http://web.mit.edu/network/isakmp/
cisco has a pair of possibly interesting web pages, that include links to web-based download forms for the cisco ISAKMP+Oakley and NRL IPv6/IPsec software, at these URLs:
ISAKMP: http://www.cisco.com/public/library/isakmp.html IPsec: http://www.cisco.com/public/library/isakmp/ipsec.html Software: http://www.cisco.com/public/library/isakmp/disclaimer.html
Further, several versions of the NRL software have mysteriously appeared online in Europe at an ordinary anonymous ftp site at this URL:
ftp://ftp.ripe.net/ipv6/nrl/