Transcript Firewall Toolkit (FWTK)

TOOLS FOR PROXYING
Tools for Proxying
• Many available applications provide proxy capabilities. The major
commercial vendors have embraced hybrid technologies that
combine proxy and stateful technologies, making it harder to
identify when proxy techniques are used in their products.
Mergers and acquisitions in the field have also added confusion
to this subject
• For Example Gauntlet firewall. Gauntlet was one of the first, and
most popular, proxy firewalls. Originally created by TIS, its
technology was first acquired in 1998 by Network Associates, Inc
(NAI). NAI continued to sell the products under the Gauntlet
name. In 2002 though, NAI sold Gauntlet to Secure Computing,
which already owned a competing firewall called Sidewinder.
Secure Computing then integrated both products together to
create a hybrid product
Firewall Toolkit (FWTK)
 Firewall Toolkit was one of the first proxy firewalls. It was developed
by Trusted Information Systems (TIS) under an Advanced Research
Projects Agency (ARPA) grant.
 It was first released in October of 1993. The key technology of FWTK
was used to create the first version of the Gauntlet firewall. FWTK is
still available at http://www.fwtk.org, but has not been updated for many
years.
Firewall Toolkit (FWTK)
 FWTK is available in source code, which is an important part of its
appeal. Anyone from a security analyst to a potential attacker can
review its design to look for defects.
TIS referred to this as a crystal box design, a term coined by one of
its first customers.
In a crystal box design, nothing about the design is hidden.
This same approach has been followed in the cryptographic
community for decades. The belief is that if a design has not been
peer-reviewed by the cryptographic community, no one should have
any confidence in its security. product.
Squid
 Squid is a highly regarded open source web proxy project. It
provides high-performance proxy caching for HTTP, HTTPS, and
FTP
 Squid can be used in several web proxy scenarios. Its most frequent
use is to cache browser requests for a site to accelerate and control
web conversations. However, it is equally useful as a web server
accelerator and as a reverse proxy server.
 Squid was designed to run under UNIX and has been successfully
compiled on a broad set, including Linux, FreeBSD, OpenBSD, Mac
OS/X, Sun Solaris, IBM AIX, and HP-UX. (Note that this is only a
partial list.)
 It can also be compiled to run under Windows if used in conjunction
with
the
Cygwin
(http://www.mingw.org)
(http://www.cygwin.com)
and
packages.
available
http://www.squid-cache.org.
Squid
is
Mingw
at
SOCKS
 SOCKS is a proxy toolkit that enables applications to be proxied
without requiring specific proxy code to be re-created for each client
application.
 The SOCKS server performs authentication and authorization
functions on requests, establishes proxy connections, and relays
data between hosts.
 A SOCKS proxy server licensed for noncommercial use is available
for free from http://www.socks.permeo.com/.
SOCKS
 For applications to work with the SOCKS proxy server, they must be
"SOCKS-ified." Most of the work involved in doing this has been
packaged into the SOCKS software development kit (SDK).
 SOCKS has evolved over time and gone through several revisions.
SOCKS version 4 was the first popular version of SOCKS and is still
in use.
 SOCKS version 5 adds important features, including the support of
UDP proxying as well as a variety of authentication methods.
 The Internet Engineering Task Force (IETF) approved SOCKSv5 as
the standard (RFC 1928) generic, proxy protocol for TCP/IP-based
networking applications.
SOCKS VERSION 4
 The
SOCKSv4
protocol
defines
the
message
format
and
conventions to allow TCP-based application users transparent
access across a firewall.
 During proxy connection setup, the SOCKS server grants access
based on TCP header information, including IP addresses and
source and destination host port numbers.
 The SOCKS server also authorizes users using Ident (RFC 1413)
information.
SOCKS VERSION 5
 The SOCKS version 5 protocol, also known as authenticated firewall
traversal (AFT), is an open Internet standard (RFC 1928) for
performing network proxies at the transport layer.
 Following are the main added features in Proxy Version 5:
1. Strong Authentication
2. Address Resolution Proxy
3. Proxy for UDP-based Applications
SOCKS VERSION 5
 There are two additional SOCKSv5-related standards to support
authentication methods:
1. Username/password authentication for SOCKSv5 (RFC 1929)
2. GSS-API (Generic Security Service Application Programming
Interface) authentication for SOCKSv5 (RFC 1961)