Date: Fri, 24 Sep 2004 23:49:09 +0200 From: Alex de Kruijff <freebsd@akruijff.dds.nl> To: "David D.W. Downey" <david.downey@gmail.com> Cc: "freebsd-security@FreeBSD.ORG" <freebsd-security@freebsd.org> Subject: Re: Attacks on ssh port Message-ID: <20040924214909.GA784@alex.lan> In-Reply-To: <6917b781040918103077c76f0c@mail.gmail.com> References: <414C2798.7060509@withagen.nl> <6917b781040918103077c76f0c@mail.gmail.com>
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On Sat, Sep 18, 2004 at 01:30:22PM -0400, David D.W. Downey wrote: > On Sat, 18 Sep 2004 14:18:32 +0200, Willem Jan Withagen <wjw@withagen.nl> wrote: > > Hi, > > > > Is there a security problem with ssh that I've missed??? > > Ik keep getting these hords of: > > Failed password for root from 69.242.5.195 port 39239 ssh2 > > with all kinds of different source addresses. > > > > They have a shot or 15 and then they are of again, but a little later on > > they're back and keep clogging my logs. > > Is there a "easy" way of getting these ip-numbers added to the > > blocking-list of ipfw?? > > > > Thanx, > > --WjW > > well you want to see those. So long as you have > > PermitRootLogin no > > in your /etc/ssh/sshd_config, they won't be able to get in since ssh > is then denied for root (except via a valid ssh key which you can > further lock down by adding No ssh key's are also denied. To enable this you have to set PermitRootLogin to 'without-password' or 'forced-commands-only' (or yes). > from="ip.addr, forward.dns.record.of.host" > > to the beginning of your ssh-dsa or ssh-rsa key line in ~/.ssh/authorized_keys) > > A better solution to the verbosity level would probably be to change > your kernel config to have something like > > options IPFIREWALL_VERBOSE_LIMIT=3 > > or using the sysctl.conf oid > > net.inet.ip.fw.verbose_limit=3 > > Then you can still see the attempts (and thus log the IP information > for contacting the abuse@ for the responsible IP controller) while > limiting your log sizes. This only logs the first tree catches (when the log attribuut is set) per rule. You may want to set this a little higher like 100. -- Alex Articles based on solutions that I use: http://www.kruijff.org/alex/FreeBSD/
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