commit 54f25db9d54c63052e789ec429d8a4296520e9d8 Author: mwenge robert@roberthogan.net Date: Sat Nov 28 10:24:01 2009 +0000
Remove non-free RFC and replace with link. --- doc/SOCKS5 | 2 + doc/SOCKS5-rfc1928.txt | 507 ------------------------------------------------ 2 files changed, 2 insertions(+), 507 deletions(-)
diff --git a/doc/SOCKS5 b/doc/SOCKS5 new file mode 100644 index 0000000..40dfcbd --- /dev/null +++ b/doc/SOCKS5 @@ -0,0 +1,2 @@ +http://www.ietf.org/rfc/rfc1928.txt + diff --git a/doc/SOCKS5-rfc1928.txt b/doc/SOCKS5-rfc1928.txt deleted file mode 100644 index 46bf46e..0000000 --- a/doc/SOCKS5-rfc1928.txt +++ /dev/null @@ -1,507 +0,0 @@ - - - - - - -Network Working Group M. Leech -Request for Comments: 1928 Bell-Northern Research Ltd -Category: Standards Track M. Ganis - International Business Machines - Y. Lee - NEC Systems Laboratory - R. Kuris - Unify Corporation - D. Koblas - Independent Consultant - L. Jones - Hewlett-Packard Company - March 1996 - - - SOCKS Protocol Version 5 - -Status of this Memo - - This document specifies an Internet standards track protocol for the - Internet community, and requests discussion and suggestions for - improvements. Please refer to the current edition of the "Internet - Official Protocol Standards" (STD 1) for the standardization state - and status of this protocol. Distribution of this memo is unlimited. - -Acknowledgments - - This memo describes a protocol that is an evolution of the previous - version of the protocol, version 4 [1]. This new protocol stems from - active discussions and prototype implementations. The key - contributors are: Marcus Leech: Bell-Northern Research, David Koblas: - Independent Consultant, Ying-Da Lee: NEC Systems Laboratory, LaMont - Jones: Hewlett-Packard Company, Ron Kuris: Unify Corporation, Matt - Ganis: International Business Machines. - -1. Introduction - - The use of network firewalls, systems that effectively isolate an - organizations internal network structure from an exterior network, - such as the INTERNET is becoming increasingly popular. These - firewall systems typically act as application-layer gateways between - networks, usually offering controlled TELNET, FTP, and SMTP access. - With the emergence of more sophisticated application layer protocols - designed to facilitate global information discovery, there exists a - need to provide a general framework for these protocols to - transparently and securely traverse a firewall. - - - - - -Leech, et al Standards Track [Page 1] - -RFC 1928 SOCKS Protocol Version 5 March 1996 - - - There exists, also, a need for strong authentication of such - traversal in as fine-grained a manner as is practical. This - requirement stems from the realization that client-server - relationships emerge between the networks of various organizations, - and that such relationships need to be controlled and often strongly - authenticated. - - The protocol described here is designed to provide a framework for - client-server applications in both the TCP and UDP domains to - conveniently and securely use the services of a network firewall. - The protocol is conceptually a "shim-layer" between the application - layer and the transport layer, and as such does not provide network- - layer gateway services, such as forwarding of ICMP messages. - -2. Existing practice - - There currently exists a protocol, SOCKS Version 4, that provides for - unsecured firewall traversal for TCP-based client-server - applications, including TELNET, FTP and the popular information- - discovery protocols such as HTTP, WAIS and GOPHER. - - This new protocol extends the SOCKS Version 4 model to include UDP, - and extends the framework to include provisions for generalized - strong authentication schemes, and extends the addressing scheme to - encompass domain-name and V6 IP addresses. - - The implementation of the SOCKS protocol typically involves the - recompilation or relinking of TCP-based client applications to use - the appropriate encapsulation routines in the SOCKS library. - -Note: - - Unless otherwise noted, the decimal numbers appearing in packet- - format diagrams represent the length of the corresponding field, in - octets. Where a given octet must take on a specific value, the - syntax X'hh' is used to denote the value of the single octet in that - field. When the word 'Variable' is used, it indicates that the - corresponding field has a variable length defined either by an - associated (one or two octet) length field, or by a data type field. - -3. Procedure for TCP-based clients - - When a TCP-based client wishes to establish a connection to an object - that is reachable only via a firewall (such determination is left up - to the implementation), it must open a TCP connection to the - appropriate SOCKS port on the SOCKS server system. The SOCKS service - is conventionally located on TCP port 1080. If the connection - request succeeds, the client enters a negotiation for the - - - -Leech, et al Standards Track [Page 2] - -RFC 1928 SOCKS Protocol Version 5 March 1996 - - - authentication method to be used, authenticates with the chosen - method, then sends a relay request. The SOCKS server evaluates the - request, and either establishes the appropriate connection or denies - it. - - Unless otherwise noted, the decimal numbers appearing in packet- - format diagrams represent the length of the corresponding field, in - octets. Where a given octet must take on a specific value, the - syntax X'hh' is used to denote the value of the single octet in that - field. When the word 'Variable' is used, it indicates that the - corresponding field has a variable length defined either by an - associated (one or two octet) length field, or by a data type field. - - The client connects to the server, and sends a version - identifier/method selection message: - - +----+----------+----------+ - |VER | NMETHODS | METHODS | - +----+----------+----------+ - | 1 | 1 | 1 to 255 | - +----+----------+----------+ - - The VER field is set to X'05' for this version of the protocol. The - NMETHODS field contains the number of method identifier octets that - appear in the METHODS field. - - The server selects from one of the methods given in METHODS, and - sends a METHOD selection message: - - +----+--------+ - |VER | METHOD | - +----+--------+ - | 1 | 1 | - +----+--------+ - - If the selected METHOD is X'FF', none of the methods listed by the - client are acceptable, and the client MUST close the connection. - - The values currently defined for METHOD are: - - o X'00' NO AUTHENTICATION REQUIRED - o X'01' GSSAPI - o X'02' USERNAME/PASSWORD - o X'03' to X'7F' IANA ASSIGNED - o X'80' to X'FE' RESERVED FOR PRIVATE METHODS - o X'FF' NO ACCEPTABLE METHODS - - The client and server then enter a method-specific sub-negotiation. - - - -Leech, et al Standards Track [Page 3] - -RFC 1928 SOCKS Protocol Version 5 March 1996 - - - Descriptions of the method-dependent sub-negotiations appear in - separate memos. - - Developers of new METHOD support for this protocol should contact - IANA for a METHOD number. The ASSIGNED NUMBERS document should be - referred to for a current list of METHOD numbers and their - corresponding protocols. - - Compliant implementations MUST support GSSAPI and SHOULD support - USERNAME/PASSWORD authentication methods. - -4. Requests - - Once the method-dependent subnegotiation has completed, the client - sends the request details. If the negotiated method includes - encapsulation for purposes of integrity checking and/or - confidentiality, these requests MUST be encapsulated in the method- - dependent encapsulation. - - The SOCKS request is formed as follows: - - +----+-----+-------+------+----------+----------+ - |VER | CMD | RSV | ATYP | DST.ADDR | DST.PORT | - +----+-----+-------+------+----------+----------+ - | 1 | 1 | X'00' | 1 | Variable | 2 | - +----+-----+-------+------+----------+----------+ - - Where: - - o VER protocol version: X'05' - o CMD - o CONNECT X'01' - o BIND X'02' - o UDP ASSOCIATE X'03' - o RSV RESERVED - o ATYP address type of following address - o IP V4 address: X'01' - o DOMAINNAME: X'03' - o IP V6 address: X'04' - o DST.ADDR desired destination address - o DST.PORT desired destination port in network octet - order - - The SOCKS server will typically evaluate the request based on source - and destination addresses, and return one or more reply messages, as - appropriate for the request type. - - - - - -Leech, et al Standards Track [Page 4] - -RFC 1928 SOCKS Protocol Version 5 March 1996 - - -5. Addressing - - In an address field (DST.ADDR, BND.ADDR), the ATYP field specifies - the type of address contained within the field: - - o X'01' - - the address is a version-4 IP address, with a length of 4 octets - - o X'03' - - the address field contains a fully-qualified domain name. The first - octet of the address field contains the number of octets of name that - follow, there is no terminating NUL octet. - - o X'04' - - the address is a version-6 IP address, with a length of 16 octets. - -6. Replies - - The SOCKS request information is sent by the client as soon as it has - established a connection to the SOCKS server, and completed the - authentication negotiations. The server evaluates the request, and - returns a reply formed as follows: - - +----+-----+-------+------+----------+----------+ - |VER | REP | RSV | ATYP | BND.ADDR | BND.PORT | - +----+-----+-------+------+----------+----------+ - | 1 | 1 | X'00' | 1 | Variable | 2 | - +----+-----+-------+------+----------+----------+ - - Where: - - o VER protocol version: X'05' - o REP Reply field: - o X'00' succeeded - o X'01' general SOCKS server failure - o X'02' connection not allowed by ruleset - o X'03' Network unreachable - o X'04' Host unreachable - o X'05' Connection refused - o X'06' TTL expired - o X'07' Command not supported - o X'08' Address type not supported - o X'09' to X'FF' unassigned - o RSV RESERVED - o ATYP address type of following address - - - -Leech, et al Standards Track [Page 5] - -RFC 1928 SOCKS Protocol Version 5 March 1996 - - - o IP V4 address: X'01' - o DOMAINNAME: X'03' - o IP V6 address: X'04' - o BND.ADDR server bound address - o BND.PORT server bound port in network octet order - - Fields marked RESERVED (RSV) must be set to X'00'. - - If the chosen method includes encapsulation for purposes of - authentication, integrity and/or confidentiality, the replies are - encapsulated in the method-dependent encapsulation. - -CONNECT - - In the reply to a CONNECT, BND.PORT contains the port number that the - server assigned to connect to the target host, while BND.ADDR - contains the associated IP address. The supplied BND.ADDR is often - different from the IP address that the client uses to reach the SOCKS - server, since such servers are often multi-homed. It is expected - that the SOCKS server will use DST.ADDR and DST.PORT, and the - client-side source address and port in evaluating the CONNECT - request. - -BIND - - The BIND request is used in protocols which require the client to - accept connections from the server. FTP is a well-known example, - which uses the primary client-to-server connection for commands and - status reports, but may use a server-to-client connection for - transferring data on demand (e.g. LS, GET, PUT). - - It is expected that the client side of an application protocol will - use the BIND request only to establish secondary connections after a - primary connection is established using CONNECT. In is expected that - a SOCKS server will use DST.ADDR and DST.PORT in evaluating the BIND - request. - - Two replies are sent from the SOCKS server to the client during a - BIND operation. The first is sent after the server creates and binds - a new socket. The BND.PORT field contains the port number that the - SOCKS server assigned to listen for an incoming connection. The - BND.ADDR field contains the associated IP address. The client will - typically use these pieces of information to notify (via the primary - or control connection) the application server of the rendezvous - address. The second reply occurs only after the anticipated incoming - connection succeeds or fails. - - - - - -Leech, et al Standards Track [Page 6] - -RFC 1928 SOCKS Protocol Version 5 March 1996 - - - In the second reply, the BND.PORT and BND.ADDR fields contain the - address and port number of the connecting host. - -UDP ASSOCIATE - - The UDP ASSOCIATE request is used to establish an association within - the UDP relay process to handle UDP datagrams. The DST.ADDR and - DST.PORT fields contain the address and port that the client expects - to use to send UDP datagrams on for the association. The server MAY - use this information to limit access to the association. If the - client is not in possesion of the information at the time of the UDP - ASSOCIATE, the client MUST use a port number and address of all - zeros. - - A UDP association terminates when the TCP connection that the UDP - ASSOCIATE request arrived on terminates. - - In the reply to a UDP ASSOCIATE request, the BND.PORT and BND.ADDR - fields indicate the port number/address where the client MUST send - UDP request messages to be relayed. - -Reply Processing - - When a reply (REP value other than X'00') indicates a failure, the - SOCKS server MUST terminate the TCP connection shortly after sending - the reply. This must be no more than 10 seconds after detecting the - condition that caused a failure. - - If the reply code (REP value of X'00') indicates a success, and the - request was either a BIND or a CONNECT, the client may now start - passing data. If the selected authentication method supports - encapsulation for the purposes of integrity, authentication and/or - confidentiality, the data are encapsulated using the method-dependent - encapsulation. Similarly, when data arrives at the SOCKS server for - the client, the server MUST encapsulate the data as appropriate for - the authentication method in use. - -7. Procedure for UDP-based clients - - A UDP-based client MUST send its datagrams to the UDP relay server at - the UDP port indicated by BND.PORT in the reply to the UDP ASSOCIATE - request. If the selected authentication method provides - encapsulation for the purposes of authenticity, integrity, and/or - confidentiality, the datagram MUST be encapsulated using the - appropriate encapsulation. Each UDP datagram carries a UDP request - header with it: - - - - - -Leech, et al Standards Track [Page 7] - -RFC 1928 SOCKS Protocol Version 5 March 1996 - - - +----+------+------+----------+----------+----------+ - |RSV | FRAG | ATYP | DST.ADDR | DST.PORT | DATA | - +----+------+------+----------+----------+----------+ - | 2 | 1 | 1 | Variable | 2 | Variable | - +----+------+------+----------+----------+----------+ - - The fields in the UDP request header are: - - o RSV Reserved X'0000' - o FRAG Current fragment number - o ATYP address type of following addresses: - o IP V4 address: X'01' - o DOMAINNAME: X'03' - o IP V6 address: X'04' - o DST.ADDR desired destination address - o DST.PORT desired destination port - o DATA user data - - When a UDP relay server decides to relay a UDP datagram, it does so - silently, without any notification to the requesting client. - Similarly, it will drop datagrams it cannot or will not relay. When - a UDP relay server receives a reply datagram from a remote host, it - MUST encapsulate that datagram using the above UDP request header, - and any authentication-method-dependent encapsulation. - - The UDP relay server MUST acquire from the SOCKS server the expected - IP address of the client that will send datagrams to the BND.PORT - given in the reply to UDP ASSOCIATE. It MUST drop any datagrams - arriving from any source IP address other than the one recorded for - the particular association. - - The FRAG field indicates whether or not this datagram is one of a - number of fragments. If implemented, the high-order bit indicates - end-of-fragment sequence, while a value of X'00' indicates that this - datagram is standalone. Values between 1 and 127 indicate the - fragment position within a fragment sequence. Each receiver will - have a REASSEMBLY QUEUE and a REASSEMBLY TIMER associated with these - fragments. The reassembly queue must be reinitialized and the - associated fragments abandoned whenever the REASSEMBLY TIMER expires, - or a new datagram arrives carrying a FRAG field whose value is less - than the highest FRAG value processed for this fragment sequence. - The reassembly timer MUST be no less than 5 seconds. It is - recommended that fragmentation be avoided by applications wherever - possible. - - Implementation of fragmentation is optional; an implementation that - does not support fragmentation MUST drop any datagram whose FRAG - field is other than X'00'. - - - -Leech, et al Standards Track [Page 8] - -RFC 1928 SOCKS Protocol Version 5 March 1996 - - - The programming interface for a SOCKS-aware UDP MUST report an - available buffer space for UDP datagrams that is smaller than the - actual space provided by the operating system: - - o if ATYP is X'01' - 10+method_dependent octets smaller - o if ATYP is X'03' - 262+method_dependent octets smaller - o if ATYP is X'04' - 20+method_dependent octets smaller - -8. Security Considerations - - This document describes a protocol for the application-layer - traversal of IP network firewalls. The security of such traversal is - highly dependent on the particular authentication and encapsulation - methods provided in a particular implementation, and selected during - negotiation between SOCKS client and SOCKS server. - - Careful consideration should be given by the administrator to the - selection of authentication methods. - -9. References - - [1] Koblas, D., "SOCKS", Proceedings: 1992 Usenix Security Symposium. - -Author's Address - - Marcus Leech - Bell-Northern Research Ltd - P.O. Box 3511, Stn. C, - Ottawa, ON - CANADA K1Y 4H7 - - Phone: (613) 763-9145 - EMail: mleech@bnr.ca - - - - - - - - - - - - - - - - - - -Leech, et al Standards Track [Page 9] -