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.



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



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