Dealing with abuse complaints to non-existent contacts

Jon Lewis jlewis at
Sun Aug 10 17:18:08 UTC 2014

On Sun, 10 Aug 2014, Gabriel Marais wrote:

> I have been receiving some major ssh brute-force attacks coming from random
> hosts in the - 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?


> 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 

  Jon Lewis, MCP :)           |  I route
                              |  therefore you are
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