SOCKS(9) XR32 REFERENCE MANUAL 11/2/2013
NAME
SOCKS -- SOCKS Proxy Server.
DESCRIPTION
The purpose of the SOCKS proxy server in XR32 is long
forgotten.
It was included in XRouter either to allow users on amprnet to
view Internet web pages, or to allow a LAN browser to gain a
44.x.x.x source address, to view amprnet web sites.
What is SOCKS?
~~~~~~~~~~~~~~
SOCKet Secure (SOCKS) V4 is a protocol that acts as a circuit
level proxy for applications, routing traffic between a client
and server through a proxy server. It was intended for
accessing external services through a firewall, as an
alternative to using NAT (Network Address Translaton).
SOCKS5 is defined in RFC 1928, and is an extension of the
SOCKS4 protocol. It offers more choices of authentication,
adds support for IPv6 and UDP that can be used for DNS
lookups.
XR32 implements both SOCKS V4 and V5. The implementation is
functional but incomplete.
How it Works
~~~~~~~~~~~~
A SOCKS proxy acts as both client and server simultaneously. A
user client makes a TCP connection to the the socks server,
and communicates with it using the SOCKS protocol. The user
instructs the SOCKS proxy to connect to the target server,
from which point onwards the proxy becomes the client of the
target server.
.---------.
.--------. 62.31.1.3 | XR32 | 44.131.91.1 .--------.
| server |-----<------| SOCKS |-------<-----| client |
'--------' | proxy | '--------'
83.1.24.5 '---------' 44.131.91.2
The above diagram depicts an amprnet client (44.131.91.2)
connected to an Internet server (83.1.24.5) via a SOCKS proxy.
On the amprnet side XR32 is using the amprnet address
44.131.91.1, and on the Internet side it is using the Internet
address 62.31.1.3.
As far as the target server is concerned, it is talking with
62.31.1.3, whilst the user client is connected to 44.131.91.1.
Anything sent by the client is relayed to the server by the
proxy and vice versa.
Client Requirements
~~~~~~~~~~~~~~~~~~~
Client programs for use with this proxy must have SOCKS client
capability. Programs such as Internet Explorer, Firefox, and
many other have this capability.
Access Control
~~~~~~~~~~~~~~
The "rules" to control which destinations are allowed to be
accessed via the SOCKS proxy are contained in theSOCKS.ACL
file.
The rules allow you to specify which destination IP
addresses and TCP ports may be accessed by specified
source IP ranges.
If the file is not present, or contains no valid rules,
all destinations are blocked. Attempting to access
a blocked destination causes the proxy to return an
"access denied" code.
Configuration
~~~~~~~~~~~~~
The server is available by default, and requires no setting
up, other than the IP routing and egress control.
The server's TCP port may be changed, or the server disabled,
by using the SOCKSPORT=n directive in XROUTER.CFG. Setting
the port to zero disables the server.
FILES
SOCKS.ACL, XROUTER.CFG
SEE ALSO
ACCESS.SYS(8) -- TCP/IP Access Control List.
NAT(9) -- Network Address Translation.
SOCKS.ACL(8) -- SOCKS Egress Control List
XROUTER.CFG(8) -- Main Configuration File
SOCKS(9) END OF DOCUMENT
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