HPR3338: Using openssl s_client like telnet

Summary: Connect to port 443 and send some HTTP signals: $ openssl s_client -connect example.com:443 [...snip...] Verify return code: 0 (ok) Extended master secret: no Max Early Data: 0 --- You're now connected. If you wait too long, your connection will likely time out. View the default landing page of the site you've connected with: GET / HTTP/1.1 HOST: example.com In return, you get a dump of the HTML source of the default page (usually index.html) in your terminal. You can also use OpenSSL s_client for email servers using SSL. Before you can send credentials, you must encode your email username and passphrase into Base64. The easiest method I know is this Perl one-liner: $ perl -MMIME::Base64 -e 'print encode_base64("myUserName");' $ perl -MMIME::Base64 -e 'print encode_base64("myPassPhrase");' Take note of the results. The s_client session, aside from authentication, is basically the same as a telnet session. You can find good telnet tutorials all over the Internet, and aside from sending your credentials, they apply to s_client. Here's a copy-paste of an example session: $ openssl s_client -starttls smtp -connect email.example.com:587 > ehlo example.com > auth login ##paste your user base64 string here#### ##paste your password base64 string here#### > mail from: noreply@example.com > rcpt to: admin@example.com > data > Subject: Test 001 This is a test email. . > quit