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Interoperation with other IPsec implementations

The IPsec protocols are designed to allow interoperation between different implementations. Other sections of this documentation have more detail on:

FreeS/WAN does interoperate successfully with many other implementations. The ones we know about are listed below.

Of course "the devil is in the details" and the IPsec protocols have a lot of details. At least one critique has argued that the protocols should be simplified. Various of those details can and do cause difficulties for interoperation. Should you encounter such problems, please let us know via the mailing list. We will likely be able to help you, and your report may be useful both to other users and to the implementation teams.

Note: This file is updated often, whenever I notice an interesting interop report on the mailing list. If you are reading the version that ships with a FreeS/WAN release or is posted on the web, and what you need isn't here, consider downloading the latest snapshot to get the latest version of the doc. Perhaps I've added what you need since the last release.

There is additional information on interoperability testing in our web links section.

Interoperability problems

The IPsec RFCs are complex and include a number of optional features. There is considerable opportunity for even two correct, standard-conforming, implementations to disagree on details in a way that blocks interoperation. Errors in either implementation -- either misinterpretations of the standards or just bugs -- can also foul things up.

The commonest cause of problems, however, seems to be configuration errors. Any IPsec implementation is somewhat complex. It has to be; neither the networks it runs on nor the protocols it implements are simple. When you have two of them to deal with, the problem you face is not trivial.

That said, FreeS/WAN interoperates successfully with many other implementations. There is a list below, with configuration details provided by various users who have already solved these problems.

Possible problem areas

Known areas where problems may appear are:

The general rule is that to interoperate with FreeS/WAN, the other implementation should be configured for:

This is possible for most implementations.

For a more detailed discussion of which parts of the IPsec specification FreeS/WAN implements, and reasons for that, see our compatibility document.

Documentation and terminology problems

Documentation can also pose problems for interoperation. The two implementations may use different terms for the same thing, or one may have features that the other does not support and therefore does not document. This can be quite confusing for the poor user who has to deal with both.

Known examples are:

If you encounter such problems, please report them to the users mailing list and I'll try to add some clarifying text on the FreeS/WAN side.

If it only works in one direction

A few users have encountered situations in which interoperation is fine when one end initiates, but fails if the other end starts the negotiation.

In such cases, you can set rekey=no in the FreeS/WAN connection description. This prevents FreeS/WAN from initiating re-keying of that connection, but it will still respond if the partner initiates.

Even if that trick solves your problem, please report the difficulty to the users mailing list. It is definitely supposed to work no matter who initiates.

"Clients" and "servers"

IPsec is not a client/server protocol. In a client/server protocol, the two ends have quite different roles. For example, consider the web. The client runs a browser and mostly does display. The server runs completely different software and does no display at all. Similarly, in a database application, the client and server play quite different roles and often run completely different software.

IPsec is a peer-to-peer protocol. The gateways on the two ends of an IPsec connection are peers, both doing the same thing. They could use identical software.

Despite this, various vendors produce products they call "clients" and others they call "servers". Typically, the "clients" do not support a subnet behind them. They are designed only to let a single remote machine connect. To get full IPsec with subnet support, you pay more for the "server version".

For example, the free version of PGPnet is only a "client"; for subnet support you need to purchase the product. Also, Windows 2000 Professional has only "client" IPsec. For subnet support you need to purchase the server version, or put Linux and FreeS/WAN on your gateways.

This difference does not cause interoperation problems as such. FreeS/WAN will happily interoperate with either a "client" or a "server" product, and will happily play either role itself, depending on how it is configured. In their marketing terms, FreeS/WAN acts as a "server" if you define a subnet behind the gateway, and as a "client" if you do not.

It does, however, often complicate things when users discover that the product they have will not do what they need because it is "only a client". Usually the only solutions are to upgrade to the "sever version" or to switch to a different product.

Systems that want to use single DES

Linux FreeS/WAN does not support single DES transforms. Neither Pluto's IKE connections nor KLIPS' IPsec connections can use DES. Since DES is insecure we do not, and will not at any future time, provide it.

DES is, unfortunately, a mandatory part of the IPsec standard. Despite that, we will not implement DES. We believe it is more important to provide security than to comply with a standard which has been subverted into allowing weak algorithms. See our history and politics section for discussion.

Some implementations may offer DES as the default. In such cases we urge you to change them to Triple DES. If this is not possible, for example because export laws prevent your vendor from offerring you adequate crytography, we urge you to complain vigorously to one or more of:

Consider using FreeS/WAN instead. PCs are cheap and we deliver 3DES now.

FreeS/WAN does have DES code in it as a sort of historical accident, since we need it to implement our default (currently, our only) block cipher, Triple DES. However, since DES is insecure, we do not provide any interface to that code.

As a matter of project policy, we will not help anyone subvert FreeS/WAN to provide insecure DES encryption.

Patches to extend interoperability

Sometimes interoperation requires user-contributed patches or add-ons on the FreeS/WAN end. See this list of available patches.

In many cases, no patches to the actual IPsec code are required. The problem is to make FreeS/WAN recognise RSA keys stored in formats other than ours. Each such format needs either a patch to make FreeS/WAN understand that format or a utility to translate it to the FreeS/WAN format. For example, unmodified FreeS/WAN cannot use RSA keys generated by PGP or keys stored in X.509 certificates, but patches or utilities are available for both those formats.

Other patches do change the IPsec code, for example to add the AES cipher. Likely this patch will be incorporated into FreeS/WAN long before AES becomes important as an interoperaibility issue.

Note that with some patches, you might be giving up some security in exchange for interoperability. There are a number of "features" of IPsec which we do not implement (details ) either because they directly reduce security or because they unnecessarily complicate things, thereby adding to security risks. Adding these "features" is not recommended..

Interop HowTo documents

The FreeS/WAN team does not have the resources to test with anything like the full range of other IPsec implementations out there. Fortunately, some of our users are doing a fine job of filling the gap by providing HowTo information:

See also our lists of:

Interop info from the IPsec 2001 conference

From a mailing list report:

     Subject: IPsec 2001 interop demo data available
        Date: Tue, 13 Nov 2001
        From: Ghislaine Labouret <>
Organization: HSC (Herve Schauer Consultants)

During the IPsec 2001 conference held in Paris last month, an
interoperability demonstration including FreeS/WAN was set up.

FreeS/WAN 1.91 + X.509 patch 0.9.3 was tested with the following
devices: 6WINDGate, Cisco IOS, Cisco PIX, Cisco VPN 3000, Netasq F100,
Netcelo VPN gateway, NetScreen NS100, Nortel Contivity, OpenBSD 3.0.

The results and configuration files are now available online:

Interoperation with specific products

Most of the information in this section is gleaned from the mailing list. For additional information, search one of the list archives.

A large thank you is in order to all the list contributors. This document would not exist without you.

Anyone who has tested with an implementation not listed here, please report results to the mailing list . I generally include the sender's email address when I quote list messages here; "credit where credit is due". If you would prefer that I not do that with yours, please mention that.

Older versions of FreeS/WAN

Any two versions of FreeS/WAN should interoperate, and many combinations have been tested doing so successfully. In particular, every release is tested against its predecessor before it goes out.

However, if you do encounter a problem involving an older version, we are likely to suggest you upgrade. We do not have the resources to support multiple versions.

Using your old config files

In general, new versions will use existing configuration files, at least until the next major version number change. For example, 1.8 can use files created for 1.7, 1.6, even back to 1.0, but not from 0.92. This behaviour will continue until we release 2.0.

As of 1.8, however, conf file checking has become stricter, so that an error that may have slipped past the checks in an earlier version may be caught in a later one. From 1.8's doc/CHANGES:

      The internal configuration-file reader is progressively getting 
      fussier about what it will accept, which may cause problems for 
      illegal ipsec.conf files whose sins previously passed unnoticed.  
      IN PARTICULAR, the "auto" parameter's values are now checked for 
      legality everywhere.


Two user-written HowTos we know of cover interoperation between FreeS/WAN and Open BSD IPsec:

The OpenBSD FAQ includes information on their IPsec implementation.

This report is from one of the OpenBSD IPsec developers, a regular participant on our mailing list:

Subject: spi.c bug
   Date: Tue, 23 Feb 1999
   From: Niklas Hallqvist <>

PS.  I don't know if you have an interop list anywhere, but you should
know FreeS/WAN interops with OpenBSD both at the IPSec level and at
the IKE level.

There is one known problem with FreeS/WAN-OpenBSD IKE interoperation. Here is a mailing message from our Pluto implementer, discussing that with the user who discovered it:

Subject: Re: [Bugs] Interoperability with OpenBSD
   Date: Sun, 30 Sep 2001

| Yes, the problem was the pre-shared key.  It seems that it cannot be
| more than 64 characters long.  I was using a longer key.
| Is this documented behaviour for either FreeS/WAN or isakmpd?  (Anyway
| a reasonable error message would not hurt.)

The limit is not in FreeS/WAN, so we don't document it :-)

I guess we could mention this on our interop pages.  Claudia?

The error message from isakmpd was not very helpful (I realize that
I'm in a glass house when I throw this stone).

- isamkpd documentation should state the limit

- isakmpd should diagnose that the PSK was too long

- isakmpd should suggest that this type of problem (undigestable
  message) might be caused by mis-matched PSK

I hope that you would have gotten a better message from Pluto.  So if
you had initiated from the isakmpd side, the resulting diagnostic from
Pluto might have lead you to the problem more quickly.

When Pluto cannot parse the first encrypted IKE message, it prints a
diagnosis of the parse failure (just like isakmpd did), but it prefixes it
        probable authentication (preshared secret) failure:

I just noticed that it will print this even if authentication is via
RSA Sig -- I will fix that.  I'll reword the prefix too:
        probable authentication failure (mismatch of preshared secrets?):


FreeBSD uses the KAME IPsec and IPv6 code.

Here is a mailing list message on FreeBSD interoperation:

Subject: Re: Interop with [Free|Open|Net]BSD
   Date: Fri, 29 Dec 2000
   From: Ghislaine Labouret <>

On Thu, 28 Dec 2000 13:53:01 -0500, Sandy Harris wrote:

> FreeBSD:
> For FreeBSD, I find list discussion of 3DES key formats, presumably for manual
> keying. We have 192-bit, 3 64-bit keys including parity bits, while FreeBSD 4.0
> used 168-bit, 3 56-bit keys without the parity bits. Has FreeBSD changed this?

I still don't understand what made Spike Gronim say that KAME wants a
168 bits key; I have always been using 192 bits keys with KAME and had
no interoperability problem between KAME and FreeS/WAN using manual

> For auto keying, I find reports of sucessful use of pre-shared secrets, but
> nothing on RSA authentication.

I had KAME (20001023 snapshot) and FreeS/WAN 1.6 successfully
interoperate using both PSK and RSA-sig authentication. The config
files, certificates and test keys used are available online:
Not much details though, as this is just a report and not a how-to. Will
improve it if I can find spare time.

> Does FreeBSD support that? 

KAME can use RSA-sig and can either exchange certificates online or get
them from a file. I tested the latter. No test with the X.509 patch for
FreeS/WAN yet, though that's in my short term plans too.

> Are the key formats compatible, or has anyone written translation code?

KAME wants the keys inside certificates, in PEM format. To extract the
keys for FreeS/WAN I used the fswcert utility, but it can be done "by
hand" using openssl.


NetBSD has an IPsec implementation based on KAME. It is described in this FAQ.

Cisco Routers

Information from Cisco

Useful pages on Cisco sites include:

To work with FreeS/WAN, a Cisco router must have 3DES software. A page on Cisco's site gives this list:

| Triple DES Encryption for IPSec
| ...
| This feature is supported only on the following platforms:
|     1720
|     2600 Series
|     3600 Series
|     4000 Series
|     4500 Series
|     AS5300 Series
|     7200 Series
|     7500 Series

From our mailing list

Our first Cisco interop success reports were from Ian Calderbank in 1999. They included configuration information for his Cisco 3640. These messages can be found in the mailing list archives or in older versions of this document, still available on the web. We no longer include them here.

Several other pages have possibly useful information:

Shared secrets work

Several users report successful interoperation using shared secrets. Here is one such message:

Subject: [Users] cisco - freeswan summary
   Date: Fri, 31 Aug 2001 

I finally got a vpn linked up between a 3000 series cisco router and a
redhat linux box using shared secrets.  The linux box is running 2.2.19 with
freeswan 1.9. The shared secret has no spaces in it, as I read somewhere
that it might break the connection.

Several people have asked me the configuration that I have used to
make this happen, so I thought I should publish it here.  

Here is the network...

                linux router
              freeswan linux
                   |    yyy.yyy.yyy.1
                   |    yyy.yyy.yyy.21
               cisco router

My ipsec.conf looks like this...

config setup
        # THIS SETTING MUST BE CORRECT or almost nothing will work;
        # %defaultroute is okay for most simple cases.
        # Debug-logging controls:  "none" for (almost) none, "all" for lots.
        # Close down old connection when new one using same ID shows up.
# defaults for subsequent connection descriptions
conn %default
        # How persistent to be in (re)keying negotiations (0 means very).
conn cisco1

My cisco configuration looks like this...

crypto map VPN 30 ipsec-isakmp   
 set peer
 set transform-set 3des-md5 
 match address 130

crypto ipsec transform-set 3des-md5 esp-3des esp-md5-hmac 

crypto isakmp key ******** address 

crypto isakmp policy 3
 encr 3des
 hash md5
 authentication pre-share
 group 2

access-list 130 permit ip

Sorry it took so long to send this out, but there is apparently an ipchains
firewall on the host behind the cisco, and it took some time to get
these rules straight.

I hope this helps someone....
Another similar post:
Subject: [Users] freeswan <--$gt; Cisco: success!
   Date: Thu, 20 Sep 2001
   From: "Wolfgang Tremmel" <>

I have seen several requests on the list for example
configurations for connection of Freeswan to Cisco, since
about 1 hour ago I had success, here my example configuration.

Background: My router is a 80486, connecting to the internet using
                PPPoE via DSL. Kernel is 2.4.9, Freeswan is snap2001sep13b
                And yes, I get a dynamic IP address

                Router is a Cisco 4700, running IOS 12.2(2)T1 with 3DES

config setup

conn %default

conn cisco
        right=x.x.x.x                   # fastEthernet0 of ciscorouter
        rightnexthop=            # next hop of ppp0
        rightsubnet=           # defaultroute via ipsec

%any x.x.x.x: PSK "thisisatestkey"

- ---- thats all on the linux router
- ---- now for the Cisco:

crypto isakmp policy 100
 encr 3des
 authentication pre-share
 group 2
 lifetime 3600
crypto isakmp key diesisteintest address y.y.0.0  !
network and mask of any possible address your ppp0 can have

crypto ipsec transform-set linuxbox esp-3des esp-sha-hmac

crypto dynamic-map linuxbox 100
 set transform-set linuxbox
 match address linuxbox

crypto map linuxbox local-address FastEthernet0
crypto map linuxbox isakmp authorization list linuxbox          ! not sure if
that is really needed
crypto map linuxbox 100 ipsec-isakmp dynamic linuxbox discover

interface FastEthernet0
 ip address x.x.x.x
 crypto map linuxbox

ip access-list extended wtremmel
 permit ip host x.x.x.x mask


RSA keys are tricky

A message from another user about using RSA keys with Cisco:

Subject: Re: [Users] RSA public key and Cisco (3640)
Date: Sat, 2 Jun 2001

We use Cisco IOS 12.1.5(T) and freeswan 1.8

Here an example on how I copied the key from cisco:

Key Data:
  117C311E 16192D86 8886C71D 11111115 11138B11 31881241 11C7E23B D6DB22 

Will become


We used at least 1024 bits long keys.

But it doesn´t matter. The problem is that cisco doesn´t agree with the RSA
schema from freeswan, I think. In Cisco, rsasig is to use with a CA, and
rsaencript did not work as well. 

My case is worse than it. My first intention was to use freeswan in a road
warrior config. I really need to use CA, as Cisco needs a fix address to
use rsa public key. The public key to cisco is always associated to an IP
address ou FQDN. I quit. Will try the X509 patch and the Open CA software.

>>(off list)
>Yes, I was just going to mention that the Cisco's key should be in
>ipsec.conf (just received your correction).
>I think that I have the Cisco side configured correctly ( I can't be sure
>because I can't test against the Freeswan).
>Starting from having the IPsec tunnel working with pre-share, I did the
>following on the Cisco side:
>#config t
>(config)# crypto key pubkey-chain rsa
>(config-pubkey-chain)# addressed-key 

>(config-pubkey-key)# key-string

># config t
>(config)# crypto isakmp policy 1
>(config-isakmp)# no authentication pre-share
>(config-isakmp)# authentication rsa-sig
>(config-isakmp)# exit
>How long is your RSA key that was generated on the Cisco? I tried copying
>the key out of the 3640 and pasting it into ipsec.conf, removing the spaces
>and adding a '0x' in the front. I get the 'key too small' error still. What
>version of freeswan are you using?
>I'm using Freeswan 1.9 w/ IOS 12.1(6).

Cisco VPN Concentrator

Another mailing list thread discussed using FreeS/WAN with the Cisco VPN Concentrator. Here is one user describing his problem:

Subject: [Users] FreeSWAN and Cisco VPN CONCENTRATOR
   Date: Thu, 25 Oct 2001
   From: "M. Sticki" <>

i have to establish a vpn tunnel between two companies.
one of the company is using the cisco vpn concentrator
and the other company is using redhat 7.1 and freeswan.

it is no a problem to estblish the tunnel between two freeswan
gateways or between a cisco vpn-client and the concentrator.

but the companies don't want to change their equipment.
and with this constellation i can't establish the tunnel.

the responce from cisco is: "THAT IS NOT SUPPORTED"

so this mailing list is my last chance, because i don't know how to go on

and another user's answer:

Subject: Re: [Users] FreeSWAN and Cisco VPN CONCENTRATOR
   Date: Thu, 25 Oct 2001 14:21:17 +0200
   From: Ghislaine Labouret <>

> i have to establish a vpn tunnel between two companies.
> one of the company is using the cisco vpn concentrator
> and the other company is using redhat 7.1 and freeswan.
> the responce from cisco is: "THAT IS NOT SUPPORTED"

At the IPsec 2001 conference which is behing held right now, we have
set up an interop demo platform which includes those two devices.
They are successfully interoperating using certificates.

Later in the same thread:

Subject: Re: [Users] FreeSWAN and Cisco VPN CONCENTRATOR
   Date: Thu, 25 Oct 2001
   From: Ghislaine Labouret <>
Organization: HSC (Herve Schauer Consultants)

Juri Jensen wrote:

> I've been trying to get those two to interoperate with certificates, but
> I have only succeeded with PSK. Can you shed some light on how you did
> it....?

I will put the config files and different tests results from the demo on next week.

With VPN3000, we had a problem with the DN comparison because of
encoding issues. The solution was to specify the VPN 3000 DN in binary
format in ipsec.conf. I leave it to Andreas Steffen to explain the exact
issue, as he is the one who solved it.

Nortel (Bay Networks) Contivity switch

There is one known issue in FreeS/WAN-to-Contivity interoperation. Recent versions of FreeS/WAN no longer support DH group 1 for key exchange. Older versions of Contivity software support nothing else. Group 2 was added in more recent releases. So:

We recommend using a current software on both ends.

Some messages from the mailing list:

Subject: Contivity Extranet Switch
   Date: Fri, 11 Jun 1999
   From: Matthias David Siebler <>
Organization: Nortel Networks

More interoperability results:

I successfully established a tunnel with a Nortel (formerly Bay (formerly New Oak)) Contivity
Extranet Switch running the latest release versions.

The CES is running V2.50 of the software and the Linux server is running V1.0.0 of the Free/SWAN
code on a RedHat 5.2 unit with the kernel upgraded to 2.0.36-3

I am using IKE with 3DES-HMAC-MD5

Note however, that tunnels cannot yet be configured as client tunnels since Free/SWAN does not yet
support aggressive mode.  Hopefully, that will arrive soon, which would allow remote users to
connect to a CES using the Free/SWAN code as clients.

and apparently Nortel want their product to work with FreeS/WAN:

Subject: Is FreeSwan 3.1 a legitamate ipsec implementation when compared to its commercial competitors?
   Date: Tue, 02 May 2000
   From: Bill Stewart <>

Nortel's Contivity IPsec server has a formal policy of interoperability
with FreeS/WAN.   I was quite pleased to hear it when they last talked to us,
and it makes sense in their business environment, since they let you use
their WinXX client software free, so this gives them support for Linux

A more recent mailing list report is:

Subject: Nortel Contivity and Free-S/WAN
   Date: Wed, 7 Mar 2001
   From:  "JJ Streicher-Bremer" <>

OK, here is a very brief nuts and bolts breakdown on how to get this
combo working.  I want to thank everyone at Free-S/WAN and everyone on
the list for your help in getting this to work.

Connecting FreeS/WAN to the Nortel Networks Contivity Extranet Switch:

What you need:
FreeS/WAN v1.5 and Contivity ver 2.5 - 3.5 (might work with earlier
versions, but I have not tested it with this config)
FreeS/WAN v1.8 and COntivity ver 3.5 (the 3.5 version supports Diffe
Hilman group 2 key exchange)

What to do:
1 - Configure the Contivity:
   Set up a branch office tunnel group with the following settings:
        Nailed Up: Disabled
        Access Hours: Anytime
        Call Admission Priority: Highest Priority
        Forwarding Priority: Low Priority
        Idle Timeout: 00:00:00
        Forced Logoff: 00:00:00
        RSVP: Disabled
        RSVP: Token Bucket Depth: 3000 Bytes
        RSVP: Token Bucket Rate: 28 Kbps
        Branch Office Bandwidth Policy: 
        - Committed Rate: 56 Kbps
        - Excess Rate: 128 Kbps
        - Excess Action: Mark

        - ESP - Triple DES with SHA1 Integrity: Enabled
        - ESP - Triple DES with MD5 Integrity: Enabled
        - ESP - 56-bit DES with SHA1 Integrity: Disabled
        - ESP - 56-bit DES with MD5 Integrity: Disabled
        *IKE Encryption and Diffie-Hellman Group: Triple DES with Group
2 (1024-bit prime)
        Vendor ID: Disabled
        Perfect Forward Secrecy: Enabled
        Compression: Disabled
        Rekey Timeout: 08:00:00
        Rekey Data Count:  (None) 
        *ISAKMP Retransmission Interval: 16
        *ISAKMP Retransmission Max Attempts: 4

        Set up a branch office tunnel inside this new group with the
following settings:
        Endpoint Addresses
        Local - Public address of your COntivity
        Remote - Your Free-S/WAN interface Address
                Tunnel Type - IPSEC
        IPSEC Authentication - Text Pre-Shared Key
                One note here, I have had some trouble trying to use HEX
or Non alphanumeric chars in this key.
        Under IP:
        Static Routing
        Local - networks you want to be able to access through the
        Remote - networks that will be allowed through the tunnel
        NAT - None

   Get routing setup on your office network:
        You will need to get a routing entry that will point all traffic
bound for your home network (the one that will be acciessible through
the tunnel) to the internal interface of the contivity system.

   Configure Free-S/WAN:
        Install, compile, and test Free-S/WAN
        Edit ipsec.conf for your new tunnel:
ipsec.conf --
config setup
conn net1
conn net2

ipsec.secrets -- "Your big secret"

The above config is for this imaginary network:

         +------+ |      | Internet  
---------|      |-------------------++===========
         +------+            Home Router         
         Free-S/WAN host

Internet ++ These
=========++--------------####--------- are here somewhere
   Office Router       Contivity
   This has worked for me.  I am still having trouble with the tunnels
dying after about 30-40 minutes of non-use.  Don't know what that is
about, but I'll keep you posted.

Raptor Firewall

Raptor 5 on NT (old info)

   Subject: Interoperability with Raptor 5 (Success!)
   Date: Wed, 06 Jan 1999 16:19:27 -0500
   From: Chuck Bushong <>

I don't know if this is useful information for anyone, but I have
successfully established a VPN between RedHat 5.1 (kernel 2.0.34) running
FreeS/WAN 0.91 and NT4 running Raptor 5.  However, Pluto does not appear
compatible with the Raptor IKE implementation. . . .

Subject: RE: Interoperability with Raptor 5 (Success!)
Date: Thu, 28 Jan 1999 17:22:55 -0500
From: Chuck Bushong <> 

... this VPN (at least the klips end) has been up under minimal
utilization for three weeks plus without interruption.  The
machine seems very stable.  Pat yourself on the back, gentlemen.
Your beta release is more stable than certain companies' shipping

Keep up the good work.

Raptor 6 on Solaris

Subject: Re: successful interop. with Raptor 6.02 
   From: "Charles G. Griebel" <> 
   Date: Tue, 25 Jul 2000

On Thu, Jul 20, 2000 at 12:04:40PM -0700, Kevin Traas wrote:
> Great!  I'm just about to start looking into this as well, so any
> docs/info you can provide would be *greatly* appreciated.  Immortalize
> yourself!  Get something written and added to the compatibility.html
> file.  Many will thank you.

Can't be that hard.  I'm just a freeswan newbie who hasn't even done a FS

tunnel yet :)

Anyway, I hope you find this helpful.



Automatically keyed 3DES VPN between Raptor 6.02 on Solaris 2.6 (left) and
   FreeS/WAN 1.5 on 2.2.16 Intel (right)

FreeS/WAN (right) information:

config setup
        interfaces="ipsec0=ppp0"    # change to suite

conn sample

# note I haven't verified that underscores will actually work PSK "some_long_secret_with_plenty_of_chars"

Raptor 6.02 (left) information:
Key Profiles:
    Name: left-external-kp-dynamic
    Type: Dynamic
    Profile Describing: local entity
    Identification Type: Address
    ISAKMP Hash Method: MD5
    ISAKMP Authentication: Shared_Key
    Shared Secret: some_long_secret_with_plenty_of_chars
    Time Expiration: 1080

    Name: right-external-kp-dynamic
    Type: Dynamic
    Profile Describing: remote entity
    Identification Type: Address

Secure Subnets:
    Name: left-ss-dynamic
    Key Profile: left-ss-dynamic

    Name: right-ss-dynamic
    Key Profile: right-ss-dynamic

Secure Tunnel:
    Name: left-to-right-tunnel
    Entity A: right-ss-dynamic
    Entity B: left-ss-dynamic
    Encapsulation: ISAKMP
    Filter: [none]
    Pass traffic through proxies: [unchecked]
    Use Authentication Header: [unchecked]
    Use Encryption Header: [checked]
    Data Integrity Algorithm: MD5
    Data Privacy Algorithm: 3DES

    [Advanced settings]
    Data volume timeout: 2100000
    Lifetime timeout: 480
    Inactivity timeout: 0
    Transport mode: [unchecked]
    Perfect forward secrecy: [unchecked]
    Proxy: [checked]

I made the addresses fictitious RFC1918 addresses.
I haven't tried PFS.
I had problems getting an SA with manual keying -- I think it may be with the

Raptor manual keying

A mailing list suggestion from FreeS/WAN technical lead Henry Spencer:

> In the Raptor settings, there are 2 sets of data (1 for each end). Each set
> contains an SPI, 3 DES Keys and 1 MD5 hash. I only know how to include one
> set, how do I include the other set? Is the other set needed?

They may be using different keys for each direction, which is a bit
unusual for manual keying, but not impossible.  The simplest thing is
probably to just give it two identical sets of data -- that should work.
FreeS/WAN has provisions for asymmetric keys etc. in manual keying, but
that stuff is lightly documented and lightly tested.

Gauntlet firewall GVPN

Subject:  Successful interop: FreeS/WAN 1.7 

 Gauntlet Firewall GVPN 5.5
   Date: Tue, 21 Nov 2000

Sending the following to the list, at Hugh's request.

-----Original Message-----
From: Reiner, Richard 
Sent: Tuesday, November 21, 2000 11:34 AM
To: ''


> Good.  But we don't think that you should be using our IPCOMP just
> yet.  It is flaky :-(

I've seen no anomalies, although "allow ipcomp" is on at the Gauntlet 
end.  Looking at my ipsec.conf I actually find no refereence to ipcomp. 
 I presume it is disabled by default.  In addition, reviewing my logs 
both on the Gauntlet end and the Linux end, I see nothing I can 
interpret as an indication that ipcomp was enabled during negotiation.  
So I have to correct my previous posting - I believe the link is *not* 
using ipcomp.

> This is interesting and we'd love a more complete writeup.  It should
> get incorporated into our interop documentation.

Here are the relevant bits from ipsec.conf:

config setup

conn freeswan17-gauntlet55

All settings on the Gauntlet side are the same (not shown here, as GUI 
screenshots are hard to show in ASCII... and the textual format that is 
generated by the Gauntlet GUI is ugly in the extreme).

Note that ikelifetime is 1440m by default on the Gauntlet end, but 
freeswan does not support this value (max appears to be 480m), thus the 
Gauntlet end is also set to 480m to match freeswan's value.

Also worth noting: I am using the excellent Seawall scripts to manage 
ipchains configuration on the freeswan end.  It automatically generates 
a correct set of firewall rules for the link (along with doing many 
other convenient things).
For more information on Seawall (the Seattle Firewall), see that project's home page on Sourceforge.

Checkpoint Firewall-1

A PDF HowTo for connecting FreeS/WAN and this product can be downloaded from the vendor's site or browsed at a VPN mailing list site.

A resource page full of Firewall-1 information.

The mailing list reports success with this combination, but also some problems. Search the archives for the full story.

Here is one message, about what seems to be the biggest problem:

Subject: Re: Pb establishing connection from FW1/3DES/SP2 with freeswan 1.5 - ACTE 2
   Date: Tue, 6 Feb 2001
   From: Claudia Schmeing <>
> Thanx to Michael and Claudia, but this doesn't work from VPN1 to linux (as
> linux to VPN1 is OK).

> I think that VPN1 doesn't send "" but "" and,
> as Claudia said, IPSEC SA need to match Exactly. 

I don't know about the rules on the VPN-1. You'll have to rely on people 
with applicable experience there...

> Is it possible that freeswan doesn't do the inclusion process (ie if he
> receive, i doesn't match that this is include in
> ?

Yes, that's correct. It needs to match exactly, and inclusion is not
part of this process.
> Btw why VPN/1 send and not (the value that
> Freeswan is waiting for)? A bug?

I think Michael may be able to help you with this.

> Have i a way to force Freeswan to do the "inclusion" (ie accept 
> as a part of, even if the 2 IPSEC Sa 
> doesn't match exactly) ?

No, but...
Another strategy is to accept the fact that the Checkpoint 
proposes separate connections for each machine. If you define 
and add each of these connections on the Linux FreeS/WAN side, then 
Linux FreeS/WAN ought to accept the Checkpoint's proposals.

The only possible difficulty with this strategy is that I don't know 
how Linux FreeS/WAN handles the concept of overlapping tunnels. I
believe, though, that these tunnels can coexist, and if for any 
packet there are two options, a more general and a less general, the
packet will be handled by the more specific tunnel. You would need
to do a little testing to ensure you understand the behaviour and
that this does actually solve your problem.

I think it would be simplest to try to get the Checkpoint to propose the 
more general tunnel. Since I don't recall having seen this problem before, 
I suspect the simpler solution is doable.

Redcreek Ravlin

We have reports of successful interoperation at an interop conference, but there is also a mailing list thread discussing difficulties some users have encountered.

SSH Sentinel

The vendor's web site has configuration examples for use with FreeS/WAN.

One user reports:

Subject: [Users] Very Useful document, can a link to it be put on the FreeS/WAN web site?
   Date: Fri, 19 Oct 2001
   From: Simon Matthews <>

This is a very useful document on getting SSH Sentinel to work with 
FreeS/WAN using x509 certificates.

Perhaps a link to it could be put on the web site.

There is also another document on FreeS/WAN <> SSH Sentinel interoperability: Simon 

The vendor seems serious about interop with us. Here is a message one of their staff posted on our list:

From: Jussi Torhonen <>
Organization: SSH Communications Security Corp -
Subject: [Users] SSH Sentinel VPN client public beta #3 now available
Date: Thu, 31 May 2001

Hello, FreeS/WAN community !

SSH Communications Security Corp has released a new public beta #3
version of SSH Sentinel VPN client for Windows. We've got a lot of
reports also from FreeS/WAN community and with that feedback we've
improved interoperability and stability. 

For example PFS (Perfect Forward Secrecy in IKE rekey) can now be used
between SSH Sentinel and FreeSWAN, and if using that user contributed
X.509 patch and exporting the certificate from SSH Sentinel, now those
-----[BEGIN|END] CERTIFICATE----- headers/footers are properly included
in the exported PEM formatted certificate, so it can be imported to
FreeSWAN with fswcert utility and OpenSSL tools. 

Thank you a lot for your feedback, colleagues !

You can get that new public beta #3 and PDF formatted User Manual from or via website

For more information about the product, please check our website

We eagerly want to make SSH Sentinel as the best VPN client on the
market. If you want to contact our support, please send e-mail to or fill up our feedback form at

Best regards,
Jussi Torhonen, SSH Sentinel Team
Kuopio, Finland

There is one known problem withh SSH-FreeS/WAN interoperation, described in this message:

Subject: Re: [Users] Any plans for AES / Rijndael support ?
   Date: Tue, 11 Dec 2001
   From: Jussi Torhonen 

Organization: SSH Communications Security Corp -

Markus Weber wrote:

> ... the installation
> of Sentinel don't let you set 3DES as the default!
> And when your want to add a connection the first
> diagnostic-test goes wrong ! :-( ...

In current SSH Sentinel release you can select 'Legacy proposal' option, 
  when setting up a VPN Connection profile. That causes it to use 3DES 
as a default cipher and DES as a alternative one. The option was added 
there just to improve interoperability with legacy systems supporting 
3DES or even DES only.

If no selecting Legacy Proposal option, SSH Sentinel sends quite a huge 
proposal list to the responder to find automatically one common cipher 
supported to be used for the connection. That proposal list is known to 
be problematic for some VPN gateway implementations like FreeSWAN. 
Typically the long proposal list itself may the a problem or fragmented 
packets of the long proposal list may be a probem.

Now we've been living in a world of DES and 3DES, but hopefully in a 
near future the use of AES/Rijndael will increase. ...

FreeS/WAN does not yet support AES.

F-Secure VPN for Windows

   Subject: Identification through other than IP number
   Date: Tue, 13 Apr 1999
   From: Thomas Bellman <>

... Currently we are trying to interop FreeS/WAN
with F-Secure VPN+ Client 4.0 (for MS Windows), and as long as
the Windows machine has a fix IP address, and are initiating the
IKE negotiations, things are working well.  However, when the IP
address is changing, it doesn't work. ...
(I'll try to write something up about the problems we are having
when Pluto is initiatior in another message.)


Watchguard make a Linux-based firewall product. Ipchains author Rusty Russell thanks them for support and recommends them in one of his HowTos. On the other hand, some comments on our mailing list about the Watchguard product have been quite unfavourable. See, for example, this archive message.

Watchguard do not use FreeS/WAN in their product. They have their own IPsec implementation.

We have had mailing list reports of successful interoperation between FreeS/WAN and the Watchguard firewall, using manually keyed connections. The user could not get automatically keyed connections to work; the message below explains this.

Here is some mail from a Watchguard employee about interoperation:

Subject: FreeS/WAN and WatchGuard Firebox interop
   Date: Mon, 18 Dec 2000
   From: Max Enders <>

I was recently given the task of testing IPSec interoperability
with our product, the Firebox. I just wanted to let you know that
I had success with a manual keyed tunnel. Here's what I used for
my test:

RedHat Linux 6.2
Linux 2.2.18 i686 unknown
Linux FreeS/WAN 1.8
"Trusted" interface:
"External" interface:

Firebox II FastVPN
WatchGuard Live Security System v4.5
Trusted interface:
External interface:

Because FreeS/WAN does not implement single DES, a dynamic keyed
tunnel will not work. Our product strictly uses DES for main mode.
We hope to address this in a future release. Here are instructions
for configuring the Firebox:

Open the Policy Manager and create a new IPSec gateway. Set the Key
Negotiation Type to manual and enter the FreeS/WAN box's external
IP address for the Remote Gateway IP. Configure a new tunnel with
a unique SPI. Select 3DES-CBC for Encryption and MD5-HMAC for
Authentication. Make an Encryption Key and Authentication Key.
Copy the values and save them for configuration of the FreeS/WAN box.
Configure a routing policy and any necessary services as you normally

Here's how I configured FreeS/WAN:

Modifications to /etc/ipsec.conf:

Under the "config setup" section, add:


At the end of the file, add the following connection:

conn firebox

The spi used here should match the Firebox's. Note that the Policy Manager
expects an SPI in decimal, not hexadecimal. The espenckey value should be
0x and the Encryption Key you're using on the Firebox. Likewise for
espauthkey and the Authentication Key on the Firebox.
A user comments:
Subject: RE: Freeswan
   Date: Wed, 7 Feb 2001
   From: "Patrick Poncet" <>

It's working!!!

Voila...  I wish to thank all the FreeS/WAN for putting out such a great
product out!  And also Philippe PAULEAU who pioneered interoperability
between FreeS/WAN and Watchguard Firebox II and therefore showed me that my
efforts would not be wasted!...

Yes indeed FreeS/WAN to WatchGuard Firebox only works in manual keying mode
and the best way to generate keys is to have the firebox generate the keys,
then copy and paste into the ipsec.conf file on the FreeS/WAN side (don't
forget to prefix the keys with '0x' in your ipsec.conf file.

Also keep in mind that the SPI is in decimal on the Firebox side and HEX on
the FreeS/WAN side!!!  We spent 4 hours on fixing this HEX-DEC issue only :)

Xedia Access Point/QVPN

   Subject: Interoperability result
   Date: Mon, 15 Mar 1999 18:08:12 -0500
  From: Paul Koning <>

Here's another datapoint for the "FreeS/WAN interoperability

I tested 0.92 against the Xedia Access Point/QVPN product, using
dynamic keying (i.e., Pluto at work).

Results: it works fine so long as you ask for 3DES.  DES and no-crypto 
modes don't work when Pluto is involved.

I did limited data testing, which seemed to be fine.  No performance
numbers yet, could do that if people are interested.

Any questions, please ask.


PGP Mac and Windows IPsec client (PGPnet)

McAfee VPN Client

From version 6.5 (1999) on, the PGP products from PGP Inc. included an IPsec client program called PGPnet.

The parent company, NAI, have since re-organised their product line. They no longer sell PGP (it was put into maintenance in February 2002) and the IPsec product is now called McAfee VPN Client

Here is the first message about PGPnet to our mailing list, from a senior PGP employee:

   Subject: PGPnet interoperable with FreeSWAN
   Date: Mon, 05 Apr 1999 18:06:13 -0700
   From: Will Price <>

Network Associates announced PGP 6.5 today.  It includes a new product
PGPnet which is a full IKE/IPSec client implementation.  This product
is for Windows and Macintosh.  I just wanted to send a brief note to
this list that the product was compatibility tested with FreeSWAN
prior to its release, and the tests were successful!
- -- 
Will Price, Architect/Sr. Mgr., PGP Client Products
Total Network Security Division
Network Associates, Inc.

One version is downloadable at no cost for non-commercial use. See our links. That version does not support subnets.

Several of the user-written HowTos mentioned above cover interoperation between PGPnet and FreeS/WAN.

A more recent post from the same PGP Inc staff member pointed out:

Make sure you're using PGP 7.0 or later as the key parser was improved
in that release.  (PGP 7.0.1 was just released)

Various users have reported various successes and problems talking to PGPnet with FreeS/WAN. There has also been a fairly complex discussion of some fine points of RFC interpretation between the implementers of the two systems. Check an archive of our mailing list for details.

A post summarising some of this, from our Pluto programmer:

   Subject: PGPnet 6.5 and freeswan
   Date: Sun, 16 Jan 2000
   From: "D. Hugh Redelmeier" <>

| From: Yan Seiner
| OK, I'm stumped.  I am trying to configure IPSEC to support road
| warriors using PGPnet 6.5.
| I've set up everything as per the man pages on the ipsec side.
| I've set up everything on the PGPnet side per the docs for that package.
| Pluto fails with this:
| Jan 16 08:14:11 aphrodite Pluto[26401]: "homeusers" #8: no acceptable
| Oakley Transform
| and then it terminates the connection.

As far as I can tell/remember, there are three common ways that PGPnet
and FreeS/WAN don't get along.

1. PGPnet proposes a longer lifetime for an SA than Pluto is willing
   to accept.

2. After rekeying (i.e. after building a new SA bundle because the old
   one is about to expire), FreeS/WAN immediately switches to the new
   one while PGPnet continues using the old

3. FreeS/WAN defaults to expecting Perfect Forward Secrecy and PGPnet
   does not.

Perhaps you are bumping into the first.  In any case, look back
in the log to see why Pluto rejected each transform

Some advice from the mailing list:

   Subject: Re: Secure Gate Fails- PGPNet & FreeSwan
   Date: Wed, 28 Jun 2000
   From: Andreas Haumer <>

I have a PGPnet setup running with FreeS/WAN working as secure 
gateway. It works quite fine, except for a re-negotiation problem 
I'm currently investigating, and in fact I have it running on some
test equipment here right now!

As I tried _several_ different non-working configuration settings 
I think I know the exact _one_ which works... :-)

Here's my short "HOWTO":

FreeS/WAN version: snap1000jun25b
PGPnet: PGP Personal Privacy, Version 6.5.3
Linux: 2.2.16 with some patches

Network setup:

internal subnet [192.168.x.0/24]
|        [192.168.x.1]
secure gateway with FreeS/WAN
|        [a.b.c.x]
|        [a.b.c.y]
router to internet
|   Internet
|        [dynamically assigned IP address]
road-warrior with PGPnet

Configuration of FreeS/WAN:

a) /etc/ipsec.conf

config setup

conn %default

conn gw-rw

conn subnet-rw

b) /etc/ipsec.secrets

a.b.c.x "my very secret secret"   

Note: If you are running ipchains on your secure gateway,
you have to open the firewall for all the IPsec packets 
and also for traffic from your ipsec interface!
Don't masquerade the IPsec traffic!

Check your logfiles if the firewall is blocking some 
important packets!

Configuration of PGPnet:

(note that there is an excellent description, including
screenshots of PGPnet, on <>)

In short, do the following:

Launch the PGPnet configuration tool and set defaults options

Start - Program - PGP - PGPnet
View - Options
General Panel :
  Expert Mode
  Allow communications with unconfigured hosts
  Require valid authentication key
  Cache passphrases between logins
  IKE Duration : 6h
  IPsec : 6h
Advanced panel :
  Selected options :
    Ciphers : Tripple DES
    Hashes : MD5
    Diffie-Hellman : 1024 and 1536
    Compression : LZS and Deflate
  Make the IKE proposal :
    Shared-Key - MD5 - 3DES -1024 bits on top of the list (move up)
  Make the IPSec proposal :
    NONE - MD5-TrippleDES -NONE on top of the list (move up)
  Select Perfect Forward Secrecy = 1024 bits
Press OK

Create the connection's definition.

In the Hosts panel, ADD
  Name : Enter a name for the right gateway
  IPaddress : Enter its IP address visible to the internet (a.b.c.x)
  Select Secure Gateway
  Set shared Paraphrase : enter you preshared key
  Identity type : select IP address
  Identity : enter
  Remote Authentication : select Any valid key
Press Ok
  Select the newly created entry for the right gateway and click ADD,
  Name : Enter a name for the central subnet
  IP address : Enter its network IP address (192.168.x.0)
  Select Insecure Subnet
  Subnet Mask : enter its subnetmask (
Press OK, YES, YES                             

This should be it. Note that with this configuration there is
still this re-keying problem: after 6 hours, the SA is expired
and the connection fails. You have to re-connect your connection
with PGPnet.

and a note from the team's tech support person:

Date: Thu, 29 Jun 2000
From: Claudia Schmeing 

There is a known issue with PGPNet which I don't see mentioned in the docs.
It's likely related to this one, that you note on the site:

>2. After rekeying (i.e. after building a new SA bundle because the old
>   one is about to expire), FreeS/WAN immediately switches to the new
>   one while PGPnet continues using the old

The issue is: When taking down and subsequently recreating a connection, 
it can appear to come up, but it is unusable because PGPNet continues
to use an old SA, which Linux FreeS/WAN no longer recognizes. The solution is
to take down the old connection using PGPNet, so that it will then
use the most recently generated SA.

IRE Safenet/SoftPK

IRE have an extensive line of IPsec products, including firewall software with IPsec, and hardware encryption devices for LAN or modem links. Their Soft-PK is a Win 98 and NT client. Quite a few people have used this with FreeS/WAN and, judging by mailing list reports, have had good results.

SoftRemote is newer product integrating the IPsec client with personal firewall software. As yet, we have few reports on this. One is quoted below.


Several documents are available:

Some messages from the mailing list:

Subject: Re: Identification through other than IP number
Date:  Fri, 23 Apr 1999
From:  Tim Miller <>

Randy Dees writes:

 > Anyone know of a low-cost MS-Win client that interoperates and does not
 > require purchasing a server license to get it?  

        SafeNet/Soft-PK from IRE ( is a low-cost
client (though I don't have the exact cost available at the moment).
I've got it running on an NT4 workstation and it interoperates nicely
(in transport mode, will try tunnel later) with FreeS/WAN.  It's also
ICSA IPsec certified.

A later report with some setup details:

Subject: RE: PGPnet and Freeswan one more time...
   Date: Sat, 16 Dec 2000
  From: "Tim Wilson" <>

Here are some details about using the IRE SafeNet Soft/PK client with a
FreeSwan gateway.

I applied the x509 patch to Pluto according to the instructions. I use the
"leftcert" and "rightcert" keywords in the ipsec.conf file. This causes
FreeSwan to read the public keys and identities from the cert files. The
identities wanted and used by FreeSwan will then be the DNs in the certs.

I used OpenSSL to generate keys and certs and to sign certs. When generating
the gateway cert, you should *not* enter an e-mail address because it turns
out that confuses Soft/PK. Also, Andreas Steffan tells me that you want to
keep the cert short to avoid fragmentation, so use a 1024-bit RSA key and
succinct names.

The FreeSwan gateway cert goes in /etc/ipsec.d/, the gateway private key is
extracted from the key file using fswcert (part of the x509 patch) and
pasted into /etc/ipsec.secrets, and a DER version of the gateway cert goes
in /etc/x509cert.der. This is all according to the instructions that
accompany the x509 patch.

The Windows client is of course running Soft/PK in this case. I generated a
private key and cert for the client on the Linux machine using OpenSSL. I
created a pkcs12 file containing the client's private key and cert, which I
put on a floppy and imported into Soft/PK. I also imported the gateway cert
into Soft/PK (you can either import a self-signed cert for the gateway or
the self-signed cert for the CA that signed the gateway cert--either works).

Soft/PK allows you to configure practically everything for the connection.
Here are the main points to watch for:

On the first panel you have to set the peer identities. The gateway will
identify itself using the DN in the gateway cert. So of course you have to
configure Soft/PK to look for the correct DN. There's no problem with this
as long as you didn't enter an e-mail address in the gateway cert. Just
check "Connect using Secure Gateway tunnel", set ID type to "Distinguished
Name", and enter the correct info in the dialog box.

In "My identity" just select the client cert that you imported in pcks12
format. Soft/PK apparently identifies itself with the DN from the cert,
which is exactly what FreeSwan is looking for.

In "Security Policy", you want Main mode and make the PFS setting agree with
whatever FreeSwan is doing (FreeSwan uses PFS by default). If you use PFS I
believe you must use DH group 2 as FreeSwan doesn't like group 1.

Phase 1 Authentication must be "RSA signatures" and 3DES plus either MD5 or
SHA-1 (I used MD5 but I believe FreeSwan accepts either). I left the
lifetime unspecified. Also you must select DH group 2 because I believe that
FreeSwan will not accept group 1.

Phase 2 also must use 3DES and MD5 or SHA-1. I used no compression and only
ESP and no AH, haven't tried other choices.

Hope this helps.


Here is a mailing list message reporting experience with the newer SoftRemote product.

From: Whit Blauvelt <>
Subject: Re: [Users] RE: SafeNet SoftRemote 6.1 - FS 1.91 - HOW?
Date: Fri, 16 Nov 2001

Things I've learned in getting SoftRemote working with FreeS/WAN:

Using SoftRemote on dial-in, if there is any configuration adjustment for
which you stop and start FreeS/WAN, SoftRemote is totally lost until you
disconnect and dial in again. The SoftRemote "Disconnect All" and subsequent
"Reload Polilcies" options that show when right-clicking its icon in the
tray do not fix this - the only thing I've found that works is hanging up
and then redialing. This makes debugging a total pain, especially if you
think you're testing your changes, because you're not. 

Not sure if this affects fixed IP connections from SoftRemote, or what the
effective equivalent to hanging up and dialing in again would be to clear
the problem there if it exists.

Also, as I noted before: In configuring SoftRemote, there are a couple of
new menu options that Soft-PK didn't have, just in case you're following
examples given for that. Importantly, in setting the "Remote Party Identity
and Addressing" choose "IP subnet" rather than "IP", and be sure to provide
a mask which matches the subnet mask for that conn in ipsec.conf (e.g. and /24). 

Much of the infornation available above for the earlier SoftPK product should also apply to SoftRemote.



Subject: ipsec interoperability FYI
   Date: Sun, 02 May 1999
   From: Sean Rooney <>

we've been doing some basic interoperability testing of the following; 

PGP NT VPN 6.5 and freeswan both seem to work reasonably well with 
Borderware 6.0 and freegate 1.3 beta. [as well as eachother] 

more details coming soon.


   Subject: TimeStep Permit/Gate interop works!
   Date: Thu, 10 Jun 1999
   From: Derick Cassidy <>

Just a quick note of success.  TimeStep Permit/Gate (2520) and
Free/Swan (June 4th snapshot) interoperate!

I have them working in AUTO mode, with IKE.  IPSec SA's are negotiated
with 3DES and MD5.

Here are the configs and a diagram for both configs.

left subnet---| Timestep | --- internet --- | Linux box |

The left subnet is defined as the red side of the timestep box.
 This network definition MUST exist in the Secure Map.

On the Linux box:


conn timestep

In the TimeStep permit/gate Secure Map

begin static-map
        target ""
        mode   "ISAKMP-Shared"
        tunnel ""

In the TimeStep Security Descriptor file

begin security-descriptor
        Name    "High"
        IPSec   "ESP 3DES MINUTES 300 or ESP 3DES HMAC MD5 MINUTES 300"
                                or DES MD5 MINUTES 1440"

The timestep has a shared secret for
set in the Shared Secret Authentication tab of Permit/Config.

Shiva/Intel LANrover

A web page with Shiva compatibility information.

Sun Solaris

   Subject: Re: FreeS/WAN and Solaris
   Date: Tue, 11 Jan 2000
   From: Peter Onion <>

Slowaris 8 has a native (in kernel) IPSEC implementation.

I've not done much interop testing yet, but I seem to rememeber we got a manual
keyed connection between it and FreeSwan a few months ago.


Subject: Re: FreeS/WAN and SonicWall
     Date: Mon, 5 Feb 2001
     From: "Dilan Arumainathan" <>

I know I HAVE TO write the mini-howto - but here is the beginning

Here is my Sonicwall configuration for my working connection:

conn testauto
#You need to set the Unique Firewall Identifier to the parameter that you
#use as the rightid. <------IMPORTANT

Your /etc/ipsec.secrets should be like this:
x.x.x.x y.y.y.y : PSK "opensesame"

On the Sonicwall create a new connection:

Name: testauto
IPSec Gateway address:
SA life time: 18000
Encryption Method: Strong Encrypt and Authenticate( EPS 3DES HMAC MD5)
Shared Secret: opensesame


Here are some mailing list comments from FreeS/WAN tech support person Claudia Schmeing on this:

It certainly has been possible to interop between Radguard VPN gateways and
past Linux FreeS/WAN versions, as is evidenced by, as well as my own interop results
from San Diego this year. There have been no major changes since SD that 
I would foresee affecting this.

The Radguard team said that their VPN gateway will not respond to a peer 
request with PFS (Perfect Forward Secrecy) on, but it *will* successfully 
establish such a connection with Linux FreeS/WAN when Radguard is the
initiator. Since PFS is a desirable feature in terms of cryptographic
security, this asymmetry may frustrate efforts to provide a connection that 
is both as reliable as secure as possible.

While it's not clear that rekeying will present a problem, I suspect that 
some fine tuning of the key life parameters may be needed. Unfortunately 
I was unable to do additional tests on this topic.

Due to the PFS issue, when trying to maintain a connection with PFS,
you may need to set the rekeying times shorter on the radguard side,
in order to ensure that it is always the initiator.

IBM System 390

IBM offer IPsec for their big mainframes. See this PDF document.

We do not know of any tests of this with FreeS/WAN. If you do any, please tell us.

IBM AS 400

From the mailing list:

Subject: [Users] AS/400 <-> FreeS/WAN connection
   Date: Mon, 24 Sep 2001 10:28:54 -0600
   From: "Brandon Peterson" <bsp@MCINTOSHSOFTWARE.COM>


FYI, I got a connection working between my Linux box & AS/400. I had to make
two adjustments to the code...

1) Ignore the commit flag. (There were some patches floating on the list
last week)

2) Make FreeS/WAN start with proposal # 1
To do this, I modified connections.c and inserted after line 1006...
/* Hack to make AS/400 happy */
if (c->policy == 0) c->policy = 1;

Since that was written, FreeS/WAN has been changed to ignore the commit bit, so that adjustment should no longer be necessary.

Windows or Mac clients

If you have Windows 2000 or XP, then you should be able to use the IPsec built into those systems. As far as we know, for all other Windows versions,, you will need a client program.

I am a little confused about IPsec for Mac OS X. Before the release, there were reports it would include IPsec, but more recent information seems to indicate that it doesn't. If anyone knows more, please post to our users mailing list. For other Mac OSs, and perhaps for OS X, you will need a client program.

Quite a number of client programs for IPsec on Windows are available. Some of the same vendors have Macintosh versions.

Some of the user-written HowTos have details of configuration for particular clients.

Most of the relevant vendors are listed in this piece of list mail:

 Subject: Re: Searching Windows95/98 and NT4.0 Clients for FreeS/WAN 
    From: Claudia Schmeing <> 
    Date: Wed, 12 Jul 2000

F-Secure VPN+
for Win 95, 98 and NT 4.0

Checkpoint SecureRemote VPN-1 4.1
for Win 95, 98 and NT

Raptor Firewall, Raptor MobileNT 5.0
Mobile NT is a "Client"* for Win 95, 98 (except SE), & First Edition Windows NT 
up to Service Pack 4. It ships with DES; triple DES may be available as an 
add-on depending on your location.

Firewall is for Win NT 4.0 or Win 2000.

IRE SafeNet SoftPK
a "Client" for Win 95, 98 and NT 4.0 *

Xedia's AccessPoint QVPN "Client" or "Builder"
"Builder" is for NT
"Client" is for Win 98 *

* "Client" in this context indicates software that does not support a subnet
behind its end of the connection.

That mail omits the PGPnet client because the user asking the question already knew of it. The SSH Sentinel client, released since the above message, is another possibility. Both of those have members of the vendor's staff active on our mailing list, an excellent sign for both interoperability and support.

We also know of some other Windows IPsec clients:

No doubt there are others we don't know of.

NT domains vs. tunnels

There has been some mailing list discussion of making NT domains work across FreeS/WAN tunnels.

Robert Cotran asked:

> I have a VPN setup between two subnets (192.168.1.x and 192.168.2.x).  I
> would like to be able to join the NT domain on 192.168.1.x from the
> 192.168.2.x subnet.  Is this possible?  Do I have to forward specific ports
> to do this?  I've already set up WINS entries for all the machines, so
> accessing computers by their NetBIOS names works perfectly.  Please let me
> know about this domain thing.  Thanks!
Dilan Arumainathan answered:
All you need to do is to:

1. Enable NetBIOS over TCP.
2. Create a "lmhosts" file and enter the address of a BDC or a PDC like
    192.168.1.[x]  [Your PDC/BDC servername] #PRE #DOM:[Your Domain Name]

3. Reboot if necessary.
and Sebastien Pfieffer provided a slightly different answer:
For a trust relationship to work between NT domains in different
(sub)nets all domain controllers of the 1st domain have to know about
all controllers of the other domain.
Either you use the described LMHOSTS entry for every domain controller
of both domains or consider setting up WINS service(s).
We suspect that in some cases it may be more complex than that. See the discussion of Linux services and Windows 2000 below and the Interop HowTo documents listed above.

Windows 2000

Windows 2000 ships with an IPsec implementation built in.

There are restrictions. We have had mailing list reports that only the server version will act as a gateway, working with a subnet behind it, and other versions offer only "client" functionality, with no subnet. We have some comment on this "client/server" distinction in an earlier section.

Some versions of Windows 2000 ship with only weak encryption. You need to upgrade them with the strong encryption pack, available either via the Windows 2000 update service or from Microsoft's web site.

Windows 2000 IPsec sometimes exhibits remarkably odd behaviour. It will allow you to configure it for 3DES only, then ignore your settings and fall back to single DES in some circumstances. Microsoft have said they will fix this. See this Wired article.

Other Linux services related to Win 2000

Windows 2000 also uses a number of other security mechanisms which have Linux equivalents. To integrate well with Windows 2000, you may need to look at several open source projects other than FreeS/WAN:

Here is a mailing list message, from FreeS/WAN team tech support person Claudia Schmeing, discussing Windows 2000 and L2TP:

You write,

> I want some information about IPsec with L2TP.
> I'm going to build the IPsec tunnel on the L2TP tunnel.
> Is it strange?
> Is there any case like this already implemented?

It's used, but rarely. In many cases, IPSec alone is sufficient. 

In this thread, Timo Teras reports that he configured the L2TP/IPSec 
hybrid with Win2k. He gives some pointers.

See also John P. Eisenmenger's report on his own experiences at:

FreeS/WAN-to-Win2000 interop

As for IPsec interoperation between Windows 2000 and FreeS/WAN, there are several web sites listed under Interop HowTo documents above.

This Microsoft page on Windows 2000 IPsec troubleshooting may also be helpful.

One user has written a tool to simplify the setup. Here is his description from the mailing list:

Subject: [Users] Win2K
   Date: Tue, 2 Oct 2001
   From: Marcus Müller <>

I've written a small Tool for freeswan-win2k Interaction.
Using this tool you can use a roadwarrior running Win2K
to connect to Freeswan 1.91 with X509 patch.

The tool has the following features:

- FreeSwan like Configuration File
- It sets up the complete Win2k configuration
- It reads dynamic RAS/DHCP adresses and updates the IPSec Config

You only need the following items:
1. Win2k Client
2. Win2k Service Pack 2 (for high encryption)
3. Microsoft ipsecpol tool (included in the resource kit / Downloadable
from Microsoft)
4. FreeSwan with working X.509 Patch and X.509 Certificates for your
5. FreeSwan like Config-File
6. The small "ipsec.exe" Tool

I have tested it on several Client PCs in different environment

I am planning to offer it as Open Source. Right now I don't know the
right way of distributing my work. Because of the widespread interest,
I would like to place it on the FreeSwan homepage.

Rightnow anyone interested should mail me for a Copy, so I get some
more testers.

Thank you for the great FreeSwan System !!!

This tool is now available from the author's web page.

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