffset=0
DEBUG [PlainSocket] 13 Jun 2008 12:44:34.187 : RepeatCallback received 2372 bytes
ERROR [SFTPChannelReceiver] 13 Jun 2008 12:44:34.187 : MAC Error : fx: MAC Error
   at g8.a(Byte[] A_0, Byte[] A_1, Int32 A_2, gz A_3, Int32 A_4, dn A_5)
   at br.c()
   at br.a(Byte[] A_0, Int32 A_1, Int32 A_2)
ERROR [SFTPMessageStore] 13 Jun 2008 12:44:34.187 : GetMessage - throwing stored exception
ERROR [SFTPMessageStore] 13 Jun 2008 12:44:34.187 : MAC Error : fx: MAC Error
   at fe.b(Int32 A_0)

Answer 1

Could you please email us the full logs from 3.0.0 and 5.0.5? support at enterprisedt dot com

Thanks

Answer 2

Here's a couple of things to try (independently of each other):

1. PreferredCipherAlgorithms = SSHCipherAlgorithm.TripleDES;
2. PreferredMACAlgorithms = SSHMACAlgorithm.HMACMD5;

Please let us know how each of these go.

testing independently:
PreferredCipherAlgorithms:
- TripleDES, All & Blowfish worked.
- AES128, AES256 had the same "MAC Error"
- AES192 failed to authenticate during login

PreferredMACAlgorithms:
- none of the choices worked. (same "MAC Error")

Answer 3

It looks like there is a problem with the AES cipher - and the reason that the earlier version worked was that AES wasn't being used.

It is quite likely that there is a bug with the server's implementation of AES - it looks like WS_FTP has released quite a few versions since the version you are using (which looks like version 1.0 of SSH). We are testing against the latest version to confirm that AES works against it.

You may need to set TripleDES as the cipher for this server.

Answer 4

We've tested AES against the latest version of WS_FTP (reported version SSH-2.0-WS_FTP-SSH_6.1.1) and been able to transfer files of up to 80 MB without any issues.

From this we conclude that your version of WS_FTP (SSH-2.0-WS_FTP-SSH_1.0) is probably buggy when it comes to its AES implementation.