On 10/21/2016 1:13 PM, vod vos wrote:
> Hi guys,
> 
> When I reviewed the mail.log, it showed a IP was trying to test if
> relay was open or not. However, the times were too many.
> 
>   *
>     What is the max limited times of postfix defaultly defined?
> 

See the STRESS_README document.
http://www.postfix.org/STRESS_README.html


> 
>   *
>     And how to modify it or how to set helo/ehlo restriction?
> 
> 
> Thanks.
> 
> Here is the log:

Many unrelated entries snipped.



> 
> Oct 19 22:21:34 mail postfix/smtpd[1796]: connect from
> unknown[61.145.214.178]

client connects.


> Oct 19 22:21:42 mail postfix/smtpd[1796]: NOQUEUE: reject: RCPT from
> unknown[61.145.214.178]: 554 5.7.1 <[email protected]>:
> Relay access denied; from=<[email protected]>
> to=<[email protected]> proto=ESMTP helo=<XL-20160621FCVQ>

Client attempts unauthorized relay, postfix rejects it.

> 
> 
> Oct 19 22:21:42 mail postfix/smtpd[1796]: NOQUEUE: reject: RCPT from
> unknown[61.145.214.178]: 554 5.7.1 <[email protected]>:
> Relay access denied; from=<[email protected]>
> to=<[email protected]> proto=ESMTP helo=<XL-20160621FCVQ>

(other Relay attempts snipped)

> 
> Oct 19 22:22:05 mail postfix/smtpd[1796]: improper command
> pipelining after DATA from unknown[61.145.214.178]:

client talks out of turn, then tries some more unauthorized relays.
...

> Oct 19 22:22:29 mail postfix/smtpd[1796]: too many errors after DATA from 
> unknown[61.145.214.178]

postfix hangs up on the bad client.

> 
> 
> Oct 19 22:22:29 mail postfix/smtpd[1796]: disconnect from 
> unknown[61.145.214.178] ehlo=1 mail=10 rcpt=0/10 data=0/10 rset=10 
> commands=21/41

Client tried 10 recipients, 0 were accepted;  all were unauthorized
relay attempts.  After the 10th attempt, postfix disconnected.


Looks as if postfix is working just fine.  Nothing more to do here.



  -- Noel Jones

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