How would you test an SSL connection?

Question

I'm experimenting with OpenSSL on my network application and I want to test if the data sent is encrypted and can't be seen by eavesdropper.

What tools can you use to check? Could this be done programmatically so it could be placed in a unit test?

Answer 1

openssl has an s_client, which is a quick and dirty generic client that you can use to test the server connection. It'll show the server certificate and negotiated encryption scheme.

Answer 2

I found this guide very helpful. These are some of the tools that he used:

$ openssl s_client -connect mail.prefetch.net:443 -state -nbio 2>&1 | grep "^SSL"

$ ssldump -a -A -H -i en0

$ ssldump -a -A -H -k rsa.key -i en0

$ ssldump -a -A -H -k rsa.key -i en0 host fred and port 443