is there any way to protect ethernet hotspot? someone is find the way to hack our passwords

p.s. :using chap auth.

please help.

Use HTTPS authentication instead of HTTP

hello, how can i register legal ssl license to use all our hotspots?

Not sure what you mean by "legal". You can use Verisign or Thawt for a paid option, or you can try cacert.org for a free option.