Date: Fri, 5 Mar 2010 10:19:09 -0500 From: mikel king <mikel.king@olivent.com> To: John <john@starfire.mn.org> Cc: freebsd-questions@freebsd.org, Programmer In Training <pit@joseph-a-nagy-jr.us> Subject: Re: Thousands of ssh probes Message-ID: <F4960422-5F59-4FF4-A2E4-1F0A4772B78B@olivent.com> In-Reply-To: <20100305132604.GC14774@elwood.starfire.mn.org> References: <20100305125446.GA14774@elwood.starfire.mn.org> <4B910139.1080908@joseph-a-nagy-jr.us> <20100305132604.GC14774@elwood.starfire.mn.org>
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On Mar 5, 2010, at 8:26 AM, John wrote: > On Fri, Mar 05, 2010 at 07:03:53AM -0600, Programmer In Training > wrote: >> On 03/05/10 06:54, John wrote: >>> My nightly security logs have thousands upon thousands of ssh probes >>> in them. One day, over 6500. This is enough that I can actually >>> "feel" it in my network performance. Other than changing ssh to >>> a non-standard port - is there a way to deal with these? Every >>> day, they originate from several different IP addresses, so I can't >>> just put in a static firewall rule. Is there a way to get ssh >>> to quit responding to a port or a way to generate a dynamic pf >>> rule in cases like this? >> >> Can you not deny all ssh attempts and then allow only from certain, >> trusted IPs? > > Ah, I should have added that I travel a fair amount, and often > have to get to my systems via hotel WiFi or Aircard, so it's > impossible to predict my originating IP address in advance. If > that were not the case, this would be an excellent suggestion. Way back about 10 years ago, I was playing around with IPFW a lot. I wrote a script to update IPFW from changes made to a MySql db. It was a just for fun project, that turned out to be rather useful I have some developers that I managed who like you were road warriors. They logged in to the https web page w/ their username and password which grabbed their IP address and stored it in a table on with their login id. The script called fud (for firewall update daemon) connected to the db and ran a query to check for any rule changes. If there were it would apply them to the rule set and clear the change flag. Using this combination I was able to allow ssh access only to the necessary ip addresses. I kind of scrapped it when VPNs became easier to deploy and I have no idea where this set of scripts are now, but it would be rather trivial to build a new version. If anyone thinks it's worth revisiting hit me off list. Cheers, Mikel King CEO, Olivent Technologies Senior Editor, BSD News Network Columnist, BSD Magazine 6 Alpine Court, Medford, NY 11763 o: 631.627.3055 c: 631.796.1499 skype:mikel.king http://olivent.com http://www.linkedin.com/in/mikelking http://twitter.com/mikelking
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