We had a previous colleague set up webmin with postfix to allow SMS messages to be sent from application servers and from email.
He left under a dark cloud and never provided any hand over!
Recently we have updated our firewall to use TLS and higher encryption levels. We made changes on our public facing systems and no issues at all! However, we have now been told that we are having issues with our SMS gateway. A web server, that sits in the DMZ on our ASA, performs SMS authentication where a user logs in, an SMS is generated from the system and sent via our SMS Gateway, and gets a login code to the users.
Since the firewall change, users are no longer receiving these text messages. After a bit of investigate it seemed our error was in relation to the CA not being listed in the TLS settings. Changing this brought us a new error, unknown CA. I created a new self signed certificate, updated all of the correct settings, and now receiving the following:
Mar 23 09:22:47 srvesms01 postfix/smtpd[14295]: connect from unknown[10.*.*.*]
Mar 23 09:22:53 srvesms01 postfix/smtpd[14083]: SSL_accept error from unknown[10.*.*.*]: -1
Mar 23 09:22:53 srvesms01 postfix/smtpd[14083]: warning: TLS library problem: 14083:error:140760FC:SSL routines:SSL23_GET_CLIENT_HELLO:unkn own protocol:s23_srvr.c:647:
Mar 23 09:22:53 srvesms01 postfix/smtpd[14083]: lost connection after CONNECT from unknown[10.*.*.*]
The web server that is generating the SMS (10...*) is set up for TLS and has secure ciphers.
Can anyone please help me get to the bottom of this issue? This is all new to me so apologies for any silly questions!
Thanks