Summary
This script repeatedly initiates SSL/TLS connections, each time trying a new cipher or compressor while recording whether a host accepts or rejects it. The end result is a list of all the ciphers and compressors that a server accepts.
SSLv3/TLSv1 requires more effort to determine which ciphers and compression methods a server supports than SSLv2. A client lists the ciphers and compressors that it is capable of supporting, and the server will respond with a single cipher and compressor chosen, or a rejection notice.
This script is intrusive since it must initiate many connections to a server, and therefore is quite noisy.