Date: Mon, 6 Feb 2006 11:18:16 -0600 From: Noel Jones <noeldude@gmail.com> To: freebsd-questions@freebsd.org Subject: Re: sshd possible breakin attempt messages Message-ID: <cce506b0602060918n2d63e08cq1b23ea4b7e5a602b@mail.gmail.com> In-Reply-To: <20060206162304.GA83056@gilmer.org> References: <20060206162304.GA83056@gilmer.org>
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On 2/6/06, Brad Gilmer <bgilmer@gilmer.org> wrote: > Hello all, > > I guess one of the banes of our existance as Sys Admins is that people ar= e always pounding away at our systems trying to break in. Lately, I have b= een getting hit with several hundred of the messages below per dayin my sec= urity report output... > > gilmer.org login failures: > Feb 5 11:18:17 gilmer sshd[78078]: reverse mapping checking getaddrinfo = for 206-171-37-232.ded.pacbell.net failed - POSSIBLE BREAKIN ATTEMPT! > Feb 5 11:18:18 gilmer sshd[78080]: reverse mapping checking getaddrinfo = for 206-171-37-232.ded.pacbell.net failed - POSSIBLE BREAKIN ATTEMPT! > Feb 5 11:18:20 gilmer sshd[78082]: reverse mapping checking getaddrinfo = for 206-171-37-232.ded.pacbell.net failed - POSSIBLE BREAKIN ATTEMPT! > > I am running FreeBSD 5.4 RELEASE, and right now this box is not a product= ion machine, but I am going to be taking it live fairly soon. Questions: > > 1) Is there anything I should be doing to thwart this particular attack? The POSSIBLE BREAKIN ATTEMPT message is caused by a failed reverse DNS lookup, and will happen with legit logins too if you have no reverse DNS. You can silence this particular message by adding to your /etc/ssh/sshd_config: UseDNS no To prevent attackers from hammering away at your server, try ports/security/bruteforceblocker Bruteforceblocker by default adds an abusive IP to the a pf firewall blacklist, but can be very easily modified for IPFW or adding a null route. > 2) Given that I am on 5.4, should I upgrade my sshd or do anything else = at this point to make sure my machine is as secure as possible? Just keep up with the version 5 security patches. > 3) (Meta-question) - Should I upgrade to 6.0 before I go live to be sure= I am in the best possible security situation going forward? Should I wait= until 6.1 for bug fixes (generally I am opposed to n.0 anything). Your call. Base your decision on what features you need. -- Noel Jones
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