Hey Tobi
Not seeing what you are seeing, but I can really recommend Fail2Ban if you are not using it already.
It's as simple as:
*** snip 8< ***
# Install fail2ban
apt install fail2ban
# Set log level to VERBOSE in sshd daemon to catch failed logins for existing accounts as well
cat >> /etc/ssh/sshd_config <<EOF
LogLevel VERBOSE
EOF
systemctl restart sshd
*** >8 snap ***
Failed attempts will now be logged and source IPs will be banned after several failed attempts.
Cheers,
Manuel
--
Manuel Schweizer
cloudscale.ch AG
Venusstrasse 29
CH-8050 Zürich
Fon: +41 44 55 222 55
Fax: +41 44 55 222 56
Web:
https://www.cloudscale.ch
> On 2 Jul 2018, at 11:42, Jeroen Massar
jeroen@massar.ch wrote:
>
> On 2018-07-02 11:25, Tobias Oetiker wrote:
>> Good Morning
>>
>> are you running an ssh daemon on non standard ports to avoid some of the
>> drive-by-scanning ? we have been doing that for quite some time now with
>> great reduction of scanning noise ...
>
> I suggest running SSH always behind white-list only firewalls.
>
> That, and otherwise use a VPN to get in to a fixed-IP so that one is in
> the whitelist.
>
> Providing an 'open over IPv6 only', or "SSH via Tor" is also a
> reasonable technique there.
>
>
> If you have to run a jumpbox style host: For SSH, it is also heavily
> suggested to disable any form of password-auth, that way, only public
> key authentication is accepted and guess what the scanner scripts do not
> support as they do not have a key which thus makes guessing impossible...
>
> for OpenSSH:
> UsePAM no
> PasswordAuthentication no
> ChallengeResponseAuthentication no
>
> Do have working pubkeys on the box first :)
>
>
>> since yesterday this has changed
>> ... we are getting a lot of connection attempts ...
>>
>> are you seeing this too ? is someone actively looking for ssh across the
>> whole port range or is this 'personal' ?
>
> There are more and more "Internet scanning" services, especially since
> people realized the amount of data that Shodan shows, every company is
> having their own scanning boxes.
>
> Next to that of course, there are thousands of kiddies running the
> default scripts just trying random username/passwords.
>
> Whitelisting is the best trick in the toolchest.
>
> Greets,
> Jeroen
>
>
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