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Network Working Group M. Leech Request for Comments: 1929 Bell-Northern Research Ltd Category: Standards Track March 1996

           Username/Password Authentication for SOCKS V5

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.

1. Introduction

 The protocol specification for SOCKS Version 5 specifies a
 generalized framework for the use of arbitrary authentication
 protocols in the initial socks connection setup. This document
 describes one of those protocols, as it fits into the SOCKS Version 5
 authentication "subnegotiation".

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.

2. Initial negotiation

 Once the SOCKS V5 server has started, and the client has selected the
 Username/Password Authentication protocol, the Username/Password
 subnegotiation begins.  This begins with the client producing a
 Username/Password request:

         +----+------+----------+------+----------+
         |VER | ULEN |  UNAME   | PLEN |  PASSWD  |
         +----+------+----------+------+----------+
         | 1  |  1   | 1 to 255 |  1   | 1 to 255 |
         +----+------+----------+------+----------+

Leech Standards Track [Page 1]  RFC 1929 Username Authentication for SOCKS V5 March 1996

 The VER field contains the current version of the subnegotiation,
 which is X'01'. The ULEN field contains the length of the UNAME field
 that follows. The UNAME field contains the username as known to the
 source operating system. The PLEN field contains the length of the
 PASSWD field that follows. The PASSWD field contains the password
 association with the given UNAME.

 The server verifies the supplied UNAME and PASSWD, and sends the
 following response:

                      +----+--------+
                      |VER | STATUS |
                      +----+--------+
                      | 1  |   1    |
                      +----+--------+

 A STATUS field of X'00' indicates success. If the server returns a
 `failure' (STATUS value other than X'00') status, it MUST close the
 connection.

3. Security Considerations

 This document describes a subnegotiation that provides authentication
 services to the SOCKS protocol. Since the request carries the
 password in cleartext, this subnegotiation is not recommended for
 environments where "sniffing" is possible and practical.

4. Author's Address

 Marcus Leech
 Bell-Northern Research Ltd
 P.O. Box 3511, Station C
 Ottawa, ON
 CANADA K1Y 4H7

 Phone: +1 613 763 9145
 EMail: mleech@bnr.ca

Leech Standards Track [Page 2]