Date: Wed, 6 Apr 2005 15:58:55 +0200 From: Emanuel Strobl <emanuel.strobl@gmx.net> To: freebsd-questions@freebsd.org Cc: "Edwin D. Vinas" <xmisoy@gmail.com> Subject: Re: too many illegal connection attempts through ssh Message-ID: <200504061559.04397@harrymail> In-Reply-To: <4253B4CE.6070504@locolomo.org> References: <36f5bbba050406001514562df7@mail.gmail.com> <4253B4CE.6070504@locolomo.org>
next in thread | previous in thread | raw e-mail | index | archive | help
--nextPart4336981.YMkWjLiIfv Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Am Mittwoch, 6. April 2005 12:07 schrieb Erik N=F8rgaard: > Edwin D. Vinas wrote: > > shown below is snapshot of too many illegal attempts to login to my > > server from a suspicious hacker. this is taken from the > > "/var/log/auth.log". my question is, how do i automatically block an > > IP address if it is attempting to guess my login usernames? can i > > configure the firewall to check the instances a certain IP has > > attempted to access/ssh the sevrer, and if it has failed to login for > > about "x" number of attempts, it will be blocked automatically? > > This question is asked on the list ever so often - see the archives for > suggestions. These are automated attacks, they come regularly as > crackers, black hats or script kidies scan across the net. Does anybody know what robots beeing used? And on what systems? All you=20 mention later in your posting is true of course and I needn't care about=20 these logs, but it's like like somebody unknown puts 10 flyers in your=20 letterbox every night. I'm sure, one night you'll hide and build a trap for= =20 that person. I'm too lazy to enter those net-circles for finding these=20 robots, but maybe some other has already done that? =2DHarry > > You can avoid the automated scanning by chaning port, but this won't > stop the determined cracker - he will scan all your ports and identify > which services are running on which ports. > > Ask yourself a few questions: > > * Do you need to allow ssh from anywhere? If not, restrict to the > relevant ip blocks. > > * Do you need to allow password based authentication? If not, disable it > and use only ssh keys, in sshd_config: > > PasswordAuthentication no > PubkeyAuthentication yes > > * Do all users need to have ssh access? If not, restrict to specific > groups of users, in sshd_config, eg: > > AllowGroups staff > > * Is it a problem appart from the log messages? Trying to login with a > nonexistent username is usually not a problem. > > Other tips: Disable ssh1, reduce the number of simultaneous non-authen- > ticated connections, set timeouts etc. > > Cheers, Erik --nextPart4336981.YMkWjLiIfv Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (FreeBSD) iD8DBQBCU+soBylq0S4AzzwRAi4FAJ0aUw/EhRjY1g0mJpQMqfUg4aV9mgCfTc0Z 22S2qUrgjlyCDKSAzFMJBbs= =NyNb -----END PGP SIGNATURE----- --nextPart4336981.YMkWjLiIfv--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200504061559.04397>