Here is a debug log from the server related to this question. Hopefully this helps. I have a ticket open with them as well. Is there any update on this?
Nov 29 18:10:23 mod_sftp/0.9.8[20618]: using ‘/etc/proftpd/ssh_host_dsa_key’ as DSA hostkey
Nov 29 18:10:23 mod_sftp/0.9.8[20618]: using ‘/etc/proftpd/ssh_host_rsa_key’ as RSA hostkey
Nov 29 18:10:23 [20618]
ssh2:6: SSH2 server-requested rekeys disabled by SFTPRekey
Nov 29 18:10:23 ftp-uk proftpd[20618] 91.197.140.4 (69.217.5.7[69.217.5.7]): SSH2 session opened.
Nov 29 18:10:23 [20618]
ssh2:9: sending KEXINIT message to client
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 1 using select(2)
Nov 29 18:10:23 [20618]
ssh2:3: sent SSH_MSG_KEXINIT (20) packet (472 bytes)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 mod_sftp/0.9.8[20618]: received client version 'SSH-2.0-aspose_network_ssh2_1.0’
Nov 29 18:10:23 mod_sftp/0.9.8[20618]: handling connection from SSH2 client 'aspose_network_ssh2_1.0’
Nov 29 18:10:23 [20618]
ssh2:5: handling connection from SSH2 client 'aspose_network_ssh2_1.0’
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against regex '^OpenSSH-2.0.
|^OpenSSH-2.1.|^OpenSSH_2.1.
|^OpenSSH_2.2.|^OpenSSH_2.3.0.
'
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match regex '^OpenSSH-2.0.|^OpenSSH-2.1.
|^OpenSSH_2.1.|^OpenSSH_2.2.
|^OpenSSH_2.3.0.'
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against regex '^OpenSSH_2.3…
|^OpenSSH_2.5.0p1.|^OpenSSH_2.5.1p1.
|^OpenSSH_2.5.0.|^OpenSSH_2.5.1.
|^OpenSSH_2.5.2.|^OpenSSH_2.5.3.
'
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match regex '^OpenSSH_2.3…|^OpenSSH_2.5.0p1.
|^OpenSSH_2.5.1p1.|^OpenSSH_2.5.0.
|^OpenSSH_2.5.1.|^OpenSSH_2.5.2.
|^OpenSSH_2.5.3.'
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against regex '^OpenSSH.
'
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match regex '^OpenSSH.'
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against regex '.
MindTerm.'
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match regex '.
MindTerm.'
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against regex '^Sun_SSH_1.0.
'
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match regex '^Sun_SSH_1.0.'
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against regex '^2.1.0.
|^2.1 .'
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match regex '^2.1.0.
|^2.1 .'
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against regex '^2.0.13.
|^2.0.14.|^2.0.15.
|^2.0.16.|^2.0.17.
|^2.0.18.|^2.0.19.
'
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match regex '^2.0.13.|^2.0.14.
|^2.0.15.|^2.0.16.
|^2.0.17.|^2.0.18.
|^2.0.19.'
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against regex '^2.0.11.
|^2.0.12.'
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match regex '^2.0.11.
|^2.0.12.'
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against regex '^2.0…
'
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match regex '^2.0…'
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against regex '^2.2.0.
|^2.3.0.'
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match regex '^2.2.0.
|^2.3.0.'
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against regex '^1.2.18.
|^1.2.19.|^1.2.20.
|^1.2.21.|^1.2.22.
|^1.3.2.|^3.2.9.
'
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match regex '^1.2.18.|^1.2.19.
|^1.2.20.|^1.2.21.
|^1.2.22.|^1.3.2.
|^3.2.9.'
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against regex '.
SSH_Version_Mapper.'
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match regex '.
SSH_Version_Mapper.'
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against regex '^Probe-.
'
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match regex '^Probe-.'
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against SFTPClientMatch regex '.
'
Nov 29 18:10:23 [20618]
ssh2:16: setting max server channel window size to 33554432 bytes, as per SFTPClientMatch
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against SFTPClientMatch regex '.
Sun_SSH.'
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match SFTPClientMatch regex '.
Sun_SSH.'
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against SFTPClientMatch regex '.
SSH Secure Shell for Windows.'
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match SFTPClientMatch regex '.
SSH Secure Shell for Windows.'
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against SFTPClientMatch regex 'GSSFTP.'
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match SFTPClientMatch regex 'GSSFTP.*'
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against SFTPClientMatch regex '.
WinSCP.'
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match SFTPClientMatch regex '.
WinSCP.'
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against SFTPClientMatch regex '.
WS_FTP.'
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match SFTPClientMatch regex '.
WS_FTP.'
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against SFTPClientMatch regex '.
Tunnelier.'
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match SFTPClientMatch regex '.
Tunnelier.'
Nov 29 18:10:23 [20618]
ssh2:18: checking client version ‘aspose_network_ssh2_1.0’ against SFTPClientMatch regex 'sshlib:.*ClientSftp’
Nov 29 18:10:23 [20618]
ssh2:18: client version ‘aspose_network_ssh2_1.0’ did not match SFTPClientMatch regex 'sshlib:.*ClientSftp’
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:20: SSH2 packet len = 332 bytes
Nov 29 18:10:23 [20618]
ssh2:20: SSH2 packet padding len = 4 bytes
Nov 29 18:10:23 [20618]
ssh2:20: SSH2 packet payload len = 327 bytes
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:23 [20618]
ssh2:20: SSH2 packet MAC len = 0 bytes
Nov 29 18:10:23 [20618]
ssh2:3: received SSH_MSG_KEXINIT (20) packet
Nov 29 18:10:23 [20618]
ssh2:9: reading KEXINIT message from client
Nov 29 18:10:23 [20618]
ssh2:3: first kex packet follows = false
20111129181023 20618 ssh2 TtUgD1vFjARF2QUHAABQirel 91.197.143.12 69.217.5.7 0:0 nobody “KEXINIT (data)” - - 369/472 - “-”//"-“
Nov 29 18:10:23 [20618]
ssh2:9: determining shared algorithms for SSH session
Nov 29 18:10:23 [20618]
ssh2:8: client-sent key exchange algorithms: diffie-hellman-group1-sha1,diffie-hellman-group14-sha1
Nov 29 18:10:23 [20618]
ssh2:9: attempt
#1 to create a good DH key
Nov 29 18:10:23 [20618]
ssh2:12: generating DH key
Nov 29 18:10:23 [20618]
ssh2:10: good DH public key: 487 bits set
Nov 29 18:10:23 mod_sftp/0.9.8[20618]: + Session key exchange: diffie-hellman-group1-sha1
Nov 29 18:10:23 [20618]
ssh2:20: session key exchange algorithm: diffie-hellman-group1-sha1
Nov 29 18:10:23 [20618]
ssh2:8: client-sent host key algorithms: ssh-rsa,ssh-dss
Nov 29 18:10:23 mod_sftp/0.9.8[20618]: + Session server hostkey: ssh-rsa
Nov 29 18:10:23 [20618]
ssh2:20: session server hostkey algorithm: ssh-rsa
Nov 29 18:10:23 [20618]
ssh2:8: client-sent client encryption algorithms: aes128-cbc,3des-cbc,aes256-cbc,aes192-cbc,none
Nov 29 18:10:23 mod_sftp/0.9.8[20618]: + Session client-to-server encryption: 3des-cbc
Nov 29 18:10:23 [20618]
ssh2:20: session client-to-server encryption algorithm: 3des-cbc
Nov 29 18:10:23 [20618]
ssh2:8: client-sent server encryption algorithms: aes128-cbc,3des-cbc,aes256-cbc,aes192-cbc,none
Nov 29 18:10:23 mod_sftp/0.9.8[20618]: + Session server-to-client encryption: 3des-cbc
Nov 29 18:10:23 [20618]
ssh2:20: session server-to-client encryption algorithm: 3des-cbc
Nov 29 18:10:23 [20618]
ssh2:8: client-sent client MAC algorithms: hmac-sha1-96,hmac-sha1,hmac-md5,hmac-md5-96,none
Nov 29 18:10:23 mod_sftp/0.9.8[20618]: + Session client-to-server MAC: hmac-sha1-96
Nov 29 18:10:23 [20618]
ssh2:20: session client-to-server MAC algorithm: hmac-sha1-96
Nov 29 18:10:23 [20618]
ssh2:8: client-sent server MAC algorithms: hmac-sha1-96,hmac-sha1,hmac-md5,hmac-md5-96,none
Nov 29 18:10:23 mod_sftp/0.9.8[20618]: + Session server-to-client MAC: hmac-sha1-96
Nov 29 18:10:23 [20618]
ssh2:20: session server-to-client MAC algorithm: hmac-sha1-96
Nov 29 18:10:23 [20618]
ssh2:8: client-sent client compression algorithms: none
Nov 29 18:10:23 mod_sftp/0.9.8[20618]: + Session client-to-server compression: none
Nov 29 18:10:23 [20618]
ssh2:20: session client-to-server compression algorithm: none
Nov 29 18:10:23 [20618]
ssh2:8: client-sent server compression algorithms: none
Nov 29 18:10:23 mod_sftp/0.9.8[20618]: + Session server-to-client compression: none
Nov 29 18:10:23 [20618]
ssh2:20: session server-to-client compression algorithm: none
Nov 29 18:10:23 [20618]
ssh2:8: client-sent client languages:
Nov 29 18:10:23 [20618]
ssh2:8: client-sent server languages:
Nov 29 18:10:23 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:24 [20618]
ssh2:20: SSH2 packet len = 140 bytes
Nov 29 18:10:24 [20618]
ssh2:20: SSH2 packet padding len = 5 bytes
Nov 29 18:10:24 [20618]
ssh2:20: SSH2 packet payload len = 134 bytes
Nov 29 18:10:24 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:24 [20618]
ssh2:20: SSH2 packet MAC len = 0 bytes
Nov 29 18:10:24 [20618]
ssh2:9: reading DH_INIT message from client
20111129181024 20618 ssh2 TtUgD1vFjARF2QUHAABQirel 91.197.143.12 69.217.5.7 0:0 nobody “DH_INIT (data)” - - 513/472 - “-”//”-“
Nov 29 18:10:24 [20618]
ssh2:9: writing DH_INIT message to client
Nov 29 18:10:24 [20618]
ssh2:12: computing DH key
Nov 29 18:10:24 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 1 using select(2)
Nov 29 18:10:24 [20618]
ssh2:3: sent SSH_MSG_KEX_DH_REPLY (31) packet (448 bytes)
Nov 29 18:10:24 [20618]
ssh2:9: sending NEWKEYS message to client
Nov 29 18:10:24 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 1 using select(2)
Nov 29 18:10:24 [20618]
ssh2:3: sent SSH_MSG_NEWKEYS (21) packet (16 bytes)
Nov 29 18:10:24 [20618]
ssh2:9: reading NEWKEYS message from client
Nov 29 18:10:24 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:26 [20618]
ssh2:20: SSH2 packet len = 12 bytes
Nov 29 18:10:26 [20618]
ssh2:20: SSH2 packet padding len = 10 bytes
Nov 29 18:10:26 [20618]
ssh2:20: SSH2 packet payload len = 1 bytes
Nov 29 18:10:26 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:26 [20618]
ssh2:20: SSH2 packet MAC len = 0 bytes
20111129181026 20618 ssh2 TtUgD1vFjARF2QUHAABQirel 91.197.143.12 69.217.5.7 0:0 nobody “NEWKEYS” - - 529/936 - “-”//”-"
Nov 29 18:10:26 [20618]
ssh2:9: setting session keys
Nov 29 18:10:26 [20618]
ssh2:4: CBC mode cipher chosen for server-to-client messages, automatically enabling ‘rogaway’ TAP policy
Nov 29 18:10:26 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:26 [20618]
ssh2:20: SSH2 packet len = 1676920850 bytes
Nov 29 18:10:26 [20618]
ssh2:20: SSH2 packet padding len = 55 bytes
Nov 29 18:10:26 [20618]
ssh2:20: SSH2 packet payload len = 1676920794 bytes
Nov 29 18:10:26 [20618]
ssh2:20: payload len (1676920794 bytes) exceeds max payload len (262144), ignoring payload
Nov 29 18:10:26 mod_sftp/0.9.8[20618]: client sent buggy/malicious packet payload length, ignoring
Nov 29 18:10:26 mod_sftp/0.9.8[20618]: unable to read payload from socket 0
Nov 29 18:10:26 [20618]
ssh2:3: reading 77820 bytes of data for discarding
Nov 29 18:10:26 [20618]
ssh2:19: waiting for max of 14400 secs while polling socket 0 using select(2)
Nov 29 18:10:26 [20618]
ssh2:20: read 36 bytes, expected 77820 bytes; pessimistically returning
Nov 29 18:10:26 [20618]
ssh2:9: disconnecting (Application error) [at packet.c:1379]
Nov 29 18:10:26 mod_sftp/0.9.8[20618]: disconnecting (Application error)
Nov 29 18:10:26 [20618]
ssh2:20: sending random SSH2_MSG_IGNORE message (152 bytes) based on ‘rogaway’ TAP policy
Nov 29 18:10:26 [20618]
ssh2:19: waiting for max of 5 secs while polling socket 1 using select(2)
Nov 29 18:10:26 [20618]
ssh2:3: sent SSH_MSG_IGNORE (2) packet (180 bytes)
Nov 29 18:10:26 [20618]
ssh2:19: waiting for max of 5 secs while polling socket 1 using select(2)
Nov 29 18:10:26 [20618]
ssh2:3: sent SSH_MSG_DISCONNECT (1) packet (60 bytes)
Nov 29 18:10:27 ftp-uk proftpd[20618] 91.197.140.4 (69.217.5.7[69.217.5.7]): SSH2 session closed.