by (at least) ICMPv6 Administratively Prohibited messages, on at least Linux.
I got these by scanning ports 21-23 on ipv6.google.com, for example.
git-svn-id: file:///home/svn/framework3/trunk@5797 4d416f70-5f16-0410-b530-b9f4589650da
so things like "21-25,80,443", "1024-" and "-" behave like you expect. This
replaces the PORTSTART and PORTSTOP options with a single PORTS option.
git-svn-id: file:///home/svn/framework3/trunk@5796 4d416f70-5f16-0410-b530-b9f4589650da