摘自 freeswan\doc\manpage.d\ipsec_pluto.8.html。
If none of the --encrypt, --authenticate, --compress, or --pfs flags is given, the initiating the connection will only build an ISAKMP SA. For such a connection, client su.nets have no meaning and must not be specified.
另外我觉得freeswan中最有用的三个文档是:
1.freeswan\doc\config.html
2. freeswan\doc\manpage.d\ipsec_pluto.8.html
3.freeswan\doc\faq.html