Old 30th November 2006, 22:15
DrZaius DrZaius is offline
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Default Strange log entries

I came across a few entries that I haven't ecountered before while looking at my messages.log. Can anyone explain to me what this means?
00:52:48 domain.com [] (may be forged): QUIT[3116]: domain.com [] (may be forged) did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
00:53:02 smtp(pam_unix)[3124]: check pass; user unknown
00:53:02 smtp(pam_unix)[3124]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
There were thousands of these messages. I'm assuming someone is attempting a dictionary attack on the SMTP server; so they can use it to spam I guess. I wasn't worried about it but two unique entries amongst thousands from this domain in mail.log got my interest. They are the entries with sendmail[9498].

These are the entries in mail.log:
15:00:46 sendmail[8655]: from=<>, size=0, class=0, nrcpts=0, proto=SMTP, daemon=MTA, relay=domain.com [] (may be forged)
15:26:37 sendmail[9498]: STARTTLS=server, relay=domain.com [] (may be forged), version=TLSv1/SSLv3, verify=NO, cipher=DHE-RSA-AES256-SHA, bits=256/256
15:26:37 sendmail[9498]: from=<>, size=12076, class=0, nrcpts=0, proto=ESMTP, daemon=MTA, relay=domain.com [] (may be forged)
08:58:30 sendmail[8220]: domain.com [] (may be forged) did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
There are thousands of entries (excluding sendmail[9498]) and the domain always stays the same, however, the ip address changes as shown above.

What's going on here?
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Old 1st December 2006, 17:39
falko falko is offline
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Spammers are trying to find out if they can use your server for spamming. If you use SMTP-AUTH and strong passwords, I don't think they will succeed.
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