Hello, I have a mail server with one virtual domain and some virtual users. The configuration of my server is: Postfix + Cyrus-SASL + Courier-IMAP + ClamAV + SpamAssassin + Amavis + Horde webmail
All of the above works almost perfectly. The users can send/receive mails, authenticate using saslauthd, connect via pop3, pop3s, imap, imaps to receive emails and via smtp, smtps to send emails, amavis content filter works fine.... I have one only question: When I connect to my server, from different networks, to port 25 I am able to send emails to local users only without authenticate! It's like bypassing Cyrus-SASL. I know, of course, that I cannot block access to that port and allow only authenticated users to send emails, because I won't receive mails from web sites. But I think this is a huge security issue for my mail server. I believe one fine solution to this issue would be like that: Somehow, when the command MAIL FROM:<u...@domani.tld> is executed, Cyrus-SASL checks if User is found in the database, and if so, force him to execute the AUTH command, otherwise (therefore the mail is sent via webmail, so the user is unknown) allow to sent the email without any authentication. I'm currently using spamhouse rbl's (smtpd_restrictions = ...) to block some IP's but this isn't a perfect solution as you cannot include all the possible domains... I have searched a lot, and found that others have the same issue with me, but I can't find any solution for that! I would be grateful if you can help me with this! Thank you very very much!!! __________ Information from ESET Smart Security, version of virus signature database 4004 (20090413) __________ The message was checked by ESET Smart Security. http://www.eset.com
