The main project web site is
Links to other project-related sites
are provided in our introduction section.
Some user-contributed patches gave been integrated into the
FreeS/WAN distribution. For a variety of reasons, those listed below
Patches believed current at time of writing (March 2001, just before
Before using these, check the mailing list
for news of newer versions and to see whether they have been
incorporated into more recent versions of FreeS/WAN.
Note: At one point the way PGP generates RSA keys
and the way FreeS/WAN checks them for validity before using them were
slightly different, so quite a few PGP-generated keys would be rejected
by FreeS/WAN, confusing users no end. This is fixed in 1.9.
A set of PKIX patches were recently announced on the mailing list:
Subject: a different PKIX patch.
Date: Mon, 5 Mar 2001
From: Luc Lanthier <firstname.lastname@example.org>
I'd like to invite volunteers to use the now-complete PKIX project I've
been working on since about August. Because of this, the patch is for
FreeSWAN 1.5, not 1.8... I haven't really felt the need to update it since
I don't use IPV6 nor DNSSec.
This is similar, but different than Andreas Steffen's pkix
implementation. I've based this work on Neil Dunbar's openssl-pkix patch
for FreeSWAN 1.1. I've updated it to run on FreeSWAN 1.5 correctly, and
added support for ID_DER_ASN1_DN ID packet support. It will do LDAP
certificate lookups no problem, as well as local flatfile, directory, or
DB lookup for testing or speed.
IE: It's a full CA-compatible client, capable of looking up, checking the
CRL for expiry and such. It will not only do the classic PSK and RSASIG
freeswan methods just fine, but also does PKIX's RSASIG, PKE and
RPKE. I've spent a lot of time adding RoadWarrior support for these last
IKE exchange methods.
The patch can be found as:
There are also freeswan-1.5 - kernel 2.4 patches for those who need them.
Let me know. Feedback is appreciated.
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
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
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
- packet spy, a
packet sniffer whose author said in a Dec 1999 message "It's very
unfinished, especially the filter, but it can give you an ascii and
hex dump at the same time. I started it specifically for snooping a
- to use opportunistic encryption, you need a recent version of
BIND. Get one from the
FreeS/WAN site or 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
- 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.
- LinuxCare's VPS (Virtual
Private Server) which builds tunnels using
- Moreton Bay's
PoPToP, PPTP for Linux
(crypto IP routers) project, using their own lightweight protocol to
encrypt between routers
- vtun "virtual tunnels",
- 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
- IPSEC 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 email@example.com mailing list where discussion of
drafts takes place.
evaluation of the protocols
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.
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
- Catherine Meadows of NRL applied the NRL Protocol Analyzer to IKE.
Her paper is available in
- An errata list
for the IPSEC RFCs.
- An introduction to IP
addressing from 3Com
- An IP tutorial that
seems to be written mainly for Netware or Microsoft LAN admins
entering a new world
- IANA, Internet Assigned Numbers
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
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.
offer a Linux-based VPN with hardware encryption
- According to a report on our mailing list,
Watchguard use Linux in their Firebox product.
- Entrust offer a developers'
toolkit for using their PKI for IPSEC
- 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.
Many firewall vendors offer IPSEC, either as a standard part of their
product, or an optional extra. A few we know about are:
- Ascend, now part of Lucent,
have some IPSEC-based products
- Bay Networks, now part
of Nortel, use IPSEC in their Contivity switch product line
have a number of VPN products, some using IPSEC
Vendors using FreeS/WAN in turnkey firewall products are listed in
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 products
- Apple's Mac OS X
has IPSEC support built in
announce a release of OS390 with IPSEC support via a crypto
Sun include IPSEC in Solaris 8
Hewlett Packard offer IPSEC for their Unix machines
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
- 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
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
Linux FreeS/WAN has been tested for interoperability with many
other IPSEC implementations. Results to date are in our
Various other sites have information on interoperability between
various IPSEC implementations:
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 doning
- 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
The Linux IP stack is getting some new features in 2.4 kernels. Most
are already available as experimental code in 2.3 kernels. Some HowTos
have been written:
Two enormous collections of links, each the standard reference in
- Gene Spafford's
- Computer and network security.
- Peter Gutmann's
Encryption and Security-related Resources
See also the interesting papers section
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
- Encryption, Privacy and Security
Resource Page with a mainly US focus
Export Control Archive, mainly links to court and govenment
documents on various challenges to US law
- 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.
- Open SEC, a link farm full of
links to freely available security tools
- PGP -- mail encryption
A message in our mailing list archive has considerable detail on
available versions of PGP and on IPSEC support in them.
Note: A fairly nasty bug exists in all commercial
PGP versions from 5.5 through 6.5.3. If you have one of those, read
advisory and upgrade now.
- SSH -- secure remote login
- ssmail -- sendmail patched to do
- web page with
links to code and to a Usenix paper describing it, in PDF
- COPS Computer
Oracle and Password System; tests a system for various weaknesses
System Administrators Tool for Analysing Networks
- NMAP Network Mapper
- Internet Traffic Archive
, various tools to analyze network traffic, mostly scripts to organise
and format tcpdump(8) output for specific purposes
Venema's page with various tools
- Crack password
saves message digests of your system files. Re-calculate the digests
and compare to saved values to detect any file changes.
- Deception Toolkit, a
collection of "honeypot" servers which emulate widely exploited
weaknesses while logging the attacks.
- Open CA project to develop a
freely distributed Certification Authority
for building a open Public Key
IP stack integrity
checker, generates legitmate and bogus packets "to test the
stability of an IP Stack and its component stacks (TCP, UDP, ICMP et.
David Wagner at Berkeley provides a set of links to
home pages of cryptographers, cypherpunks and computer security