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diff --git a/lib/ssh/doc/standard/draft-ietf-secsh-filexfer-04.txt b/lib/ssh/doc/standard/draft-ietf-secsh-filexfer-04.txt deleted file mode 100644 index 9f51883cd2..0000000000 --- a/lib/ssh/doc/standard/draft-ietf-secsh-filexfer-04.txt +++ /dev/null @@ -1,2130 +0,0 @@ - - - -Secure Shell Working Group J. Galbraith -Internet-Draft VanDyke Software -Expires: June 18, 2003 T. Ylonen - S. Lehtinen - SSH Communications Security Corp - December 18, 2002 - - - SSH File Transfer Protocol - draft-ietf-secsh-filexfer-04.txt - -Status of this Memo - - This document is an Internet-Draft and is in full conformance with - all provisions of Section 10 of RFC2026. - - Internet-Drafts are working documents of the Internet Engineering - Task Force (IETF), its areas, and its working groups. Note that - other groups may also distribute working documents as - Internet-Drafts. - - Internet-Drafts are draft documents valid for a maximum of six months - and may be updated, replaced, or obsoleted by other documents at any - time. It is inappropriate to use Internet-Drafts as reference - material or to cite them other than as "work in progress." - - The list of current Internet-Drafts can be accessed at http:// - www.ietf.org/ietf/1id-abstracts.txt. - - The list of Internet-Draft Shadow Directories can be accessed at - http://www.ietf.org/shadow.html. - - This Internet-Draft will expire on June 18, 2003. - -Copyright Notice - - Copyright (C) The Internet Society (2002). All Rights Reserved. - -Abstract - - The SSH File Transfer Protocol provides secure file transfer - functionality over any reliable data stream. It is the standard file - transfer protocol for use with the SSH2 protocol. This document - describes the file transfer protocol and its interface to the SSH2 - protocol suite. - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 1] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -Table of Contents - - 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 3 - 2. Use with the SSH Connection Protocol . . . . . . . . . . . 4 - 3. General Packet Format . . . . . . . . . . . . . . . . . . 5 - 3.1 The use of stderr in the server . . . . . . . . . . . . . 6 - 4. Protocol Initialization . . . . . . . . . . . . . . . . . 8 - 4.1 Client Initialization . . . . . . . . . . . . . . . . . . 8 - 4.2 Server Initialization . . . . . . . . . . . . . . . . . . 8 - 4.3 Determining Server Newline Convention . . . . . . . . . . 9 - 5. File Attributes . . . . . . . . . . . . . . . . . . . . . 10 - 5.1 Flags . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 5.2 Type . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 - 5.3 Size . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 - 5.4 Owner and Group . . . . . . . . . . . . . . . . . . . . . 11 - 5.5 Permissions . . . . . . . . . . . . . . . . . . . . . . . 12 - 5.6 Times . . . . . . . . . . . . . . . . . . . . . . . . . . 12 - 5.7 ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 - 5.8 Extended attributes . . . . . . . . . . . . . . . . . . . 14 - 6. Requests From the Client to the Server . . . . . . . . . . 15 - 6.1 Request Synchronization and Reordering . . . . . . . . . . 15 - 6.2 File Names . . . . . . . . . . . . . . . . . . . . . . . . 16 - 6.3 Opening, Creating, and Closing Files . . . . . . . . . . . 16 - 6.4 Reading and Writing . . . . . . . . . . . . . . . . . . . 19 - 6.5 Removing and Renaming Files . . . . . . . . . . . . . . . 20 - 6.6 Creating and Deleting Directories . . . . . . . . . . . . 21 - 6.7 Scanning Directories . . . . . . . . . . . . . . . . . . . 21 - 6.8 Retrieving File Attributes . . . . . . . . . . . . . . . . 22 - 6.9 Setting File Attributes . . . . . . . . . . . . . . . . . 23 - 6.10 Dealing with Symbolic links . . . . . . . . . . . . . . . 24 - 6.11 Canonicalizing the Server-Side Path Name . . . . . . . . . 25 - 6.11.1 Best practice for dealing with paths . . . . . . . . . . . 25 - 7. Responses from the Server to the Client . . . . . . . . . 26 - 8. Vendor-Specific Extensions . . . . . . . . . . . . . . . . 30 - 9. Security Considerations . . . . . . . . . . . . . . . . . 31 - 10. Changes from previous protocol versions . . . . . . . . . 32 - 10.1 Changes between versions 4 and 3 . . . . . . . . . . . . . 32 - 10.2 Changes between versions 3 and 2 . . . . . . . . . . . . . 33 - 10.3 Changes between versions 2 and 1 . . . . . . . . . . . . . 33 - 10.4 Changes between versions 1 and 0 . . . . . . . . . . . . . 33 - 11. Trademark Issues . . . . . . . . . . . . . . . . . . . . . 34 - References . . . . . . . . . . . . . . . . . . . . . . . . 35 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . 35 - Intellectual Property and Copyright Statements . . . . . . 37 - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 2] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -1. Introduction - - This protocol provides secure file transfer (and more generally file - system access) functionality over a reliable data stream, such as a - channel in the SSH2 protocol [5]. - - This protocol is designed so that it could be used to implement a - secure remote file system service, as well as a secure file transfer - service. - - This protocol assumes that it runs over a secure channel, and that - the server has already authenticated the user at the client end, and - that the identity of the client user is externally available to the - server implementation. - - In general, this protocol follows a simple request-response model. - Each request and response contains a sequence number and multiple - requests may be pending simultaneously. There are a relatively large - number of different request messages, but a small number of possible - response messages. Each request has one or more response messages - that may be returned in result (e.g., a read either returns data or - reports error status). - - The packet format descriptions in this specification follow the - notation presented in the secsh architecture draft. [5] - - Even though this protocol is described in the context of the SSH2 - protocol, this protocol is general and independent of the rest of the - SSH2 protocol suite. It could be used in a number of different - applications, such as secure file transfer over TLS RFC 2246 [1] and - transfer of management information in VPN applications. - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 3] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -2. Use with the SSH Connection Protocol - - When used with the SSH2 Protocol suite, this protocol is intended to - be used from the SSH Connection Protocol [7] as a subsystem, as - described in section ``Starting a Shell or a Command''. The - subsystem name used with this protocol is "sftp". - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 4] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -3. General Packet Format - - All packets transmitted over the secure connection are of the - following format: - - uint32 length - byte type - byte[length - 1] data payload - - That is, they are just data preceded by 32-bit length and 8-bit type - fields. The `length' is the length of the data area, and does not - include the `length' field itself. The format and interpretation of - the data area depends on the packet type. - - All packet descriptions below only specify the packet type and the - data that goes into the data field. Thus, they should be prefixed by - the `length' and `type' fields. - - The maximum size of a packet is in practice determined by the client - (the maximum size of read or write requests that it sends, plus a few - bytes of packet overhead). All servers SHOULD support packets of at - least 34000 bytes (where the packet size refers to the full length, - including the header above). This should allow for reads and writes - of at most 32768 bytes. - - There is no limit on the number of outstanding (non-acknowledged) - requests that the client may send to the server. In practice this is - limited by the buffering available on the data stream and the queuing - performed by the server. If the server's queues are full, it should - not read any more data from the stream, and flow control will prevent - the client from sending more requests. Note, however, that while - there is no restriction on the protocol level, the client's API may - provide a limit in order to prevent infinite queuing of outgoing - requests at the client. - - The following values are defined for packet types. - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 5] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - #define SSH_FXP_INIT 1 - #define SSH_FXP_VERSION 2 - #define SSH_FXP_OPEN 3 - #define SSH_FXP_CLOSE 4 - #define SSH_FXP_READ 5 - #define SSH_FXP_WRITE 6 - #define SSH_FXP_LSTAT 7 - #define SSH_FXP_FSTAT 8 - #define SSH_FXP_SETSTAT 9 - #define SSH_FXP_FSETSTAT 10 - #define SSH_FXP_OPENDIR 11 - #define SSH_FXP_READDIR 12 - #define SSH_FXP_REMOVE 13 - #define SSH_FXP_MKDIR 14 - #define SSH_FXP_RMDIR 15 - #define SSH_FXP_REALPATH 16 - #define SSH_FXP_STAT 17 - #define SSH_FXP_RENAME 18 - #define SSH_FXP_READLINK 19 - #define SSH_FXP_SYMLINK 20 - - #define SSH_FXP_STATUS 101 - #define SSH_FXP_HANDLE 102 - #define SSH_FXP_DATA 103 - #define SSH_FXP_NAME 104 - #define SSH_FXP_ATTRS 105 - - #define SSH_FXP_EXTENDED 200 - #define SSH_FXP_EXTENDED_REPLY 201 - - RESERVED_FOR_EXTENSIONS 210-255 - - Additional packet types should only be defined if the protocol - version number (see Section ``Protocol Initialization'') is - incremented, and their use MUST be negotiated using the version - number. However, the SSH_FXP_EXTENDED and SSH_FXP_EXTENDED_REPLY - packets can be used to implement vendor-specific extensions. See - Section ``Vendor-Specific-Extensions'' for more details. - -3.1 The use of stderr in the server - - Packets are sent and received on stdout and stdin. Data sent on - stderr by the server SHOULD be considered debug or supplemental error - information, and MAY be displayed to the user. - - For example, during initialization, there is no client request - active, so errors or warning information cannot be sent to the client - as part of the SFTP protocol at this early stage. However, the - - - -Galbraith, et al. Expires June 18, 2003 [Page 6] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - errors or warnings MAY be sent as stderr text. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 7] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -4. Protocol Initialization - - When the file transfer protocol starts, the client first sends a - SSH_FXP_INIT (including its version number) packet to the server. - The server responds with a SSH_FXP_VERSION packet, supplying the - lowest of its own and the client's version number. Both parties - should from then on adhere to particular version of the protocol. - - The version number of the protocol specified in this document is 4. - The version number should be incremented for each incompatible - revision of this protocol. - -4.1 Client Initialization - - The SSH_FXP_INIT packet (from client to server) has the following - data: - - uint32 version - - Version 3 of this protocol allowed clients to include extensions in - the SSH_FXP_INIT packet; however, this can cause interoperability - problems with version 1 and version 2 servers because the client must - send this packet before knowing the servers version. - - In this version of the protocol, clients MUST use the - SSH_FXP_EXTENDED packet to send extensions to the server after - version exchange has completed. Clients MUST NOT include extensions - in the version packet. This will prevent interoperability problems - with older servers - -4.2 Server Initialization - - The SSH_FXP_VERSION packet (from server to client) has the following - data: - - uint32 version - <extension data> - - 'version' is the lower of the protocol version supported by the - server and the version number received from the client. - - The extension data may be empty, or may be a sequence of - - string extension_name - string extension_data - - pairs (both strings MUST always be present if one is, but the - `extension_data' string may be of zero length). If present, these - - - -Galbraith, et al. Expires June 18, 2003 [Page 8] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - strings indicate extensions to the baseline protocol. The - `extension_name' field(s) identify the name of the extension. The - name should be of the form "name@domain", where the domain is the DNS - domain name of the organization defining the extension. Additional - names that are not of this format may be defined later by the IETF. - Implementations MUST silently ignore any extensions whose name they - do not recognize. - -4.3 Determining Server Newline Convention - - In order to correctly process text files in a cross platform - compatible way, the newline convention must be converted from that of - the server to that of the client, or, during an upload, from that of - the client to that of the server. - - Versions 3 and prior of this protocol made no provisions for - processing text files. Many clients implemented some sort of - conversion algorithm, but without either a 'canonical' on the wire - format or knowledge of the servers newline convention, correct - conversion was not always possible. - - Starting with Version 4, the SSH_FXF_TEXT file open flag (Section - 6.3) makes it possible to request that the server translate a file to - a 'canonical' on the wire format. This format uses \r\n as the line - separator. - - Servers for systems using multiple newline characters (for example, - Mac OS X or VMS) or systems using counted records, MUST translate to - the canonical form. - - However, to ease the burden of implementation on servers that use a - single, simple separator sequence, the following extension allows the - canonical format to be changed. - - string "newline" - string new-canonical-separator (usually "\r" or "\n" or "\r\n") - - All clients MUST support this extension. - - When processing text files, clients SHOULD NOT translate any - character or sequence that is not an exact match of the servers - newline separator. - - In particular, if the newline sequence being used is the canonical - "\r\n" sequence, a lone \r or a lone \n SHOULD be written through - without change. - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 9] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -5. File Attributes - - A new compound data type is defined for encoding file attributes. - The same encoding is used both when returning file attributes from - the server and when sending file attributes to the server. When - sending it to the server, the flags field specifies which attributes - are included, and the server will use default values for the - remaining attributes (or will not modify the values of remaining - attributes). When receiving attributes from the server, the flags - specify which attributes are included in the returned data. The - server normally returns all attributes it knows about. - - uint32 flags - byte type always present - uint64 size present only if flag SIZE - string owner present only if flag OWNERGROUP - string group present only if flag OWNERGROUP - uint32 permissions present only if flag PERMISSIONS - uint64 atime present only if flag ACCESSTIME - uint32 atime_nseconds present only if flag SUBSECOND_TIMES - uint64 createtime present only if flag CREATETIME - uint32 createtime_nseconds present only if flag SUBSECOND_TIMES - uint64 mtime present only if flag MODIFYTIME - uint32 mtime_nseconds present only if flag SUBSECOND_TIMES - string acl present only if flag ACL - uint32 extended_count present only if flag EXTENDED - string extended_type - string extended_data - ... more extended data (extended_type - extended_data pairs), - so that number of pairs equals extended_count - - -5.1 Flags - - The `flags' specify which of the fields are present. Those fields - for which the corresponding flag is not set are not present (not - included in the packet). New flags can only be added by incrementing - the protocol version number (or by using the extension mechanism - described below). - - The flags bits are defined to have the following values: - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 10] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - #define SSH_FILEXFER_ATTR_SIZE 0x00000001 - #define SSH_FILEXFER_ATTR_PERMISSIONS 0x00000040 - #define SSH_FILEXFER_ATTR_ACCESSTIME 0x00000008 - #define SSH_FILEXFER_ATTR_CREATETIME 0x00000010 - #define SSH_FILEXFER_ATTR_MODIFYTIME 0x00000020 - #define SSH_FILEXFER_ATTR_ACL 0x00000040 - #define SSH_FILEXFER_ATTR_OWNERGROUP 0x00000080 - #define SSH_FILEXFER_ATTR_SUBSECOND_TIMES 0x00000100 - #define SSH_FILEXFER_ATTR_EXTENDED 0x80000000 - - In previous versions of this protocol flags value 0x00000002 was - SSH_FILEXFER_ATTR_UIDGID. This value is now unused, and OWNERGROUP - was given a new value in order to ease implementation burden. - 0x00000002 MUST NOT appear in the mask. Some future version of this - protocol may reuse flag 0x00000002. - -5.2 Type - - The type field is always present. The following types are defined: - - #define SSH_FILEXFER_TYPE_REGULAR 1 - #define SSH_FILEXFER_TYPE_DIRECTORY 2 - #define SSH_FILEXFER_TYPE_SYMLINK 3 - #define SSH_FILEXFER_TYPE_SPECIAL 4 - #define SSH_FILEXFER_TYPE_UNKNOWN 5 - - On a POSIX system, these values would be derived from the permission - field. - -5.3 Size - - The `size' field specifies the size of the file on disk, in bytes. - If it is present during file creation, it should be considered a hint - as to the files eventual size. - - Files opened with the SSH_FXF_TEXT flag may have a size that is - greater or less than the value of the size field. - -5.4 Owner and Group - - The `owner' and `group' fields are represented as UTF-8 strings; this - is the form used by NFS v4. See NFS version 4 Protocol. [3] The - following text is selected quotations from section 5.6. - - To avoid a representation that is tied to a particular underlying - implementation at the client or server, the use of UTF-8 strings has - been chosen. The string should be of the form user@dns_domain". - This will allow for a client and server that do not use the same - - - -Galbraith, et al. Expires June 18, 2003 [Page 11] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - local representation the ability to translate to a common syntax that - can be interpreted by both. In the case where there is no - translation available to the client or server, the attribute value - must be constructed without the "@". Therefore, the absence of the @ - from the owner or owner_group attribute signifies that no translation - was available and the receiver of the attribute should not place any - special meaning with the attribute value. Even though the attribute - value can not be translated, it may still be useful. In the case of - a client, the attribute string may be used for local display of - ownership. - -5.5 Permissions - - The `permissions' field contains a bit mask of file permissions as - defined by POSIX [1]. - -5.6 Times - - The 'atime', 'createtime', and 'mtime' contain the access, creation, - and modification times of the files, respectively. They are - represented as seconds from Jan 1, 1970 in UTC. - - A negative value indicates number of seconds before Jan 1, 1970. In - both cases, if the SSH_FILEXFER_ATTR_SUBSECOND_TIMES flag is set, the - nseconds field is to be added to the seconds field for the final time - representation. For example, if the time to be represented is - one-half second before 0 hour January 1, 1970, the seconds field - would have a value of negative one (-1) and the nseconds fields would - have a value of one-half second (500000000). Values greater than - 999,999,999 for nseconds are considered invalid. - -5.7 ACL - - The 'ACL' field contains an ACL similar to that defined in section - 5.9 of NFS version 4 Protocol [3]. - - uint32 ace-count - - repeated ace-count time: - uint32 ace-type - uint32 ace-flag - uint32 ace-mask - string who [UTF-8] - - ace-type is one of the following four values (taken from NFS Version - 4 Protocol [3]: - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 12] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - const ACE4_ACCESS_ALLOWED_ACE_TYPE = 0x00000000; - const ACE4_ACCESS_DENIED_ACE_TYPE = 0x00000001; - const ACE4_SYSTEM_AUDIT_ACE_TYPE = 0x00000002; - const ACE4_SYSTEM_ALARM_ACE_TYPE = 0x00000003; - - ace-flag is a combination of the following flag values. See NFS - Version 4 Protocol [3] section 5.9.2: - - const ACE4_FILE_INHERIT_ACE = 0x00000001; - const ACE4_DIRECTORY_INHERIT_ACE = 0x00000002; - const ACE4_NO_PROPAGATE_INHERIT_ACE = 0x00000004; - const ACE4_INHERIT_ONLY_ACE = 0x00000008; - const ACE4_SUCCESSFUL_ACCESS_ACE_FLAG = 0x00000010; - const ACE4_FAILED_ACCESS_ACE_FLAG = 0x00000020; - const ACE4_IDENTIFIER_GROUP = 0x00000040; - - ace-mask is any combination of the following flags (taken from NFS - Version 4 Protocol [3] section 5.9.3: - - const ACE4_READ_DATA = 0x00000001; - const ACE4_LIST_DIRECTORY = 0x00000001; - const ACE4_WRITE_DATA = 0x00000002; - const ACE4_ADD_FILE = 0x00000002; - const ACE4_APPEND_DATA = 0x00000004; - const ACE4_ADD_SUBDIRECTORY = 0x00000004; - const ACE4_READ_NAMED_ATTRS = 0x00000008; - const ACE4_WRITE_NAMED_ATTRS = 0x00000010; - const ACE4_EXECUTE = 0x00000020; - const ACE4_DELETE_CHILD = 0x00000040; - const ACE4_READ_ATTRIBUTES = 0x00000080; - const ACE4_WRITE_ATTRIBUTES = 0x00000100; - const ACE4_DELETE = 0x00010000; - const ACE4_READ_ACL = 0x00020000; - const ACE4_WRITE_ACL = 0x00040000; - const ACE4_WRITE_OWNER = 0x00080000; - const ACE4_SYNCHRONIZE = 0x00100000; - - who is a UTF-8 string of the form described in 'Owner and Group' - (Section 5.4) - - Also, as per '5.9.4 ACE who' [3] there are several identifiers that - need to be understood universally. Some of these identifiers cannot - be understood when an client access the server, but have meaning when - a local process accesses the file. The ability to display and modify - these permissions is permitted over SFTP. - - OWNER The owner of the file. - - - - -Galbraith, et al. Expires June 18, 2003 [Page 13] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - GROUP The group associated with the file. - - EVERYONE The world. - - INTERACTIVE Accessed from an interactive terminal. - - NETWORK Accessed via the network. - - DIALUP Accessed as a dialup user to the server. - - BATCH Accessed from a batch job. - - ANONYMOUS Accessed without any authentication. - - AUTHENTICATED Any authenticated user (opposite of ANONYMOUS). - - SERVICE Access from a system service. - - To avoid conflict, these special identifiers are distinguish by an - appended "@" and should appear in the form "xxxx@" (note: no domain - name after the "@"). For example: ANONYMOUS@. - -5.8 Extended attributes - - The SSH_FILEXFER_ATTR_EXTENDED flag provides a general extension - mechanism for vendor-specific extensions. If the flag is specified, - then the `extended_count' field is present. It specifies the number - of extended_type-extended_data pairs that follow. Each of these - pairs specifies an extended attribute. For each of the attributes, - the extended_type field should be a string of the format - "name@domain", where "domain" is a valid, registered domain name and - "name" identifies the method. The IETF may later standardize certain - names that deviate from this format (e.g., that do not contain the - "@" sign). The interpretation of `extended_data' depends on the - type. Implementations SHOULD ignore extended data fields that they - do not understand. - - Additional fields can be added to the attributes by either defining - additional bits to the flags field to indicate their presence, or by - defining extended attributes for them. The extended attributes - mechanism is recommended for most purposes; additional flags bits - should only be defined by an IETF standards action that also - increments the protocol version number. The use of such new fields - MUST be negotiated by the version number in the protocol exchange. - It is a protocol error if a packet with unsupported protocol bits is - received. - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 14] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -6. Requests From the Client to the Server - - Requests from the client to the server represent the various file - system operations. Each request begins with an `id' field, which is - a 32-bit identifier identifying the request (selected by the client). - The same identifier will be returned in the response to the request. - One possible implementation is a monotonically increasing request - sequence number (modulo 2^32). - - Many operations in the protocol operate on open files. The - SSH_FXP_OPEN request can return a file handle (which is an opaque - variable-length string) which may be used to access the file later - (e.g. in a read operation). The client MUST NOT send requests the - server with bogus or closed handles. However, the server MUST - perform adequate checks on the handle in order to avoid security - risks due to fabricated handles. - - This design allows either stateful and stateless server - implementation, as well as an implementation which caches state - between requests but may also flush it. The contents of the file - handle string are entirely up to the server and its design. The - client should not modify or attempt to interpret the file handle - strings. - - The file handle strings MUST NOT be longer than 256 bytes. - -6.1 Request Synchronization and Reordering - - The protocol and implementations MUST process requests relating to - the same file in the order in which they are received. In other - words, if an application submits multiple requests to the server, the - results in the responses will be the same as if it had sent the - requests one at a time and waited for the response in each case. For - example, the server may process non-overlapping read/write requests - to the same file in parallel, but overlapping reads and writes cannot - be reordered or parallelized. However, there are no ordering - restrictions on the server for processing requests from two different - file transfer connections. The server may interleave and parallelize - them at will. - - There are no restrictions on the order in which responses to - outstanding requests are delivered to the client, except that the - server must ensure fairness in the sense that processing of no - request will be indefinitely delayed even if the client is sending - other requests so that there are multiple outstanding requests all - the time. - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 15] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -6.2 File Names - - This protocol represents file names as strings. File names are - assumed to use the slash ('/') character as a directory separator. - - File names starting with a slash are "absolute", and are relative to - the root of the file system. Names starting with any other character - are relative to the user's default directory (home directory). Note - that identifying the user is assumed to take place outside of this - protocol. - - Servers SHOULD interpret a path name component ".." as referring to - the parent directory, and "." as referring to the current directory. - If the server implementation limits access to certain parts of the - file system, it must be extra careful in parsing file names when - enforcing such restrictions. There have been numerous reported - security bugs where a ".." in a path name has allowed access outside - the intended area. - - An empty path name is valid, and it refers to the user's default - directory (usually the user's home directory). - - Otherwise, no syntax is defined for file names by this specification. - Clients should not make any other assumptions; however, they can - splice path name components returned by SSH_FXP_READDIR together - using a slash ('/') as the separator, and that will work as expected. - - In order to comply with IETF Policy on Character Sets and Languages - [2], all filenames are to be encoded in UTF-8. The shortest valid - UTF-8 encoding of the UNICODE data MUST be used. The server is - responsible for converting the UNICODE data to whatever canonical - form it requires. - - For example, if the server requires that precomposed characters - always be used, the server MUST NOT assume the filename as sent by - the client has this attribute, but must do this normalization itself. - - It is understood that the lack of well-defined semantics for file - names may cause interoperability problems between clients and servers - using radically different operating systems. However, this approach - is known to work acceptably with most systems, and alternative - approaches that e.g. treat file names as sequences of structured - components are quite complicated. - -6.3 Opening, Creating, and Closing Files - - Files are opened and created using the SSH_FXP_OPEN message, whose - data part is as follows: - - - -Galbraith, et al. Expires June 18, 2003 [Page 16] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - uint32 id - string filename [UTF-8] - uint32 pflags - ATTRS attrs - - The `id' field is the request identifier as for all requests. - - The `filename' field specifies the file name. See Section ``File - Names'' for more information. - - The `pflags' field is a bitmask. The following bits have been - defined. - - #define SSH_FXF_READ 0x00000001 - #define SSH_FXF_WRITE 0x00000002 - #define SSH_FXF_APPEND 0x00000004 - #define SSH_FXF_CREAT 0x00000008 - #define SSH_FXF_TRUNC 0x00000010 - #define SSH_FXF_EXCL 0x00000020 - #define SSH_FXF_TEXT 0x00000040 - - These have the following meanings: - - SSH_FXF_READ - Open the file for reading. - - SSH_FXF_WRITE - Open the file for writing. If both this and SSH_FXF_READ are - specified, the file is opened for both reading and writing. - - SSH_FXF_APPEND - Force all writes to append data at the end of the file. The - offset parameter to write will be ignored. - - SSH_FXF_CREAT - If this flag is specified, then a new file will be created if one - does not already exist (if O_TRUNC is specified, the new file will - be truncated to zero length if it previously exists). - - SSH_FXF_TRUNC - Forces an existing file with the same name to be truncated to zero - length when creating a file by specifying SSH_FXF_CREAT. - SSH_FXF_CREAT MUST also be specified if this flag is used. - - SSH_FXF_EXCL - Causes the request to fail if the named file already exists. - SSH_FXF_CREAT MUST also be specified if this flag is used. - - - - -Galbraith, et al. Expires June 18, 2003 [Page 17] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - SSH_FXF_TEXT - Indicates that the server should treat the file as text and - convert it to the canonical newline convention in use. (See - Determining Server Newline Convention. (Section 4.3) - - When a file is opened with the FXF_TEXT flag, the offset field in - both the read and write function are ignored. - - Servers MUST correctly process multiple parallel reads and writes - correctly in this mode. Naturally, it is permissible for them to - do this by serializing the requests. It would not be possible for - a client to reliably detect a server that does not implement - parallel writes in time to prevent damage. - - Clients SHOULD use the SSH_FXF_APPEND flag to append data to a - text file rather then using write with a calculated offset. - - To support seeks on text file the following SSH_FXP_EXTENDED - packet is defined. - - - - string "text-seek" - string file-handle - uint64 line-number - - line-number is the index of the line number to seek to, where byte - 0 in the file is line number 0, and the byte directly following - the first newline sequence in the file is line number 1 and so on. - - The response to a "text-seek" request is an SSH_FXP_STATUS - message. - - An attempt to seek past the end-of-file should result in a - SSH_FX_EOF status. - - Servers SHOULD support at least one "text-seek" in order to - support resume. However, a client MUST be prepared to receive - SSH_FX_OP_UNSUPPORTED when attempting a "text-seek" operation. - The client can then try a fall-back strategy, if it has one. - - Clients MUST be prepared to handle SSH_FX_OP_UNSUPPORTED returned - for read or write operations that are not sequential. - - The `attrs' field specifies the initial attributes for the file. - Default values will be used for those attributes that are not - specified. See Section ``File Attributes'' for more information. - - - - -Galbraith, et al. Expires June 18, 2003 [Page 18] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - The response to this message will be either SSH_FXP_HANDLE (if the - operation is successful) or SSH_FXP_STATUS (if the operation fails). - - A file is closed by using the SSH_FXP_CLOSE request. Its data field - has the following format: - - uint32 id - string handle - - where `id' is the request identifier, and `handle' is a handle - previously returned in the response to SSH_FXP_OPEN or - SSH_FXP_OPENDIR. The handle becomes invalid immediately after this - request has been sent. - - The response to this request will be a SSH_FXP_STATUS message. One - should note that on some server platforms even a close can fail. - This can happen e.g. if the server operating system caches writes, - and an error occurs while flushing cached writes during the close. - -6.4 Reading and Writing - - Once a file has been opened, it can be read using the following - message: - - byte SSH_FXP_READ - uint32 id - string handle - uint64 offset - uint32 len - - where `id' is the request identifier, `handle' is an open file handle - returned by SSH_FXP_OPEN, `offset' is the offset (in bytes) relative - to the beginning of the file from where to start reading, and `len' - is the maximum number of bytes to read. - - In response to this request, the server will read as many bytes as it - can from the file (up to `len'), and return them in a SSH_FXP_DATA - message. If an error occurs or EOF is encountered before reading any - data, the server will respond with SSH_FXP_STATUS. - - For normal disk files, it is normally guaranteed that this will read - the specified number of bytes, or up to end of file. However, if the - read length is very long, the server may truncate it if it doesn't - support packets of that length. See General Packet Format (Section - 3). - - For e.g. device files this may return fewer bytes than requested. - - - - -Galbraith, et al. Expires June 18, 2003 [Page 19] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - Writing to a file is achieved using the following message: - - byte SSH_FXP_WRITE - uint32 id - string handle - uint64 offset - string data - - where `id' is a request identifier, `handle' is a file handle - returned by SSH_FXP_OPEN, `offset' is the offset (in bytes) from the - beginning of the file where to start writing, and `data' is the data - to be written. - - The write will extend the file if writing beyond the end of the file. - It is legal to write way beyond the end of the file; the semantics - are to write zeroes from the end of the file to the specified offset - and then the data. On most operating systems, such writes do not - allocate disk space but instead leave "holes" in the file. - - The server responds to a write request with a SSH_FXP_STATUS message. - -6.5 Removing and Renaming Files - - Files can be removed using the SSH_FXP_REMOVE message. It has the - following format: - - uint32 id - string filename [UTF-8] - - where `id' is the request identifier and `filename' is the name of - the file to be removed. See Section ``File Names'' for more - information. This request cannot be used to remove directories. - - The server will respond to this request with a SSH_FXP_STATUS - message. - - Files (and directories) can be renamed using the SSH_FXP_RENAME - message. Its data is as follows: - - uint32 id - string oldpath [UTF-8] - string newpath [UTF-8] - - where `id' is the request identifier, `oldpath' is the name of an - existing file or directory, and `newpath' is the new name for the - file or directory. It is an error if there already exists a file - with the name specified by newpath. The server may also fail rename - requests in other situations, for example if `oldpath' and `newpath' - - - -Galbraith, et al. Expires June 18, 2003 [Page 20] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - point to different file systems on the server. - - The server will respond to this request with a SSH_FXP_STATUS - message. - -6.6 Creating and Deleting Directories - - New directories can be created using the SSH_FXP_MKDIR request. It - has the following format: - - uint32 id - string path [UTF-8] - ATTRS attrs - - where `id' is the request identifier. - - `path' specifies the directory to be created. See Section ``File - Names'' for more information on file names. - - `attrs' specifies the attributes that should be applied to it upon - creation. Attributes are discussed in more detail in Section ``File - Attributes''. - - The server will respond to this request with a SSH_FXP_STATUS - message. If a file or directory with the specified path already - exists, an error will be returned. - - Directories can be removed using the SSH_FXP_RMDIR request, which has - the following format: - - uint32 id - string path [UTF-8] - - where `id' is the request identifier, and `path' specifies the - directory to be removed. See Section ``File Names'' for more - information on file names. - - The server responds to this request with a SSH_FXP_STATUS message. - Errors may be returned from this operation for various reasons, - including, but not limited to, the path does not exist, the path does - not refer to a directory object, the directory is not empty, or the - user has insufficient access or permission to perform the requested - operation. - -6.7 Scanning Directories - - The files in a directory can be listed using the SSH_FXP_OPENDIR and - SSH_FXP_READDIR requests. Each SSH_FXP_READDIR request returns one - - - -Galbraith, et al. Expires June 18, 2003 [Page 21] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - or more file names with full file attributes for each file. The - client should call SSH_FXP_READDIR repeatedly until it has found the - file it is looking for or until the server responds with a - SSH_FXP_STATUS message indicating an error (normally SSH_FX_EOF if - there are no more files in the directory). The client should then - close the handle using the SSH_FXP_CLOSE request. - - The SSH_FXP_OPENDIR opens a directory for reading. It has the - following format: - - uint32 id - string path [UTF-8] - - where `id' is the request identifier and `path' is the path name of - the directory to be listed (without any trailing slash). See Section - ``File Names'' for more information on file names. This will return - an error if the path does not specify a directory or if the directory - is not readable. The server will respond to this request with either - a SSH_FXP_HANDLE or a SSH_FXP_STATUS message. - - Once the directory has been successfully opened, files (and - directories) contained in it can be listed using SSH_FXP_READDIR - requests. These are of the format - - uint32 id - string handle - - where `id' is the request identifier, and `handle' is a handle - returned by SSH_FXP_OPENDIR. (It is a protocol error to attempt to - use an ordinary file handle returned by SSH_FXP_OPEN.) - - The server responds to this request with either a SSH_FXP_NAME or a - SSH_FXP_STATUS message. One or more names may be returned at a time. - Full status information is returned for each name in order to speed - up typical directory listings. - - If there are no more names available to be read, the server MUST - respond with a SSH_FXP_STATUS message with error code of SSH_FX_EOF. - - When the client no longer wishes to read more names from the - directory, it SHOULD call SSH_FXP_CLOSE for the handle. The handle - should be closed regardless of whether an error has occurred or not. - -6.8 Retrieving File Attributes - - Very often, file attributes are automatically returned by - SSH_FXP_READDIR. However, sometimes there is need to specifically - retrieve the attributes for a named file. This can be done using the - - - -Galbraith, et al. Expires June 18, 2003 [Page 22] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - SSH_FXP_STAT, SSH_FXP_LSTAT and SSH_FXP_FSTAT requests. - - SSH_FXP_STAT and SSH_FXP_LSTAT only differ in that SSH_FXP_STAT - follows symbolic links on the server, whereas SSH_FXP_LSTAT does not - follow symbolic links. Both have the same format: - - uint32 id - string path [UTF-8] - uint32 flags - - where `id' is the request identifier, and `path' specifies the file - system object for which status is to be returned. The server - responds to this request with either SSH_FXP_ATTRS or SSH_FXP_STATUS. - - The flags field specify the attribute flags in which the client has - particular interest. This is a hint to the server. For example, - because retrieving owner / group and acl information can be an - expensive operation under some operating systems, the server may - choose not to retrieve this information unless the client expresses a - specific interest in it. - - The client has no guarantee the server will provide all the fields - that it has expressed an interest in. - - SSH_FXP_FSTAT differs from the others in that it returns status - information for an open file (identified by the file handle). Its - format is as follows: - - uint32 id - string handle - uint32 flags - - where `id' is the request identifier and `handle' is a file handle - returned by SSH_FXP_OPEN. The server responds to this request with - SSH_FXP_ATTRS or SSH_FXP_STATUS. - -6.9 Setting File Attributes - - File attributes may be modified using the SSH_FXP_SETSTAT and - SSH_FXP_FSETSTAT requests. These requests are used for operations - such as changing the ownership, permissions or access times, as well - as for truncating a file. - - The SSH_FXP_SETSTAT request is of the following format: - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 23] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - uint32 id - string path [UTF-8] - ATTRS attrs - - where `id' is the request identifier, `path' specifies the file - system object (e.g. file or directory) whose attributes are to be - modified, and `attrs' specifies the modifications to be made to its - attributes. Attributes are discussed in more detail in Section - ``File Attributes''. - - An error will be returned if the specified file system object does - not exist or the user does not have sufficient rights to modify the - specified attributes. The server responds to this request with a - SSH_FXP_STATUS message. - - The SSH_FXP_FSETSTAT request modifies the attributes of a file which - is already open. It has the following format: - - uint32 id - string handle - ATTRS attrs - - where `id' is the request identifier, `handle' (MUST be returned by - SSH_FXP_OPEN) identifies the file whose attributes are to be - modified, and `attrs' specifies the modifications to be made to its - attributes. Attributes are discussed in more detail in Section - ``File Attributes''. The server will respond to this request with - SSH_FXP_STATUS. - -6.10 Dealing with Symbolic links - - The SSH_FXP_READLINK request may be used to read the target of a - symbolic link. It would have a data part as follows: - - uint32 id - string path [UTF-8] - - where `id' is the request identifier and `path' specifies the path - name of the symlink to be read. - - The server will respond with a SSH_FXP_NAME packet containing only - one name and a dummy attributes value. The name in the returned - packet contains the target of the link. If an error occurs, the - server may respond with SSH_FXP_STATUS. - - The SSH_FXP_SYMLINK request will create a symbolic link on the - server. It is of the following format - - - - -Galbraith, et al. Expires June 18, 2003 [Page 24] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - uint32 id - string linkpath [UTF-8] - string targetpath [UTF-8] - - where `id' is the request identifier, `linkpath' specifies the path - name of the symlink to be created and `targetpath' specifies the - target of the symlink. The server shall respond with a - SSH_FXP_STATUS indicating either success (SSH_FX_OK) or an error - condition. - -6.11 Canonicalizing the Server-Side Path Name - - The SSH_FXP_REALPATH request can be used to have the server - canonicalize any given path name to an absolute path. This is useful - for converting path names containing ".." components or relative - pathnames without a leading slash into absolute paths. The format of - the request is as follows: - - uint32 id - string path [UTF-8] - - where `id' is the request identifier and `path' specifies the path - name to be canonicalized. The server will respond with a - SSH_FXP_NAME packet containing the name in canonical form and a dummy - attributes value. If an error occurs, the server may also respond - with SSH_FXP_STATUS. - -6.11.1 Best practice for dealing with paths - - The client SHOULD treat the results of SSH_FXP_REALPATH as a - canonical absolute path, even if the path does not appear to be - absolute. A client that use REALPATH(".") and treats the result as - absolute, even if there is no leading slash, will continue to - function correctly, even when talking to a Windows NT or VMS style - system, where absolute paths may not begin with a slash. - - For example, if the client wishes to change directory up, and the - server has returned "c:/x/y/z" from REALPATH, the client SHOULD use - "c:/x/y/z/..". - - As a second example, if the client wishes to open the file "x.txt" in - the current directory, and server has returned "dka100:/x/y/z" as the - canonical path of the directory, the client SHOULD open "dka100:/x/y/ - z/x.txt" - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 25] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -7. Responses from the Server to the Client - - The server responds to the client using one of a few response - packets. All requests can return a SSH_FXP_STATUS response upon - failure. When the operation is successful, any of the responses may - be returned (depending on the operation). If no data needs to be - returned to the client, the SSH_FXP_STATUS response with SSH_FX_OK - status is appropriate. Otherwise, the SSH_FXP_HANDLE message is used - to return a file handle (for SSH_FXP_OPEN and SSH_FXP_OPENDIR - requests), SSH_FXP_DATA is used to return data from SSH_FXP_READ, - SSH_FXP_NAME is used to return one or more file names from a - SSH_FXP_READDIR or SSH_FXP_REALPATH request, and SSH_FXP_ATTRS is - used to return file attributes from SSH_FXP_STAT, SSH_FXP_LSTAT, and - SSH_FXP_FSTAT requests. - - Exactly one response will be returned for each request. Each - response packet contains a request identifier which can be used to - match each response with the corresponding request. Note that it is - legal to have several requests outstanding simultaneously, and the - server is allowed to send responses to them in a different order from - the order in which the requests were sent (the result of their - execution, however, is guaranteed to be as if they had been processed - one at a time in the order in which the requests were sent). - - Response packets are of the same general format as request packets. - Each response packet begins with the request identifier. - - The format of the data portion of the SSH_FXP_STATUS response is as - follows: - - uint32 id - uint32 error/status code - string error message (ISO-10646 UTF-8 [RFC-2279]) - string language tag (as defined in [RFC-1766]) - - where `id' is the request identifier, and `error/status code' - indicates the result of the requested operation. The value SSH_FX_OK - indicates success, and all other values indicate failure. - - Currently, the following values are defined (other values may be - defined by future versions of this protocol): - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 26] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - #define SSH_FX_OK 0 - #define SSH_FX_EOF 1 - #define SSH_FX_NO_SUCH_FILE 2 - #define SSH_FX_PERMISSION_DENIED 3 - #define SSH_FX_FAILURE 4 - #define SSH_FX_BAD_MESSAGE 5 - #define SSH_FX_NO_CONNECTION 6 - #define SSH_FX_CONNECTION_LOST 7 - #define SSH_FX_OP_UNSUPPORTED 8 - #define SSH_FX_INVALID_HANDLE 9 - #define SSH_FX_NO_SUCH_PATH 10 - #define SSH_FX_FILE_ALREADY_EXISTS 11 - #define SSH_FX_WRITE_PROTECT 12 - #define SSH_FX_NO_MEDIA 13 - - SSH_FX_OK - Indicates successful completion of the operation. - - SSH_FX_EOF - indicates end-of-file condition; for SSH_FX_READ it means that no - more data is available in the file, and for SSH_FX_READDIR it - indicates that no more files are contained in the directory. - - SSH_FX_NO_SUCH_FILE - is returned when a reference is made to a file which does not - exist. - - SSH_FX_PERMISSION_DENIED - is returned when the authenticated user does not have sufficient - permissions to perform the operation. - - SSH_FX_FAILURE - is a generic catch-all error message; it should be returned if an - error occurs for which there is no more specific error code - defined. - - SSH_FX_BAD_MESSAGE - may be returned if a badly formatted packet or protocol - incompatibility is detected. - - SSH_FX_NO_CONNECTION - is a pseudo-error which indicates that the client has no - connection to the server (it can only be generated locally by the - client, and MUST NOT be returned by servers). - - SSH_FX_CONNECTION_LOST - is a pseudo-error which indicates that the connection to the - server has been lost (it can only be generated locally by the - - - -Galbraith, et al. Expires June 18, 2003 [Page 27] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - client, and MUST NOT be returned by servers). - - SSH_FX_OP_UNSUPPORTED - indicates that an attempt was made to perform an operation which - is not supported for the server (it may be generated locally by - the client if e.g. the version number exchange indicates that a - required feature is not supported by the server, or it may be - returned by the server if the server does not implement an - operation). - - SSH_FX_INVALID_HANDLE - The handle value was invalid. - - SSH_FX_NO_SUCH_PATH - The file path does not exist or is invalid. - - SSH_FX_FILE_ALREADY_EXISTS - The file already exists. - - SSH_FX_WRITE_PROTECT - The file is on read only media, or the media is write protected. - - SSH_FX_NO_MEDIA - The requested operation can not be completed because there is no - media available in the drive. - - The SSH_FXP_HANDLE response has the following format: - - uint32 id - string handle - - where `id' is the request identifier, and `handle' is an arbitrary - string that identifies an open file or directory on the server. The - handle is opaque to the client; the client MUST NOT attempt to - interpret or modify it in any way. The length of the handle string - MUST NOT exceed 256 data bytes. - - The SSH_FXP_DATA response has the following format: - - uint32 id - string data - - where `id' is the request identifier, and `data' is an arbitrary byte - string containing the requested data. The data string may be at most - the number of bytes requested in a SSH_FXP_READ request, but may also - be shorter if end of file is reached or if the read is from something - other than a regular file. - - - - -Galbraith, et al. Expires June 18, 2003 [Page 28] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - The SSH_FXP_NAME response has the following format: - - uint32 id - uint32 count - repeats count times: - string filename [UTF-8] - ATTRS attrs - - where `id' is the request identifier, `count' is the number of names - returned in this response, and the remaining fields repeat `count' - times (so that all three fields are first included for the first - file, then for the second file, etc). In the repeated part, - `filename' is a file name being returned (for SSH_FXP_READDIR, it - will be a relative name within the directory, without any path - components; for SSH_FXP_REALPATH it will be an absolute path name), - and `attrs' is the attributes of the file as described in Section - ``File Attributes''. - - The SSH_FXP_ATTRS response has the following format: - - uint32 id - ATTRS attrs - - where `id' is the request identifier, and `attrs' is the returned - file attributes as described in Section ``File Attributes''. - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 29] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -8. Vendor-Specific Extensions - - The SSH_FXP_EXTENDED request provides a generic extension mechanism - for adding vendor-specific commands. The request has the following - format: - - uint32 id - string extended-request - ... any request-specific data ... - - where `id' is the request identifier, and `extended-request' is a - string of the format "name@domain", where domain is an internet - domain name of the vendor defining the request. The rest of the - request is completely vendor-specific, and servers should only - attempt to interpret it if they recognize the `extended-request' - name. - - The server may respond to such requests using any of the response - packets defined in Section ``Responses from the Server to the - Client''. Additionally, the server may also respond with a - SSH_FXP_EXTENDED_REPLY packet, as defined below. If the server does - not recognize the `extended-request' name, then the server MUST - respond with SSH_FXP_STATUS with error/status set to - SSH_FX_OP_UNSUPPORTED. - - The SSH_FXP_EXTENDED_REPLY packet can be used to carry arbitrary - extension-specific data from the server to the client. It is of the - following format: - - uint32 id - ... any request-specific data ... - - There is a range of packet types reserved for use by extensions. In - order to avoid collision, extensions that turn on the use of - additional packet types should determine those numbers dynamically. - - The suggested way of doing this is have an extension request from the - client to the server that enables the extension; the extension - response from the server to the client would specify the actual type - values to use, in additional to any other data. - - Extension authors should be mindful of the limited range of packet - types available (there are only 45 values available) and avoid - requiring a new packet type where possible. - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 30] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -9. Security Considerations - - This protocol assumes that it is run over a secure channel and that - the endpoints of the channel have been authenticated. Thus, this - protocol assumes that it is externally protected from network-level - attacks. - - This protocol provides file system access to arbitrary files on the - server (only constrained by the server implementation). It is the - responsibility of the server implementation to enforce any access - controls that may be required to limit the access allowed for any - particular user (the user being authenticated externally to this - protocol, typically using the SSH User Authentication Protocol [8]. - - Care must be taken in the server implementation to check the validity - of received file handle strings. The server should not rely on them - directly; it MUST check the validity of each handle before relying on - it. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 31] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -10. Changes from previous protocol versions - - The SSH File Transfer Protocol has changed over time, before it's - standardization. The following is a description of the incompatible - changes between different versions. - -10.1 Changes between versions 4 and 3 - - Many of the changes between version 4 and version 3 are to the - attribute structure to make it more flexible for non-unix platforms. - - o Clarify the use of stderr by the server. - - o Clarify handling of very large read requests by the server. - - o Make all filenames UTF-8. - - o Added 'newline' extension. - - o Made time fields 64 bit, and optionally have nanosecond resultion. - - o Made file attribute owner and group strings so they can actually - be used on disparate systems. - - o Added createtime field, and added separate flags for atime, - createtime, and mtime so they can be set separately. - - o Split the file type out of the permissions field and into it's own - field (which is always present.) - - o Added acl attribute. - - o Added SSH_FXF_TEXT file open flag. - - o Added flags field to the get stat commands so that the client can - specifically request information the server might not normally - included for performance reasons. - - o Removed the long filename from the names structure-- it can now be - built from information available in the attrs structure. - - o Added reserved range of packet numbers for extensions. - - o Added several additional error codes. - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 32] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -10.2 Changes between versions 3 and 2 - - o The SSH_FXP_READLINK and SSH_FXP_SYMLINK messages were added. - - o The SSH_FXP_EXTENDED and SSH_FXP_EXTENDED_REPLY messages were - added. - - o The SSH_FXP_STATUS message was changed to include fields `error - message' and `language tag'. - - -10.3 Changes between versions 2 and 1 - - o The SSH_FXP_RENAME message was added. - - -10.4 Changes between versions 1 and 0 - - o Implementation changes, no actual protocol changes. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 33] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -11. Trademark Issues - - "ssh" is a registered trademark of SSH Communications Security Corp - in the United States and/or other countries. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 34] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -References - - [1] Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A. and - P. Kocher, "The TLS Protocol Version 1.0", RFC 2246, January - 1999. - - [2] Alvestrand, H., "IETF Policy on Character Sets and Languages", - BCP 18, RFC 2277, January 1998. - - [3] Shepler, S., Callaghan, B., Robinson, D., Thurlow, R., Beame, - C., Eisler, M. and D. Noveck, "NFS version 4 Protocol", RFC - 3010, December 2000. - - [4] Institute of Electrical and Electronics Engineers, "Information - Technology - Portable Operating System Interface (POSIX) - Part - 1: System Application Program Interface (API) [C Language]", - IEEE Standard 1003.2, 1996. - - [5] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S. - Lehtinen, "SSH Protocol Architecture", - draft-ietf-secsh-architecture-13 (work in progress), September - 2002. - - [6] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S. - Lehtinen, "SSH Protocol Transport Protocol", - draft-ietf-secsh-transport-15 (work in progress), September - 2002. - - [7] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S. - Lehtinen, "SSH Connection Protocol", draft-ietf-secsh-connect-16 - (work in progress), September 2002. - - [8] Rinne, T., Ylonen, T., Kivinen, T., Saarinen, M. and S. - Lehtinen, "SSH Authentication Protocol", - draft-ietf-secsh-userauth-16 (work in progress), September 2002. - - -Authors' Addresses - - Joseph Galbraith - VanDyke Software - 4848 Tramway Ridge Blvd - Suite 101 - Albuquerque, NM 87111 - US - - Phone: +1 505 332 5700 - EMail: [email protected] - - - -Galbraith, et al. Expires June 18, 2003 [Page 35] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - Tatu Ylonen - SSH Communications Security Corp - Fredrikinkatu 42 - HELSINKI FIN-00100 - Finland - - EMail: [email protected] - - - Sami Lehtinen - SSH Communications Security Corp - Fredrikinkatu 42 - HELSINKI FIN-00100 - Finland - - EMail: [email protected] - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 36] - -Internet-Draft SSH File Transfer Protocol December 2002 - - -Intellectual Property Statement - - The IETF takes no position regarding the validity or scope of any - intellectual property or other rights that might be claimed to - pertain to the implementation or use of the technology described in - this document or the extent to which any license under such rights - might or might not be available; neither does it represent that it - has made any effort to identify any such rights. 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Expires June 18, 2003 [Page 37] - -Internet-Draft SSH File Transfer Protocol December 2002 - - - HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF - MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. - - -Acknowledgement - - Funding for the RFC Editor function is currently provided by the - Internet Society. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Galbraith, et al. Expires June 18, 2003 [Page 38] - - |