David,

 

You might try the suggestions here: 
https://www.taverner-rich.com/mitigating-brute-force-attacks/

 

I put them in place on my server and it definitely helped.

 

Jaime

 

From: Eric Broch <ebr...@whitehorsetc.com>
Reply-To: <qmailtoaster-list@qmailtoaster.com>
Date: Wednesday, April 22, 2020 at 9:40 AM
To: <qmailtoaster-list@qmailtoaster.com>
Subject: Re: [qmailtoaster] SMTPS Port - Who is Failing ?

 

Hi David,

I think you're on to something with fail2ban (keying off maillog). I was 
monitoring my smtps port (watching the certificate and encryption scroll by) 
using /usr/bin/recordio and /var/log/maillog and found that the bad guys are 
trying to login. Here are some failures from maillog:

vchkpw-smtps: vpopmail user not found testforu...@whitehorsetc.com:92.118.38.83

vchkpw-smtps: password fail (pass: 'somepassword') 
someu...@whitehorsetc.com:185.50.149.2

Maybe a fail2ban rule?!

Eric

 

On 4/18/2020 4:12 AM, David Bray wrote:

Hi thanks - yes can block that IP

But it’s not just one, and the solution is not fine enough

I want more of a fail2ban rule, bad use bad pass 3 strikes your out

 

I need to know they are mucking round.

 

I tried sending myself through the port with a bad password- sure it blocks it, 
but there is no log of the event - it looks like a legit, connection from Ann IP

 

On Sat, 18 Apr 2020 at 7:30 pm, Chris <boh...@gmail.com> wrote:

Here's a great article with instructions on how to implement an IP blacklist in 
iptables. Unless you've got a user in Panama, it looks like you's want to block 
141.98.80.30 


https://linux-audit.com/blocking-ip-addresses-in-linux-with-iptables/

 

On Sat, Apr 18, 2020 at 5:49 PM David Bray <da...@brayworth.com.au> wrote:

sure - thanks for replying, this comes in waves taking the server to it's 
maximum at times 

 

as far as I can see this only logs are this:

 

==> /var/log/qmail/smtps/current <==
2020-04-18 05:04:48.450871500 tcpserver: status: 6/60
2020-04-18 05:04:48.480785500 tcpserver: pid 13339 from 141.98.80.30
2020-04-18 05:04:48.480787500 tcpserver: ok 13339 
dev.brayworth.com:172.105.181.18:465 :141.98.80.30::25638
2020-04-18 05:04:52.797644500 tcpserver: status: 7/60
2020-04-18 05:04:52.830767500 tcpserver: pid 13340 from 141.98.80.30
2020-04-18 05:04:52.830768500 tcpserver: ok 13340 
dev.brayworth.com:172.105.181.18:465 :141.98.80.30::14862
2020-04-18 05:04:57.248902500 tcpserver: status: 8/60
2020-04-18 05:04:57.304003500 tcpserver: pid 13342 from 141.98.80.30
2020-04-18 05:04:57.304006500 tcpserver: ok 13342 
dev.brayworth.com:172.105.181.18:465 :141.98.80.30::9646
2020-04-18 05:05:01.854790500 tcpserver: status: 9/60
2020-04-18 05:05:01.902265500 tcpserver: pid 13345 from 141.98.80.30
2020-04-18 05:05:01.902266500 tcpserver: ok 13345 
dev.brayworth.com:172.105.181.18:465 :141.98.80.30::54058
2020-04-18 05:05:09.729711500 tcpserver: end 13338 status 256
2020-04-18 05:05:09.729713500 tcpserver: status: 8/60
2020-04-18 05:06:05.965715500 tcpserver: end 13342 status 256
2020-04-18 05:06:05.965716500 tcpserver: status: 7/60
2020-04-18 05:06:06.141272500 tcpserver: end 13340 status 256
2020-04-18 05:06:06.141273500 tcpserver: status: 6/60


David Bray

0418 745334
2 ∞ & <

 

 

On Sat, 18 Apr 2020 at 15:41, Eric Broch <ebr...@whitehorsetc.com> wrote:

Can you send the log of one of the "bad" connections?

On 4/17/2020 10:59 PM, David Bray wrote:

I can see I'm getting hammered on my smtps port 

 

How can I mitigate this?

 

I can see the IP's in /var/log/qmail/smtps/current

 

but where do I actually see that the smtp auth actually fails ?

 

or do I need to increase the logging somewhere ?

 

if I tail -f /var/log/dovecot.log

 

I can see the imap and pop failures

 

thanks in advance


David Bray

0418 745334
2 ∞ & <

-- 

# David

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