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 <[email protected]> Reply-To: <[email protected]> Date: Wednesday, April 22, 2020 at 9:40 AM To: <[email protected]> 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 [email protected]:92.118.38.83 vchkpw-smtps: password fail (pass: 'somepassword') [email protected]: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 <[email protected]> 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 <[email protected]> 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 <[email protected]> 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
