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Network Security Incidents
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Re: Internet SSH scans

Subject: Re: Internet SSH scans
Date: Mon, 06 Mar 2006 20:09:02 -0300
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Hello Alexandre,

        I also had that problem. I decided not to change the port number, and
to live with the log noise, but to increase security I decided to deny
root access via ssh, and to Allow access to users that really require
ssh access (in my network there are more than 300 users, but only 5 need
ssh access, one of them is me). This reduces the possibility of a
successful brute force attack. Just add these lines in the sshd_config file:

PermitRootLogin no
AllowUsers <xx> <yy> <zz>

        where <xx>, <yy> and <zz> are the users that REALLY require ssh access,
after checking they do not have a weak user name (like 'john' or 'mary')
and/or a weak password.

Alexandre H wrote:
Hi,

I've witnessed what I think is an increase in SSH scans over the
Internet in the past four or five weeks. The scan seems to originate
from various countries around the globe which makes me think of it to be
a worm-like spreading virus searching for vulnerable systems running the
SSH service. I confirmed the attack with a friend of mine who also
happens to run a SSH server at home. We both live in Montreal, QC,
Canada and are using the same ISP.
.
.
.
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