RE: ssh attempts

[Martín Biamonte <martin () vincolo com>]

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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> education and the case study affords you unmatched consulting
experience. 
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> customizations including Emergency Management, Business Continuity
Planning, 
> Computer Emergency Response Teams, and Digital Investigations. 
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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.

http://www.msia.norwich.edu/secfocus
---------------------------------------------------------------------------