nanog mailing list archives

Re: Dealing with abuse complaints to non-existent contacts


From: Christopher Rogers <phiber () phiber org>
Date: Sun, 10 Aug 2014 10:20:15 -0700

http://www.fail2ban.org/




2014-08-10 10:18 GMT-07:00 Jon Lewis <jlewis () lewis org>:

On Sun, 10 Aug 2014, Gabriel Marais wrote:

 I have been receiving some major ssh brute-force attacks coming from
random
hosts in the 116.8.0.0 - 116.11.255.255 network. I have sent a complaint
to
the e-mail addresses obtained from a whois query on one of the IP
Addresses.

My e-mail bounced back from both recipients. Once being rejected by filter
and the other because the e-mail address doesn't exist. I would have
thought that contact details are rather important to be up to date, or
not?


Why?


 Besides just blocking the IP range on my firewall, I was wondering what
others would do in this case?


I've been blocking SSH from random IPs for many years.  Unless you have to
run an open system that customers SSH into (unlikely in these times), my
recommendation is block SSH entirely from non-trusted networks and setup
some form of port-knocking or similar access controls such that legitimate
users can open a window to make their connection, but the rest of the world
never sees your sshd.

Playing whack-a-mole with firewall or access log violations is a waste of
time.

----------------------------------------------------------------------
 Jon Lewis, MCP :)           |  I route
                             |  therefore you are
_________ http://www.lewis.org/~jlewis/pgp for PGP public key_________



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