hpr3338 :: Using openssl s_client like telnet
OpenSSL s_client is the new telnet. Here is how to use it.
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telnet, openssl.
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Duration: 00:19:49
Networking.
This series will try and explain the basics of networking to the listener as well as introduce more detailed topics.
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