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[ale] ssh brute-force
The reason why changing the port drops hits to near zero even if someone is doing a port scan is that the port scan doesn't tell them the port is ssh - just that it is open. Of course doing a telnet to an open port might reveal that..
The fail2ban idea is a good one. So is using the high number but you CAN do nmap for high numbers - most people just don't. Security is all about hardening so the bad guys move on to easier targets. Nothing is really going to stop the determined folks specifically targeting you but it will keep out most of the hit and run types and script kiddies.
From: ale-bounces at ale.org [mailto:ale-bounces at ale.org] On Behalf Of Chuck Payne
Sent: Sunday, February 16, 2014 5:23 PM
To: Atlanta Linux Enthusiasts
Subject: Re: [ale] ssh brute-force
At one of my jobs they used ssh keys and move the port to 20000 something, at first I wonder why, but now it makes a lot of sense.
Specially the keys. If you are going to leave it on port 22, set yourself up with ssh-keys and anyone less that use it. You turn off password in ssh were it will only use the keys.
On Sun, Feb 16, 2014 at 4:34 PM, Wolf Halton <wolf.halton at gmail.com> wrote:
> Unless you are being specifically, there are about 60,000 ports that
> aren't scanned by tools in default mode. High numbers without
> registered services will get almost zero hits.
> On Feb 16, 2014 3:45 PM, "John Heim" <john at johnheim.com> wrote:
>> My experience is that changing the port reduces the random attempts
>> to near zero. But if someone specifically targets you, it doesn't help.
>> Hackersprobably aren't doing port scans of your server. They are
>> probably scanning your network for machines with port 22 open.
>> On 02/16/14 13:20, Edward Holcroft wrote:
>>> I have a server that I had to open to the world for ssh. It's
>>> getting a lot of brute-force hits, although I've managed to bring it
>>> down to an "acceptable" level by using a suitable level of paranoia in denyhosts.
>>> Obviously I'd rather not have these hits at all.
>>> I often hear the suggestion made that I should be using a
>>> non-standard port for ssh to reduce such attacks. I wonder though
>>> what the real value of this would be, since would a portscan not
>>> reveal the open port to would-be hackers anyway?
>>> I've heard it said that unwanted ssh hits have been reduced to zero
>>> by changing the port from 22 to something else. Of course I can test
>>> the hypothesis by simply changing the port, but I'd like to hear
>>> some opinions on this question before doing so.
>>> Edward Holcroft | Madsen Kneppers & Associates Inc.
>>> 11695 Johns Creek Parkway, Suite 250 | Johns Creek, GA 30097 O (770)
>>> 446-9606 | M (770) 630-0949
>>> MADSEN, KNEPPERS & ASSOCIATES USA, MKA Canada Inc.
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