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.

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