Resolved Logfile entry - connect from unknown

[TomE]

Hello everyone,

since almost two weeks i have the following logfile entries every second

postfix/smtpd[9353]: connect from unknown[xx.xxx.xx.xx]
postfix/smtpd[9353]: disconnect from unknown[xx.xxx.xx.xx] ehlo=1 auth=0/1 rset=0/1 quit=1 commands=2/4
postfix/smtpd[9353]: warning: hostname ip-38-41.ZervDNS does not resolve to address xx.xxx.xx.xx: Name or service not known

To me it looks like someone is trying to connect to my mail server.

Somebody can tell me if it's harmless and if not, how I can stop it?

Many thanks and regards, Tom

 

[IgorG]

Consider using Fail2Ban to protect from brute force attacks.
There is already "plesk-postfix" jail in the Fail2Ban shipped with Plesk.

postfix/smtpd[9353]

Looks like you have Plesk for Linux. Don't know why you post this thread in Plesk for Windows forum section.

 

[TomE]

Hi Igor,

thank you and you're right i posted in the wrong forum. sorry! Can I move the post to obsidian?

Fail2Ban is running an the jail plesk-postfix ist active and also blocks ip addresses but the messages in the log file are just very many and worry me a little.

Thanks, Tom

 

[IgorG]

If it is permanent IP address just block it with firewall rule.

 

[TomE]

ok it is always the same and i have block it

many thanks igor