Date: Mon, 11 Jan 2010 14:53:46 +0000 From: Anton Shterenlikht <mexas@bristol.ac.uk> To: Tim Judd <tajudd@gmail.com> Cc: Anton Shterenlikht <mexas@bristol.ac.uk>, David Southwell <david@vizion2000.net>, freebsd-questions@freebsd.org Subject: Re: denying spam hosts ssh access - good idea? Message-ID: <20100111145346.GK61025@mech-cluster241.men.bris.ac.uk> In-Reply-To: <ade45ae91001110618w76abd4cdrf95470712aabefac@mail.gmail.com> References: <20100111140105.GI61025@mech-cluster241.men.bris.ac.uk> <201001111408.43361.david@vizion2000.net> <ade45ae91001110618w76abd4cdrf95470712aabefac@mail.gmail.com>
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On Mon, Jan 11, 2010 at 07:18:04AM -0700, Tim Judd wrote: > On 1/11/10, David Southwell <david@vizion2000.net> wrote: > >> I'm thinking of denying ssh access to host from which > >> I get brute force ssh attacks. > >> > >> HOwever, I see in /etc/hosts.allow: > >> > >> # Wrapping sshd(8) is not normally a good idea, but if you > >> # need to do it, here's how > >> #sshd : .evil.cracker.example.com : deny > >> > >> Why is it not a good idea? > >> > >> Also, apparently in older ssh there was DenyHosts option, > >> but no longer in the current version. > >> Is there a replacement for DenyHOsts? > >> Or is there a good reason for such option not to be used? > >> > >> many thanks > >> anton > >> > > I use denyhosts ( /usr/ports/security/denyhosts ) works well for me. I also > > use blackhole and sshguard > > > > david > > > I've been meaning to check this out. My firewall ssh rules are very > strict, in fact, if the remote IP is "unknown" meaning, I don't know > where the heck it's coming from, it's blocked. It's easier to say it > this way: I allow ssh connections from IPs I know, preferably static > IPs. > > Given that there are more than one general blacklists out there that > list unwanted behavior, and that we have ports that make use of these > lists, I wonder if we can use a list (in this case, for spam) > effective for blocking ssh connections. This means: > install spamd > setup pf (requirement for spamd, it is built by OpenBSD after all) > in the pf rules, block *ANYTHING* coming from the blacklisted IPs > > > I don't know how effective it is, but since the spamd blacklist IPs > are hosted on what seems to be only one server/server farm, I am also > looking for any way I can provide a mirror (even if it's slightly > outdated) of this data. I'm very grateful for all advice, but I'm still unsure why denying ssh access to a particular host via /etc/hosts.allow is a bad idea. many thanks anton -- Anton Shterenlikht Room 2.6, Queen's Building Mech Eng Dept Bristol University University Walk, Bristol BS8 1TR, UK Tel: +44 (0)117 331 5944 Fax: +44 (0)117 929 4423
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