Change the port to something different than port 22. Configure the
firewall to deny any access to another ports,
with this you will "deny" port scanning.
Also if you use pf as packet filter you could use a authpf to open and
close ports on the fly.
BTW, has somebody known some free implementation similar to secureID?.
Slte
Mrtn
-----Original Message-----
From: Matt Alexander [mailto:lowbassman@gmail.com]
Sent: Domingo, 22 de Enero de 2006 02:52 a.m.
To: Robert Bauer
Cc: security-basics@securityfocus.com
Subject: Re: ssh attempts
Another fun addition is port knocking with iptables:
http://www.neep.co.uk/index.php?tab=Projects&menu=Port%20Knocking
Robert Bauer wrote:
Limiting SSH to a particular IP (or set of IP's) isn't always
practical.
As for how & where to do the blocking, besides TCPWrappers, don't
forget the excellent iptables firewall you probably already have on
your system.
Also, consider changing the port SSH listens on. This will stop
nearly all of the scripted attacks. Another valuable technique is to
have your system detect these attacks and dynamically block the source
IP addresses. Scripts for doing this are pretty easy to find on the
net.
Robert Bauer
Snow Enterprises
(336) 623-7772 ext. 307
Leif Ericksen wrote:
Lock down your box a little more... Enable TCPWrappers in the very
least. IF they are able to hit your system like that via SSH it is
obvious that you are not blocking. This is common. My firewall logs
show and have shown attempts to ssh (This is for a personal system)
they get stopped at the firewall because they are not coming from the
correct IP address(es) Incidentally the ones I see hitting my
firewall cam from China, Korea, and Taiwan for the most part, least
wise that is what the IP indicated as long as it was not spoofed.
Before I locked down my firewall to IP I would see the rejects
because of Wrappers.
If the system is on the net LOCK IT DOWN.
--
Leif Ericksen
On Wed, 2006-01-04 at 11:35 +0100, Emilio Casbas wrote:
I´ve noticed that several Linux Machines I have running are getting
scanned via ssh for
multiple accounts such as "guest webmaster mysql info shell apache
test..." and many others,
the log show:
Jan 3 01:31:08 machine sshd2[22087]: WARNING: DNS lookup failed for
"X.X.X.233".
Jan 3 01:31:10 machine sshd2[22087]: password authentication
failed.
Login to account webmaster not allowed or account non-existent.
Jan 3 01:31:13 machine sshd2[21757]: LoginGraceTime exceeded.
as well there are attempts to connect with root login, with the log
message show as:
WARNING: DNS lookup failed for "X.X.X.233".
Jan 3 01:17:53 machine sshd2[21651]: root login denied for user
'root'.
Obviously, We don´t have accounts with that name on our systems, and
the
root account
is disabled for ssh, but I would like to know which software can do
this
scan type, because
while it's running, the machine proccesses grow too much.
Thanks.
Emilio C.
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EARN A MASTER OF SCIENCE IN INFORMATION ASSURANCE - ONLINE
The Norwich University program offers unparalleled Infosec management
education and the case study affords you unmatched consulting experience.
Tailor your education to your own professional goals with degree
customizations including Emergency Management, Business Continuity Planning,
Computer Emergency Response Teams, and Digital Investigations.
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