Interoperability

Following table shows known issues of interoperability with various SFTP, FTP and WebDAV servers. It includes both problems of the servers or known problems (typically fixed) of WinSCP that emerge with particular server only. It also includes special (even proprietary) features of some servers that WinSCP can use.

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Workarounds for bugs of major SFTP servers can be configured on SFTP page of Advanced Site Settings dialog.

Server Issue Solution / Use
OpenSSH Supports SFTP version 3 only.
Cannot handle SFTP packets larger than 256 KB, but due to support for SFTP version 3 only, it cannot report the limitation. Since 3.7.6 WinSCP automatically limits size of SFTP packet to 256 KB when connected to OpenSSH SFTP server.
Reverses order of link command arguments (SSH_FXP_SYMLINK request). Since 3.6.1 WinSCP automatically reverses the order too, when connected to OpenSSH SFTP server. Since 3.7.2 the behavior is configurable.
Misinterprets file timestamps prior to 1970. Since 3.7.4 WinSCP automatically interprets the timestamps in the same incorrect way when connected to OpenSSH SFTP server.
Proprietary SFTP protocol extension statvfs@openssh.com for checking space available. WinSCP supports that since 5.2.7 RC.
Proprietary SFTP protocol extension hardlink@openssh.com for creating hard links. WinSCP supports that since 5.6.1 beta. 1192
Cannot set special permissions. User can issue remote command to set these permissions.
Bitvise WinSSHD Does not announce support for SFTP extensions (checking space available, checksum calculation, remote file duplication). WinSCP can handle that since 5.6.1 beta. 1191
ProFTPD/mod_sftp Incorrectly encodes space-available SFTP packet. WinSCP can handle that since 5.5.5. 1184
Follows OpenSSH bug Reverses order of link command arguments for both symbolic links and hard links. WinSCP can handle that since 5.5.5 (symbolic links) 1185 and 5.6.1 (hard links)
Incorrectly pads RSA signature. WinSCP can handle that since 5.5.3. 1091
Proprietary FTP protocol extension SITE COPY/CPFR/CPTO to duplicate a remote file. WinSCP supports that since 5.6.2 beta.
Proprietary FTP protocol extension SITE SYMLINK to create a symbolic link. WinSCP supports that since 5.6.2 beta.
Incorrectly encodes response to SSH_FXP_REALPATH with SFTP version 6 (fixed in 1.3.5a and 1.3.6rc1). WinSCP can handle that since 5.7.1. 1289
VShell Windows version does not have Unix-like behavior. WinSCP can handle that since 3.2, but if version 4 or newer of SFTP protocol is used only.
Provides file attributes (SSH_FILEXFER_ATTR_BITS) with SFTP version 4, when it is allowed since version 5 only. WinSCP can handle that since 3.7.3.
Incorrectly encodes list of supported SFTP versions. WinSCP can handle that since 3.8.1.
Windows version does not provide owner/group in directory listing. WinSCP can request them explicitly before showing Properties dialog since 3.8.
If single root option is disabled on the Windows version of the server, it provides list of drives on startup. WinSCP can show the drives on remote directory tree since 3.7.5.
Incorrectly announces support for checksum calculation in versions 4.0.3 and older. WinSCP can handle that since 5.5.5. 1190
Sun SSH See OpenSSH.
FTPshell Does not support reading of file attributes (SSH_FXP_LSTAT request). WinSCP uses this also to check existence of directory before entering it. To allow user to enter to directory on FTPshell server, since 3.7.5 WinSCP automatically fall backs to checking the existence by reading directory content. This in turn forbids used to enter traverse-only directories (with permissions 110).
MultiNet For SFTP version 4, it indicates presence of UID/GUI in directory listing, but actually it does not include them. These attributes are not allowed for SFTP version 4 and newer, so WinSCP ignores the indication since 3.7.5.
Foxit WAC server Does not use UTF-8 encoding for SFTP version 4 and newer. WinSCP does not expect UTF-8 encoding when connected to Foxit WAC server since 3.7.2.
Titan FTP server Incorrectly encodes the filenames to UTF-8. Force SFTP version 3 either on server or client side to avoid UTF-8 encoding.
Incorrectly encodes server capabilities packet (supported2 extension). Force SFTP version 4 or lower either on server or client side to avoid the server provide the incorrect packet.
CoreFTP server Violates SFTP protocol in response to changing file properties. Turn off setting file properties in transfer settings.
WeOnlyDo/freeSSHd server Ignores SSH_FXF_EXCL flag when opening file, so WinSCP won’t detect that remote file already exists when uploading and won’t show overwrite confirmation prompt. No workaround exists.
IIS FTP Does not support standard FTP command MDTM to preserve file timestamp, instead supports non-standard syntax of MFMT command. WinSCP supports non-standard syntax of MFMT since 5.6.2 beta. 1221
Malformed FEAT response WinSCP can handle the malformed response to FEAT request sent by old versions of IIS (and by WS_FTP) since 5.6.4 RC.
Includes free bytes in the status message of directory listing when FTP Directory Browsing > Directory Listing Options > Available bytes option is enabled. WinSCP can parse the information and display it since 5.8.2 beta.
IIS WebDAV Translate header WinSCP uses IIS Translate header to allow download of files with unregistered extensions and source code of script files since 5.6.4 RC. 1225
mod_dav executable property Displayed as Executable keyword in Rights column of remote file panel since 5.8 beta.
Cerberus FTP server Incorrectly indicates end of directory listing in SFTP-6. WinSCP ignores the indication since 5.7.5 1338

 
  interoperability.txt · Last modified: by martin
 

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