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SOCKS
By
BITSnBYTES
(Bhargavi, Maya, Priya, Rajini and Shruti)
Outline
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Definition
History
Major components
Working
Features
Functions
Applications
Need for protocol
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Widespread use of firewalls
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Need to provide a general framework for sophisticated
application layer protocols to transparently and securely
traverse a firewall with strong authentication capabilities
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Need to provide a framework for client-server
applications in both TCP and UDP domains to
conveniently and securely use the services of a network
firewall
What is SOCKS?
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Acronym for SOCKet Secure
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Networking proxy protocol for TCP/IP based network
applications
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Intermediate layer between application layer and
transport layer
History
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Originally developed by David Koblas in 1992
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Protocol extended to version 4 by Ying-Da Lee of NEC
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Designed to allow clients to communicate with Internet
servers through firewalls
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Two major versions of SOCKS –
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SOCKS V4
SOCKS V5
Components of SOCKS
Application Layer
Application Layer
SOCKS Server
SOCKS Client
Secure Proxy data channel
Transport Layer
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SOCKS server – implemented at the application layer
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SOCKS client – implemented between application and
transport layer
How does it work?
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Establishes a secure proxy data channel between two computers in
a client/server environment
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SOCKS server handles requests from clients inside a network's
firewall and allows/rejects connection requests, based on the
requested Internet destination or user identification
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Once a connection and a subsequent "bind" request have been set
up, the flow of information exchange follows the usual protocol
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Client's perspective - SOCKS is transparent
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Server's perspective - SOCKS is a client
How does it work?
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SOCKS is typically implemented on proxy servers
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SOCKS uses sockets to represent and keep track of individual
connections
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Client side of SOCKS is built into Web browsers
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Server side can be added to a proxy server
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The SOCKS server –
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authenticates and authorizes requests
establishes a proxy connection
relays data between hosts
Relation with OSI reference model
Purpose of SOCKS
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Enables Hosts on one side of the SOCKS server to gain
access to the other side of the SOCKS server without
requiring direct IP-reachability
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Clients behind a firewall wanting to access exterior
servers connect to a SOCKS proxy server which controls
the eligibility of the client to access the external server
and passes the request on to the server.
Major Functions
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The SOCKS protocol performs four functions:
 Making connection requests
 Setting up proxy circuits
 Relaying application data
 Performing user authentication (optional)
Two versions of SOCKS
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SOCKSv4
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Makes connection request
Sets up proxy server
Relays application data
SOCKSv5
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Adds authentication to V4
- Username/Password (RFC 1929)
- GSS-API (RFC 1961)
Authentication Method Negotiation
Address Resolution Proxy
UDP proxy
Control flow of SOCKS
Features
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Allows for transparent network access across multiple
proxy servers
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Provides a flexible framework for developing secure
communications by easily integrating other security
technologies
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Rapid deployment of new network applications
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Simple network security policy management
Benefits
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Single communication protocol to authenticate users and
establish communication channels
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Universal – works with several internet protocols
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Application-Independent proxy
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Can be used with either UDP or TCP based protocols
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Bi-directional proxy support
Benefits (continued..)
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Easy deployment of authentication and encryption
methods
Firewall tunneling service - allows many machines
behind a firewall to access the Internet without actually
being on the Internet themselves
Drawbacks
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SOCKS v4 does not support UDP and authentication
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The SOCKSv5 protocol does not support SOCKSv4
protocol
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SOCKS implementations do not support data encryption
(except for some commercial software) making data
transfers vulnerable to interception
Applications
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Most common use - Network firewall
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Authorized data relay between Hosts
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Supported as a proxy configuration option in popular
Web browsers and instant messaging programs
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Found in some VPN implementations
Emerging as one of the best ways to secure multimedia
applications across the Internet
Summary
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SOCKS is easy to deploy and manage
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SOCKS is transparent to the user, while providing
multiple layers of security
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Allows client-server applications to transparently use the
services of a network firewall without requiring direct IPrechability
References
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RFC 1928 - base SOCKS v5 specification
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RFC 1929 , RFC 1961 - additional details
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http://www.socks.permeo.com/AboutSOCKS/SOCKSOverview.asp
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http://whatis.techtarget.com/definition/0,,sid9_gci213023,00.html
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http://www.socks.permeo.com/TechnicalResources/SOCKSFAQ/SO
CKSGeneralFAQ/index.asp
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The SOCKS reference architecture and client are owned
by Permeo Technologies, spin-off from NEC. NEC
Corporation has promoted SOCKS.
A SOCKSv4 implementation is available through
anonymous ftp from ftp://ftp.nec.com:/pub/socks/
SOCKV5 Reference implementation by Permeo.
Questions?