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The main project web site is
 www.freeswan.org.
Links to other project-related sites
 are provided in our introduction section.
Some user-contributed patches have been integrated into the FreeS/WAN
 distribution. For a variety of reasons, those listed below have not.
Note that not all patches are a good idea.
- There are a number of "features" of IPsec which we do not implement
 because they reduce security. See this
 discussion. We do not recommend using patches that implement these.
 One example is aggressive mode.
- We do not recommend adding "features" of any sort unless they are
 clearly necessary, or at least have clear benefits. For example,
 FreeS/WAN would not become more secure if it offerred a choice of 14
 ciphers. If even one was flawed, it would certainly become less secure
 for anyone using that cipher. Even with 14 wonderful ciphers, it would
 be harder to maintain and administer, hence more vulnerable to various
 human errors.
This is not to say that patches are necessarily bad, only that using
 them requires some deliberation. For example, there might be perfectly
 good reasons to add a specific cipher in your application: perhaps GOST
 to comply with government standards in Eastern Europe, or AES for
 performance benefits.
Current patches
Patches believed current::
There is also one add-on that takes the form of a modified FreeS/WAN
 distribution, rather than just patches to the standard distribution:
Before using any of the above,, check the mailing
 lists for news of newer versions and to see whether they have been
 incorporated into more recent versions of FreeS/WAN.
Older patches
These patches are for older versions of FreeS/WAN and will likely not
 work with the current version. Older versions of FreeS/WAN may be
 available on some of the distribution sites
, but we recommend using the current release.
Finally, there are some patches to other code that may be useful with
 FreeS/WAN:
Note that this is not required if the same machine does IPsec and
 masquerading, only if you want a to locate your IPsec gateway on a
 masqueraded network. See our firewalls
 document for discussion of why this is problematic.
At last report, this patch could not co-exist with FreeS/WAN on the
 same machine.
The introductory section of our document set lists several
 Linux distributions which include FreeS/WAN.
- /dev/random support page,
 discussion of and code for the Linux
 random number driver. Out-of-date when we last checked (January
 2000), but still useful.
- other programs related to random numbers:
- a Linux L2TP Daemon which
 might be useful for communicating with Windows 2000 which builds L2TP
 tunnels over its IPsec connections
- to use opportunistic encryption, you need a recent version of
 BIND. You can get one from the
 Internet Software Consortium who maintain BIND.
- other Linux IPsec implementations
- ENskip, a free
 implementation of Sun's SKIP protocol
- vpnd, a non-IPsec VPN
 daemon for Linux which creates tunnels using
 Blowfish encryption
- Zebedee, a simple
 GPLd tunnel-building program with Linux and Win32 versions. The name is
 from Zlib compression, Blowfish
 encryption and Diffie-Hellman key exchange.
- There are at least two PPTP implementations for Linux
- CIPE
 (crypto IP encapsulation) project, using their own lightweight protocol
 to encrypt between routers
- tinc, a VPN Daemon
There is a list of
 Linux VPN software in the
 Linux Security Knowledge Base.
- Our document listing the RFCs relevant to
 Linux FreeS/WAN and giving various ways of obtaining both RFCs and
 Internet Drafts.
- VPN Standards
 page maintained by VPNC. This covers
 both RFCs and Drafts, and classifies them in a fairly helpful way.
- RFC archive
- Internet Drafts
 related to IPsec
- US government site
 with their FIPS standards
- Archives of the ipsec@tis.com mailing list where discussion of
 drafts takes place.
- Counterpane's
 evaluation of the protocols
- Simpson's
 IKE Considered Dangerous paper. Note that this is a link to an
 archive of our mailing list. There are several replies in addition to
 the paper itself.
- Fate Labs Virual
 Private Problems: the Broken Dream
- Catherine Meadows' paper Analysis of the Internet Key Exchange
 Protocol Using the NRL Protocol Analyzer, in
 PDF or
 Postscript.
- Perlman and Kaufmnan
- Bellovin's
 papers page including his:
- Security Problems in the TCP/IP Protocol Suite (1989)
- Problem Areas for the IP Security Protocols (1996)
- Probable Plaintext Cryptanalysis of the IP Security Protocols
 (1997)
 
- An errata list
 for the IPsec RFCs.
- An IP tutorial that
 seems to be written mainly for Netware or Microsoft LAN admins entering
 a new world
- IANA, Internet Assigned Numbers
 Authority
- CIDR,
 Classless Inter-Domain Routing
- Also see our bibliography
Vendors using FreeS/WAN in turnkey firewall or VPN products are
 listed in our introduction.
Other vendors have Linux IPsec products which, as far as we know, do
 not use FreeS/WAN
- Redcreek
 provide an open source Linux driver for their PCI hardware VPN card.
 This card has a 100 Mbit Ethernet port, an Intel 960 CPU plus more
 specialised crypto chips, and claimed encryption performance of 45
 Mbit/sec. The PC sees it as an Ethernet board.
- Paktronix
 offer a Linux-based VPN with hardware encryption
- Watchguard use Linux in
 their Firebox product.
- Entrust offer a developers'
 toolkit for using their PKI for IPsec
 authentication
- According to a report on our mailing list,
 Axent have a Linux version of their product.
All the major router vendors support IPsec, at least in some models.
- Cisco
 IPsec information
- Ascend, now part of Lucent,
 have some IPsec-based products
- Bay Networks, now part
 of Nortel, use IPsec in their Contivity switch product line
- 3Com have
 a number of VPN products, some using IPsec
Many firewall vendors offer IPsec, either as a standard part of their
 product, or an optional extra. A few we know about are:
Vendors using FreeS/WAN in turnkey firewall products are listed in
 our introduction.
All the major open source operating systems support IPsec. See below
 for details on BSD-derived Unix variants.
Among commercial OS vendors, IPsec players include:
- 
Microsoft have put IPsec in their Windows 2000 and XP products
- IBM
 announce a release of OS390 with IPsec support via a crypto
 co-processor
- 
Sun include IPsec in Solaris 8
- 
Hewlett Packard offer IPsec for their Unix machines
- Certicom have IPsec available for the
 Palm.
- There were reports before the release that Apple's Mac OS X would
 have IPsec support built in, but it did not seem to be there when we
 last checked. If you find, it please let us know via the
 mailing list.
Network cards with built-in IPsec acceleration are available from at
 least Intel, 3Com and Redcreek.
We like to think of FreeS/WAN as the Linux IPsec
 implementation, but it is not the only one. Others we know of are:
- pipsecd, a
 lightweight implementation of IPsec for Linux. Does not require kernel
 recompilation.
- Petr Novak's ipnsec,
 based on the OpenBSD IPsec code and using
 Photuris for key management
- A now defunct project at
 U of Arizona (export controlled)
- NIST Cerebus
 (export controlled)
- KAME,
 several large Japanese companies co-operating on IPv6 and IPsec
- US Naval Research Lab
 implementation of IPv6 and of IPsec for IPv4 (export controlled)
- OpenBSD includes IPsec as a
 standard part of the distribution
- IPsec for FreeBSD
- a FAQ
 on NetBSD's IPsec implementation
The IPsec protocols are designed so that different implementations
 should be able to work together. As they say "the devil is in the
 details". IPsec has a lot of details, but considerable success has been
 achieved.
Linux FreeS/WAN has been tested for interoperability with many other
 IPsec implementations. Results to date are in our
 interoperability section.
Various other sites have information on interoperability between
 various IPsec implementations:
- interop results
 from a bakeoff in Atlanta, September 1999.
- a French company, HSC's,
 interoperability test data covers FreeS/WAN, Open BSD, KAME, Linux
 pipsecd, Checkpoint, Red Creek Ravlin, and Cisco IOS
- ICSA offer certification programs
 for various security-related products. See their list of
 certified IPsec products. Linux FreeS/WAN is not currently on that
 list, but several products with which we interoperate are.
- VPNC have a page on why they are not yet doing
 interoperability testing and a page on the
 spec conformance testing that they are doing
- a review
 comparing a dozen commercial IPsec implemetations. Unfortunately, the
 reviewers did not look at Open Source implementations such as FreeS/WAN
 or OpenBSD.
- 
results from interoperability tests at a conference. FreeS/WAN was
 not tested there.
- test results from the
 IPSEC 2000 conference
Nearly any Linux documentation you are likely to want can be found at
 the Linux Documentation Project
 or LDP.
- Meta-FAQ
 guide to Linux information sources
- The LDP's HowTo documents are a standard Linux reference. See this
 list. Documents there most relevant to a FreeS/WAN gateway are:
- The LDP do a series of Guides, book-sized publications with more
 detail (and often more "why do it this way?") than the HowTos. See this list. Documents there
 most relevant to a FreeS/WAN gateway are:
You may not need to go to the LDP to get this material. Most Linux
 distributions include the HowTos on their CDs and several include the
 Guides as well. Also, most of the Guides and some collections of HowTos
 are available in book form from various publishers.
Much of the LDP material is also available in languages other than
 English. See this
 LDP page.
The Linux IP stack has some new features in 2.4 kernels. Some HowTos
 have been written:
See also the LDP material above.
Our FreeS/WAN and firewalls document
 includes links to several sets of
 scripts known to work with FreeS/WAN.
Other information sources:
Two enormous collections of links, each the standard reference in its
 area:
- Gene Spafford's
 COAST hotlist
- Computer and network security.
- Peter Gutmann's
 Encryption and Security-related Resources
- Cryptography.
See also the interesting papers section
 below.
There are several collections of cryptographic quotes on the net:
- RFC 1984, the
 IAB and IESG Statement on
 Cryptographic Technology and the Internet.
- John Young's collection of documents
 of interest to the cryptography, open government and privacy movements,
 organized chronologically
- AT&T researcher Matt Blaze's Encryption, Privacy and Security
 Resource Page
- A good overview of
 the issues from Australia.
See also our documentation section on the
 history and politics of cryptography.
These papers emphasize important issues around the use of
 cryptography, and the design and management of secure systems.
David Wagner at Berkeley provides a set of links to
 home pages of cryptographers, cypherpunks and computer security
 people.
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