[Vpn-help] compression support

[Matthew Grooms]

Thorsten Albrecht wrote:
> Hi,
> is it planned to support the compress algorithm "LZS"? My router
> manual recommends it instead of "Deflate".
> 
> Is compression already supported (the field is not greyed out as stated in
> the manual...)?
> 
> BTW Your Shrew VPN Clients 2.03 (XP) works great and reliable with an
> Lancom 1823 device. Thanks for development!
> 
> Thorsten
> 

Thorsten,

Thanks for reminding me of this. I will need to go back and check but 
believe there are a few things missing in the policy generation code 
that prevents compression from working properly. It should be grayed 
back out until I get that sorted. IPcomp ( compression ) AH as well as 
transport mode support for AH/ESP was added to the IPsec Daemon during 
the 2.0.0 development cycle but options never fully made it into the 
Site Configuration dialogs. If compression will help you, I can look 
into reviving this support for the 2.1.x branch.

As for LZS, the algorithms are patent encumbered. Here is the text 
included in RFC 2395 ...

1.3 Licensing

    Hi/fn, Inc. holds patents on the LZS algorithm. Licenses for a
    reference implementation are available for use in IPPCP, IPSec, TLS
    and PPP applications at no cost.  Source and object licenses are
    available on a non-discriminatory basis. Hardware implementations are
    also available.  For more information, contact Hi/fn at the address
    listed with the authors' addresses.

... which makes me believe that it would be possible for Shrew Soft to 
obtain a license to use an LZS reference implementation at no cost since 
we will be using it with IPsec. I tried to email the addresses listed in 
the RFC several times but have never had a reply. There is an additional 
disclosure made by a hifn representative here ...

http://www.ietf.org/ietf/IPR/hifn-ipr-multiple-rfcs.txt

... which makes me think I may need to snail mail them something. I just 
know that I haven't had much time to look into it. Maybe one of the 
other non-technical Shrew Soft guys can tackle this for us. They own 
suits and fancy degrees which surely gives them an advantage :) I will 
keep you posted.

Thanks,

-Matthew