Testing Linux Mail Servers with OpenSSL
Feb 15, 2011, 21:34 (0 Talkback[s])
(Other stories by Carla Schroder)
Re-Imagining Linux Platforms to Meet the Needs of Cloud Service Providers
"Yesterday Juliet Kemp showed us how to perform basic server
tests with telnet. Today Carla Schroder shows how to test
TLS/SSL-enabled POP3 and IMAP servers.
"This is a followup to Juliet Kemp's excellent Troubleshooting
Linux Servers with telnet article. This is adapted from my aging
but still-excellent Linux Cookbook.
"Testing POP3 TLS/SSL
"Telnet does not support any encryption. If you are protecting
your POP3 sessions with TLS/SSL then you need s_client, which is
part of OpenSSL. You can query both local and remote mail servers,
using your own server names of course. Commands that you type are
$ openssl s_client -connect localhost.com:995
$ openssl s_client -connect remotehost.com:995
"You'll see a whole lot of lines about certificates and
protocols, and eventually something like this:
+OK Dovecot ready.