I'm trying to use gpg auth between a Windows XP SP3 32bits client and an Ubuntu 10.04.4 64bits (fwknop server), but the following message is displayed when I execute the fwknop-static client downloaded from http://www.cipherdyne.org/fwknop/download/fwknop-static.exe :

$ ./fwknop-static.exe -A tcp/22 --gpg-recipient-key 55AC3012 -a -D
fwknop: fko_set_gpg_recipient: Error 19 - Unsupported or unimplemented feature or function

$ ./fwknop-static.exe --help

fwknop client version 2.0.0rc1
Single Packet Authorization client

Usage: fwknop -A <port list> [-s|-R|-a] -D <spa_server> [options]

Bruno Galindro da Costa